Добірка наукової літератури з теми "Flexion pure"
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Статті в журналах з теми "Flexion pure":
1
Got, C., B. G. Vopat, P. K. Mansuripur, P. M. Kane, A. P. C. Weiss, and J. J. Crisco. "The effects of partial carpal fusions on wrist range of motion." Journal of Hand Surgery (European Volume) 41, no. 5 (October 9, 2015): 479–83. http://dx.doi.org/10.1177/1753193415607827.
Анотація:
The objective of this investigation was to evaluate the effects of different partial wrist fusions on wrist motion. A total of 20 cadaveric wrists were tested in the intact state and after undergoing either a four-corner fusion or 2- and 3-bone fusion. The moment-rotation behaviour was measured in 24 directions of wrist motion about the forearm axis. The 2- and 3-bone fusion groups demonstrated increased radial deviation and pure flexion. Pure flexion was decreased in the four-corner fusion group. Radial extension and pure extension were decreased in all treatments compared with normal range of motion. Increasing the number of carpal bones within the fusion construct did not alter the functional axis of the wrist. Essentially equivalent motion is possible with 2-bone, 3-bone and four-corner fusions, with the exceptions of pure flexion and radial deviation. This data may influence surgeons when choosing between treatment methods. Level of evidence: N/A
2
Qiu, Tian-Xia, Ee-Chon Teo, and Qing-Hang Zhang. "VALIDATION OF FINITE ELEMENT MODELS OF THORACOLUMBAR T11-T12 AND T12-L1 AND COMPARISON OF THEIR BIOMECHANICAL RESPONSES." Journal of Musculoskeletal Research 09, no. 03 (September 2005): 133–43. http://dx.doi.org/10.1142/s0218957705001576.
Анотація:
The objective of this study was to build and validate the FE models of thoracolumbar junctional T11-T12 and T12-L1 functional spinal units (FSUs) and compare the biomechanical responses of the two FSUs under physiological loading modes: flexion, extension, lateral bending and axial rotation. Anatomically accurate FE models of thoracolumbar T11-T12 and T12-L1 FSUs were developed and validated against published experimental results in terms of load displacement responses and range of motion (ROM) under flexion and extension pure moments of 7.5 Nm, left and right lateral bending pure moments of 7.5 Nm and left and right axial torque of 7.5 Nm. The overall responses predicted by the T11-T12 and T12-L1 FE models showed differences in stiffness under different load configurations. Amongst all loading configurations, the motions at T11-T12 and T12-L1 were the stiffest under axial torque. The lateral bending motions of T11-T12 and T12-L1 were relatively flexible. Under sagittal moments, the motion in extension was greater than in flexion at level T11-T12, while the rotation in flexion was greater than in extension at level T12-L1.
3
Frediani, Gabriele, Federica Vannetti, Leonardo Bocchi, Giovanni Zonfrillo, and Federico Carpi. "Monitoring Flexions and Torsions of the Trunk via Gyroscope-Calibrated Capacitive Elastomeric Wearable Sensors." Sensors 21, no. 20 (October 9, 2021): 6706. http://dx.doi.org/10.3390/s21206706.
Анотація:
Reliable, easy-to-use, and cost-effective wearable sensors are desirable for continuous measurements of flexions and torsions of the trunk, in order to assess risks and prevent injuries related to body movements in various contexts. Piezo-capacitive stretch sensors, made of dielectric elastomer membranes coated with compliant electrodes, have recently been described as a wearable, lightweight and low-cost technology to monitor body kinematics. An increase of their capacitance upon stretching can be used to sense angular movements. Here, we report on a wearable wireless system that, using two sensing stripes arranged on shoulder straps, can detect flexions and torsions of the trunk, following a simple and fast calibration with a conventional tri-axial gyroscope on board. The piezo-capacitive sensors avoid the errors that would be introduced by continuous sensing with a gyroscope, due to its typical drift. Relative to stereophotogrammetry (non-wearable standard system for motion capture), pure flexions and pure torsions could be detected by the piezo-capacitive sensors with a root mean square error of ~8° and ~12°, respectively, whilst for flexion and torsion components in compound movements, the error was ~13° and ~15°, respectively.
4
Gál, J. M. "Mammalian spinal biomechanics. I. Static and dynamic mechanical properties of intact intervertebral joints." Journal of Experimental Biology 174, no. 1 (January 1, 1993): 247–80. http://dx.doi.org/10.1242/jeb.174.1.247.
Анотація:
Four-point bending was used to apply pure extension and flexion moments to the ligamentous lumbosacral spine and pelvic girdle of monkey (Macaca fascicularis), rabbit (domestic and wild, Oryctolagus cuniculus), badger (Meles meles), wallaby (Wallabia rufogrisea frutica), sheep (Ovis aries), seal (Phoca vitulina) and tiger (Panthera tigris). The absolute ranges of angular change in lumbar-lumbar joints (from X-radiographs) were considerable and similar in monkey and wallaby (greater in flexion) and in rabbit and badger (symmetrical in extension and flexion). Mass-specific bending comparisons showed that monkey and seal joints were the most and least resistant, respectively, to these moments. The patterns of mobility showed no clear scaling effects. Subsequently, additional ligamentous joint complexes (three vertebrae and two intervertebral discs) of monkey, wallaby, tiger, jaguar (Panthera onca) and seal (Halichoerus grypus) were subjected to cyclic extension and flexion moments. Changes in intervertebral angle (y, from X-radiographs) were modelled as functions of applied specific bending moments (x):y=A(1-e-Bx). A and B values represented bending capacities and joint compliances respectively. Homologous monkey and wallaby joints had considerable flexion capacities, with low compliances. Homologous jaguar and tiger joints had limited flexion capacities, but greater compliances. The data suggest that flexion resistance may be controlled by different mechanisms in different species.
5
Malavolta, Michele, Andrea Cochetti, Silvio Mezzari, Alberto Residori, and Gianpietro Lista. "Evaluation of Femoral–Tibial Flexion Gap in Total Knee Arthroplasty with Everted or Lateralized Patella." Journal of Knee Surgery 32, no. 10 (November 9, 2018): 1028–32. http://dx.doi.org/10.1055/s-0038-1675422.
Анотація:
AbstractIntraoperative patellar position (eversion, lateralization, or in situ) influences the ligamentous balancing in knee flexion and thereby the correct positioning of the femoral component during total knee arthroplasty. The correct ligament balancing is crucial when, as in our experience, prostheses with medial pivot design are used. It was shown that the flexion gap in the normal knee is not rectangular and that the lateral compartment is significantly slacker than the medial. Therefore, to obtain a correct kinematics of a medial pivot anatomical prosthesis, it is essential to recreate an anatomical flexion gap slacker in the lateral compartment. We conducted a prospective study on a consecutive series of 87 total knee prostheses. The objective of this study is to evaluate the femoral external rotation angle in each patient with everted patella as well as with pure subluxated patella. The purpose of this study is to offer guidance about the optimal femoral rotation angle to achieve best outcomes of a knee replacement. The evaluation was done using an instrument developed by Medacta International (Switzerland) with our direct collaboration (Tensor, Medacta, Switzerland) and standardizing the basic conditions of each patient (knee 90 degrees flexed, medial transquadricipital surgical access, lateral displacement of the patella, tourniquet inflated at 250 mm Hg, spinal anesthesia). Each group was subdivided into subgroups according to gender, preoperative varus or valgus deformity, and patellar height. Our study advises against evaluating the flexion gap with everted patella due to high risk of underestimation of the lateral compartment laxity (differences up to + 3 degrees with pure subluxated patella compared with everted patella).
6
Teo, Ee-Chon, Tian-Xia Qiu, Kai Yang, Hong-Wan Ng, and Kim-Kheng Lee. "BIOMECHANICAL EFFECT OF THORACIC POSTERIOR VERTEBRAL ELEMENTS ON PATTERNS OF THE LOCI OF INSTANTANEOUS AXES OF ROTATION IN SAGITTAL PLANE." Journal of Musculoskeletal Research 07, no. 03n04 (September 2003): 191–200. http://dx.doi.org/10.1142/s0218957703001095.
Анотація:
The objective of this study was to investigate the effect of the thoracic posterior vertebral elements on the kinematics of T10–T11 motion segment in sagittal plane by assessing the locations and loci of the instantaneous axes of rotation (IARs) under flexion and extension pure moments using finite element (FE) method. The IAR has proven to be a useful parameter of vertebral motion and it is an indicator of spinal instability. An anatomically accurate FE model of thoracic T10–T11 functional spinal unit (FSU) was used to characterize the loci of centers of rotation for the intact T10–T11 FSU and disc body unit (without posterior vertebral elements) under flexion and extension pure moments. The centers of rotation predicted by the intact model and disc body unit of thoracic T10–T11 for both flexion and extension were directly below the geometrical center of the moving vertebra. However, the loci of the IARs were significantly affected by the posterior vertebral elements. The loci of instantaneous axes of rotation for the intact model were tracked superoanteriorly and inferoposteriorly for flexion and extension with rotation, respectively. While, for the disc body unit, the loci were detected to diverge lateroinferiorly from the mid-height of the intervertebral disc, they converge medio-inferiorly toward the superior endplate of the inferior vertebra T11 with increased moment. These findings may offer an insight to better understanding the kinematics of the human thoracic spine and provide clinically relevant information for the evaluation of spinal stability and implant devices functionality.
7
Dumas, G. A., D. A. Bednar, and J. P. Dickey. "Comparison of porcine and human lumbar spine flexion mechanics*." Veterinary and Comparative Orthopaedics and Traumatology 16, no. 01 (2003): 44–49. http://dx.doi.org/10.1055/s-0038-1632753.
Анотація:
SummaryAnimal models have been proposed as an alternative to human spinal specimens for in vitro mechanical testing due to the limited availability, poor reproducibility, high cost, and potential health risk associated with human specimens. The purpose of this study was to directly compare the flexion biomechanics of porcine and human lumbar spines. We determined the range of motion, laxity zone and the stiffness under pure-moment flexion loading. The porcine and human specimens showed qualitative similarities in mechanical behaviour. However the porcine specimens demonstrated a number of quantitative differences including a less-stiff, more extensive, low-stiffness region around the neutral position and a larger flexion range of motion. The results suggest that the porcine lumbar spine may be a potential model for the human lumbar spine for certain in vitro mechanical tests including comparisons between spinal fixation constructs.
8
Davis, Kermit G., Riley E. Splittstoesser, and William S. Marras. "Kinematic contribution and synchronization of the trunk, hip, and knee during free-dynamic lifting." Occupational Ergonomics 3, no. 2 (July 24, 2003): 99–108. http://dx.doi.org/10.3233/oer-2003-3202.
Анотація:
Although there have been numerous studies evaluating the difference between stooped and squat lifting styles, there remains a lack of understanding of whole body kinematics during unrestricted lifting. The current study evaluated nine males and nine females while lifting two box weights (9.1 kg, 18.2 kg) from five origins below the waist (0, 19, 38, 57, and 76 cm above the floor) and from three task asymmetries (sagittally symmetric, 45° clockwise, 45° counter-clockwise). While the lifting style was significantly influenced by the height of lift origin and to a lesser extent gender, box weight, and task asymmetry, none of the conditions resulted in pure squat or stoop lifting style. However, for lifts above knee height, the lifting style resembled more of a stoop lift while lifts originating below knee height were more of a squat lift. As the origin moved closer to the floor, participants relied more on their hips to accomplish the sagittal flexion but overall adopted a more coordinated whole-body lifting style. All together, as more sagittal flexion is required, more joints are relied upon in a more coordinated effort. The current study indicates that caution needs to be exercised when applying results of pure squat or pure stoop lifting studies to free-style (realistic) lifting.
9
WILLIAMS, N. W., J. M. T. PENROSE, and D. R. HOSE. "Computer Model Analysis of the Swanson and Sutter Metacarpophalangeal Joint Implants." Journal of Hand Surgery 25, no. 2 (April 2000): 212–20. http://dx.doi.org/10.1054/jhsb.1999.0352.
Анотація:
A representative model which mimics the behaviour of Silastic® finger metacarpophalangeal joint implants was constructed using a finite element software package. The modelled implants were moved through a range of flexion, lateral deviation and a combination of both. Pistoning of both implants stems occurred within the modelled medullary cavities. For equivalent flexion angles, the Sutter implant produced a higher stress field than the Swanson implant, and the field was positioned at the central hinge mechanism. In both implants, lateral deviation increased the internal stress concentrations more than when pure flexion was applied. Overall the Swanson style of implant had lower stress magnitudes than the Sutter implant, and it is predicted that the Sutter implant will be more likely to fail than the Swanson. The failure mode for the Sutter implant would be at the central hinge region. The Swanson implant is likely to fail at the central hinge-stem interface regions.
10
Karam, Bashaer Hameed, Hussain S. Hasan, and Hassan Thabit Saeed. "A study on the association of cervical spondylosis severity, as indicated by cervical motions, with hearing impairment." Biomedical Human Kinetics 13, no. 1 (January 1, 2021): 43–48. http://dx.doi.org/10.2478/bhk-2021-0006.
Анотація:
Abstract Study aim: The present study investigates the possible relation between the limitation of cervical motion in a patient with cervical spondylosis and hearing impairment. Material and methods: Cross-sectional research was performed based on 60 participants suffering from cervical spondylosis (CS) selected from an orthopaedic and physiotherapy department. The data collection techniques included questionnaire, electronic tools, measurements with a mechanical device including measuring the cervical range of motion (ROM) by goniometer, and physical examination including pure tone audiometry (PTA) and tympanogram. Results: Right rotation was the most common limitation, which affected 43 patients, followed by left rotation limitation, which was recorded in 40 patients. The extension, left lateral flexion, flexion, and right lateral flexion limitation showed less effect. Conclusions: Left rotation limitation was found to be an independent predictor of hearing impairment especially in men. Age was also a risk factor for sensory neural hearing loss (SNHL). These findings are important in the facilitation of investigating SNHL in cervical spondylosis patients.
Дисертації з теми "Flexion pure":
1
Dratz, Bruno. "Modélisation numérique du planage et caractérisation du comportement en flexion alternée des tôles d'acier." Paris, ENMP, 2009. http://www.theses.fr/2009ENMP1691.
Анотація:
La première étape de la fabrication d'une voiture chez PSA PEUGEOT CITROEN est la construction de la carrosserie. Elle est réalisée à l'aide de tôles minces fournies sous forme de bobines, qui sont tout d'abord découpées puis embouties pour obtenir la forme souhaitée et assemblées. Ces tôles sont légèrement cintrées car elles sont découpées dans la bobine, elle-même courbée. Pour éviter ce cintrage, une opération de planage est effectuée avant emboutissage. L'objectif de la thèse est d'étudier cette opération. Pour comprendre ce procédé, trois modélisations ont été construites : la première est une simulation par éléments finis, la deuxième est un modèle analytique et la troisième, un modèle pseudo analytique. Les trois modèles se sont révélés équivalents en terme de précision ; le modèle analytique a montré son atout vis-à-vis du temps de calcul. Pour prendre en compte le comportement cyclique des tôles dans les simulations, une machine de flexion pure a été conçue, fabriquée et mise au point au CEMEF. Après avoir défini la taille optimale des éprouvettes pour réaliser les essais, des lois de comportement ont pu être obtenues avec un programme d'identification inverse réalisé sur MATLAB. Une petite planeuse a été fabriquée au CEMEF et son instrumentation a permis de valider les simulations numériques et d'estimer les erreurs de prédictions. Des essais ont aussi été effectués chez PSA PEUGEOT CITROEN pour comparer les modèles numériques et les machines du Groupe. Cette comparaison a permis de mettre en évidence le cédage des machines. Ce phénomène d'abord observé expérimentalement a pu être modélisé puis introduit dans les modèles numériquesThe first step in car manufacturing is the construction of the body. It is produced using thin sheets supplied in coils. These coils are first cut out and then deep drawn to obtain the desired shape and assembled. These blanks are slightly curved because they are cut from the coil which is curved. To prevent plate curvature, a leveling operation is performed. The objective of this work is to study this operation. To understand the process, three models were developed : the first one is a finite elements model, the second one is an analytical model and the fhird one a semi analytical model. The three models were found to be equivalent in terms of precision ; the analytical model has shown its strength in terms of computational time. To take into account the cyclic behaviour of blank material in the simulations, a pure bending machine was manufactured out CEMEF. Optimal specimen sizes for testing were determined and beheviour laws were identified with an inverse MATLAB identification. A small leveler was also developed at CEMEF. The instrumentation of this machine served to validate the numerical simulations and to estimate the predictions errors. Testing campaigns were performed at PSA PEUGEOT CITROEN plants to compare numerical models and PSA PEUGEOT CITROEN levellers. These comparisons highlighted the elastic deformation of the frame. This elastic behaviour was quantified and taken into account in numerical models
2
Rodriguez, Bravo Harold. "Diseño de los mecanismos de excitación y centrado de una máquina de ensayos de fatiga por flexión pura." Bachelor's thesis, Pontificia Universidad Católica del Perú, 2018. http://hdl.handle.net/20.500.12404/14290.
3
Mikail, Solange Corrêa. "Avaliação da terapia por laser de arsenito e gálio em tendinite de cavalos Puro Sangue Inglês de corrida." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/10/10136/tde-23122008-101158/.
Анотація:
Para avaliar a eficácia do laser de arsenito de gálio em acelerar a cicatrização tendínea em cavalos PSI de corrida com lesão no tendão flexor digital superficial, foram realizados dois experimentos, primeiro (E1) com 14 casos clínicos onde as lesões foram decorrentes do esporte em um dos membros torácicos, o segundo (E2) com cinco casos experimentais, onde as lesões foram induzidas com colagenase em ambos os membros torácicos. No E1, após a detecção da lesão no tendão flexor digital superficial por exame ultra-sonográfico, todos os animais receberam antiinflamatório não esteróide associado à dimetilsulfóxido por via intravascular, crioterapia no local da lesão, e caminharam ao passo duas vezes ao dia por 15 minutos durante os 30 dias de acompanhamento. Os membros tratados pertenceram a onze animais que receberam uma sessão diária de laser de arsenito de gálio na dose de 20 J/cm2, realizadas durante 10 dias consecutivos, após término do antiinflamatório e da crioterapia. Os membros controle pertenceram a três animais, os quais não foram tratados com laser. No E2, após identificação das lesões, foram escolhidos aleatoriamente um membro torácico controle e outro a ser tratado por laser em cada animal. Da mesma forma, estes animais foram mantidos a passo e receberam o mesmo protocolo de laserterapia que os membros tratados do E1. Todos os membros foram avaliados através de exames ultra-sonográficos, utilizando-se como parâmetros o paralelismo das fibras tendíneas em corte longitudinal; a ecogenicidade, a área do tendão, a área da lesão e a porcentagem de ocupação da lesão em corte transversal. No E1, os membros controle não apresentaram diferença significativa (P>0,05) nos parâmetros avaliados entre os dias 0 e 30. Nos membros tratados, a área do tendão também não apresentou diferença significativa (P>0,05) entre os dias analisados, porém houve diminuição muito significativa nos escores de ecogenicidade e paralelismo (P<0,001), assim como diminuição no tamanho da lesão (P<0,05) e na porcentagem de ocupação da lesão (P<0,05). No E2 também não houve diferença significativa entre os dias em todos os critérios avaliados nos membros controles (P>0,05). Nos membros tratados a ecogenicidade, o paralelismo e o tamanho do tendão, não sofreram alterações significativas (P>0,05) entre os dias avaliados, porém o tamanho da lesão (P<0,05) e a porcentagem de ocupação da lesão (P<0,01) apresentaram diminuição significativa. O laser de arsenito de gálio na dose de 20 J/cm2 mostrou-se eficaz em acelerar a reparação da lesão tendínea nos membros tratados em relação aos membros controle, tanto no grupo de casos clínicos quanto no grupo experimental, quando comparados aos 30 dias do aparecimento da lesão. Esses resultados sugerem a participação positiva do laser de arsenito de gálio nos resultados e a validação do mesmo no tratamento da tendinite do flexor digital superficial de cavalos Puro Sangue Inglês de corrida.This study conducted two trials to evaluate the efficacy of Gallium Arsenide Laser in the speed of the healing process of superficial digital flexor tendon (SDFT) lesions in thoroughbred horses. One trial group (T1) comprises 14 horses with lesions, which resulted from the sport, in the SDFT in one of the front limbs. The other trial group (T2) was formed by five horses that had lesions induced in both front limbs by collagenase injection. In the T1, after the detection of the lesion in the SDFT by ultrasonography all horses were treated by intravenous injection, once a day, over five days, with an association of two AINS: phenylbutazone and dimethylsulfoxide. Cryotherapy was also applied on the affected tendon (three times a day over five days) and the horses were kept in stalls and allowed controlled exercise (hand-walked twice daily for 15 minutes) during the 30 days of the study. The treated limbs belong to 11 horses that received laser sessions once a day for ten days at a dosage of 20J/cm2. These sessions started after the AINS association and cryotherapy. The control limbs belong to the other three horses that received the same treatment, except by the laser sessions. In the T2, after the detection of the lesion, a limb from each horse was randomly chosen to be the control limb and the other limb was treated by laser. These horses were also kept in stall under controlled exercise and the treated limb was under the same laser protocol that T1. All horses were evaluated by two ultrasonographic exams with a 30-day interval. The parameters evaluated were: the fiber alignment, the echogenicity, the tendon area, the lesion area and the proportion of the cross sectional area involved. In the T1, the control limbs showed no significant difference (p>0,05) in the echogenicity, the fiber alignment, the tendon area, the lesion area or the proportion of the cross sectional area involved, between the day 0 and 30. The treated limb, didn´t show any significant difference of the tendon area, but showed a significant difference on the echogenicity (P<0,001), the fiber alignment (P<0,001), the lesion area (P<0,05) and the proportion of the cross sectional area involved (P<0,05). In the T2, only one limb received the laser treatment, the other limb acted as a control. The control limbs showed no significant difference (P>0,05) in the echogenicity, the fiber alignment, the tendon area, the lesion area and the proportion of the cross sectional area involved between the day 0 and 30. The treated limbs showed no significant difference (P>0,05) in the echogenicity, the fiber alignment and the tendon area, but showed significant difference in the lesion area (P<0,05) and the proportion of the cross sectional area involved (P<0,01). The treatment dose of 20J/cm2 of gallium arsenide laser was efficient in speeding the healing process of SDFT lesions of the laser treated limbs in both groups (T1 and T2), when compared with the control limbs, at 30 days of the onset of the lesion. The group which lesions occurred due to the sport (T1) had a better response to the treatment than the group which lesions were induced by collagenasis (T2). The limbs treated by laser showed a positive response which validates the use of the Gallium Arsenide laser for the treatment of tendinitis in the Superficial Digital Flexor in race horses.
4
Greig, Carolina Roxana. "Relevância da ultra-sonografia dos tendões flexores em cavalos puro sangue de corrida na adaptação ao treinamento." Universidade Federal de Santa Maria, 2002. http://repositorio.ufsm.br/handle/1/9997.
Анотація:
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe cross-sectional area (CSA) of the superficial digital flexor tendon (SDFT) and deep digital flexor tendon (DDFT) of twenty four thoroughbreds was ultrasonographically evaluated before and during their initial training to determine the effect of exercise on the tendon CSA, texture and echogenicity to characterize the response to training. Ultrasonographic transverse images of the left forelimb were obtained every fifteen days. The SDFT CSA of zones IA and IIIA showed a decrease (p<0.05, f=0.010 e f=0.023 res.) during the breaking and training period and an increase (p< 0.05) of zone IIIC (f=0.039). Evaluating just the training period, SDFT CSA results of zones IA, IIIA and IIIC were similar. The DDFT showed no variation during the breaking phase but when the training phase was evaluated there was a decrease(P<0.05) in zones IA (f=0.006) and IIIA(f=0.006). Evaluating both breaking and training periods the DDFT showed a decrease (P<0.05) in zones IA (f=0.027), IIIA (f=0.0001) and IIIB (f=0.0031). Fiber texture and tendon echogenicity showed no significant difference between breaking and last reading during training. This study failed to provide evidence of ultrasonographic image variations that would indicate adaptation of both SDFT and DDFT to exercise during training of thoroughbred horses.
Vinte e quatro potros Puro Sangue de Corrida (PSC), com dois anos de idade foram avaliados ultra-sonograficamente, durante o período final da doma e início de treinamento, através da imagem transversal dos tendões flexor digital superficial (TFDS) e profundo (TFDP). As avaliações foram realizadas com intervalos de 15 dias. A área transversal (AT), a textura dos ecos e a ecogenicidade dos tendões foram avaliadas nas sete zonas da região metacarpiana através de um programa de mensuração de imagens do próprio aparelho de ultra-sonografia. Durante a doma e treinamento houve diminuição da AT na zona IA e IIIA (p<0,05, f=0,001 e 0,0266 resp.) e aumento da zona IIIC (p< 0,05 f=0,0391) do TFDS. Ao considerar apenas o período do treinamento, o resultado foi semelhante (p<0,05) na zona IA (f=0,010), IIIA (f=0,023) e IIIC (f =0,0391). O TFDP apresentou uma diminuição na AT durante a doma e treinamento nas zonas IA, IIIA e IIIB (p<0,05, f=0,027; f=0,0001 e f=0,0031 resp.) e nas zonas IA e IIIA durante o treinamento (p<0,05, f=0,006 e f=0,006, resp.). No período da doma a AT do TFDP não variou significativamente. A textura dos ecos se manteve homogênea e não houve variação significativa na ecogenicidade dos tendões entre o período da doma e após quatro meses de treinamento. A avaliação quinzenal da AT, textura e ecogenicidade das zonas IA a IIIC dos TFDS e TFDP não apresentou variações ultra-sonográficas que sugerissem adaptação ao regime de exercício ao qual os potros PSC estavam sendo submetidos.
5
Vasconcelos, Geilson Márcio Albuquerque de. "Verificação simultânea dos estados limites últimos e de serviço em análises não-lineares de peças de concreto armado submetidas à flexão pura." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-10062005-150528/.
Анотація:
Neste trabalho foram discutidos os aspectos de dimensionamento e verificação da segurança de elementos estruturais de concreto armado considerando a não-linearidade dos materiais. O estudo abordou uma nova proposta para a verificação simultânea dos estados limites últimos (ELU) e dos estados limites de serviço (ELS) para elementos de concreto armado submetidos à flexão, voltada especialmente para aplicações considerando a não-linearidade física utilizando o método dos elementos finitos. As propostas alternativas apresentadas na consideração de coeficientes minoradores das resistências dos materiais, trataram da utilização de valores médios para as relações tensão-deformação e para as resistências dos materiais; valores de referência que permitiram a composição de coeficientes globais de segurança, que independem da ruptura ser causada por esgotamento da capacidade resistente do concreto ou do aço e, finalmente, valores médios para as relações tensão-deformação no aço e no concreto, com limitação das resistências em seus valores de projeto. Foram analisadas seções transversais retangulares e do tipo T submetidas à flexão pura, com o uso das propostas alternativas. Foram, também, estudadas vigas isostáticas e hiperestáticas incluindo a verificação das reservas da capacidade resistente da estrutura, sendo que foi considerada a redistribuição dos esforços internos no caso hiperestático. As análises realizadas serviram de base para assumir-se que a terceira proposta anteriormente citada, é a mais adequada e a que atendeu, simultaneamente, às verificações dos ELU e ELS; o que a torna viável para aplicações práticasThe present work deals with dimensioning and verification of the safety conditions of reinforced concrete structural elements, taking into account the material non-linearity. It includes a new proposal for the simultaneous verification of the ultimate limit states (ULS) and the serviceability limit states (SLS) for reinforced concrete bending elements, enhancing finite element applications with physical non-linearities. The alternative proposals for the material safety factors include the use of mean values for the stress-strain relationships and the strength of materials; reference values that allow the composition of global safety coefficients that do not dependent on the type of failure, brittle in the concrete or ductile in the steel and, finally, means values for the concrete and steel stress-strain relationships, keeping the stresses always lower than the design strength values. Rectangular and T-type cross-sectional areas in pure bending were analyzed, using the alternative proposals. Statically determinate and hyperstatic beams were also studied to verify the safety conditions, including the redistribution of the internal forces in the hyperstatic cases. According to the analyses performed it is apparent that the third proposal is the most adequate and satisfies simultaneously the ULS and SLS verifications, being viable for practical applications
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Makni, Amine. "Comportement mécanique et physico-chimique en flexion 4 points et en température des couches d'oxydes formées sur le fer et sur l'acier mi-dur." Compiègne, 2007. http://www.theses.fr/2007COMP1700.
Анотація:
Ce travail s'intéresse aux problématiques rencontrées lors du laminage à chaud des tôles d'acier mi-dur. Les couches de calamine formées pendant ce procédé de mise en forme peuvent, en effet, être à l'origine de différents défauts de surface. Ceci est lié aux propriétés de ces calamines. Notre contribution porte donc sur le suivi du comportement mécanique et physico-chimique de ces oxydes développés sous atmosphères oxydantes humides. Suite à une étude mécanique réalisée à l'aide d'essais de flexion 4 points, nous avons déterminé une loi de comportement de la ferrite A ; il s'agit d'une loi de viscosité parfaite de type Norton qui caractérise le comportement mécanique du fer pur entre 500 et 800°C. L'analyse élémentaire des oxydes de fer montre une stabilité physico-chimique dépendante des conditions d'oxydation (nature de l'atmosphère, température et sollicitations mécaniques). En fait, la stabilité physicochimique de ces oxydes n'est assurée que lorsque l'acier est en phase Y ; cette stabilité est conservée après une sollicitation mécanique externe. Cette étude a également mis en évidence un rôle marqué de la nature de l'atmosphère de refroidissement sur la redistribution de l'oxygène dans les couches de calamine. L'influence de l'humidité est également étudiée vis-à-vis du comportement mécanique du système acier / calamine en flexion 4 points. La vapeur d'eau améliore les caractéristiques mécaniques de la calamine. Après sollicitation mécanique, deux modes d'endommagement des oxydes ont été observés : une fissuration transverse ou un décollement. Le mode d'endommagement dépend principalement de la température de sollicitation et de la nature de l'atmosphèreThis work is devoted to the problems met during the hot rolling of semi-hard steel sheets. The oxide layers formed during this working process can, indeed, induce various surface defects. These problems s are related to the oxide scale properties. Our contribution thus relates to the follow-up of the mechanical and physicochemical behavior of these oxides developed under wet oxidizing atmospheres. Following a mechanical study carried out using 4 point bending tests, we determined a behavior law of A-iron ; this is a law of perfect viscosity of the Norton type which characterizes the mechanical behavior of pure iron between 500 and 800°C. The elementary analysis of iron oxides shows a physicochemical stability which depends on the oxidation conditions (nature of the atmosphere, temperature and mechanical loading). In fact, the physicochemical stability of these oxides is assured on1y when steel is in the Y-phase; this stability is preserved after an external mechanical loading. This study also highlighted the role of the nature of the cooling atmosphere on the oxygen redistribution within the oxide layers. The influence of humidity is also studied with respect to the mechanical behavior of the steel / oxide system under 4 point bending. The water vapors improves the mechanical characteristics of the oxide scales. After mechanical loading, two damaging mechanisms of the oxides were observed : a transverse cracking or a delamination. The damaging mechanism depends mainly on the temperature during mechanical loading and the nature of the atmosphere
Частини книг з теми "Flexion pure":
1
Bosseboeuf, Alain, Pierre Etienne Allain, Fabien Parrain, Serge Jacob, Alexis Poisat, Nathalie Isac, Sylvain Perrot, and Arnaud Walther. "Système de flexion 4 points de puce semiconductrice pour une station sous pointes cryogénique." In Instrumentation et Interdisciplinarité, 307–14. EDP Sciences, 2020. http://dx.doi.org/10.1051/978-2-7598-1206-6-039.
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Bosseboeuf, Alain, Pierre Etienne Allain, Fabien Parrain, Serge Jacob, Alexis Poisat, Nathalie Isac, Sylvain Perrot, and Arnaud Walther. "Système de flexion 4 points de puce semiconductrice pour une station sous pointes cryogénique." In Instrumentation et Interdisciplinarité, 307–14. EDP Sciences, 2020. http://dx.doi.org/10.1051/978-2-7598-1206-6.c039.
Тези доповідей конференцій з теми "Flexion pure":
1
Kiapour, A., M. Parnianpour, and A. Shirazi-Adl. "Control of Different FEM Based Musculoskeletal Models of Human Lumbar Spine Under Different Loading Conditions Using Optimization Method." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95224.
Анотація:
In this study the effects of using different musculoskeletal models on load-displacement behavior of FE models of the human lumbar spine under external loads and moments have been analyzed in terms of equilibrium and clinical stability. A simplified and a complex architecture of muscles have been integrated to FE based models of lumbar spine and were loaded to simulate the load carrying behavior of human lumbar spine in flexion, extension and lateral bending. The displacement values as well as muscle forces have been computed and compared in both cases using optimization methods with different cost functions. The models showed similar kinematics in pure flexion but the simplified model showed instability in flexion-lateral bending and pure lateral bending conditions. The complex model was loaded and analyzed with different cost function and it was observed that displacements in the model are lower while the angle between the load vector and spine curvature at each level is minimized. It was shown that the model is less stable in case an asymmetric loading condition is applied.
2
Roland, Michelle, Maury L. Hull, and Stephen M. Howell. "Virtual Axis Finder: A New Method to Identify the Two Kinematic Axes of Rotation for the Tibio-Femoral Joint." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206292.
Анотація:
Kinematic modeling of the knee requires an accurate method to identify the rotational axes [1]. The tibio-femoral joint has two fixed rotational axes: the flexion-extension axis in the femur (FE) and the longitudinal rotational axis in the tibia (LR) [2–4]. Because the knee naturally produces coupled rotation about the LR axis during flexion, attempting to identify the axes from natural flexion alone creates an underdetermined system. A previous study using a mechanical axis finder identified the FE and LR axes by initially identifying the LR axis from pure internal-external (I/E) rotations [4]. Because the major source of error in this method was the visually-based alignment of the axis finder, it should become more repeatable and reliable by utilizing a mathematical optimization to situate the axis finder. Therefore, the two objectives were to develop and validate a new axis finding method, which is based on a mathematical optimization, for identifying the two fixed rotational axes of the tibio-femoral joint.
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Tang, Jessica A., Justin K. Scheer, Christopher P. Ames, and Jenni M. Buckley. "Pure Moment Testing for Spinal Biomechanics Applications: Fixed Versus 3D Floating Ring Cable-Driven Test Designs." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80132.
Анотація:
For spine biomechanical tests, the cable-driven system in particular has been widely used to apply pure bending moments. The advantages to pure moment testing lie in its consistency as an accepted standard protocol across previous literature and its ability to ensure uniform loading across all levels of the spinal column. Of the methods used for pure moment testing, cable-driven set-ups are popular due to their low requirements and simple design. Crawford et al [1] were the first to employ this method, but prior work by our group indicated a discrepancy between applied and intended moment for this system in flexion-extension only [2]. We hypothesize that this discrepancy can be observed in other bending modes and minimized with a second-generation floating ring design to eliminate off-axis loads.
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DeVries, Nicole A., Anup A. Gandhi, Douglas C. Fredericks, Joseph D. Smucker, and Nicole M. Grosland. "In Vitro Study of the C2-C7 Sheep Cervical Spine." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53167.
Анотація:
Due to the limited availability of human cadaveric specimens, animal models are often utilized for in vitro studies of various spinal disorders and surgical techniques. Sheep spines have similar geometry, disc space, and lordosis as compared to humans [1,2]. Several studies have identified the geometrical similarities between the sheep and human spine; however these studies have been limited to quantifying the anatomic dimensions as opposed to the biomechanical responses [2–3]. Although anatomical similarities are important, biomechanical correspondence is imperative to understand the effects of disorders, surgical techniques, and implant designs. Some studies [3–5] have focused on experimental biomechanics of the sheep cervical functional spinal units (FSUs). Szotek and colleagues [1] studied the biomechanics of compression and impure flexion-extension for the C2-C7 intact sheep spine. However, to date, there is no comparison of the sheep spine using pure flexion-extension, lateral bending, or axial rotation moments for multilevel specimen. Therefore, the purpose of this study was to conduct in vitro testing of the intact C2-C7 sheep cervical spine.
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Cusick, Joseph F., Srirangam Kumaresan, Brian Bunch, Narayan Yoganandan, and Frank A. Pintar. "Biomechanics of Lumbar Spondylotic Degeneration." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2599.
Анотація:
Abstract Human lumbar spinal columns exhibit different degrees of spondylotic degeneration. However, the biomechanical effects of these changes have not been fully studied. Understanding the potential patterns of such responses relative to the severity of degenerative changes assist in clarifying the influence on clinical and laboratory investigations. This study was conducted to obtain the three-dimensional biomechanical stability parameters of degenerated and non-degenerated spines. The degree of degeneration in disc and facet joints was graded individually for severity allowing evaluation of overall effects as well as individual component influences. Pure moment and complex loading were applied under flexion, extension, and left and right lateral bending modalities. The degenerated columns responded with greater variations in the moment-rotation (pure-moment loading) and force-deflection and moment-rotation (combined loading) than normal spinal columns. Furthermore, the response of the degenerated column depended not only on the overall quality of the spine, but also on the difference in severity and type of components affected. Complex loading showed increased sensitivity to variations in the biomechanical responses compared to pure moment loading. Disc degeneration showed increased changes in rotational stability, whereas facet alterations demonstrated greater effects on axial stiffness.
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Xu, Ming, Thomas Scholl, Pedro Berjano, Jazmin Cruz, and James Yang. "Rod Stress Prediction in Spinal Alignment Surgery With Different Supplementary Rod Constructing Techniques: A Finite Element Study." In ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/detc2018-85601.
Анотація:
Rod fracture and nonunion are common complications associated with pedicle subtraction osteotomies (PSO). Supplementary rods and interbody cage (IB) are added to reduce the primary rod stress. As supplementary rods, delta rods and cross rods have been proposed to reduce more stress on the primary rods compared to conventional supplementary rods (accessary rods) in PSO. The objective of this study is to investigate the effects of cross rods and delta rods on reducing primary rod stress in PSO subject. A validated 3D finite element model of a T12-S1 spine segment with 25° PSO at L3 and bilateral rods fixation from T12-S1 was used to compare different rod configurations: 1) PSO and two primary rods (PSO+2P); 2) PSO with an IB at L2-L3 (PSO+2P+IB); 3) PSO with accessory rods and an IB at L2-L3 (PSO+2P+IB+2A); 4) PSO with delta rods and an IB at L2-L3 (PSO+2P+IB+2D); 5) PSO with single cross rod and an IB at L2-L3 (PSO+2P+IB+1C); 6) PSO with double cross rods and an IB at L2-L3 (PSO+2P+IB+2C). The spine model was loaded with a follower load of 400 N combined with pure moments of 7.5 Nm in flexion, extension, right lateral bending, and right axial rotation. Von Mises stress of the primary rods were predicted for all test conditions. The PSO without IB condition had the largest primary rod stress in flexion. With IB at L2-L3, the rod stress in flexion reduced by 15%. Adding 2 conventional supplementary rods reduced the rod stress in flexion by 29%, which was achieved by adding single cross rod. The maximum von Mises stress occurred in the middle of the primary rods without supplementary rods whereas the maximum stress concentrated adjacent to the contact region between the connectors and the primary rods. Delta rods and double cross rods reduced the most rod stress in flexion, which were by 33% and 32% respectively. Under lateral bending, 2 delta rods reduced the most primary rod stress (−33%). Under axial rotation, the single cross rod reduced the most primary rod stress (−48%). Interbody cages and supplementary rods reduced the primary rod stress in a comparable way. Primary rod stress with 2 delta rods and double cross rods were comparable, which were marginally lower than those with conventional supplementary rods. Adding single cross rod was comparable to adding 2 conventional accessory rods in rod stress reduction in flexion. Under lateral bending, delta rods reduced most rod stress whereas under axial rotation, cross rods reduced most rod stress. This study suggested that both delta rods and cross rods reduce more primary rod stress than conventional accessory rods do.
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Camacho, Daniel L. A., Roger W. Nightingale, and Barry S. Myers. "Computational Modeling of Axial Neck Impact: Influence of Head Motion and Cervical Spine Buckling on Dynamic Behavior." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1203.
Анотація:
Abstract A computational head-neck model was developed to better understand the influence of head motion and cervical spine buckling on dynamic responses to near-vertex head impact. The model consisted of rigid vertebrae interconnected by assemblies of nonlinear springs and dashpots, and a finite element shell model of the skull. Model parameters were based upon quasi-static pure moment testing of cadaveric cervical spine motion segments and existing data reported in the literature. Geometric and inertial characteristics were derived from three-dimensional reconstructions of skull and vertebral CT images. The model correctly reproduced the complex cervical spine buckling deformations observed in high speed video of near-vertex impacts to cadaveric head-neck specimens, including a buckle at 6 msec and subsequent local post-buckled regions of both flexion and extension. Head and neck load histories agreed with those reported in the cadaveric studies. Sensitivity analyses of the cervical spine modeling parameters revealed that head and neck responses were most sensitive to changes in flexion-extension properties, consistent with structural stability theory for a slender column buckling under compressive loads. A sensitivity analysis of head mass demonstrated that even in the absence of a pocketing impact surface, the head inertia can oppose translational motion of the upper cervical spine during impact, resulting in increased neck loads.
8
Caillaud, Se´bastien, Christophe Lambert, Jean-Paul Devos, and Philippe Lafon. "Aeroacoustical Coupling and Its Structural Effects on a PWR Steam Line: Part 2 — Vibroacoustical Analysis of Pipe Shell Deformations." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33363.
Анотація:
A pure tone phenomenon has been observed at 460 Hz in a PWR steam line. The acoustical energy has been identified to be generated in an open gate valve. The objective here is to understand the way of energy transfer from the fluid to the main pipe using two fully coupled methods. The first method consists in a modal analysis of the line using a fluid-structure finite elements model. The second one is based on the analysis of dispersion diagrams derived from the local equations of cylindrical shells filled with fluid. The way of energy transfer in transverse acoustical waves induced combined flexion-ovalisation deformations of the pipe is highlighted using both methods. The dispersion diagrams allow a fast and accurate analysis. The modal analysis using a finite elements model may complete the first one with quantitative data.
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Chirvi, Sajal, Frank A. Pintar, and Narayan Yoganandan. "An Examination of Isolated and Interaction-Based Biomechanical Metrics for Potential Lower Neck Injury Criteria." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52108.
Анотація:
Lower neck injuries inferior to C4 level, such as fractures and dislocations, occur in motor vehicle crashes, sports, and military events. The recently developed interaction criterion, termed Nij, has been used in automotive safety standards and is applicable to the upper neck. Such criterion does not exist for the lower neck. This study was designed to conduct an analysis of data of lower neck injury metrics toward the development of a mechanistically appropriate injury criterion. Axial loads were applied to the crown of the head of post mortem human subject (PMHS) head-neck complexes at different loading rates. The generalized force histories at the inferior end of the head-neck complex were recorded using a load cell and were transformed to the cervical-thoracic joint. Peak force and peak moment (flexion or extension) were quantified for each test from corresponding time histories. Initially, a survival analysis approach was used to derive injury probability curves based on peak force and peak moment alone. Both force and moment were considered as primary variables and age a covariate in the survival analysis. Age was found to be a significant (p<0.05) covariate for the compressive force and flexion moment but insignificant for extension moment (p>0.05). A lower neck Nij formulation was done to derive a combined interactive metric. To derive cadaver-based metrics, critical intercepts were obtained from the 90% injury probability point on peak force and peak moment curves. The PMHS-based critical intercepts derived from this study for compressive force, flexion, and extension moment were 4471 N, 218 Nm, and 120 Nm respectively. The lower cervical spine injury criterion, Lower Nij (LNij), was evaluated in two different formulations: peak LNij and mechanistic peak LNij. Peak LNij was obtained from the LNij time history regardless of when it occurred. Mechanistic peak LNij was obtained from the LNij time history only during the time when the resulting injury mechanism occurred. Injury mechanism categorization included compression-flexion, compression-extension, and those best represented by a more pure compression-related classification. Mechanistic peak LNij was identified based on the peak timing of the injury mechanism. Peak LNij and mechanistic peak LNij were found to be significant (p<0.05) predictors of injury with age as a covariate. The 50% injury probability was 1.38 and 1.13 for peak LNij and mechanistic peak LNij, respectively. These results provide preliminary data based on PMHS tests for establishing lower neck injury criteria that may be used in automotive applications, sports and military research to advance safety systems.
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Natarajan, R. N., B. H. Chen, H. S. An, and G. B. J. Andersson. "Biomechanical Study on C4-C7 Cervical Spine." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0099.
Анотація:
Abstract It is known that surgery performed at one level in the spine affects the biomechanical characteristics of adjacent levels. Study of biomechanical response such as change in flexibility at the level of surgery as well as change in motions at the adjacent levels to applied multiplaner loadings will help to understand effects of surgery and rehabilitation requirements in these tissues. Experimental studies on the effect of large number of different surgeries on the stability of cervical spine are very expensive and time consuming if not impossible. Finite element modeling can be effectively used under these circumstances. Recent developments in this area have produced 2 segment (C4-C6) finite element models (Yoganandan et al., 1996). Three-motion segment model becomes necessary to understand the unconstrained effect of different surgical procedures performed at the middle level. The present study focuses on the biomechanical characteristics of a three motion segment model (C4-C7) so that it is possible to study the effect of surgery at the C5-C6 level without any interference from either the applied loading or the boundary conditions. The three-motion segment finite element model was validated under pure flexion and torsion moment loadings.