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Chen, Yupei. "Classification of Atypical Femur Fracture with Deep Neural Networks." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-255677.
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Atypical Femur Fracture(AFF) is a type of stress fracture that occurs in conjunction with prolonged bisphosphonate treatment. In practice, AFF is very rarely identified from Normal Femur Fracture(NFF) correctly on the first diagnostic X-ray examination. This project aims at developing an algorithm based on deep neural networks to assist clinicians with the diagnosis of atypical femurfracture. Two diagnostic pipelines were constructed using the Convolutional Neural Network (CNN) as the core classifier. One is a fully automatic pipeline, where the X-rays image is directly input into the network with only standardized pre-processing steps. Another interactive pipeline requires the user to re-orient the femur bones above the fractures to a vertical position and move the fracture line to the image center, before the repositioned image is sent to the CNNs. Three most popular CNNs architectures, namely VGG19, InceptionV3 and ResNet50,were tested for classifying the images to either AFF or NFF. Transfer learning technique was used to pre-train these networks using images form ImageNet. The diagnosis accuracy was evaluated using 5-fold cross-validation. With the fully automatic diagnosis pipeline, we achieved diagnosis accuracy of 82.7%, 89.4%, 90.5%, with VGG19, InceptionV3 and ResNet50, respectively. With the interactive diagnostic pipeline, the diagnosis accuracy was improved to 92.2%, 93.4% and 94.4%, respectively. To further validate the results, class activation mapping is used for indicating the discriminative image regions that the neural networks learn to identify a certain class.
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Arnault, Nicolas Vincent. "Essai de classification therapeutique en traumatologie mandibulaire." Paris 7, 1988. http://www.theses.fr/1988PA071129.
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Frankl, Joseph, Michael P. Sakata, Gagandeep Choudhary, Seung Hur, Andrew Peterson, and Charles T. Hennemeyer. "A Classification System for the Spread of Polymethyl Methacrylate in Vertebral Bodies Treated with Vertebral Augmentation." GRAPHO PUBLICATIONS, 2016. http://hdl.handle.net/10150/623034.
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In this study, we develop a classification system for describing polymethyl methacrylate (PMMA) spread in vertebral bodies after kyphoplasty or vertebroplasty for vertebral compression fractures (VCFs) and for assessing whether PMMA spread varies between operators, VCF etiology, or vertebral level. Intraoperative fluoroscopic images of 198 vertebral levels were reviewed in 137 patients (women, 84; men, 53; mean age, 75.8 +/- 12.5; and those with a diagnosis of osteoporosis, 63%) treated with kyphoplasty between January 01, 2015 and May 31, 2015 at a single center to create a 5-class descriptive system. PMMA spread patterns in the same images were then classified by 2 board-certified radiologists, and a third board-certified radiologist resolved conflicts. A total of 2 primary PMMA spread patterns were identified, namely, acinar and globular, with subtypes of localized acinar, diffuse globular, and mixed, to describe an equal combination of patterns. Interrater reliability using the system was moderate (kappa = 0.47). After resolving conflicts, the most common spread class was globular (n = 63), followed by mixed (n = 58), diffuse globular (n = 30), acinar (n = 27), and localized acinar (n = 20). The spread class after treatment by the 2 most frequent operators differed significantly (n(1) = 63, n(2) = 70; P <.0001). There was no difference in the spread class between VCF etiologies or vertebral levels. PMMA spread may, therefore, be a modifiable parameter that affects kyphoplasty and vertebroplasty efficacy and adverse events.
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Saarenpää, I. (Ismo). "Extracapsular hip fractures—aspects of intramedullary and extramedullary fixation." Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514289347.
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Abstract
The purposes of the present research were (1) to analyse and characterize the hip fractures treated at Oulu University Hospital during a one-year period using the special forms of the Standardized Audit of Hip Fractures in Europe (SAHFE) and to evaluate their value for quality control, (2) to compare gamma nail (GN) and dynamic hip screw (DHS) fixation for the treatment of trochanteric hip fractures, focusing especially on the functional aspects, (3) to compare the short-term outcome of gamma nail (GN) and dynamic hip screw (DHS) fixation for the treatment of subtrochanteric hip fractures, and (4) to examine the rate and reliability of the classification of basicervical hip fractures and the outcome of the operative methods used for their treatment.
Oulu University Hospital joined the Swedish Hip Fracture Project (Rikshöft), aimed at developing the quality control of hip fracture treatment, in 1989, and this later evolved into a project called the Standardized Audit of Hip Fractures in Europe (SAHFE), funded by the European Commission. Registration of hip fractures on the SAHFE forms was common practise in Oulu from 1st September 1997 until the end of December 2003. SAHFE data collection forms were used in all four studies belonging to this thesis.
There were 238 hip fracture patients during the one-year period of registration at Oulu University Hospital. The intracapsular / extracapsular fracture rate (60/40) and the female/male rate (80/20) seemed to be similar to those reported in the recent Finnish Health Care Register data. The most frequent method for treating cervical fractures was Austin-Moore hemiarthroplasty (68%) and that for trochanteric and subtrochanteric fractures GN fixation (86%). The SAHFE forms proved to be easy to use and practicable for evaluating the quality of hip fracture treatment.
In a matched-pair study the short-term outcomes of the treatment of trochanteric fractures (after 4 months) were slightly better in the DHS group than in the GN group with respect to walking ability and mortality. The difference in mortality was at least partly due to the higher number of complications requiring re-operations associated with GN fixation.
In the treatment of subtrochanteric hip fractures, there were four intraoperative complications (9.3%) in the GN group but none in the DHS group. On the other hand, postoperative complications were more common in the DHS group (20% vs. 2%). It is significant that all these complications in the DHS group occurred in Seinsheimer type IIIA fractures. It is concluded that, despite the perioperative problems associated with gamma nailing, this technique may be preferable to DHS fixation for specific fracture types with medial cortical comminutation, such as Seinsheimer type IIIA.
Altogether 108 of the 1624 hip fractures were initially classified by the surgeons as basicervical fractures, but after a careful second look only 30 fulfilled all the criteria. The definitive rate of basicervical fractures was thus 1.8%. Treatment of basicervical fractures as trochanteric fractures proved superior to their treatment as cervical fractures, resulting in lower re-operation rates.
In conclusions; this thesis suggests that SAHFE forms are very useful for evaluating the quality of hip fracture treatment. Both GN fixation and DHS fixation are effective methods for the treatment of trochanteric hip fractures in elderly patients; in less comminuted fractures, the DHS method is the preferred method of treatment whereas GN fixation is alternative treatment for more comminuted fractures. GN fixation is preferable for the subtrochanteric fratures. Basicervical fractures shoud be regarded clinically as extracapsular fractures and managed in a similar manner to trochanteric fractures.
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SCHILLIO, VALERIE. "La classification simplifiee des fractures : son utilite dans l'informatisation du dossier medical en chirurgie orthopedique et traumatologique." Nice, 1993. http://www.theses.fr/1993NICE6003.
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PRADINES, MICHEL. "Les ruptures de l'urethre feminin au cours des fractures de l'anneau pelvien : a propos de deux observations nouvelles ; essai de classification des mecanismes." Besançon, 1992. http://www.theses.fr/1992BESA3044.
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Pickett, Alexandra. "Distal Radius Fracture : – Treatment, Complications, and Risk Factors for Re-operation." Thesis, Örebro universitet, Institutionen för medicinska vetenskaper, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-86255.
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Introduction: Distal radius fractures (DRF’s) are one of the most common types of fractures,especially in elderly women. In the last decade, there has been a shift in the treatment methodemployed for DRF’s from the traditional non-operative to an operative method using plates andscrews even though there is no evidence to suggest that this method has superior outcomes. Aim: The primary objective of this study was to identify risk factors for complications and reoperationsin the treatment of DRF’s. Method: The study was designed as a retrospective cohort study. Patients treated for DRF’sbetween 2016-2017 were included through the Swedish Fracture Register and complementedwith the patients’ charts and classification of X-Ray Images from The Orthopedic Clinic at TheCentral Hospital in Karlstad. The risk for re-operation was valued through treatment methodsand fracture classification and presented as Odds Ratio. Result: Positive ulnar variance was correlated to having an increased risk for re-operation, OR4.8 (95% CI 1.7-13.8). Those who had volar comminution in their fracture had a greater risk forre-operation, OR 12.4 (95% CI 4.6-34.1, p<0.001), but also a greater risk for correctiveosteotomy, OR 12.6 (95% CI 1.4-113.9, p=0.024). Conclusion: Volar comminution and positive ulnar variance are associated with an increasedrisk for re-operation. However, the degree of the risk is difficult to measure due to the lowincidence of re-operations.
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Castiglia, Marcello Teixeira. "Complementação tomográfica da classificação de Schatzker para as fraturas do planalto tibial." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/17/17142/tde-23042018-171943/.
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As fraturas do planalto tibial são lesões com um espectro muito variado de manifestação clínica. Diversos sistemas de classificação foram desenvolvidos para facilitar a compreensão e a tomada de decisões no tratamento dessas lesões. O presente estudo teve como objetivo primário avaliar o impacto da tomografia computadorizada na concordância inter e intraobservador da classificação de Schatzker. Além disso, procurou-se avaliar o impacto da tomografia computadorizada na tomada de decisões a respeito da via de acesso cirúrgico ao planalto tibial, utilizando para esta análise a classificação de Schatzker modificada por Kfuri. Um banco de dados com imagens de 70 pacientes, incluindo radiografias, tomografia computadorizada e reconstruções tridimensionais computadorizadas foi oferecido a um grupo de 10 observadores para análise. Como resultados, observou-se que a classificação de Schatzker apresentou coeficiente de concordância moderado, quando baseado no uso de radiografias (k=0,58), e substancial quando esta análise foi complementada por tomografia (k=0,62/0,64). A nova classificação de Schatzker modificada por Kfuri obteve nível moderado de concordância interobservador (k=0,53) e substancial intraobservador (k=0,63). A tomografia computadorizada, elemento básico da nova classificação, influenciou decisivamente os cirurgiões a mudarem a opção pela via de acesso cirúrgico, especialmente em fraturas com orientação no plano coronal. Como conclusão, verificou-se que a classificação de Schatzker modificada por Kfuri demonstrou substancial índice de concordância intraobservador e moderado índice de concordância intraobservador, e devem ser úteis para a prática clínica.Tibial plateau fractures are lesions with a varied spectrum of clinical presentation. Several classification systems have been developed to facilitate the understanding and decision making in the treatment of these injuries. The present study aimed to evaluate the impact of computerized tomography on the inter and intraobserver correlation of the Schatzker classification. In addition, we sought to evaluate the impact of the computed tomography in the decision making regarding the surgical approaches to the tibial plateau, using the Schatzker classification modified by Kfuri for this analysis. A database of 70 patient images, including radiographs, computerized tomography, and computerized three-dimensional reconstructions were offered to a group of 10 observers for analysis. As a result we observed that the Schatzker classification presents a moderate agreement when based on radiographs (k=0,58) and substantial when this analysis is complemented by tomography (k=0,62/0,64). The new Schatzker classification modified by Kfuri has a moderate level of interobserver agreement (k=0,53) and substantial intraobserver agreement (k=0,63). Computerized tomography, a basic element of the new classification, decisively influenced surgeons to change the option for surgical access, especially in fractures with orientation in the coronal plane. In conclusion, the Schatzker classification modified by Kfuri have a substantial intraobserver and moderate interobserver correlation, and should be useful for clinical practice.
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Wadsten, Mats. "Distal Radius Fractures : aspects on radiological and clinical outcome and evaluation of a new classification system." Doctoral thesis, Umeå universitet, Institutionen för kirurgisk och perioperativ vetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-118544.
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Distal radius fracture (DRF) is the most common fracture encountered in clinical practice. Every year, more than 20000 people in Sweden suffer from this injury. It has been shown that there is a correlation between malalignment and function following distal radial fractures and malunion may cause persistent pain and disability. A problem has been in making a correct initial assessment of the fracture. Many fractures are unstable despite an acceptable position on the initial radiographic examination or following a successful closed fracture reduction. Numerous classification systems have been developed for evaluation of DRF in order to predict the outcome. However, the values of these are limited since they have not shown satisfactory reliability. Furthermore, the utility of these systems to predict radiographic or clinical outcome is not yet proven. These shortcomings may be one reason why optimal DRF management is still controversial. Requests for a new classification system of DRF, predictive of outcome and easy to use, have been made. Improvement in initial assessment of DRF will benefit a large group of patients, as well as the society, by reducing persistent symptoms and disability. Study I: In this study we evaluated the interobserver and intraobserver reliability of a new classification system (the Buttazzoni classification). Two hundred and thirty-two patients with acute DRF were blindly evaluated using the new classification by three orthopaedic surgeons twice with a 1-year interval. The new classification showed fair to substantial interobserver and intraobserver reliability, i.e., results comparable with other commonly used classification systems. Study II: This was a prospective multicenter study of fracture stability in 428 DRF. The study investigated whether cortical comminution and intra-articular involvement, as well as the new classification system, could predict displacement in DRF. Logistic regression analysis showed that initial position of the fracture and volar or dorsal comminution predicted later displacement, while intra-articular involvement did not. Volar comminution was the strongest predictor of displacement. The new classification system, which is the first to include volar comminution as a separate parameter, was highly predictive of fracture instability. Furthermore we found that it is quite common for non-operatively treated fractures to displace at a later stage than two weeks. Study IV: In study II it was found that late displacement of DRF, still in acceptable radiologic position after 10-14 days, occurred in approximately 1/3 of cases. Despite this, we have not been able to find any study focusing on evaluating the clinical outcome in patients with late displacement. Two hundred and nine unilateral DRF from study II were still in good position after 10-14 days and were included in the study. One hundred and seventy five patients had radiographs taken at a minimum of 3 months and a clinical examination 1 year after the fracture. Late displaced distal radius fractures had significantly higher loss of ROM and grip strength compared to fractures that didn’t displace. No significant differences were seen in subjective outcome. In conclusion, initial position of the fracture predicted later displacement and was the most important parameter in predicting clinical outcome. Comminution of the fracture also affected radiological stability and clinical outcome. Volar comminuted fractures are highly unstable and need surgical intervention if displacement is to be avoided. Intra-articular involvement affected clinical outcome. Late displacement is common in DRF and may result in loss of range of motion and grip strength. To detect late displacement, DRF should be followed for more than 2 weeks. The new classification system had a moderate reliability and reproducibility. The classification was found predictive of radiologic and objective clinical outcome. However, it was not predictive of subjective outcome. The classification system was also predictive of fractures at risk for late displacement.
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Ahrberg, Annette B., and Johannes K. M. Fakler. "Missed foot fractures in polytrauma patients." Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-137137.
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BACKGROUND: Missed foot fractures are a known problem in the care of the traumatized patient. They do not usually have an influence on the survival, but on the long-term result and the quality of the patient's life. The aim of this study is to find out how many of these fractures are overlooked in a Level I trauma center and what the consequences for the patients are hypothesing that patients with a delayed diagnosis will have worse clinical results. METHODS: Forty-seven patients (7.3%) with foot fractures could be identified in 642 polytrauma patients, retrospectively. All patients were divided into two groups: early diagnosed fractures and delayed diagnosed fractures, the latter defined as diagnosed after Secondary Survey. Patients were evaluated according to the Hannover Outcome Score, the Short Form-36 Health Survey, the AOFAS Score and the Hannover Scoring System. The average follow-up was 5 years and 8 months. Reasons for overlooking a foot fracture were analyzed. RESULTS: The foot fracture was early diagnosed in 26 (55.3%) patients, but delayed in 21 (44.7%). There were no significant differences in the mean stay in the hospital or in the ICU. The fractures that were most often missed were those of the cuboid or the metarsalia. The highest risk factor for a delayed diagnosis was a fracture already diagnosed on the same foot. In 52.4% of the delayed diagosed fractures, an operative therapy was necessary. There were no significant differences between the two groups in the clinical results. CONCLUSIONS:
In summary, the results of this study show that foot injuries can be a safety problem for the patient and the examination of the feet in the trauma room has to be a compulsory part of the algorithm. Although the majority of delayed diagnosed foot fractures demonstrated comparable results to the immediately diagnosed fractures, approximately 10% might have benefited from an earlier diagnosis. Even if there were no significant differences in the clinical results, we have to be aware that missing a fracture in the foot can lead to worse results in the complete polytrauma care.
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Euchler, Eric, Radek Stocek, Michael Gehde, Jörg-Michael Bunzel, Wolfgang Saal, and Reinhold Kipscholl. "Fracture behavior of rubber powder modified rubber blends applied for conveying belt top covers." Technische Universität Chemnitz, 2014. https://monarch.qucosa.de/id/qucosa%3A20409.
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The aim of this study is concentrated on the experimental investigation of wear resistance of rubber powder modified rubber blends. Styrene-Butadiene-Rubber (SBR) blends applied for conveying belt top covers have been modified by ground rubber (rubber powder) based on SBR. We theoretically described the rubber wear mechanism due to loading conditions occurring at conveyor belts in the field, to simulate wear behavior of top cover rubber materials. An own developed testing equipment based on gravimetric determination of mass loss of rubber test specimen was used investigating dynamic wear with respect to fracture properties of top cover materials. Furthermore we investigated fatigue crack growth (FCG) data over a broad range of tearing energy by Tear Analyzer to characterize crack propagation behavior of rubber powder modified rubber blends. Thus, we demonstrate the influence of rubber powder on resistance against occurrence of fracture as well as dynamic wear as a function of the rubber powder content in rubber blends applied for conveying belt top covers.
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Reiche, geb Höde Nora. "Frühe postoperative Vollbelastung nach Sprunggelenksfraktur." Doctoral thesis, Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-189639.
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Frühe postoperative Vollbelastung nach Sprunggelenksfrakturen
Höde N, Ahrberg A, Josten C
Fragestellung:
Laut Leitlinien der DGU soll es nach einer operativ versorgten Sprunggelenksfraktur zur Frühmobilisation kommen. In Literatur und Lehrbüchern wird jedoch häufig eine p.o. Ruhigstellung im Gips oder Cast bis zu 6 Wochen empfohlen.
Bei den eigenen Patienten erfolgt nach Versorgung einer Malleolarfraktur (AO 44 B oder C) ab dem 1. p.o. Tag eine schmerzorientierte Vollbelastung mit AirCast®-Schiene. Kommt es unter dieser frühen Vollbelastung zu einer erhöhten Komplikationsrate wie Materialversagen? Oder überwiegen die Vorteile durch das Vermeiden immobilisationsbedingter Komplikationen wie Thrombosen?
Methodik
Im Rahmen einer retrospektiven Studie wurden 82 Patienten (w:m = 47:35, 20-84 Jahre, Median 51 Jahre) eingeschlossen. Der Nachuntersuchungszeitraum betrug 5 - 68 Monate (Median 34,5 Monate). Nach der AO-Klassifikation lagen 46 (56,1%) B1-Frakturen, 15 (18,3%) B2-Frakturen, 12 (14,6%) B3-Frakturen und 9 (11%) C-Frakturen vor. Ausschlusskriterien waren Einschränkungen der aktiven Mobilisation durch Vorerkrankungen oder weitere Verletzungen sowie die Versorgung mit einer Stellschraube. Die Patienten wurden klinisch anhand des AOFAS-Scores nachuntersucht, es erfolgte eine radiologische Kontrolle und die Erfassung peri- und postoperativer Komplikationen wie Thrombosen, Infekte, Materialversagen und verzögerte Frakturheilung/Pseudarthrosen.
Ergebnisse und Schlussfolgerung
Der durchschnittliche Punktwert für den AOFAS Score beträgt für alle Patienten 89,38 Punkte (35-100, Median 98) und für den Score nach Olerud und Molander 85,24 Punkte (15-100, Median 95). Insgesamt traten neun (10,98%) Komplikationen auf: vier (4,88%) oberflächliche Wundheilungsstörung, vier Wundinfektionen (4,88%), darunter zwei Schraubenlockerungen (2,44%) und eine Redislokation nach erneutem Distorsionstrauma (1,22%). Weiteres Materialversagen oder Thrombosen traten nicht auf.
Die frühe postoperative Vollbelastung führt nicht zu einer erhöhten Komplikationsrate, die beschriebenen Infekte sind mit der Vollbelastung zu assoziieren. Immobilisationsbedingte Komplikationen werden vermieden, der Patient kann schneller mobilisiert werden. Daher ist eine Ruhigstellung nach operativ versorgten Malleolarfrakturen nicht zu empfehlen.
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Hartwich, Kathleen, Alejandro Lorente Gomez, Jaroslaw Pyrc, Radosław Gut, Stefan Rammelt, and René Grass. "Biomechanical Analysis of Stability of Posterior Antiglide Plating in Osteoporotic Pronation Abduction Ankle Fracture Model With Posterior Tibial Fragment." Sage, 2017. https://tud.qucosa.de/id/qucosa%3A35489.
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Background: We performed a biomechanical comparison of 2 methods for operative stabilization of pronation-abduction stage III ankle fractures; group 1: Anterior-posterior lag screws fixing the posterior tibial fragment and lateral fibula plating (LSLFP) versus group 2: locked plate fixation of the posterior tibial fragment and posterior antiglide plate fixation of the fibula (LPFP). Methods: Seven pairs of fresh-frozen osteoligamentous lower leg specimens (2 male, and 5 female donors) were used for the biomechanical testing. Bone mineral density (BMD) of each specimen was assessed by means of dual-energy x-ray absorptiometry. After open transection of the deltoid ligament, an osteotomy model of pronation abduction stage III ankle fracture was created. Specimens were systematically assigned to LSLFP (group 1, left ankles) or LPPFP (group 2, right ankles). After surgery, all specimens were evaluated via CT to verify reduction and fixation. Axial load was then applied onto each specimen using a servohydraulic testing machine starting from 0 N (Zwick/Roell, Ulm, Germany) at a speed of 10 N/s with the foot fixed in a 10 degrees pronation and 15 degrees dorsiflexion position. Construct stiffness, yield, and ultimate strength were measured and dislocation patterns were documented with a high-speed camera. The normal distribution of all data was analyzed using Shapiro-Wilk test. The group comparison was performed using paired Student t test. Statistical significance was assumed at a P value of .05. Results: All specimens had BMD values consistent with osteoporosis. BMD values did not differ between the left and right ankles of the same pair (P = .762). The mean BMD values between feet of men (0.603 g/cm²) and women (0.329 g/cm²) were statistically different (P = .005). The ultimate strength for LSLFP (group 1) with 1139 ± 669 N and LPPFP (group 2) with 2008 ± 943 N was statistically different (P = .036) as well as the yield in LSLFP (group 1) 812 ± 452 N and LPPFD (group 2) 1292 ± 625 N (P = .016). Construct stiffness trended to be higher in group 2 (179 ± 100 kNn) compared to group 1 (127 ± 73 kN/m) but this difference was not statistically significant (P = .120). BMD correlated with bone-construct failure. Conclusion: Fixation of the posterior tibial edge with a posterolateral locking plate resulted in higher biomechanical stability than anterior-posterior lag screw fixation in an osteoporotic pronation-abduction fracture model. Clinical Relevance: The clinical implication of this biomechanical study is that the posterior antiglide plating might be advantageous in patients with osteoporotic pronation abduction stage III ankle fracture.
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Viehrig, H. W., and D. Kalkhof. "Application of the Master Curve approach to fracture mechanics characterisation of reactor pressure vessel steel." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-61451.
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The paper presents results of a research project founded by the Swiss Federal Nuclear Inspectorate concerning the application of the Master Curve approach in nuclear reactor pressure vessels integrity assessment. The main focus is put on the applicability of pre-cracked 0.4T-SE(B) specimens with short cracks, the verification of transferability of MC reference temperatures T0 from 0.4T thick specimens to larger specimens, ascertaining the influence of the specimen type and the test temperature on T0, investigation of the applicability of specimens with electroerosive notches for the fracture toughness testing, and the quantification of the loading rate and specimen type on T0. The test material is a forged ring of steel 22 NiMoCr 3 7 of the uncommissioned German pressurized water reactor Biblis C.
SE(B) specimens with different overall sizes (specimen thickness B=0.4T, 0.8T, 1.6T, 3T, fatigue pre-cracked to a/W=0.5 and 20% side-grooved) have comparable T0. T0 varies within the 1σ scatter band. The testing of C(T) specimens results in higher T0 compared to SE(B) specimens. It can be stated that except for the lowest test temperature allowed by ASTM E1921-09a, the T0 values evaluated with specimens tested at different test temperatures are consistent. The testing in the temperature range of T0 ± 20 K is recommended because it gave the highest accuracy. Specimens with a/W=0.3 and a/W=0.5 crack length ratios yield comparable T0. The T0 of EDM notched specimens lie 41 K up to 54 K below the T0 of fatigue pre-cracked specimens. A significant influence of the loading rate on the MC T0 was observed. The HSK AN 425 test procedure is a suitable method to evaluate dynamic MC tests. The reference temperature T0 is eligible to define a reference temperature RTTo for the ASME-KIC reference curve as recommended in the ASME Code Case N-629. An additional margin has to be defined for the specific type of transient to be considered in the RPV integrity assessment. This margin also takes into account the level of available information of the RPV to be assessed.
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Hümpfner-Hierl, Heike, Alexander Bohne, Andreas Schaller, Gert Wollny, and Thomas Hierl. "Does facial soft tissue protect against zygomatic fractures?" Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-171696.
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Introduction: Zygomatic fractures form a major entity in craniomaxillofacial traumatology. Few studies have dealt with biomechanical basics and none with the role of the facial soft tissues. Therefore this study should investigate, whether facial soft tissue plays a protecting role in lateral midfacial trauma.
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Hübner, P., U. Mahn, and J. Arndt. "Bruch der Königswelle einer 6300 T–Presse." Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-226082.
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Die bruchmechanische Analyse des Bruches einer Königswelle zeigt, dass der Ermüdungsriss von einer Fehlstelle ausging und durch die Betriebsbeanspruchung gewachsen ist. Die errechneten Lebensdauerwerte decken sich mit den tatsächlich erreichtenThe fracture mechanics analysis of the rupture of an upright shaft shows that the fatigue crack originated from a defect was able to grow with the operational stress. The calculated and actual lifetime are the same
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Donner, Ralf, Andreas Geier, and André John. "UPNS4D+ – Neue Ansätze für die Kluftflächen- und Haufwerksanalyse." Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2017. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-228533.
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Der Zugang zu wirtschaftsstrategischen Bodenschätzen ist für moderne Industriegesellschaften von essenzieller Bedeutung. Für Deutschland besteht für die Versorgung mit nichtenergetischen Rohstoffen wie Stahlveredlern und Seltenen-Erden eine weitgehende Importabhängigkeit. Vorhandene heimische Lagerstätten weisen eine komplexe geologische Struktur mit geringen Abbaumächtigkeiten in großen Teufen auf. Um diese Lagerstätten nutzen zu können, soll ein untertagetaugliches Positionierungs- und Navigationssystem, UPNS4D+, für die Erkundung der Lagerstätte entwickelt und als Demonstrationssystem gebaut werden. Das Institut für Markscheidewesen und Geodäsie der TU Bergakademie ist Teil des Entwicklerkonsortiums. Es ist zuständig für die markscheiderische und bergmännische Nutzbarkeit der mit dem Erkundungssystem gewonnen Daten. Entsprechend dem aktuellen Arbeitsfortschritt werden im vorliegenden Beitrag die Lösungen für die Kluftflächen- und die Haufwerksanalyse vorgestellt. Die teilautomatisierte Haufwerksanalyse dient der Detektion großer Partikel und deren Lagebestimmung in einem relativen KoordinatensystemAccess to strategic mineral resources is essential for modern industrial societies. Germany is largely dependent on imports of non-energy raw materials such as steel refiners and rare earth elements. Existing indigenous deposits have a complex geological structure with low extraction thickness in large depths. In order to use these deposits, an underground positioning and navigation system, namely UPNS4D+, as a demonstration system has to be developed for deposit exploration. As part of the developer consortium, the Institute for Mining Surveying and Geodesy of the TU Bergakademie Freiberg is responsible for the utilization of the acquired data in the field of mining. According to the current work status, in this paper the solutions for rock fracture analysis and grain size analysis are presented. The partly automated grain size analysis is used for the detection of large particles and their position in a relative coordinate system
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Osterman, Fredrik. "Comparison of Photogrammetry Interpretation with Physical Structural Field Measurements." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-324699.
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Fracture mapping of bedrock and knowledge about how fractures influence rock strength and stability is of great importance in a constructional context. These factors largely dictate where one can build and not build in rock, and to what extent reinforcements and safety measurements are needed. In a city like Stockholm where infrastructure has been forced to expand due to a rapidly growing population, this type of knowledge plays a central role to ensure continued development. Fracture mapping is traditionally executed by a geologist who manually measures fracture orientations with a compass. However, this method bears obvious risks as the geologist must physically approach a possibly unstable rock face to carry out manual measurements of fractures and structures. In some cases, the geologist is not even allowed to approach the rock face for safety reasons. The aspect of time should not be neglected either since the process of manual measurements is often time consuming. This has resulted in newer and safer technological methods being developed and tested. In 2015, The Geological Survey of Sweden (SGU) acquired photogrammetrical equipment and 3D-modelling software ShapeMetriX to ease the fracture mapping process, obtain data of higher quality and increase personnel safety in the field. In this report, the photogrammetrical system is quality tested by comparing its results with manual field measurements. The control was carried out on three different rock faces in two locations; Torsgatan, a central street in Stockholm, and Kungens kurva, a construction site southwest of central Stockholm. The study shows that the results of ShapeMetriX correspond well to the manual field measurements and that the method has several advantages as well as disadvantages compared to conventional mapping methods.Sprickkartering av berggrund och kunskap om hur bergets hållfasthet och stabilitet påverkas av sprickor är viktigt i konstruktionssammanhang. Dessa faktorer dikterar till stor del var man kan och inte kan bygga i berg samt till vilken grad förstärkningar och säkerhetsåtgärder behövs. I en stad lik Stockholm vars infrastruktur tvingas anpassa sig efter en kraftigt växande befolkning sätts dessa kunskaper i en ännu mer central roll för att kunna säkerställa stadens fortsatta utveckling. Sprickkartering utförs traditionellt av en geolog som med hjälp av en kompass manuellt mäter sprickors orientering. Detta medför dock uppenbara risker då denna fysiskt måste befinna sig nära bergskärningen för att kunna utföra mätningar av sprickor och strukturer. I vissa fall kan geologen, av säkerhetsskäl, inte alls närma sig den berörda ytan vilket omöjliggör en detaljerad kartering. Tidsaspekten av det hela bör inte heller bortses då manuella fältmätningar ofta är tidskrävande. Detta har resulterat i att nyare och säkrare teknologiska metoder för kartering och klassificering av berg både utvecklas och prövas. Sveriges geologiska undersökning (SGU) förvärvade 2015 fotogrammetrisk karteringsutrustning och 3D-modelleringsprogrammet ShapeMetriX för att effektivisera sprickkarteringsarbetet, erhålla data med högre kvalitét och öka säkerheten för personal I fält. I denna rapport utvärderas nämnda stereofotogrammetriska karteringsmetod med tillhörande analysmjukvara genom en jämförelse av dess resultat med manuella fältmätningar. Kontrollen utfördes på tre berghällar; en belägen på Torsgatan, en central gågata strax nordväst om centrala Stockholm och de andra vid Kungens kurva, en byggarbetsplats i närheten av Skärholmen i södra Stockholm. Resultat av studien visar att ShapeMetriX mätningar väl stämmer överens med manuella fältmätningar och även att metoden har en
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Reinhardt, Sophia, Heiner Martin, Benjamin Ulmar, Stefan Döbele, Hans Zwipp, Stefan Rammelt, Martinus Richter, Martin Pompach, and Thomas Mittlmeier. "Interlocking Nailing Versus Interlocking Plating in Intra-articular Calcaneal Fractures: A Biomechanical Study." Sage, 2016. https://tud.qucosa.de/id/qucosa%3A35488.
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Background: Open reduction and internal fixation with a plate is deemed to represent the gold standard of surgical treatment for displaced intra-articular calcaneal fractures. Standard plate fixation is usually placed through an extended lateral approach with high risk for wound complications. Minimally invasive techniques might avoid wound complications but provide limited construct stability. Therefore, 2 different types of locking nails were developed to allow for minimally invasive technique with sufficient stability. The aim of this study was to quantify primary stability of minimally invasive calcaneal interlocking nail systems in comparison to a variable-angle interlocking plate. Material and Methods: After quantitative CT analysis, a standardized Sanders type IIB fracture model was created in 21 fresh-frozen cadavers. For osteosynthesis, 2 different interlocking nail systems (C-Nail; Medin, Nov. Město n. Moravě, Czech Republic; Calcanail; FH Orthopedics SAS; Heimsbrunn, France) as well as a polyaxial interlocking plate (Rimbus; Intercus GmbH; Rudolstadt, Germany) were used. Biomechanical testing consisted of a dynamic load sequence (preload 20 N, 1000 N up to 2500 N, stepwise increase of 100 N every 100 cycles, 0.5 mm/s) and a load to failure sequence (max. load 5000 N, 0.5 mm/s). Interfragmentary movement was detected via a 3-D optical measurement system. Boehler angle was measured after osteosynthesis and after failure occurred. Results: No significant difference regarding load to failure, stiffness, Boehler angle, or interfragmentary motion was found between the different fixation systems. A ignificant difference was found with the dynamic failure testing sequence where 87.5% of the Calcanail implants failed in contrast to 14% of the C-Nail group (P < .01) and 66% of the Rimbus plate. The highest load to failure was observed for the C-Nail. Boehler angle showed physiologic range with all implants before and after the biomechanical tests. Conclusion: Both minimally invasive interlocking nail systems displayed a high primary stability that was not inferior to an interlocking plate. Clinical relevance: Based on our results, both interlocking nails appear to represent a viable option for treating displaced intra-articular calcaneal fractures.
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Mayet, François. "Classification d'images par analyse fractale et multifractale." Saint-Etienne, 2001. http://www.theses.fr/2001STET4020.
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Ce travail propose une approche nouvelle de la caractérisation de l'homogénéité des images lorsque celle-ci est due à la bonne ou mauvaise répartition spatiale des niveaux de gris. Cette répartition est naturellement décrite par l'analyse multifractale, généralisation de l'analyse fractale, et plus particulièrement par le spectre des singularités. Le critère d'homogénéité retenu sera un point particulier de ce spectre : la dimension d'entropie. Un algorithme robuste et rapide utilisant l'histogramme de l'image et la notion de filtre moyenne est développé. Il permet de calculer des spectres de singularités paramétrés et des critères d'homogénéité peu sensibles au bruit de quantification, au flou, aux variations d'échelle et aux positions d'observation. Nous l'avons modifié afin de l'adapter aux zones d'analyse comportant des parties masquées. Cet algorithme a été testé sur 2 catégories d'images. D'une part, des images de moquettes usées artificiellement ; toutes ont été classées avec succès par ordre d'homogénéité croissante. Et d'autre part, des images de béton où certaines zones ont été masquées. Ces dernières ont été très correctement classées en accord avec un classement " psychovisuel ". Nous terminerons en présentant un critère d'homogénéité mettant en œuvre la propagation géodésique et plus précisément la dimension fractale du front de propagation.
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Schwarzer, Norbert, and Peggy Heuer-Schwarzer. "Qualitative failure analysis on laminate structures of windsurfing boards using analytical linear elastic modelling." Universitätsbibliothek Chemnitz, 2006. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200600107.
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Recently developed mathematical tools for the modelling of contact problems on thin film structures are adapted to allow the investigation of arbitrarily mixed purely isotropic and transversally isotropic laminate structures. The new tool is applied to model a variety of load problems resulting in the failure of windsurfing boards consisting of a relatively thin laminate shell and a soft polymer foam core. It is shown that local impact and distributed bending loads due to “bad landing” after high jumps or contact with parts of the sailing gear (the so called rig) especially the front part of the boom are leading to the most critical stress distributions resulting in failure. So most of the investigated boards were damaged because the rider (windsurfer) landed flat and thus produced a sudden impact force under his feet (impact defect). Other overloading occurred due to overturning of so called loop movements or the landing of the board exactly on respectively between two waves and this way producing high bending moments. Some of those typical loads are analysed in detail and the stresses occurring in the complex structure of the windsurfing boards are evaluated.
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Theopold, Jan, Bastian Marquaß, Johannes Fakler, Hanno Steinke, Christoph Josten, and Pierre Hepp. "The bicipital groove as a landmark for reconstruction of complex proximal humeral fractures with hybrid double plate osteosynthesis." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-206088.
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Background: Complex proximal humerus fractures with metaphyseal comminution remain challenging regarding reduction and stability. In most fracture patterns the hard bone of the bicipital groove remains intact. In this case series, we describe a novel technique of hybrid double plate osteosynthesis of complex proximal humerus fractures with metaphyseal comminution. Methods: In randomly chosen shoulder specimens and synthetic bones, pilot studies for evaluation of the feasibility of the technique were performed. Between 4/2010 and 1/2012 10 patients underwent hybrid double plate osteosynthesis. Seven patients (4 male, 3 female, mean age was 50 years (range 27–73)) were available for retrospective analysis. Based on plain radiographs (anterior-posterior and axial view), the fractures were classified according to the Orthopaedic Trauma Association classification (OTA) and by descriptive means (head-split variant (HS), diaphyseal extension or comminution (DE)). Results: Follow-up radiographs demonstrated complete fracture healing in six patients and one incomplete avascular necrosis. None of the patients sustained loss of reduction. Three patients where reoperated. The medium, not adapted, Constant score was 80 Points (58–94). Patients subjective satisfaction was graded mean 3 (range: 0–6) in the visual analog scoring system (VAS). Conclusion: The technique of hybrid double plate osteosynthesis using the bicipital groove as anatomic landmark may re-establish shoulder function after complex proximal humerus fractures in two dimensions. Firstly the anatomy is restored due to a proper reduction based on intraoperative landmarks. Secondly additional support by the second plate may provide a higher stability in complex fractures with metaphyseal comminution.
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Hümpfner-Hierl, Heike, Andreas Schaller, and Thomas Hierl. "Biomechanical investigation of the supraorbital arch." Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-143957.
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Introduction: As fractures of the supraorbital region are far less common than midfacial or orbital fractures, a study was initiated to investigate whether fist blows could lead to fractures similar to those often seen in the midface. Methods: A detailed skull model and an impactor resembling a fist were created and a fist blow to the supraorbital region was simulated. A transient finite element analysis was carried out to calculate von Mises stresses, peak force, and impact time. Results: Within the contact zone of skull and impactor critical stress values could be seen which lay at the lower yield
border for potential fractures. A second much lower stress zone was depicted in the anterior-medial orbital roof. Conclusions: In this simulation a fist punch, which could generate distinct fractures in the midface and naso-ethmoid-orbital region, would only reach the limits of a small fracture in the supraorbital region. The reason is seen in the strong bony architecture. Much higher forces are needed to create severe trauma in the upper face which is supported by clinical findings. Finite element analysis is the method of choice to investigate the impact of trauma on the human skeleton.
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Fakler, Johannes, Antonia Grafe, Jamila Dinger, Christoph Josten, and Gabriela Aust. "Perioperative risk factors in patients with a femoral neck fracture – influence of 25-hydroxyvitamin D and C-reactive protein on postoperative medical complications and 1-year mortality." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-206107.
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Background: This study examined the association of 25-hydroxyvitamin D (25(OH)D) and C-reactive protein (CRP) with postoperative medical complications and one year mortality of elderly patients sustaining a low-energy cervical hip fracture scheduled for surgery. We hypothesized that vitamin D deficiency and CRP in these patients might be associated with an increased 1-year mortality. Methods: The prospective single-center cohort study included 209 patients with a low-energy medial femoral neck fracture; 164 women aged over 50 years and 45 men aged over 60 years. Referring to 1-year mortality and
postoperative medical complications multiple logistic regression analysis including 10 co-variables (age, sex, BMI, ASA, creatinine, CRP, leukocytes hemoglobin, 25(OH)D, vitamin D supplementation at follow-up) was performed. Results: Vitamin D deficiency was prevalent in 87 % of all patients. In patients with severe (<10 ng/ml) and moderate (10–20 ng/ml) vitamin D deficiency one year mortality was 29 % and 13 %, respectively, compared to 9 % in patients with > 20 ng/ml 25(OH)D levels (p =0.027). Patients with a mild (CRP 10–39.9 mg/l) or active inflammatory response (CRP ≥ 40 mg/l) showed a higher one year mortality of 33 % and 40 % compared to 16 % in patients with no (CRP < 10 mg/l) inflammatory response (p = 0.002). Multiple logistic regression analysis identified CRP (OR 1.01, 95 % CI 1.00- 1.02; p = 0.007), but not 25(OH)D (OR 0.97, 95 % CI 0.89-1.05; p = 0.425) as an independent predictor for one year mortality. 20 % of patients suffered in-hospital postoperative medical complications (i.e. pneumonia, thromboembolic events, etc.). 25(OH)D (OR 0.89, 95 % CI 0.81–0.97; p = 0.010), but not CRP (OR 1.01, 95 % CI 1.00-1.02; p = 0.139), was
identified as an independent risk factor. Conclusion: In elderly patients with low-energy cervical hip fracture, 25(OH)D is independently associated with postoperative medical complications and CRP is an independent predictor of one year mortality.
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Hübner, Peter, and Uwe Mahn. "Bruchmechanische Bewertung von Bauteilen." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-172432.
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Bauteile mit Rissen können mit Hilfe der Bruchmechanik bewertet werden. Da die Ermittlung der Rissspitzenbeanspruchung nicht immer analytisch gelingt, ist die Nutzung numerischer Verfahren von Vorteil. Nach einer kurzen Einführung in die Bruchmechanik wird an zwei Beispielen die Vorgehensweise diskutiert.
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Bayer, Daniela, and Mike Richter. "Zur Anwendung bruchmechanischer Konzepte für die Modellierung der rissüberbrückenden Wirkung von Rovings." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244047456442-11748.
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Textilbeton ist ein Verbundwerkstoff aus einer Feinbetonmatrix und einer textilen Bewehrung, die aus sogenannten Rovings besteht. Nach Reißen der spröden Matrix sind diese Rovings in der Lage, die Risse in der Matrix zu überbrücken. In diesem Beitrag wird ein analytisches Modell vorgestellt, welches den Einfluss der Rovings auf das Rissverhalten erfassen kann. Die Wirkung der Fasern wird durch rissüberbrückende Spannungen approximiert. Dabei kommt unter Annahme linear elastischen Materialverhaltens das bruchmechanische Konzept der Methode der Gewichtsfunktionen zum Einsatz. Als ein spezielles Anwendungsgebiet des vorgestellten bruchmechanischen Konzeptes werden Risse im Bereich von Übergreifungen der textilen Bewehrung untersucht. Hier kann es, abhängig von der vorhandenen Übergreifungslänge, zum Auszug der Rovings kommen. Um diesen Versagensmechanismus zu verhindern, ist eine Mindestübergreifungslänge erforderlich.
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Bidesi, Anup Singh. "Comparison of texture classification methods to evaluate spongy bone texture in osteoporosis /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1422912.
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Staudinger, Ulrike. "Morphologie und Bruchverhalten von Block- und Multipfropfcopolymeren." Doctoral thesis, [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1187261828675-34703.
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Chalhoub, Michel. "Apports des méthodes d'homogénéisation numériques à la classification des massifs rocheux fracturés." Phd thesis, École Nationale Supérieure des Mines de Paris, 2006. http://tel.archives-ouvertes.fr/tel-00412033.
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Cette thèse présente d'abord la méthodologie de calcul des propriétés élastoplastiques à grande échelle d'un massif rocheux par la méthode d'homogénéisation numérique en éléments finis. Des chargements simulant différents essais mécaniques de compression et de cisaillement sont appliqués sur un Volume Elémentaire Représentatif (VER). La loi de comportement homogénéisée est déduite des contraintes et déformations moyennes calculées dans ce VER. Les différents types de chargements numériques, en contrainte ou en déplacement imposés, et leur effets sur les paramètres homogénéisés sont discutés.
Une attention particulière est portée à l'application de la théorie d'élasticité ellipsoïdale de Saint Venant au cas des massifs rocheux. Cette théorie présente plusieurs avantages. En particulier, elle permet de fixer pour les massifs que nous étudions, un modèle élastique tridimensionnel à partir d'un calcul plan.
Une comparaison entre les tailles de VER mécanique et géométrique a été faite et il a été montré que pour les massifs étudiés le VER mécanique peut être déduit du VER géométrique qui est plus simple à calculer. Une formule approchée donnant la taille du VER en fonction des paramètres géométriques des fractures a été établie pour des massifs non périodiques.
L'apport fondamental de cette thèse consiste à établir une classification mécanique de certains types de massifs rocheux fondée sur la méthode d'homogénéisation numérique que nous avons proposée. Ensuite, une étude paramétrique a été réalisée pour déterminer la sensibilité des résultats aux paramètres géométriques et mécaniques de la matrice rocheuse et des discontinuités. Les paramètres mécaniques homogénéisés ainsi obtenus constituent des données très utiles pour la conception et l'étude des ouvrages dans les massifs rocheux (tunnels, déblais, fondations au rocher). L'ajustement de quelques paramètres mécaniques fondamentaux (module d'Young, module de cisaillement) a conduit à l'élaboration d'expressions analytiques généralisant la formulation d'Amadei et Goodman [1981] pour des cas où l'extension des fractures est finie.
L'élaboration de cette classification numérique a exigé le développement et la validation d'un outil d'homogénéisation numérique performant (HELEN) et qui est aussi facilement utilisable dans le cas d'autres types de milieux hétérogènes fissurés et anisotropes (bétons, maçonnerie...)
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Götz, Sebastian. "Weiterentwicklung eines bruchmechanischen Konzepts zur formzahlfreien Abschätzung der Dauerfestigkeit gekerbter Strukturen am Beispiel verschiedener Sinterstähle." Doctoral thesis, TUDpress - Verlag der Wissenschaften GmbH, 2012. https://tud.qucosa.de/id/qucosa%3A29911.
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In der Dissertation werden Konzepte vorgestellt, mit denen die Abschätzung der Dauerfestigkeit von Bauteilen auf Grundlage von Werkstoffkennwerten möglich ist. Aus den sich dabei ergebenden Problemen sowie den speziellen Anforderungen der Werkstoffgruppe Sinterstahl wird ein neues Konzept aus bruchmechanischen Überlegungen abgeleitet. Damit ist eine Anwendung ohne prinzipielle Einschränkung bezüglich der Bauteilgeometrie und unter Berücksichtigung der individuellen Kerbempfi ndlichkeit des Werkstoffs möglich. Die Validierung und statistische Auswertung anhand einer breiten Datenbasis belegt eine gute Treffsicherheit im Vergleich zu anderen Verfahren. Empfehlungen zur praktischen Anwendung und den Grenzen der verschiedenen Konzepte werden gegeben.
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Naumann, Michael. "MEMS reliability in shock environments." Doctoral thesis, Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-117360.
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In der vorliegenden Arbeit wird eine Methode vorgestellt, mit welcher die Zuverlässigkeit mikroelektromechanischer Systeme (MEMS) bezüglich stoßinduzierter Fehlermechanismen bereits in der Entwurfsphase neuer Produkte abgeschätzt bzw. verbessert werden kann. Der Ansatz bezieht sich dabei auf bruch- sowie adhäsionsbedingte Ausfallmechanismen und erfordert zwei wesentliche Schritte. Zuerst werden Systemmodelle der jeweils zu untersuchenden mikromechanischen Systeme erstellt, welche die Berechnung der Stoßantwort wie auch der dabei auftretenden Belastungen in Sinne von Auslenkungen, Deformationen und Aufprallkräften ermöglichen. In einem zweiten Schritt wird die zur Fertigung vorgesehene Technologie bezüglich des Auftretens beider stoßbedingter Ausfallmechanismen sowie deren Abhängigkeit von verschiedenen Umgebungsbedingungen oder Betriebsparametern systematisch untersucht. Die aus der Prozesscharakterisierung resultierenden Daten dienen zur Ableitung prozessspezifischer Fehlerkriterien, welche die Einschätzung der zuvor berechneten Lasten ermöglichen. Auf diese Weise kann abgeschätzt werden, inwieweit die Zuverlässigkeit der betrachteten mikromechanischen Strukturen beeinflusst wird bzw. mit welchen Maßnahmen diese gesteigert werden kann.
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Settgast, Christoph. "Numerische Untersuchungen der Bruchfestigkeit und inelastischen Deformationen von offenzelligen keramischen Schaumstrukturen." Technische Universität Bergakademie Freiberg, 2019. https://tubaf.qucosa.de/id/qucosa%3A35315.
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Die im Rahmen des Sonderforschungsbereiches SFB 920 entstandene Arbeit beschäftigt sich mit bruchmechanischen Vorgängen und der makroskopischen Beschreibung von offenzelligen Keramikschäumen unter Berücksichtigung des Materialverhaltens des Kompaktmaterials mithilfe von numerischen Simulationen. Dabei steht die thermomechanische Belastung einer solchen Struktur während eines Gießprozesses im Vordergrund. Im Rahmen der bruchmechanischen Untersuchungen konnte der Einfluss von verschiedenen Strukturparametern aufgezeigt werden. Die Belastungen entlang der scharfen Kerben im Inneren der Stege ergaben sich dabei als weniger kritisch als entlang der Stegaußenseiten. Das Kriechverhalten des kohlenstoffgebundenen Aluminiumoxides bei Hochtemperatur konnte erfolgreich beschrieben und für Schaumstrukturen angewendet werden. Das vorgeschlagene Modell kann dabei sowohl für virtuell erzeugte Schaumstrukturen als auch für reale Schaumproben angepasst werden. Mithilfe von homogenisierten Materialmodellen basierend auf neuronalen Netzen ergab sich eine drastische Reduzierung der Rechenzeit für komplexe Filterstrukturen. Es ist dabei eine Berücksichtigung von Plastizität und Schädigung für das Kompaktmaterial möglich.This thesis developed within the collaborative research centre SFB 920 deals with fracture mechanical analyses and the macroscopic description of open-cell ceramic foams considering the material behaviour of the bulk material by means of numerical simulations. In the centre of interest is the thermomechanical loading of such a structure during a casting process. Within the framework of fracture mechanical investigations, the influence of various structural parameters is demonstrated. The loads along the sharp notches inside the struts turned out to be less critical than along the outer surfaces of the struts. The creep behaviour of the carbon-bonded alumina at high temperature were successfully described and the mathematical description is applied to foam structures. The proposed model can be adapted for virtually generated foam structures as well as for real foam samples. Using homogenized material models based on neuronal networks, a drastic reduction of the computing time for complex filter structures was achieved. Meanwhile, it is possible to consider plasticity and damage effects for the bulk material.
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Li, Xiang. "Lifetime prediction for rocks." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-126371.
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A lifetime prediction scheme is proposed based on the assumption that the lifetime (time to failure) of rocks under load is governed by the growth of microstructual defects (microcracks). The numerical approach is based on linear elastic fracture mechanics. The numerical calculation scheme is implemented as a cellular automat, where each cell contains a microcrack with length and orientation following certain distributions. The propagation of the microcrack is controlled by the Charles equation, based on subcritical crack growth. The zone inside the numerical model fails if the microcrack has reached the zone dimension or the stress intensity factor of the crack reached the fracture toughness. Macroscopic fractures are formed by these coalesced propagating microcracks, and finally lead to failure of the model. In the numerical approaches, elasto-plastic stress redistributions take place during the forming of the macroscopic fractures. Distinct microcrack propagation types have been programmed and applied to the proposed numerical models. These numerical models are studied under different loading conditions. Numerical results with excellent agreement with the analytical solutions are obtained with respective to predicted lifetime, important parameters for the microcracks, fracture pattern and damage evolution. Potential applications of the proposed numerical model schemes are investigated in some preliminary studies and simulation results are discussed. Finally, conclusions are drawn and possible improvements to the numerical approaches and extensions of the research work are given本文认为微结构缺陷（微裂纹）的扩展决定了受力岩石的寿命（破坏时间）。基于此假设，提出了岩石寿命预测方法。利用线弹性断裂力学理论，通过FLAC进行了数值模拟。数值模型中每个单元定义一条初始裂纹，其长度与方向服从特定分布。基于亚临界裂纹扩展理论，由Charles方程决定微裂纹的扩展（速度）。如微裂纹发展至单元边界，或应力强度系数到达断裂韧度，则单元破坏。宏观裂纹由微裂纹所联合形成，并最终贯穿模型导致破坏。在形成宏观裂纹的过程中，发生弹塑性应力重分布。在数值模型中，编制了不同类型的微裂纹扩展方式，并在不同的受力条件下加以分析。数值模型的岩石寿命，裂纹形状，破坏方式以及一些重要的参数的数值模拟结果与解析解有较好的一致性。对本文所提出的数值模型的初步实际应用进行了分析，并讨论了计算结果。最后讨论了本文所提出的岩石寿命预测方法的可能改良与发展，并对进一步的研究工作给出建议。
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Orellana, Pérez Teresa. "Mechanical behavior of alternative multicrystalline silicon for solar cells." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-117455.
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The usage of more inexpensive silicon feedstock for the crystallization of multicrystalline silicon blocks promises cost reduction for the photovoltaic industry. Less expensive substrates made out of metallurgical silicon (MG-Si) are used as a mechanical support for the epitaxial solar cell. Moreover, conventional inert solar cells can be produced from up-graded metallurgical silicon (UMG-Si). This feedstock has higher content of impurities which influences cell performance and mechanical strength of the wafers. Thus, it is of importance to know these effects in order to know which impurities should be preferentially removed or prevented during the crystallization process. Solar cell processing steps can also exert a change in the values of mechanical strength of processed multicrystalline silicon wafers until the fabrication of a solar cell.
Bending tests, fracture toughness and dynamic elastic modulus measurements are performed in this work in order to research the mechanical behavior of multicrystalline silicon crystallized with different qualities of silicon feedstock. Bending tests and residual stress measurements allows the quantification of the mechanical strength of the wafers after every solar cell processing step. The experimental results are compared with theoretical models found in the classical literature about the mechanical properties of ceramics. The influence of second phase particles and thermal processes on the mechanical strength of silicon wafers can be predicted and analyzed with the theoretical models.
Metals like Al and Cu can decrease the mechanical strength due to micro-cracking of the silicon matrix and introduction of high values of thermal residual stress. Additionally, amorphous silicon oxide particles (SiOx) lower the mechanical strength of multicrystalline silicon due to thermal residual stresses and elastic mismatch with silicon. Silicon nitride particles (Si3N4) reduce fracture toughness and cause failure by radial cracking in its surroundings due to its thermal mismatch with silicon. Finally, silicon carbide (SiC) and crystalline silicon oxide (SiOx) introduce thermal residual stresses but can have a toughening effect on the silicon matrix and hence, increase the mechanical strength of silicon wafers if the particles are smaller than a certain size.
The surface of as-cut wafers after multi-wire sawing presents sharp micro-cracks that control their mechanical behavior. Subsequent removal of these micro-cracks by texture or damage etching approximately doubles the mechanical strength of silicon wafers. The mechanical behavior of the wafers is then governed by defects like cracks and particles formed during the crystallization of multicrystalline silicon blocks. Further thermal processing steps have a minor impact on the mechanical strength of the wafers compared to as-cut wafers. Finally, the mechanical strength of final solar cells is comparable to the mechanical strength of as-cut wafers due to the high residual thermal stress introduced after the formation of the metallic contacts which makes silicon prone to crack.
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Abadi, Mohamed. "Couleur et texture pour la représentation et la classification d'images satellite multi-résolutions." Antilles-Guyane, 2008. http://www.theses.fr/2008AGUY0215.
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La Caractérisation des couverts forestiers et des parcelles agricoles est d'un grand intérêt pour différents organismes locaux et nationaux. Ces derniers sont à la recherche d'outils spécifiques permettant de réaliser avec précision la séparation entre ces espaces. Ce travail de recherche propose d'utiliser des techniques de traitement d'images appliquées sur des images satellite pour réaliser une classification des différents couverts. La chaine de traitement mise en place est la suivante: Après avoir représenté de manière optimale les images sources, nous définisson et calculons des attributs de couleur et de texture avant d'appliquer un algorithme de classification. La représentation optimale des données est faite (i) en déterminant l'espace couleur hybride permettant d'obtenir une discrimination maximale des classes tout en minimisant la corrélation entre les composantes de cet espace. (ii) en réalisant une fusion de l'image panchromatique et de l'image multispectrale. Les attributs sont ensuite extraits pour caractériser les classes en utilisant la couleur et la texture à travers différentes approches (statistiques, géométriques, fréquentielles, fractales et multifractales). Enfin, différentes techniques de classification (MMG, SVM, K-means, ISODATA) sont utilisées afin de séparer les couverts forestiers des couverts agricoles. L'originalité de nos travaux consiste à construire un espace couleur hybride basé sur les composantes intensité. Saturation et teinte en utilisant une approche multi-objective. Ce même espace est utilisé lors du processus de fusion d'images afin de généraliser les méthode perceptuellesLand use mapping and characterization are very important for local and national institutions. These institutions are nowadays searching for specifie and specialized tools that can distinguish betweendifferent land covers. This research work proposes to use different methods for satellite image processing. Allowing a strong and reliable land cover classification. The conceptual and experimental design has been developed as it follows. First, an optimal description of ail images is done. Then, COIOL and texture attributs are defined and computed. Finally, sorne algorithm classifications are realized. The optimal description of ail images is made by (i) determination of the hybrid colour space to obtain a good discrimination of this classes while correlation between space components is mininized. (ii) merging a high spatial resolution panchromatic image with a low spatial resolution multispectral image in order to obtain a high spatial and spectral resolutions image. Attributes are then extracted to characterize land cover classes using colour and texture information through different approaches (statistics, geometry, frequency, fractal, multifractal). At last, different classification techniques are applied (SVM, MMG, K-means, ISODATA) in order to separate forest areas from agriculturc parcels. Our work originality is based on the construction of a hybrid colour space derived from the image intensity, saturation and hue omponents using a multiobjective approach that integrates the correlation and discriminating power. This same space ls used in the merging images process in order to aeneralize the perceptual methods
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Bamberg, Marlene. "Planetary mapping tools applied to floor-fractured craters on Mars." Phd thesis, Universität Potsdam, 2014. http://opus.kobv.de/ubp/volltexte/2014/7210/.
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Planetary research is often user-based and requires considerable skill, time, and effort. Unfortunately, self-defined boundary conditions, definitions, and rules are often not documented or not easy to comprehend due to the complexity of research. This makes a comparison to other studies, or an extension of the already existing research, complicated. Comparisons are often distorted, because results rely on different, not well defined, or even unknown boundary conditions.
The purpose of this research is to develop a standardized analysis method for planetary surfaces, which is adaptable to several research topics. The method provides a consistent quality of results. This also includes achieving reliable and comparable results and reducing the time and effort of conducting such studies. A standardized analysis method is provided by automated analysis tools that focus on statistical parameters. Specific key parameters and boundary conditions are defined for the tool application. The analysis relies on a database in which all key parameters are stored. These databases can be easily updated and adapted to various research questions. This increases the flexibility, reproducibility, and comparability of the research. However, the quality of the database and reliability of definitions directly influence the results. To ensure a high quality of results, the rules and definitions need to be well defined and based on previously conducted case studies. The tools then produce parameters, which are obtained by defined geostatistical techniques (measurements, calculations, classifications).
The idea of an automated statistical analysis is tested to proof benefits but also potential problems of this method. In this study, I adapt automated tools for floor-fractured craters (FFCs) on Mars. These impact craters show a variety of surface features, occurring in different Martian environments, and having different fracturing origins. They provide a complex morphological and geological field of application. 433 FFCs are classified by the analysis tools due to their fracturing process. Spatial data, environmental context, and crater interior data are analyzed to distinguish between the processes involved in floor fracturing.
Related geologic processes, such as glacial and fluvial activity, are too similar to be separately classified by the automated tools. Glacial and fluvial fracturing processes are merged together for the classification. The automated tools provide probability values for each origin model. To guarantee the quality and reliability of the results, classification tools need to achieve an origin probability above 50 %. This analysis method shows that 15 % of the FFCs are fractured by intrusive volcanism, 20 % by tectonic activity, and 43 % by water & ice related processes. In total, 75 % of the FFCs are classified to an origin type. This can be explained by a combination of origin models, superposition or erosion of key parameters, or an unknown fracturing model. Those features have to be manually analyzed in detail. Another possibility would be the improvement of key parameters and rules for the classification.
This research shows that it is possible to conduct an automated statistical analysis of morphologic and geologic features based on analysis tools. Analysis tools provide additional information to the user and are therefore considered assistance systems.Planetenforschung umfasst oft zeitintensive Projekte, bei denen Expertise und Erfahrung eine wesentliche Rolle spielen. Auf Grund äusserst komplexer und sich selten wiederholender Forschungsfragen sind Annahmen, Definitionen und Regeln zur Lösung dieser Fragen nicht leicht nachvollziehbar oder aber nicht eindeutig dokumentiert. Ein Vergleich der Ergebnisse unterschiedlicher Forscher zum selben Thema oder eine Erweiterung der Forschungsfrage macht dies somit nur schwer möglich. Vergleiche liefern oftmals verzerrte Ergebnisse, da die Ausgangslage und Randbedingungen unterschiedlich definiert worden sind. Das Ziel dieser Arbeit ist es eine Standardmethode zur Oberflächenanalyse zu entwickeln, die auf zahlreiche Untersuchungsfragen angewandt werden kann. Eine gleichbleibende Qualität der Ergebnisse muss durch diese Methode gewährleistet sein. Ein weiteres Ziel ist es, dass diese Methode ohne Vorwissen und Expertise angewandt werden kann und die Ergebnisse in kurzer Zeit vorliegen. Ausserdem müssen die Ergebnisse vergleichbar und nachvollziehbar sein. Automatisch operierende Analysewerkzeuge können die zahlreichen Anforderungen erfüllen und als Standardmethode dienen. Statistische Ergebnisse werden durch diese Methode erzielt. Die Werkzeuge basieren auf vordefinierten, geowissenschaftlichen Techniken und umfassen Messungen, Berechnungen und Klassifikationen der zu untersuchenden Oberflächenstrukturen. Für die Anwendung dieser Werkzeuge müssen Schlüsselstrukturen und Randbedingungen definiert werden. Des Weiteren benötigen die Werkzeuge eine Datenbank, in der alle Oberflächenstrukturen, aber auch Informationen zu den Randbedingungen gespeichert sind. Es ist mit geringem Aufwand möglich, Datenbanken zu aktualisieren und sie auf verschiedenste Fragestellungen zu adaptieren. Diese Tatsache steigert die Flexibilität, Reproduzierbarkeit und auch Vergleichbarkeit der Untersuchung. Die vordefinierten Randbedingungen und die Qualität der Datenbank haben jedoch auch direkten Einfluss auf die Qualität der Ergebnisse. Um eine gleichbleibend hohe Qualität der Untersuchung zu gewährleisten muss sichergestellt werden, dass alle vordefinierten Bedingungen eindeutig sind und auf vorheriger Forschung basieren. Die automatisch operierenden Analysewerkzeuge müssen als mögliche Standardmethode getestet werden. Hierbei geht es darum Vorteile, aber auch Nachteile zu identifizieren und zu bewerten. In dieser Arbeit werden die Analysewerkzeuge auf einen bestimmten Einschlagskratertyp auf dem Mars angewandt. Krater mit zerbrochenen Kraterböden (Floor-Fractured Craters) sind in verschiedensten Regionen auf dem Mars zu finden, sie zeigen zahlreiche Oberflächenstrukturen und wurden durch unterschiedliche Prozesse geformt. All diese Fakten machen diesen Kratertyp zu einem interessanten und im geologischen und morphologischen Sinne sehr komplexen Anwendungsgebiet. 433 Krater sind durch die Werkzeuge analysiert und je nach Entstehungsprozess klassifiziert worden. Für diese Analyse sind Position der Krater, Art des Umfeldes und Strukturen im Kraterinneren ausschlaggebend. Die kombinierten Informationen geben somit Auskunft über die Prozesse, welche zum Zerbrechen des Kraterbodens geführt haben. Die entwickelten Analysewerkzeuge können geologische Prozesse, die sehr ähnlich zueinander sind, von einander abhängig sind und zusätzlich auch dieselben Oberflächenstrukturen formen, nicht eindeutig unterscheiden. Aus diesem Grund sind fluviale und glaziale Entstehungsprozesse für den untersuchten Kratertyp zusammengefasst. Die Analysewerkzeuge liefern Wahrscheinlichkeitswerte für drei mögliche Entstehungsarten. Um die Qualität der Ergebnisse zu verbessern muss eine Wahrscheinlichkeit über 50 % erreicht werden. Die Werkzeuge zeigen, dass 15 % der Krater durch Vulkanismus, 20 % durch Tektonik und 43 % durch Wasser- und Eis-bedingte Prozesse gebildet wurden. Insgesamt kann für 75 % des untersuchten Kratertyps ein potentieller Entstehungsprozess zugeordnet werden. Für 25 % der Krater ist eine Klassifizierung nicht möglich. Dies kann durch eine Kombination von geologischen Prozessen, einer Überprägung von wichtigen Schlüsselstrukturen, oder eines bisher nicht berücksichtigten Prozesses erklärt werden. Zusammenfassend ist zu sagen, dass es möglich ist planetare Oberflächenstrukturen quantitativ durch automatisch operierende Analysewerkzeuge zu erfassen und hinsichtlich einer definierten Fragestellung zu klassifizieren. Zusätzliche Informationen können durch die entwickelten Werkzeuge erhalten werden, daher sind sie als Assistenzsystem zu betrachten.
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Huempfner-Hierl, Heike, Andreas Schaller, and Thomas Hierl. "Maxillofacial fractures and craniocerebral injuries." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-167376.
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Background: Severe facial trauma is often associated with intracerebral injuries. So it seemed to be of interest to study stress propagation from face to neurocranium after a fistlike impact on the facial skull in a finite element analysisHintergrund: Frakturen des Gesichtsschädels gehen häufig mit intrakraniellen Verletzungen einher. Deshalb erschien es interessant, die Weiterleitung und Verteilung von Spannungen, wie sie bei einem Faustschlag auftreten, vom Gesichtsschädel zum Hirnschädel in einer Finite Elemente Analyse zu untersuchen
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Yamaguchi, Makoto, Kazunori Suzuki, and Stephen Altobelli. "Diffusion of water in thermally fractured granite rock cores studied by PFG NMR and MRI: Diffusion of water in thermally fractured granite rock coresstudied by PFG NMR and MRI." Diffusion fundamentals 3 (2005) 24, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14315.
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Diffusion of water in thermally fractured granite was studied by using pulsed field gradient NMR (PFGNMR) and MRI methods. Two different approaches gave consistent results, indicating that these methods can be applied for materials of low porosity with fracture networks.
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Gutermann, Marc. "Ein Beitrag zur experimentell gestützten Tragsicherheitsbewertung von Massivbrücken." Doctoral thesis, Technische Universität Dresden, 2002. https://tud.qucosa.de/id/qucosa%3A24260.
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In September 2000 the DAfStb issued a technical recommendation for the experimental assessment of structural safety and usability of concrete structures. By now, the influence of pavement or floor layers and of other factors on the load carrying capacity is not known exactly. In this thesis, it has been investigated how road pavements, the geometry and bridge caps reduce the actions on concrete bridge structures and how these influences should be taken into account in the experimental evaluation of the bending capacity by an additional test load increment. In co-operation with a local authority in Stralsund, Germany, comprehensive loading test could be performed at an abandoned concrete bridge with prefabricated girders. Between loading cycles, the pavement has been stepwise disassembled. In addition, the ultimate load of the structure as well as of an individual girder has been determined in fracture tests. By means of a hybrid analysis, i.e. a numerical simulation supported by experimental data, the influences of the pavement layers have been determined. These results were verified by experimental observations obtained in past bridge tests. The influence of the pavement layers on the load carrying capacity appeared to be as high as 28% at the maximum for the bridges investigated. Since the loading vehicle BELFA has been completed in March 2001, test loads can be applied now self-securing to bridges in the so-called large load circuit, i.e. the structure is loaded including supports and foundation. The technical concept, the principle and possible applications of the BELFA are described. The results presented will allow to determine the additional test load increment for compensating the influence of pavement layers, structural geometry and bridge caps in future experimental safety evaluations. For this analysis, the exact geometry of the structure, the thickness of the pavement layers as well as their material properties, especially the modulus of elasticity, have to be known. Guidelines for the analysis procedure as well as for simplifying assumptions are given.Experimentelle Nachweise der Tragsicherheit und Gebrauchstauglichkeit von Betonbauwerken sind seit September 2000 in einer DAfStb-Richtlinie geregelt. Der Einfluss mittragender Aufbauschichten und anderer Faktoren war bisher quantitativ unbekannt. In der vorliegenden Arbeit wurde untersucht, wie Straßenbeläge, Bauwerksgeometrie und Kappen die Beanspruchung der Tragkonstruktion von Massivbrücken mindern und im experimentellen Nachweis der Biegetragsicherheit durch eine Überlast zu berücksichtigen sind. In Zusammenarbeit mit dem Straßenbauamt Stralsund konnten an einer Fertigteilträgerbrücke Belastungsversuche mit sukzessivem Rückbau des Fahrbahnaufbaus sowie Bruchversuche am Gesamtsystem und an ausgebauten Fertigteilträgern mit Ortbetonergänzung erfolgen. Mit Hilfe der hybriden Statik, also der Modifikation und Evaluation von Rechnungen anhand experimentell erlangter Messwerte, wurden die Einflüsse der Aufbauschichten quantifiziert und durch Auswertung weiterer Brückenbelastungsversuche verifiziert. Der Einfluss der Aufbauschichten betrug bei den untersuchten Brücken bis zu 28%. Seit der Inbetriebnahme des Belastungsfahrzeuges BELFA im März 2001 können Versuchlasten auch im großen Kräftekreislauf, d.h. am Gesamtsystem einschließlich Auflager- und Gründungssituation, selbstsichernd aufgebracht werden. Die Entwicklung des BELFA, seine Funktionsweise und seine Einsatzmöglichkeiten werden erläutert. Mit den Ergebnissen dieser Arbeit ist es zukünftig möglich, die notwendige Überlast bei Belastungsversuchen zur Kompensation der Einflüsse aus Straßenbelag, Bauwerksgeometrie und Kappen mit genauem Aufmaß der Bauwerksgeometrie und der Schichtdicken sowie mit ingenieurmäßigem Abschätzen der Materialkennwerte (E-Moduli) hinreichend genau zu bestimmen. Handlungsempfehlungen geben Hinweise zur generellen Vorgehensweise sowie für vereinfachte Rechenannahmen.
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Dinh, Quoc Dan. "Brazilian test on anisotropic rocks." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2011. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-76331.
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The present work describes investigations on the anisotropic strength behavior of rocks in the splitting tensile test (Brazilian test). Three transversely isotropic rocks (gneiss, slate and sandstone) were studied in the Lab. A total of more than 550 indirect tensile strength tests were conducted, with emphasis was placed on the investigation of the influence of the spatial position of anisotropic weakness plane to the direction of the load on the fracture strength and fracture or fracture mode. In parallel, analytical solutions were evaluated for stress distribution and developed 3D numerical models to study the stress distribution and the fracture mode at the transversely isotropic disc. There were new findings on the fracture mode of crack propagation, the influence of the disc thickness, the influence of the applying loading angle and angle of the loading-foliation for transversely isotropic materialInhalt der Arbeit sind Untersuchungen zum anisotropen Festigkeitsverhalten von Gesteinen beim Spaltzugversuch (Brazilian Test). Laborativ wurden drei transversalisotrope Gesteine (Granit, Schiefer und Sandstein) untersucht. Insgesamt wurden mehr als 550 Spaltzugversuche durchgeführt, wobei der Schwerpunkt auf die Untersuchung des Einflusses der räumlichen Lage der Anisotropieebene zur Richtung des Lasteintrages auf die Bruchfestigkeit und das Bruchbild bzw. den Bruchmodus gelegt wurde. Parallel dazu wurden analytische Lösungen zur Spannungsverteilung ausgewertet sowie numerische 3D-Modelle entwickelt, um die Spannungsverteilung sowie den Bruchmodus bei einer transversalisotropen Scheibe zu untersuchen. Es wurden neue Erkenntnisse zum Bruchmodus, der Rissausbreitung, des Einflusses der Scheibendicke, dem Einfluss des Lasteinleitungswinkel sowie des Winkels Lasteintrag - Anisotropieebene für transversalisotropes Material gewonnen
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Hütter, Geralf. "Multi-scale simulation of crack propagation in the ductile-brittle transition region." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-121281.
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In the present thesis the crack propagation in the ductile-brittle transition region is studied on two scales with deterministic models. In the macroscopic model the ductile failure is described by a non-local Gurson-model whereas the discrete void microstructure is resolved around the crack tip in the microscopic model. The failure by cleavage is not evaluated by means of a post-processing criterion but is modeled equivalently using a cohesive zone model on both scales. Thus, cleavage is not a priori identified with unstable crack propagation but the transition between stable and unstable mode of propagation is a result of the simulation. The problem of handling completely failed material within the framework of non-local damage models is pointed out. A method to overcome this problem is proposed and successfully applied. The case of contained plastic yielding at the crack tip is addressed with a modified-boundary layer model. The macroscopic simulations reproduce many features which are known from experiments like the formation of stretch zones, cleavage after initial ductile tearing, pop-ins with crack arrest, among others. The microscopic simulations substantiate the understanding of the macroscopically observed behavior. Systematic parameter studies are performed. Starting with considerations on the limit cases like pure ductile failure or the lower-ductile brittle transition region allows to separate the effects of the different constitutive parameters. Based on these results, a methodology is proposed to extract the macroscopic material parameters from experiments. This scheme is successfully applied to experimental data from literature. The results show that the behavior of a low-constraint specimen can be reliably predicted with the parameters extracted from a high-constraint specimenIn der vorliegenden Arbeit wird die Rissausbreitung im spröd-duktilen Übergangsbereich auf zwei Skalen mittels deterministischer Modelle untersucht. Das duktile Versagen wird im makroskopischen Modell durch ein nichtlokales Gurson-Modell beschrieben, während im mikroskopischen Modell die Porenmikrostruktur im Bereich um die Rissspitze diskret aufgelöst wird. Das mögliche Versagen durch Spaltbruch wird nicht, wie üblich, nachträglich durch ein spannungsbasiertes Kriterium bewertet. Stattdessen wird der Spaltbruch auf beiden Skalen durch ein Kohäsivzonenmodell abgebildet. Somit wird die Spaltbruchinitiierung nicht a priori mit instabiler Rissausbreitung gleichgesetzt. Vielmehr ist die Stabilität der Rissausbreitung ein Ergebnis der Simulationen. Außerdem wird das Problem der der Handhabung vollständig ausgefallenen Materials im Rahmen nichtlokaler Schädigungsmodelle herausgestellt. Es wird eine Methode vorgestellt, dieses Problem zu behandeln und erfolgreich angewendet. In den Simulationen wird der Fall vollständig eingebetteten, plastischen Fließens untersucht. Die Simulationen mit dem makroskopischen Modell geben viele Effekte wieder, die aus Experimenten bekannt sind. Dazu zählen die Ausbildung von Stretchzonen, die Spaltbruchinitiierung nach anfänglichem, duktilem Reißen oder lokale Instabilitäten mit Rissarrest. Die mikroskopischen Simulationen tragen zum Verständnis des makroskopisch beobachteten Verhaltens bei. In der vorliegenden Arbeit werden systematische Parameterstudien durchgeführt. Zunächst werden Grenzfälle wie das rein duktile Versagens oder der Spaltbruch in Abwesenheit der Mikroporen untersucht, um die Einflüsse der einzelnen Materialparameter abzugrenzen. Ausgehend von diesen Ergebnissen wird eine Prozedur vorgeschlagen, die Materialparameter des makroskopischen Modells Schritt für Schritt aus Experimenten zu bestimmen. Diese Prozedur wird erfolgreich auf experimentelle Daten aus der Literatur angewendet. Die Ergebnisse zeigen, dass es das entwickelte Modell erlaubt, das Verhalten einer Bruchmechanikprobe mit geringer Dehnungsbehinderung an der Rissspitze mit denjenigen Materialparametern vorherzusagen, die an Proben mit einer hohen Dehnungsbehinderung ermittelt wurden
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Gao, Shang-Lin, Jian-Wen Liu, Rong-Chuang Zhuang, Rosemarie Plonka, and Edith Mäder. "Healing Microcracks and Early Warning Composite Fractures." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-77852.
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A functional nanometer-scale hybrid coating layer with multi-walled carbon nanotubes (MWCNTs) and/or nanoclays, as mechanical enhancement to ‘heal’ surface microcracks and environmental barrier layer is applied to alkaliresistant glass (ARG) fibres. The nanostructured and functionalised traditional glass fibres show both significantly improved mechanical properties and environmental corrosion resistance. Early warning material damage can be achieved by carbon nanotubes concentrated interphases in the compositesEine funktionale nanometerskalige Hybridbeschichtung mit multi-walled carbon nanotubes (MWCNTs) und/oder Nanoclay wurde als mechanische Verbesserung des „Ausheilens“ von Oberflächen-Mikrorissen und Barriereschicht gegenüber Umwelteinflüssen auf alkaliresistente Glasfasern (ARG) appliziert. Die nanostrukturierten und funktionalisierten traditionellen Glasfasern zeigen signifikant verbesserte mechanische Eigenschaften und Korrosionsbeständigkeit. Die Frühwarnung des Materialversagens kann durch Carbon Nanotubes, konzentriert in der Grenzschicht der Composites, erreicht werden
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Guigal, Pierre-Michel. "Modélisation de la propagation infectieuse dans un réseau organise d'individus : apport de la prétopologie et de la géometrie fractale." Lyon, INSA, 1995. http://www.theses.fr/1995ISAL0064.
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Ce travail s'inscrit dans le cadre d'une modélisation du pronostic et du diagnostic d'une maladie dont la propagation est très liée à l'organisation de la population. Compte tenu des hypothèses, on met en évidence le fait que les caractéristiques de susceptibilité (déterminées à partir de relations locales) engendrent un type d'organisation globale de la population et constitue un facteur essentiel pour le pronostic. La tremblante du mouton nous sert de support concret dans notre démarche. La prétopologie nous a permis de formaliser un premier modèle ensembliste de l'organisation de la population et suggère qu'une loi d'échelle structure le réseau des relations locales. Cette propriété conduit à rechercher un comportement autosimilaire dans la constitution des clusters. Les méthodes syntaxiques de la reconnaissance de forme nous ont permis de dégager un modèle grammatical de la constitution d'un cluster au sein d'un réseau de relations locales. Celui-ci met en évidence la propriété d'autosimilarité qui nous autorise à formuler notre objectif d'analyse de la structure globale dans le cadre de la géométrie fractale. L'adaptation de la loi de distribution de Zifp-Mandelbrot à l'organisation hiérarchique de cette relation locale nous a permis d'en construire une méthode d'analyse paramétrique. L'intégration des données paramétriques issues de cette analyse dans un système d'équations différentielles nous a conduit à proposer un modèle compartimental d'un type nouveau pour une représentation analytique des phénomènes complexes de la diffusion dans un réseau. Afin de valider notre approche synthétique des phénomènes de diffusion dans un réseau organisé, nous avons construit un algorithme d'automate cellulaire pour la simulation des événements locaux de relation et de diffusion. Les résultats obtenus par la méthode analytique sont en accord avec ceux que donne le modèle distribué, et montrent que ce type d'approche est opérantThis report deals with forecast and diagnosis modelling of a disease wich spread is intimately linked to the population organisation. According to some hypothesis, we bring to the fore that the characteristics of susceptibility (defined as local relations) give raise to a kind of global organisation in the population. This characteristic forms a main factor in forecasting. Scrapie in sheep give us a concrete support for this approach. The pretopological theory allows us to design a simplified model of the population organisation and suggests that a scale law may structure a network of local relations. This property leads to look for a self similar process in the clusters consitution. We implement pattern recognition methods based on syntax to design a model of cluster constitution on a network of local relations. This on reveals the self similarity property wich allows us to formulate the aim of analysis in the frame of fractal geometry. An adaptation of the Zifp-Mandelbrot law to hierarchic organisation of the local relations enable us to propose a parametric method of anlaysis. We use these results in a new kind of compartmental model that give an analytic representation of the complex phenomena of spreak in a network. In order to validate this synthetic approach of complex spreak in a network, we propose a cellular automaton for simulation of local events as relation and spread. We obtain similar results by the two ways. This result suggests that the synthetic approach is operative
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Marin, Grégory. "Modélisation de données cliniques de grande dimension : application aux pathologies respiratoires." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20011/document.
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Cette thèse est consacrée à l'application et au développement de méthodes biostatistiques originales pour des applications médicales et cliniques concernant plus particulièrement les pathologies respiratoires. Il s'agit ainsi d'un travail de recherche transversale, visant à la modélisation de données hétérogènes, colinéaires et de grande dimension pour des applications cliniques. Un état de l'art traitant du diagnostic de l'asthme et de hyperactivité bronchique a tout d'abord été dressé, avant de proposer une première application statistique, prenant la forme de modèles de régressions multiples. Ce type de modèle étant particulièrement sensible à la dimension et la colinéarité des données, les chapitres suivants proposent plusieurs améliorations, après avoir explicité en détail l'enjeu et les méthodes actuelles d'analyse de données de grande dimension. Un premier modèle de classification hiérarchique non supervisé a été mis au point et appliqué au cas de la quantification du piégeage aérique. Un algorithme de régression Partial Least Square a également été mis en œuvre, prédisant une ou plusieurs variables Y à partir d'un set de variables X hétérogènes et colinéaires, ce qui a permis de mettre en évidence l'impact de l'âge sur les petites voies aériennes, tout en considérant de nombreux autres paramètres. Enfin, un algorithme d'analyse fractale a été créé, en vue de quantifier en une seule valeur la complexité spatiale et géométrique d'images de scanners thoraciques, cela constituant un innovant outil d'aide au diagnostic radiologiqueThis thesis outlines new statistic methods devoted to clinical and medical applications, dealing more precisely with respiratory diseases. Our goal was to model and analyze high-dimensional clinical data, often heterogeneous, and collinear. A clinical state of the art of asthma diagnosis and bronchial hyperreactivity was first stated, before proposing a first statistical application, which took the shape of multiple regression models. This type of models is particularly tricky when treating high-dimensional collinear data, which is why the other chapters are an enhancement of this first model. Firstly, a non-supervised hierarchical classification was carried out and applied to air trapping quantification. A Partial Least Square regression model was also executed, allowing prediction of one or more variables from a set of X variables, which allowed us to highlight the impact of age on small airway impairment. Finally, a fractal analysis was performed, in order to quantify the geometrical and spatial complexity of a CT scan image into a single value. This kind a prospective methodology, where the statistics are directly involved in the clinical work, represents a brand new tool which can help medical diagnosis
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Freche, Thierry. "Application des mesures fractales sur des images de manuscrit en niveaux de gris." Tours, 2000. http://www.theses.fr/2000TOUR4020.
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Le travail présente dans cette thèse se place dans le domaine de recherche sur l'analyse de l'écrit et du document. A l'origine de ce travail se trouvent les recherches qui ont mis en exergue la factualité de l'écrit. Au contraire de ces études antérieures, l'approche fractale ne se fait plus sur un espace unidimensionnel mais sur un degré deux ou trois. Dans un premier temps, la représentation de l'écriture par ses profils à partir d'images binaires permet de compléter les résultats obtenus à l'aide de la dimension fractale seule : régularité de la forme écrite, son penche, sa lisibilité, son caractère boucle ou la prédominance de ses détails à basse résolution d'analyse puis une avancée pertinente résultant de la généralisation de l'emploi des images en niveaux de gris a été mise en avant. Une nouvelle procédure de réhaussement de l'écrit, susceptible de nous fournir un masque binaire prenant en compte le trait de l'écrit en négligeant autant que possible son voisinage bruite a donc été développée. Puis l'utilisation systématique des fractales et l'usage des changements d'échelle associés à l'emploi de la géométrie et des mesures euclidiennes, a permis de dégager de nombreux paramètres liés aux traits, à la forme globale de la ligne et aux documents manuscrits ou imprimés.
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Pietschmann, Peter, Martina Rauner, Wolfgang Sipos, and Katharina Kerschan-Schindl. "Osteoporosis: An Age-Related and Gender-Specific Disease – A Mini-Review." Karger, 2009. https://tud.qucosa.de/id/qucosa%3A27601.
Full textAbstract:
Osteoporosis, a classical age-related disease and known to be more common in women than in men, has been reported increasingly often in men during the past few years. Although men at all ages after puberty have larger bones than women, resulting in greater bending strength, mortality after a hip fracture, one of the major complications of osteoporosis, is more common in men than in women. Sex hormone deficiency is associated with unrestrained osteoclast activity and bone loss. Even though estrogen deficiency is more pronounced in women, it appears to be a major factor in the pathogenesis of osteoporosis in both genders. In contrast to osteoporosis in postmenopausal women, the treatment of osteoporosis in men has been scarcely reported. Nevertheless, some drugs commonly used for the treatment of osteoporosis in women also appear to be effective in men. The aim of this study is to review primary osteoporosis in the elderly with particular emphasis on gender-related aspects.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Castropil, Wagner. ""Valor disgnóstico e prognóstico dos métodos de imagem na fratura de estresse da tíbia: correlação clínico-radiológica"." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/5/5151/tde-08082006-112053/.
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Um grande problema em atletas com fraturas por estresse é o tempo necessário para sua recuperação completa. Nenhum método de imagem tem se mostrado eficaz em apresentar dados objetivos com relação ao tempo de recuperação dos atletas em casos de fraturas por estresse. Dois grupos foram incluídos no nosso estudo: grupo I consistente de 21 atletas com suspeita clínica de fratura de estresse (13 masculinos, idade média de 31,62 9,39) e grupo II consistente de 10 atletas sem sinais clínicos de fraturas de estresse (grupo controle) (seis masculinos, idade média 29,80 3,94). Todos os indivíduos do grupo I tiveram seguimento mínimo de seis meses e foram submetidos ao mesmo protocolo de reabilitação. Todos os atletas foram submetidos à ressonância magnética e cintilografia óssea com intervalo, entre os exames, inferior a sete dias. Um índice quantitativo foi obtido utilizando a técnica de ROI, comparando o lado afetado com o contralateral não afetado. Esta análise quantitativa foi comparada à análise semiquantitativa da ressonância magnética. Ambos os métodos mostraram 100% de sensibilidade; entretanto, sinais inespecíficos foram encontrados em 40% dos atletas assintomáticos na ressonância magnética e na cintilografia óssea. A média de captação de MDP-Tc99m na perna sintomática foi estatisticamente diferente no grupo I (2,54 0,77) em comparação ao grupo II (1,05 0,11) (p < 0,001). Um índice de 1,30 foi considerado ponto crítico onde 99% dos atletas apresentarão diagnóstico de fratura de estresse. Uma equação de regressão foi obtida, associando o tempo de recuperação necessário para o atleta e o índice calculado. Na presente amostragem de pacientes, o índice obtido por meio da cintilografia óssea nos permite obter um método objetivo para estimar o apropriado tempo de recuperação após um diagnóstico de fratura por estresse da tíbia. Entretanto, mais estudos prospectivos, com maior amostragem, são necessários para comprovar nosso achado.A major problem in athletes with stress fractures is the length of resting time required for complete recovery. No imaging tool has been capable of offering objective data regarding the appropriate recovery time in athletes with stress fractures. Two groups of athletes were included in our study: Group I consisted of 21 athletes with clinical suspicion of tibial stress fracture (13 male; mean age + SD: 31.62 + 9.39) and, Group II consisted of 10 athletes without clinical signs of stress fracture (control group) (6 male; mean age + SD: 29.80 + 3.94). All individuals of Group I had minimum 6 months of follow up and the symptoms were recorded according to the same rehabilitation protocol. All athletes underwent to bone scintigraphy and MRI, with a mean interval between them no longer than 7 days. A quantitative index was obtained using ROI technique, comparing the affected to the non affected leg. This quantitative analysis was compared to a semi quantitative evaluation of MRI findings). Both methods showed 100% sensitivity; however, non specific signs were found in 40% of asymptomatic athletes either by MRI or by bone scan. The mean uptake of MDP-Tc99m in affected limbs were statistically different in Group I (2.54 + 0.77) in comparison to Group II (1.05 + 0.11) (p<0.001). An index of 1.30 was considered a critical point where 99% of athletes will present the clinical diagnosis of tibial stress fracture. A regression equation was obtained associating the time of recovery required for each athlete with the uptake index calculated. In the present sample of athletes the uptake index obtained through bone scintigraphy allowed us to obtain an objective method to estimate the appropriate recovering time after the tibial stress fracture diagnosis. However, more prospective studies using larger samples are needed to prove that assumption.
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Farda, Nurya Aghnia, and 方達. "Sanders CT Classification of Calcaneal Fracture Images using PCANet and Data Augmentation Techniques." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/bkr9rv.
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碩士國立中央大學
資訊工程學系
106
Calcaneus fracture has contributed to more than 60% of all adult fractures on the tarsal bones area. It is suggested that determining if a patient is having a calcaneal fracture can be very challenging. Doctors usually will perform an X-Ray and CT examination and doing additional tests with the patients. In order to give the best treatment, orthopedics need to know the type of the calcaneal fracture. However, it is still becoming a problem for them to determine the fracture type even with the help of CT images. Apart from that, machine learning and deep learning has grown significantly that it is able to solve complex tasks in many different fields. In biomedical fields, it has been used to detect and classify cancer tissues from medical images. In this research, we apply PCANet for the deep neural network architecture. Also, due to the small number of patients having the calcaneal fracture CT images which affect on the number of dataset, we employ a data augmentation technique to generate new dataset for the training phase. Our observation shows that the addition of augmented data for training can increase the detection accuracy significantly. In the end, we present a preliminary study regarding the possibility, opportunities, and challenges which are involved in building a robust calcaneal fracture detection system. Our experimental results show that our proposed approach can reach up to 70% of detection accuracy.
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Pranata, Yoga Dwi, and 优嘉逸. "Deep Learning and Speeded Up Robust Features (SURF) for Calcaneus Fracture Classification and Detection on CT Images." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/e6z4yr.
Full textAbstract:
碩士國立中央大學
資訊工程學系在職專班
105
Calcaneus, also called as heel bone, is the largest tarsal bone that forms the rear part of the foot. Cuboid bone articulates with its anterior and superior sides together with talus bone. Calcaneus is known to be the most fracture prone tarsal bone. Calcaneal fractures represent only about 2% of all fractures but 60% of tarsal bones fractures[1]. Based on subtalar joint involvement, calcaneal fractures can be categorized into two types: intraarticular fracture and extraarticular fracture. Intraarticular fractures are more common where posterior talar articular facet involves calcaneus. Patient data can be stored in several kinds of imaging format, e.g. Computer Tomography (CT) data. The CT images is the evolution of the medical images that recently used for determine the disease from the patient. It is a sequence of 2-D images that construct 3-D images. CT images contain a significant amount of information, such as fracture information in each slice of 2-D images that may not be thoroughly and accurately analyzed via visual inspection. This study proposed a new method to classify and detect the fracture in calcaneus bone CT images. In this experiment, we do the experiment in two dataset. The first one in just one Dicom case and the second one in the all dataset (two Dicom case). Both morphological operation and edge detection methods were combined in order to achieve better input in classification and detection processes. In the pre-processing step, the images were resized into the same size (224 x 224) to fit in the CNN method. After that the input images were converted in the grayscale images. After that, the images were subtracted with the images mean. Convolutional Neural Network was also applied in the classification process in order to classify the bone into several classes. Two classes were classified (fracture and non-fracture) from three views that are coronal, transversal, and sagittal view. After classification, the detection were done from the fracture class and determine in which part of calcaneus bone was broken. The detection is from three views also that is transversal, sagittal, and coronal views.
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Schuldt, Stefan. "Analysis of rate-dependent deformation and fracture phenomena during cutting of viscoelastic materials." Doctoral thesis, 2017. https://tud.qucosa.de/id/qucosa%3A30989.
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The cutting of foods is characterized by deformation, fracture and friction processes, and the viscoelastic properties of the cutting materials determine their rate-dependent cutting behavior. This is responsible for uncontrolled fracture and deformation events with increasing cutting velocity. There is a significant information deficit regarding the assignment of material properties and cutting parameters, as well as regarding a process description for industrial high-speed cutting.
The aim of the work is the analysis of the velocity-dependent cutting behavior of foods up to the high-speed range. The focus is on the deformation and fracture phenomena, analysed by methods of classical material analysis but also associated cutting experiments performed in the range from low to high cutting velocities. For high-speed analyses, a test station enabling cutting velocities of up to 10 m/s was designed. To identify relevant material and cutting parameters and to establish a systematic experimental program, elastomer-based model systems with controllable viscoelastic profiles were developed. The results of the respective investigations were further verified for foods. The velocity-dependent deformation behavior during cutting could be described by dynamic-mechanical material analyses in the frequency range. Cutting force slopes at the beginning of the cutting process correlated with the complex moduli and were furthermore dependent on the cutting velocity; this dependency corresponded to the frequency behavior from material analysis. The fracture properties could be attributed to ductile (polymeric systems) or brittle behavior (cellular plant systems). Confectionary products had a strong temperature- and time-dependent behavior with ductile-brittle transition within the experimental conditions.
The results obtained demonstrate that there is a significant relationship between viscoelasticity and velocity-dependent cutting behavior. They allow a phenomenological process description of high-speed cutting and can be used as a basis for the balancing of cutting forces and as input parameters for numerical analyses of the cutting process.Das Schneiden von Lebensmitteln ist geprägt durch Deformations-, Bruch- und Reibvorgänge. Dabei bestimmen die viskoelastischen Eigenschaften der Schneidgüter deren geschwindigkeitsabhängiges Schneidverhalten. Dies führt mit zunehmender Schneidgeschwindigkeit zu unkontrollierten Bruch- und Deformationsereignissen. Dabei besteht ein Informationsdefizit bei der konkreten Zuweisung von Materialeigenschaften und Schneidparametern sowie einer Verfahrensbeschreibung für das industrielle Hochgeschwindigkeitsschneiden. Ziel der Arbeit ist die Analyse des geschwindigkeitsabhängigen Schneidverhaltens von Lebensmitteln bis in den Hochgeschwindigkeitsbereich. Der Fokus richtet sich auf die Untersuchung der Teilphänomene Deformation und Bruch durch Methoden der klassischen Materialanalyse sowie zugeordnete Schneidexperimente im Bereich von niedrigen bis hohen Schneidgeschwindigkeiten. Für entsprechende Hochgeschwindigkeitsanalysen wurde ein Versuchsstand mit Schneidgeschwindigkeiten von bis zu 10 m/s konzipiert. Zur Identifikation relevanter Material- und Schneidparameter und zur Aufstellung des systematischen Versuchsprogramms wurden Modellsysteme auf Elastomerbasis mit steuerbarem viskoelastischen Profil entwickelt. Die Ergebnisse wurden für Lebensmittel verifiziert. Das geschwindigkeitsabhängige Deformationsverhalten beim Schneiden konnte durch dynamisch-mechanische Materialanalysen im Frequenzbereich beschrieben werden. Dabei korrelierten Kraftanstiege zu Beginn des Schneidvorganges mit den Komplexmoduln. Die Anstiege zeigten eine Abhängigkeit von der Geschwindigkeit; diese entsprach dem Frequenzverhalten aus der Materialanalyse. Die Brucheigenschaften konnten produktspezifisch duktilem (polymere Systeme) oder sprödem Verhalten (zelluläre, pflanzliche Systeme) zugeordnet werden. Zuckerwaren zeigten ein stark temperatur - und zeitabhängiges Verhalten mit duktil-sprödem Übergang innerhalb der Versuchsbedingungen. Die gewonnenen Erkenntnisse demonstrieren den Zusammenhang von Viskoelastizität und geschwindigkeitsabhängigem Schneidverhalten. Sie erlauben eine phänomen ologische Verfahrensbeschreibung des Hochgeschwindigkeitsschneidens und können als Basis für die Bilanzierung von Schneidkräften und als Eingangsparameter für numerische Analysen des Schneidvorganges dienen.