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1
Bertorello, Argüelles, Mollón, Bonhomme, Viña, and Viña. "Use of a LHFB Device for Testing Mode III in a Composite Laminate." Polymers 11, no. 8 (2019): 1243. http://dx.doi.org/10.3390/polym11081243.
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The present paper studies the fatigue delamination behaviour of an epoxy/carbon composite material under mode III loading using a longitudinal half fixed beam (LHFB) device initially designed for mode III static tests of composite materials formed by the stacking of plies. For this purpose, a series of tests was carried out at different levels of loading representative of the fatigue behaviour of the material, from the crack onset phase through the delamination phase to final fracture. The experimental results were treated statistically, obtaining the values of the fatigue limit for probabilities of fracture of 5% and 50%. Finally, a fractographic analysis of the fracture surfaces was performed which allowed us to identify the same characteristic patterns of static mode III fracture, namely broken fibres, cusps and saw-teeth, in addition to a new morphology consisting of the formation of agglomerations of resin produced by the friction between the lips of the specimen in the fracture zone that point to dynamic mode III fracture. These agglomerations eventually crack and become detached from the fibres, leaving these free of resin.
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Shimamoto, Akira, Do Yeon Hwang, and Tetsuya Nemoto. "Development of Biaxial Servo Controlled Fatigue Testing System." Key Engineering Materials 321-323 (October 2006): 57–62. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.57.
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Destructive accident sometimes takes place though the equivalent stress is rather low in the viewpoint of strength of materials. The propagation of fatigue cracks under multi-axial stress state and cycling load gives the reason. Fatigue fracture has been considered as one of the most commonly encountered industrial problems that lead to the damage of components in engineering products. In general, the machine structure is always under stress concentration or stress cycles. Moreover, the structure material is usually under two axes or multi-axial stresses instead of uniaxial stress state. It is important, therefore, to clarify the propagation behavior and the fatigue failure problem of the crack under the multi-axial stresses and cycling load from the safety reliability and accident prevention measure. In this study, a biaxial fatigue experimental device was developed which can carry out a wide range of fatigue tests under biaxial stresses. The developed experimental device was identified with a biaxial fatigue experiments including static uniaxial and biaxial tensile test by using the aluminum alloy flat plate as specimens. The propagation behavior of fatigue crack for center notched cruciform specimen in the equal biaxial fatigue test was verified.
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Sharma, Kartik, Aditi Goel, and Khushnuma Shah. "Cyclic Fatigue Fracture Resistance Evaluation of Three NiTi Rotary Multiple File Systems: An in-vitro Comparative Study." Journal of Advances in Medicine and Medical Research 35, no. 5 (2023): 25–31. http://dx.doi.org/10.9734/jammr/2023/v35i54968.
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Background: This in-vitro study used cyclic fatigue testing device to compare the cyclic fatigue fracture resistance of three rotary multiple file system; Neoendo flex, Hanu Dent and Hero Gold.
 Place and Duration of Study: Between November 2022 and January 2023 in Department of Conservative Dentistry and Endodontics at the Institute of Dental Sciences Sehora in Jammu, Union Territory of Jammu and Kashmir.
 Methodology: In this research three rotary nickel titanium systems Neoendo flex, Hanu Dent and Hero Gold; Micromega of size #25 with 4% taper were subjected to cyclic fatigue testing. Each system contained ten files which were 25 mm long. Each experimental file had EDTA gel applied to it before being put into endodomotor handpiece with rubber stopper. The dental hand piece was attached to portable device making it easy to insert each instrument inside the artificial canal. The files were working in the artificial canal as long as fracture occurred. The number of cycles until fracture was then calculated using the time. NCF = Number of rotations per minute x Time to fracture.
 Results: Hero Gold was followed by Hanu Dent in terms of mean values for the number of seconds to fracture. When utilized in curved canals, Neoendo Flex showed least resistance to cyclic fatigue fracture.
 Clinical Significance: To endodontists, the choice of file systems in cleaning and shaping of root canal is a mystery. This in vitro study investigated the choice of rotary root canal preparation file systems. NiTi endodontic files that have undergone heat treatment have dramatically enhanced the cyclic fatigue résistance extending the average life of file systems.
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Somashekharayya, Hiremath. "Engineering Solutions for evaluating durability and Enhancing Safety of Coronary, Aortic, and Structural Heart Class III medical devices: A Comprehensive Framework." International Journal of Innovative Research in Engineering & Multidisciplinary Physical Sciences 7, no. 6 (2019): 1–7. https://doi.org/10.5281/zenodo.14774310.
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Durability testing for Coronary, Aortic, and Structural Heart (Cardiovascular) Class III medical devices (implants), such as heart valves and stents, is critical for ensuring patient safety and device reliability. The mechanical failures and associated complications in the Coronary, Aortic, and Structural Heart Class III devices can lead to significant clinical consequences, including reduced cardiac function, reintervention, or even death. This paper explores the challenges associated with Coronary, Aortic, and Structural Heart Class III medical device durability, focusing on engineering methods and test approaches such as fatigue-to-fracture testing, bench modeling, and computational modeling. By understanding and implementing these methods, the medical device industry can improve device design, enhance patient safety, and meet regulatory standards effectively.
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Langaliya, Akshayraj, Neeta Patel, Athulya Pallipurath, Girish Parmar, Anjali Kothari, and Kairavi Jhala. "Analysis of cyclic fatigue resistance of different endodontic nickel–titanium rotary instruments: An in vitro study." Journal of Conservative Dentistry and Endodontics 27, no. 1 (2024): 95–99. http://dx.doi.org/10.4103/jcde.jcde_204_23.
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Abstract Aims: The aim of this in vitro study was to compare the cyclic fatigue resistance of three different endodontic nickel–titanium rotary instruments using a dynamic testing device. Materials and Methods: Ten files each of ProTaper Gold (PG), Hyflex Electro-discharge Machining (HEDM), and TruNatomy (TN) were tested in a custom-fabricated dynamic cyclic fatigue testing device at 60° curvature having a radius of curvature of 5 mm. The number of cycles to the fracture (NCF) of each instrument was calculated and three continuous groups were compared by the Kruskal–Wallis test and Dunn post hoc test was used for pairwise comparison. Results: Cyclic fatigue resistance of HEDM was the highest, followed by TN. PG had the lowest among the three. Conclusion: Within the limitations of the present in vitro results, it can be concluded that HEDM files appeared to be suitable for shaping complex canals with the greater number of cycles before it fractures.
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Sekar, Vadhana, Ranjith Kumar, Suresh Nandini, Suma Ballal, and Natanasabapathy Velmurugan. "Assessment of the role of cross section on fatigue resistance of rotary files when used in reciprocation." European Journal of Dentistry 10, no. 04 (2016): 541–45. http://dx.doi.org/10.4103/1305-7456.195171.
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ABSTRACT Objective: The purpose of this study was to assess the role of cross section on cyclic fatigue resistance of One Shape, Revo-S SU, and Mtwo rotary files in continuous rotation and reciprocating motion in dynamic testing model. Materials and Methods: A total of 90 new rotary One Shape, Revo-S SU, and Mtwo files (ISO size 25, taper 0.06, length 25 mm) were subjected to continuous rotation or reciprocating motion. A cyclic fatigue testing device was fabricated with 60° angle of curvature and 5 mm radius. The dynamic testing of these files was performed using an electric motor which permitted the reproduction of pecking motion. All instruments were rotated or reciprocated until fracture occurred. The time taken for each instrument to fracture was recorded. All the fractured files were analyzed under a scanning electron microscope (SEM) to detect the mode of fracture. Statistical analysis was performed using one-way ANOVA, followed by Tukey's honestly significant difference post hoc test. Results: The time taken for instruments in reciprocating motion to fail under cyclic loading was significantly longer when compared with groups in continuous rotary motion. There was a statistically significant difference between Mtwo rotary and the other two groups in both continuous and reciprocating motion. One Shape rotary files recorded significantly longer duration to fracture resistance when compared with Revo-S SU files in both continuous and reciprocating motion. SEM observations showed that the instruments of all groups had undergone a ductile mode of fracture. Conclusion: Reciprocating motion improved the cyclic fatigue resistance of all tested groups.
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Vanderby, R., R. P. McCabe, and R. T. Dueland. "Fatigue Study of Six and Eight mm Diameter Interlocking Nails with Screw Holes of Variable Size and Number." Veterinary and Comparative Orthopaedics and Traumatology 10, no. 04 (1997): 194–99. http://dx.doi.org/10.1055/s-0038-1632595.
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SummaryClinical fatigue failure of 6 mm diameter interlocked nails (ILN) with holes accommodating 3.5 mm screws has been reported. This problem was investigated by testing eight different designs of 6 mm and 8 mm diameter ILN with a 2 plus 2 screw hole pattern and a multiple holed pattern. Interlocking nails with holes to accommodate 3.5 and 4.5 mm screws in 8 mm ILN and 2.7 and 3.5 mm screws in 6 mm diameter ILN were used. A rotating beam testing device produced uniform bending moments across a test region of the ILN containing at least two holes. These moments fully reversed with each cycle. Fatigue failure occurred through screw holes. Using statistical modeling, reduction of the 6 mm ILN hole size from accommodating 3.5 screws to 2.7 mm screws increased the estimated fatigue life (EFL) of the latter by 52 times, comparable to the EFL of the 8 mm ILN with 4.5 screw holes. Reducing the 8 mm ILN screw hole size from accommodating 4.5 screws to 3.5 mm screws increased the comparative EFL by eight times. Fatigue testing is a good method to compare fatigue behavior of various implant designs. This gives a surgeon more information when selecting an ILN for fracture fixation.Occasional breakage of interlocking nails (ILN) in clinical cases prompted fatigue testing of original ILN and new designs of ILN. This study documented base line fatigue resistance information of the various ILN designs. Results indicated smaller screw holes markedly increased the fatigue resistance of both 6 mm and 8 mm diameter ILN. This information will aid the surgeon in planning fracture treatment.
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Feng, Ning, Xin Wang, Jiazheng Guo, Qun Li, Jiangtao Yu, and Xuecheng Zhang. "Design Theory and Experimental Research of Ultrasonic Fatigue Test." Machines 10, no. 8 (2022): 635. http://dx.doi.org/10.3390/machines10080635.
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Ultrasonic fatigue testing is a key technology that is more efficient and energy saving compared to conventional fatigue testing. In order to investigate the behavior of metallic materials at ultra-high frequencies and to verify the validity of ultrasonic fatigue test results, this paper builds a test apparatus that can be used to conduct ultrasonic fatigue tests, and this paper proposes a complete procedure from theoretical analysis to the investigation of test laws for 20 kHz tensile and the compression test. Firstly, the initial sizes of the sample are calculated with an analytical method, then the three-dimensional model is simulated and optimized with finite element software, and the optimum result for the sample size is then obtained according to the sensitivity of the sample size to the effect of frequency. The next step is to analyze the influenced trend of the sample size, including L1, L2, L3, R1 and R2, on the resonant frequency and maximum stress of the sample. According to the optimized results, the sample was processed, and an ultrasonic fatigue test was carried out to ensure the sample fatigue fracture finally occurred. Finally, the S-N curve of the material was plotted based on the data recorded in the test and compared with the conventional fatigue life curve to verify the feasibility of the ultrasonic fatigue test device and test method. The fracture of the sample was observed using an optical microscope, and its macroscopic fracture morphology was analyzed. The fracture morphology of the sample can be divided into three typical zones: the fatigue crack source zone, the extension zone and the transient zone, where the fatigue cracks all originate from on the surface of the sample. The results demonstrate the validity of the ultrasonic fatigue test results and provide new ideas for the design and optimization of ultrasonic fatigue samples and shorter processing times, providing a reference for subsequent ultrasonic fatigue tests on typical materials.
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Vaško, Alan, Juraj Belan, and Eva Tillová. "Study of the fatigue behaviour of synthetic nodular cast irons at low and high frequency cyclic loading." MATEC Web of Conferences 157 (2018): 07014. http://dx.doi.org/10.1051/matecconf/201815707014.
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The paper presents the results of low and high frequency fatigue tests carried out on nodular cast iron. The specimens of synthetic nodular cast irons from three different melts were studied in the high cycle fatigue region (from 105 to 108 cycles) using fatigue experimental equipments for low and high frequency cyclic loading. Low frequency fatigue tests were carried out at frequency f ≈ 120 Hz using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100. High frequency fatigue tests were carried out at frequency f ≈ 20 kHz using the ultrasonic fatigue testing device KAUP-ZU. Both of them were carried out at sinusoidal cyclic push-pull loading (stress ratio R = -1) at ambient temperature (T ≈ 20 °C). The relationship σa = f (N) and fatigue strengths were determined experimentally; mechanical properties, microstructures and fracture surfaces were investigated.
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Deptuła, Adam, Wojciech Macek, and Marian A. Partyka. "Analysis of loading history influence on fatigue and fracture surface parameters using the method of induction trees." MATEC Web of Conferences 252 (2019): 08003. http://dx.doi.org/10.1051/matecconf/201925208003.
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In fatigue life testing under various loading conditions, researchers observe the profile, surface and morphology of materials. In this study authors research the fatigue life of material and the surface fracture geometry. Areal field and fractal based characterisation are evaluated for the whole fracture surfaces. Results of this test were correlated to notch geometry and loading conditions. It was confirmed, for notched specimens, that the change from torsion to proportional bending with torsion fatigue life increase significantly, the same as changing loading from bending with torsion to bending. The measurement device was equipped with a motorised nosepiece using five dedicated microscopic objective lenses from 2.5× to 100× magnification. This paper presents the application of the induction tree method for analysis of loading history influence on fatigue and fracture surface parameters. In a decision tree, nodes store tests checking values of example attributes and leaves store categories assigned to them. For each of possible test results, there is one branch coming from a node to a subtree. In this way, it is possible to represent any attributes of the hypothesis admissible for a given set. Analysis of selected parameters will estimate their impact on the surface structure.
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Senthilnathan, Karthikeyan, Ali Shamimi, Craig Bonsignore, Harshad Paranjape, and Tom Duerig. "Effect of Prestrain on the Fatigue Life of Superelastic Nitinol." Journal of Materials Engineering and Performance 28, no. 10 (2019): 5946–58. http://dx.doi.org/10.1007/s11665-019-04334-2.
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Abstract Three types of fatigue testing are performed to elucidate the effects of prestraining superelastic Nitinol on its subsequent fatigue lifetime: rotary bending and tension–tension testing of wire, and beam bending using diamond-shaped specimens fabricated from tubing. Results show that local plastic deformation during prestraining induces residual stresses that have a pronounced effect on fatigue performance, enhancing performance when the fatigue duty cycle is of the same sense as the prestraining (tensile prestraining followed by a tensile duty cycle, for example), and decreasing fatigue lifetime when the sense of the duty cycle is opposite to that of prestraining. This provides an avenue to increasing fatigue lifetime, but more importantly it highlights the need to fully understand the nature of the duty cycle: for example, prestraining a stent by crimping it into a delivery catheter induces favorable residual stresses with respect to subsequent pulsatile fatigue, but might accelerate fracture in other modes, such as axial or crush fatigue. Caution is also advised when trying to apply data from “constant life diagrams” derived from the literature (Ref 1, 2 for example) that may not properly reflect the strain history of the device being analyzed.
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Rezanezhad, Saeid, and Mohammad Azadi. "Amazing epsilon-shaped trend for fretting fatigue characteristics in AM60 magnesium alloy under stress-controlled cyclic conditions at bending loads with zero mean stress." PLOS ONE 18, no. 2 (2023): e0281263. http://dx.doi.org/10.1371/journal.pone.0281263.
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In the present article, fatigue properties (pure and fretting) of magnesium alloys (AM60) under cyclic bending loading were compared. For this objective, a rotary fatigue testing device was utilized with a fretting module on standard cylindrical samples under bending loads with zero means stress. The fretting fatigue condition decreased fatigue lifetime compared with pure fatigue but in an amazing Epsilon-shaped trend. Comparatively speaking to the state of pure fatigue, the fatigue lifetime of the fretting fatigue condition reduced by 91.0% and 44.8%, respectively, between the lowest level of stress (80 MPa) and the greatest level of stress (120 MPa). To study the fracture behavior and the fractography analysis, field-emission scanning electron microscopy (FESEM) was utilized. In general, since both quasi-cleavage and cleavage were seen; therefore, the fracture behavior for all samples was brittle. In both test conditions (fretting fatigue and pure fatigue), at higher stress levels, the average crack length was higher than at low-stress levels. In addition, the number of cracks (in high- and low-stress levels) was observed to be less in fretting fatigue conditions than in pure fatigue conditions, but the average crack length in fretting fatigue conditions in high-stress levels and low-stress levels was 212.82% and 259.47% higher than the average crack length under the pure fatigue condition, respectively.
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Vincze, Kata Dóra. "Examination of Damage Processes of Orthopaedic Orthosis." Acta Materialia Transylvanica 6, no. 2 (2023): 121–26. http://dx.doi.org/10.33924/amt-2023-02-10.
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In my work, I examined a palmar forearm splint manufactured by a Hungarian medical device producer. Considering the test results that come from failure analysis, material composition analysis, hardness testing, macroscopic and microscopic examination, scanning electron microscopy and implemented on a product damaged under real conditions, I concluded that the medical device, returned by the customer, had broken prematurely due to improper use. The results of the fatigue test carried out as a physical simulation of the load show that the medical device can withstand more than 850 cycles of micromotion without any problems. Macrofractographic comparisons were performed between the fracture surfaces of the device returned by the users and those of that dismantled under laboratory conditions, thus confirming the validity of my measurement.
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Berti, Francesca, Alma Brambilla, Giancarlo Pennati, and Lorenza Petrini. "Relevant Choices Affecting the Fatigue Analysis of Ni-Ti Endovascular Devices." Materials 16, no. 8 (2023): 3178. http://dx.doi.org/10.3390/ma16083178.
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Ni-Ti alloys are widely used for biomedical applications due to their superelastic properties, which are especially convenient for endovascular devices that require minimally invasive insertion and durable effects, such as peripheral/carotid stents and valve frames. After crimping and deployment, stents undergo millions of cyclic loads imposed by heart/neck/leg movements, causing fatigue failure and device fracture that can lead to possibly severe consequences for the patient. Standard regulations require experimental testing for the preclinical assessment of such devices, which can be coupled with numerical modeling to reduce the time and costs of such campaigns and to obtain more information regarding the local state of stress and strain in the device. In this frame, this review aimed to enlighten the relevant choices that can affect the outcome of the fatigue analysis of Ni-Ti devices, both from experimental and numerical perspectives.
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Amato, Massimo, Giuseppe Pantaleo, Dina Abdellatif, Andrea Blasi, Roberto Lo Giudice, and Alfredo Iandolo. "Evaluation of cyclic fatigue resistance of modern Nickel-Titanium rotary instruments with continuous rotation." Giornale Italiano di Endodonzia 31, no. 2 (2017): 78–82. http://dx.doi.org/10.4081/j.gien.2017.23.
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Aim: The aim of present study was to compare cyclic fatigue resistance of three modern Ni-Ti instruments used with continuous rotation. Materials and methods: For this study 3 groups of rotating instruments with continuous rotation (HyFlex EDM, Twisted File Adaptive, Revo S SU) have been used, each group consisted of 20 files. The various groups were subjected to cyclic fatigue testing through an artificial metal device. A statistical analysis with Kruskal-Wallis test and Mann-Whitney test was performed. Results: There were statistically significant differences between the three groups. The HyFlex EDM instruments have a fracture resistance slightly higher than the Twisted file and far higher than Revo S SU. Conclusions: Modern Ni-Ti alloys increase resistance of the rotating instruments to cyclic fatigue.
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Ilanković, Nikola, Dragan Živanić, and Ninoslav Zuber. "The Influence of Fatigue Loading on the Durability of the Conveyor Belt." Applied Sciences 13, no. 5 (2023): 3277. http://dx.doi.org/10.3390/app13053277.
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The conveyor belt is by its structure a textile composite. As a load-supporting element of the conveyor, the belt withstands variable loads during its operations. In order to investigate the influence of the level and variability of loading on the life of the belt, tests were carried out on specimens in laboratory conditions. A testing device was specially designed and made for these tests that enabled precise control and monitoring of the loading as well as number of loading cycles up to fracture. This research provides an overview of the influence of fatigue loading on the fatigue life of the belt. The methodology of the conducted research is explained with a description of important technical parameters of the testing device. A physical experiment and a corresponding numerical simulation using the FEM method were carried out with multiple loading levels of belt specimens. Based on the obtained results, appropriate conclusions were made; at loads less than 70% of the breaking strength, the lifetime of the belt is very long. Attention was drawn to additional influences that could not be covered by the experiment and possible directions for further research were indicated.
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Li, Guoai, Liang Wang, Min Hao, Xiangjie Wang, and Zheng Lu. "Microstructure Characteristic and Fatigue Damage Behaviors of 2060 Al-Li Alloy Thin Plate." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 38, no. 2 (2020): 384–91. http://dx.doi.org/10.1051/jnwpu/20203820384.
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The microstructure characteristic, fatigue damage behaviours and evolution of microstructure during the fatigue testing of 2060 Al-Li alloy thin plate were studied by fatigue tester equipped with in-situ observation device, OM, EBSD, SEM and TEM. The results show that recrystallized grains with irregularity shape and large size are observed, the Goss and Cube texture are the mainly types, abundant of T1 with size of 50~60nm are found in grains. During axial loaded fatigue testing, a crack initiates from the edge of sample and extend into grain along the direction with maximum Schmid factor. When the crack reaches and crosses the first grain boundary, the extending direction deflects from 45° degree to perpendicular with loading direction, and propagates along this direction till the sample quickly fracture. A large size deformation region contains numerous slip strips around the crack tip during the initiation and extending process is observed. The dislocations cut across the T1 precipitates located in grains during deformation, and release the stress concentration on the crack tip. The fatigue crack extends across the grains with serrated shape can result from the big orientation difference of grains and easy screwed T1 precipitates.
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Gao, Hong Li, Shan Shan Shen, and Yan Yun. "Fatigue Crack Length Real Time Measurement Method Based on Camera Automatically Tracking and Positioning." Applied Mechanics and Materials 130-134 (October 2011): 3111–18. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.3111.
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Fatigue crack propagation test is a very important testing way to study the metallic engineering material fatigue fracture characteristics by on-line measuring crack length under the cyclically varying loads. Crack length has been obtained through crack image capture, image processing and image analysis. In order to improve the crack measurement precision when the fatigue crack keeps growing, a new crack length real time measurement method based on the image processing and camera automatically tracking techniques was presented in this paper. This method includes the crack image processing algorithms and camera tracking and positioning movement control. The crack length measurement errors based on the camera tracking and fixed camera are respectively 0.076mm and 0.148mm.The experiment results show the proposed method has greatly improved the crack length measuring precision with the ordinary optical device.
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Pedullà, Eugenio, Francesco Saverio Canova, Giusy Rita Maria La Rosa, et al. "Influence of NiTi Wire Diameter on Cyclic and Torsional Fatigue Resistance of Different Heat-Treated Endodontic Instruments." Materials 15, no. 19 (2022): 6568. http://dx.doi.org/10.3390/ma15196568.
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We compared the mechanical properties of 2Shape mini TS2 (Micro-Mega, Besançon, France) obtained from 1.0 diameter nickel-titanium (NiTi) wires and 2Shape TS2 from 1.2 diameter nickel-titanium (NiTi) wires differently thermally treated at room and body temperature. We used 120 NiTi TS2 1.0 and TS2 1.2 files made from controlled memory (CM) wire and T-wire (n = 10). Cyclic fatigue resistance was tested by recording the number of cycles to fracture (NCF) at room and body temperatures using a customized testing device. Maximum torque and angle of rotation at failure were recorded, according to ISO 3630-1. Data were analyzed by a two-way ANOVA (p < 0.05). The CM-wire files had significantly higher NCFs at both temperatures, independent of wire dimensions. Testing at body temperature negatively affected cyclic fatigue of all files. The 1.0-mm diameter T-wire instruments showed higher NCF than the 1.2-mm diameter, whereas no significant differences emerged between the two CM wires at either temperature. The maximum torque was not significantly different across files. The TS2 CM-wire files showed significantly higher angular rotation to fracture than T-wire files. The TS2 CM-wire prototypes showed higher cyclic fatigue resistance than T-wire prototypes, regardless of wire size, exhibiting suitable torsional properties. Torsional behavior appears to not be affected by NiTi wire size.
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Ivanytskyj, Y. L., T. M. Lenkovskiy, Y. V. Molkov, V. V. Kulyk, and Z. A. Duriagina. "Influence of 65G steel microstructure on crack faces friction factor under mode II fatigue fracture." Archives of Materials Science and Engineering 82, no. 2 (2016): 49–56. http://dx.doi.org/10.5604/01.3001.0009.7103.
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Purpose: The aim of the paper is to evaluate the dependence of microstructure parameters,strength and plasticity of steel on crack faces friction factor.Design/methodology/approach: The specimens for the investigation were cut out fromthe 10 mm thick hot-rolled plate of 65G steel used as a model material for fatigue anddurability testing of whole-rolled railway wheels. The mechanical characteristics of the steelwere determined according to the state standard using cylindrical specimens of diameter5 mm and effective length 50 mm. The specimens were heat-treated at the mentionedconditions. Fatigue testing under mode II loading was carried out on a special rigid loadingmachine in the standard laboratory conditions at symmetric sinusoidal cycle with a frequencyof 12 Hz in the range of fatigue crack growth rates da/dN = 5∙10-8…5∙10-7 m/cycle untilits reaches relative length l/b ≥ 0.8. The obtained microsections were investigated using theoptical metallographic microscope Neophot 9 equipped with a digital camera Nikon D50 andelectronic scanning microscope Zeiss EVO 40XVP. Hardness of the specimens with differentmicrostructure was determined using durometer TK-2. The crack faces friction factor wasdetermined using original device for fractured surfaces sliding under certain compressionforce realizationFindings: The dependences of microstructure parameters, strength and plasticity of steelon crack faces friction factor are obtained.Research limitations/implications: The investigation of the influence of microstructureparameters, strength and plasticity of real wheel steels on crack faces friction factor at themode II fatigue crack growth will be carried out.Practical implications: The value of crack faces friction factor have strong impact onstress intensity at the crack tip and must be taken into account at crack growth rates curvesplotting.Originality/value: Mode II fatigue crack faces friction factor of steel is firstly experimentallydetermined.
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Patel, Neeta, Akshayraj Kantilal Langaliya, Shwetika Patel, Anjali Kairav Kothari, Gunja Malaviya, and Siddharth Yadav. "Analysis of dynamic cyclic fatigue resistance of different endodontic nickel–titanium instruments with different sterilization methods: An in vitro study." Journal of Conservative Dentistry and Endodontics 28, no. 4 (2025): 314–18. https://doi.org/10.4103/jcde.jcde_767_24.
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Abstract Aim: This study aimed to evaluate the influence of autoclave sterilization on the cyclic fatigue resistance of nickel–titanium (NiTi) endodontic files with different NiTi alloy treatments. Materials and Methodology: The research examined Hyflex CM, Bassi Logic, TruNatomy, and ProTaper Gold files, which were divided into control, conventional sterilization, and flash sterilization groups. Poststerilization, the instruments were tested using a custom-made Dynamic Cyclic Fatigue Testing Device replicating root canal procedures. Group 1 used HyFlex CM (size 25, taper 0.04), Group 2 used Bassi Logic (size 25, taper 0.04), Group 3 used TruNatomy (size 25, taper 0.04), and Group 4 used ProTaper Gold (size F1). After rotating each instrument until it fractured, the number of cycles to failure was determined and the time to fracture was noted. Statistical Analysis: Statistical analysis was conducted using SPSS 26.0 (Statistical software developed by IBM) with one-way ANOVA and Tukey honestly significant difference post hoc tests. Results: HyFlex CM had the highest fracture resistance, whereas ProTaper Gold had the lowest. Sterilization increased the cyclic fatigue resistance of HyFlex CM, Bassi Logic, and ProTaper Gold but decreased that of TruNatomy. Conclusion: The study concluded that sterilization enhances cyclic fatigue resistance, except for TruNatomy files, and emphasized understanding NiTi alloy properties to mitigate instrument failure.
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Zhou, Zhao-ming, Jin-song Tan, Fu Wan, and Bo Peng. "Improvement and determination of the influencing factors of coiled tubing fatigue life prediction." Advances in Mechanical Engineering 11, no. 9 (2019): 168781401988013. http://dx.doi.org/10.1177/1687814019880131.
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The fatigue life prediction model cannot accurately predict the service life of coiled tubing operations, resulting in waste and accidental fracture of coiled tubing. This article introduces the fatigue life prediction model of coiled tubing and a detection system developed using weak magnetic detection method and eddy current detection method. The detection device is used to detect accurate defect dimension, wall thickness reduction, and diameter deformation to improve the accuracy of fatigue life prediction. Furthermore, the actual defect dimension is included in the fatigue life assessment calculation to eliminate the influence of the existing model on the immobilization of defects and corrosion influence factors. By analyzing field operation cases and measured values, the effects of defects, wall thickness reduction, and diameter growth on fatigue life are studied to improve the accuracy of parameters and the integrity of basic data in the calculation process. The influence of reverse bending and weld on fatigue life is discussed. The residual life can be predicted more accurately by combining field testing technology and fatigue life evaluation method. Field measurement input of fatigue life prediction model is the main means to improve its accuracy and practicability.
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Eppell, S. J., B. N. Smith, H. Kahn, and R. Ballarini. "Nano measurements with micro-devices: mechanical properties of hydrated collagen fibrils." Journal of The Royal Society Interface 3, no. 6 (2005): 117–21. http://dx.doi.org/10.1098/rsif.2005.0100.
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The mechanical response of a biological material to applied forces reflects deformation mechanisms occurring within a hierarchical architecture extending over several distinct length scales. Characterizing and in turn predicting the behaviour of such a material requires an understanding of the mechanical properties of the substructures within the hierarchy, the interaction between the substructures, and the relative influence of each substructure on the overall behaviour. While significant progress has been made in mechanical testing of micrometre to millimetre sized biological specimens, quantitative reproducible experimental techniques for making mechanical measurements on specimens with characteristic dimensions in the smaller range of 10–1000 nm are lacking. Filling this void in experimentation is a necessary step towards the development of realistic multiscale computational models useful to predict and mitigate the risk of bone fracture, design improved synthetic replacements for bones, tendons and ligaments, and engineer bioinspired efficient and environmentally friendly structures. Here, we describe a microelectromechanical systems device for directly measuring the tensile strength, stiffness and fatigue behaviour of nanoscale fibres. We used the device to obtain the first stress–strain curve of an isolated collagen fibril producing the modulus and some fatigue properties of this soft nanofibril.
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Baptista, C. A. R. P., L. S. Rossino, M. A. S. Torres, and C. Y. Shigue. "Evaluation of the fretting fatigue behaviour of commercially pure titanium." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 221, no. 3 (2007): 143–50. http://dx.doi.org/10.1243/14644207jmda122.
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Fretting fatigue occurs when the contact surfaces of two components undergo small oscillatory movement while they are subjected to a clamping force. A cyclic external load gives rise to the early initiation of fatigue cracks, thus reducing their service life. In this paper, the fretting fatigue behaviour of commercially pure titanium flat samples (1.5mm thick) is evaluated. A fretting device composed of a frame, load cell, and two screw-mounted cylindrical fretting pads with convex extremities was built and set to a servo-hydraulic testing machine. The fatigue tests were conducted under load control at a frequency of 10 Hz and stress ratio R = 0.1, with various contact load values applied to the fretting pads. Additional tests under inert environment allowed assessing the role of oxidation on the wear debris formation. The fracture surfaces and fretting scars were analysed via scanning electron microscopy in order to evaluate the surface damage evolution and its effect on the fatigue crack features. The effect of the fretting condition on the S-N curve of the material in the range of 104-106 cycles is described. Fatigue crack growth calculations allowed estimating the crack initiation and propagation lives under fretting conditions. The effect of the fretting condition in fatigue life is stronger for the lower values of cyclic stress and does not seem to depend on the contact loading value.
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Liew, Li-Anne, David T. Read, and Nicholas Barbosa. "Fatigue testing of bulk materials using a microsystems based approach." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2014, DPC (2014): 000632–64. http://dx.doi.org/10.4071/2014dpc-ta34.
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Fatigue, the degradation of a material's mechanical properties due to cyclic loading, is a critical issue limiting the reliability of structural materials[1]. Fatigue testing of materials is typically carried out in controlled laboratory conditions on specially prepared specimens, and the results are extrapolated to real world conditions. In the past two decades, conventional fatigue testing machines and specimens have undergone miniaturization for the purpose of evaluating the fatigue properties of miniaturized mechanical components such as sensors and biomedical implants, with the smallest test specimens having dimensions on the order of 1 mm length [2] or consisting of foils and wires [3]. Challenges with miniaturization include difficulty in specimen handling, gripping, and alignment. At the same time, MEMS technology has been used to fabricate the actuators and sensors for fatigue testing of thin films [4]. In this approach, the specimen is typically part of the MEMS actuator and is fabricated in-situ. While this eliminates the problems with specimen gripping and alignment, it limits the specimen materials to those from which MEMS actuators and sensors can be readily fabricated, is destructive to the MEMs device, and furthermore is typically limited to thin films. We seek to use the advantages of MEMS to study the fatigue properties of bulk materials rather than thin films, but at the micrometer scale. This allows for greater accuracy and spatial resolution, compared to the state of the art, of property measurements of structural materials such as aluminum and stainless steel alloys as well as other materials used in civil infrastructure, aerospace, transportation and energy industries. Our approach is to use MEMS as chip-scale re-useable test instruments into which small specimens cut from bulk materials can be inserted and tested [5]. We describe the design of the MEMS test instrument and the metal foil specimen, whose gage section was 135 um wide and 25 um thick. The test instrument was fabricated from silicon and glass wafers, and the specimens were etched from commercially available Al 1145 H19 foil. Our S-N curve agrees within expectation with published values for similar aluminum alloys tested using conventional methods at much larger specimen size scales, and the fracture surface shows distinct regions corresponding to slow and fast crack growth. We envision this test technique as a tool to further the study of the fatigue properties of structural materials.
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TUSZYŃSKI, Waldemar, Michał GIBAŁA, Marek KALBARCZYK, et al. "CHARACTERISTICS OF A NEW TEST RIG AND METHODOLOGY FOR CYCLIC TESTING OF GEAR TOOTH BENDING FATIGUE STRENGTH." Tribologia 283, no. 1 (2019): 57–65. http://dx.doi.org/10.5604/01.3001.0013.1438.
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Tooth fracture is the most dangerous form of gear wear that excludes the gear from further use. In order to counteract the occurrence of this type of damage, it is very important to properly design the toothed gear. To calculate the gear tooth bending strength, a strength parameter called the nominal stress number σFlim is necessary. ISO 6336-5:2003(E) and available material databases provide σFlim values for the most popular engineering materials used for gears, including those for case-hardened steels. There is, however, no data for a new generation of nanostructured engineering materials, which are the subject of research conducted at the Tribology Department of ITeE – PIB. The σFlim parameter is most often determined in cyclic fatigue tests on toothed gears with specially selected tooth geometry. In order to determine the above strength parameter, a pulsator (symbol T-32) was developed and manufactured at ITeE-PIB in Radom. The article presents a new device, research methodology, and the results of verification tests for case-hardened steel 18CrNiMo7-6, confirming the correctness of the adopted design assumptions and the developed research methodology. The results of tooth bending fatigue tests are the basis for the selection of a new engineering material dedicated to gears, which later undergoes tribological testing.
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Duran, Jorge Alberto Rodriguez, and Dionisio Jose Rodrigues da Costa. "An Evaluation of the Nominal Stress Method for Life Prediction of Cylindrical Circumferential V-Notched Specimens Tested under Variable Amplitude Loading." Applied Mechanics and Materials 851 (August 2016): 310–16. http://dx.doi.org/10.4028/www.scientific.net/amm.851.310.
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An experimental device was constructed with the aim of testing various cylindrical V-notched specimens until fracture and under variable amplitude torsional loads. The specimens had different notch depths resulting in the same number of values for the stress concentration factor. Strain gages directly bonded at the specimens’ surface and using a slip ring system for their communication with the conditioner, allowed the measurement of the actual applied loads. The well-known rain flow cycle counting procedure was then applied on the scaled signal for identifying the frequency of the 64 classes of stress amplitudes and means. The traditional nominal stress-based approach was then evaluated as the most widely used tool for fatigue lifetime calculations. As the occurrence of stress amplitudes above the endurance fatigue limit tends to lower it, the Miner elementary method was used. The results show damage sum ranges between 0.5 and 6.4 with a mean value of 2.0. Despite the small size of the sample used in the present paper (only 13 tests), these significant deviations are in agreement with previous results reported by different researchers.
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Brandes, Laura Leonie, Luis Fernando Nicolini, Johannes Greven, et al. "Biomechanical Performance of BoneHelix® Compared with Elastic Stable Intramedullary Nailing (ESIN) in a Pediatric Tibia Fracture Model." Life 11, no. 11 (2021): 1189. http://dx.doi.org/10.3390/life11111189.
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Tibial shaft fractures are common injuries in the pediatric and adolescent populations. Elastic stable intramedullary nailing (ESIN) is the treatment of choice for cases that require surgical stabilization. A new intramedullary device, BoneHelix® (BH), may be an alternative for use with fractures that cannot be satisfactorily stabilized with ESIN. This study aimed to assess the biomechanical performance of BH compared with ESIN in a porcine tibia fracture model, observing cyclic fatigue and load to failure. Computed tomography was used to monitor the implant position and to rule out unintended damage. No implant or bone failure occurred during the fatigue testing. An increase in the cumulative plastic displacement was observed in both test groups over the loading cycles applied. Both implant–bone constructs displayed a trend toward closure of the osteotomy gap. During the load-to-failure test, the average loads at failure in specimens instrumented with ESIN and BH were 5364 N (±723) and 4350 N (±893), respectively, which were not statistically significant (p = 0.11). The values of both groups were two to three times higher than the estimated maximal load (2000 N) during physiological weight bearing. The biomechanical results thus indicate equivalent performance and stability by the implants tested.
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Segura Trujillo, Carlos Ricardo, Yenny Marcela Orozco Ocampo, and César Augusto Álvarez Vargas. "Application of Modular Design Methodology for Endodontic Instrument Fatigue Test Bench." Scientia et Technica 29, no. 4 (2024): 148–57. https://doi.org/10.22517/23447214.25373.
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In endodontic procedures, Nickel-Titanium (NiTi) instruments are used, which adapt to the geometry of root canals. These alloys have favored the mechanical properties of the files. However, the high cost of these instruments leads to repeated use, increasing the risk of fatigue fracture during treatment. Different brands and references of endodontic instruments are offered on the market, so it is essential to characterize the mechanical properties of the files and their behavior when subjected to fatigue loads. So far, there is no standardization for the tests used to check their fatigue resistance, and therefore, in each research, equipment, and analysis methodology are proposed. In this project, a test bench is developed for fatigue testing of endodontic instruments without material, cross-section, and external design restrictions, allowing static and dynamic tests. For the test bench, the modular design strategy is applied to identify components susceptible to acquiring this characteristic, using easy-to-acquire elements and manufacturing techniques such as 3D printing, favoring the modularization of the design. The device moves in two axes, X and Y, and it is possible to regulate the depth of entry of the instrument into the channel. It also has an electronic system that automates the dynamic and static test, an LCD screen for menu access, and records the number of cycles to file breakage.
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Bruchhausen, Matthias, Burkhard Fischer, Ana Ruiz, Peter Hähner, and Sebstian Soller. "Impact of High-Pressure Gaseous Hydrogen on the Fatigue Behaviour of Austenitic Steel A-286 under Asymmetric Loading Conditions." Key Engineering Materials 664 (September 2015): 156–67. http://dx.doi.org/10.4028/www.scientific.net/kem.664.156.
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Ultrasonic techniques are an established means for carrying out fatigue tests at very highnumbers of cycles. These techniques are based on the formation of a standing ultrasonic wave inthe specimen and usually use frequencies around 20 kHz. Although such systems allow testing to avery high number of cycles in a relatively short time, the use of a standing wave for creating thestrains restricts them to symmetric push-pull mode. This limitation can be overcome by coupling an ultrasonic test device to a universal test rig. In this work a different approach is presented that is particularly well suited for studying environmental effects. The load train with the specimen is enclosed in a pressure vessel. An acoustic horn divides this pressure vessel into two separate chambers. Applying a pressure difference between the two chambers then leads to a static stress in the specimenon which the oscillating stress from ultrasonic excitation is superposed. The addition of both stresses allows testing at varying R ratio. The deteriorating effect of high-pressure gaseous hydrogen on the steel A-286 is investigated as function of oscillating and static stresses at room temperature. SEM analysis of the fracture surface is presented.
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Zimmerman, Mark, John R. Parsons, and Harold Alexander. "The design and analysis of a laminated partially degradable composite bone plate for fracture fixation." Journal of Biomedical Materials Research 21, S3 (1987): 345–61. http://dx.doi.org/10.1002/j.1097-4636.1987.tb00029.x.
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During the early stages of fracture healing, rigid internal fixation maintains alignment and promotes primary osseous union. Unfortunately, as healing progresses rigid fixation from bone plating can cause bone in the region of the plate to undergo stress protection atrophy. This can result in significant loss of bone mass and osteoporosis. Refracture of the bone upon device removal is a widely reported complication. In an effort to minimize or eliminate stress protection atrophy, we have designed a partially absorbable, fiber‐reinforced bone plate. Ideally, such a plate gradually loses rigidity as the fracture heals, increasingly transferring stress to the bone. Stress protection may be avoided and removal or the device after healing may be unnecessary. Composite theory was used to determine an optimum fiber layup for a composite bone plate. Composite analysis suggested the mechanical superiority of a 0°/ $pM45° laminae layup. Given this laminated design, a thermoplastic absorbable polymer (polylactic acid polymer) was reinforced with high‐modulus carbon fiber to produce a semiabsorbable composite. Implant evaluation included optimizing fabrication techniques, thorough mechanical device testing, and implantation on canine femurs to determine biocompatibility and efficacy. The composite design proved to have superior static and fatigue properties to laminated or random fiber designs used previously. Two techniques for hole fabrication were tested. The production of screw holes during the molding process rather than machining postmolding, improved the mechanical integrity of the finished plate. Although the 0°/±45° carbon/polylactic acid composite possessed superior mechanical properties, it was unsuccessful in the in vivo environment. Water absorption and subsequent delamination made the plate flexible. Hypertrophic nonunions developed. Further development to prevent water intrusion and premature loss of mechanical properties is necessary.
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Nan, Rong Li, Xin Sun, Bo Zhao Shu, et al. "Threaded Failure Analysis for Three-Dimensional Horizontal Wells Casing." Materials Science Forum 993 (May 2020): 1155–59. http://dx.doi.org/10.4028/www.scientific.net/msf.993.1155.
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In view of the external thread fracture during casing running in a well in Xinjiang Oilfield, the failure reasons of thread fracture were analyzed by combining the theory with experiment, and the casing safe service window with harsh working conditions was given. The operation of the failed casing and determined the actual working conditions of the casing threaded joints during the running process were investigated in this paper. According to the theoretical method, the boundary conditions and load conditions of the fracture casing joint in service were determined. With the aid of full-scale physical simulation test device, as well as the above boundary conditions and load conditions, the same batch casing tensile bearing characteristics were determined. Through nondestructive testing, the metallographic observation, scanning electron microscopy, spectral analysis and up-and-down test, the main controlling factors of casing thread fracture were determined. By the finite element analysis, the casing threads service state under axial tension and bending loads was established, the safety performance of threads under ideal working conditions was studied, and the fatigue mechanism of threads was revealed. Combined with the analysis results, the corresponding relationship between the casing tensile bearing characteristics and safety factor was given, which provides technical support for the safe service selection of casing body and thread under harsh conditions, saving cost and shortening the well construction period.
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Hamandi, Farah, Stephen Whatley, Gerard Simon, Indresh Venkatarayappa, and Tarun Goswami. "Failure Analysis of a Femoral Cephalomedullary Nail." Metals 13, no. 3 (2023): 506. http://dx.doi.org/10.3390/met13030506.
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A fractured cephalomedullary femoral nailing system was investigated for the clinical and mechanical reasons responsible for its failure. Optical and scanning electron microscopes were utilized to investigate the fracture surface characteristics. Striations presented on the surface indicated mechanical fatigue. A qualitative material conformity test was conducted using available resources and found to be inconclusive, requiring more advanced testing of Ti-15Mo per ASTM standards in a third-party laboratory. In addition, the investigation showed that there is evidence of overloading failure once the fatigue-propagated crack reached a critical size. Based on the observed features, it is possible that nail and self-tapping helical screw interference may have occurred. The interior wall of the nail exhibited damage, allowing a surface crack to form. This surface crack was propagated due to cyclic loading occurring as a result of activities of daily living. The propagation of cracks formed the striations seen on the failed device. This continued for a period of time up until the crack grew to the point where the structure of the nail could no longer withstand the load and catastrophically failed by overloading.
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Horníková, Jana, Pavel Šandera, and Jaroslav Pokluda. "Linear-Elastic and Elastoplastic Mode II and III Crack Tip Stress-Strain Fields in Cylindrical Specimens with Circumferential Crack." Key Engineering Materials 417-418 (October 2009): 321–24. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.321.
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A numerical analysis by means of the ANSYS code was performed in order to identify the ratio of both stress intensity factors and crack tip opening displacements for a cylindrical specimen with circumferential V-notch loaded by remote pure shear stress. This kind of loading produces pure mode II and III loading in four points on the circumferential crack front while the mix mode II+III exists in all other crack front points. In the linear-elastic range, the ratio of maximum values of mode III and mode II stress intensity factors was found to be . On the other hand, the ratio of crack tip opening displacements in the elastoplastic range approaches . These results can be used for the construction of fatigue crack growth rate curves in austenitic and ferritic steels measured in the near-threshold and near-fracture regions by means of a special testing device.
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Müller, Alexandra, Anja Weidner, and Horst Biermann. "Influence of Reinforcement Geometry on the Very High-Cycle Fatigue Behavior of Aluminium-Matrix-Composites." Materials Science Forum 825-826 (July 2015): 150–57. http://dx.doi.org/10.4028/www.scientific.net/msf.825-826.150.
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During technical operation, high performance materials are partially exposed to high frequency cyclic loading conditions. Furthermore, the small strains in the very high cycle fatigue (VHCF)-regime lead to accumulative damage which causes crack initiation related to an appropriate local deformation leading to final fatal fracture. At the same time, quite high requirements with regard to high number of cycles without any damage are demanded for many applications. Fields of application of these light-weight, but expensive materials, are e.g. in the automobile industry (e.g. engine blocks, cylinder heads, brakes).The fatigue behavior of Al-matrix composites (Al-MMCs) reinforced by alumina particles (15 vol.% Al2O3) or short fibers (20 vol.% Saffil), respectively, was already intensively studied in the LCF and HCF range. The present study is focusing on investigations in the very high cycle fatigue regime at stress amplitudes up to 140 MPa to reach fatigue life of about 1010 cycles. All experiments were carried out using an ultrasonic fatigue testing device under symmetric loading conditions (R=-1). Fatigue tests were accompanied by in situ thermography measurements to record the temperature of the whole specimen and to find “hot spots” indicating changes in microstructure and therefore the initiation or growth of cracks. Moreover, the resonant frequency as well as the damage parameter were evaluated to determine the beginning of damage. For a better understanding of the damage mechanism (matrix decohesion, matrix failure or failure of reinforcement) all fractured surfaces were investigated by scanning electron microscopy. The combination of these methods contributes to a better understanding of the underlying mechanism of damage in aluminum-matrix-composites.
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Güneç, Hüseyin Gürkan, Neslihan Büşra Keskin, and Faruk Haznedaroğlu. "Comparison of cyclic fatigue resistance of different and novel heat-treated nickel-titanium rotary file systems at the intracanal temperature." International Dental Research 11, no. 3 (2021): 158–64. http://dx.doi.org/10.5577/intdentres.2021.vol11.no3.4.
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Aim: The aim of this study was to compare the cyclic fatigue resistance of different heat-treated nickel-titanium rotary systems at intracanal temperature. 
 Methodology: A total of 90 OneCurve (Micro-Mega, Besançon, France), VDW.ROTATE (VDW Dental, Munich, Germany), Typhoon (Clinician’s Choice, New Milford, CT, USA), HyFlex EDM (Coltene/Whaledent AG, Altstatten, Switzerland), and EndoArt Gold and Blue (Inci Dental, Istanbul, Turkey) (n = 15) rotary files (#25/0.06) were tested at intracanal temperature (35.5 ℃) using a dynamic model in a stainless-steel artificial canal with an inner diameter of 1.5 mm, 60° angle of curvature, and 2 mm radius of curvature. Testing was conducted until fracturing, at which time the device stopped automatically, and the number of rotations was calculated as seconds. Lengths of fractured parts were measured using a digital caliper. One-way ANOVA test followed by Tukey’s test was used to compare the groups. Scanning electron microscopic evaluation was performed to confirm the types of fracture.
 Results: EndoArt Blue group had a significantly higher mean time to fracture in all groups, followed by the HyFlex EDM, VDW.ROTATE, OneCurve, EndoArt Gold, and Typhoon. In addition, the HyFlex EDM and VDW.ROTATE groups had no significant differences between each other and were significantly better than the others. No significant differences were found between the OneCurve, EndoArt Gold, and Typhoon groups (p>0.05).
 Conclusion: This is the first study in the literature for EndoArt NiTi files and the second study for VDW.ROTATE that evaluated cyclic fatigue resistance. Novel EndoArt Blue files exhibited significantly greater cyclic fatigue resistance than the other NiTi files.
 
 How to cite this article: Güneç HG, Keskin NB, Haznedaroğlu F. Comparison of cyclic fatigue resistance of different and novel heat-treated nickel-titanium rotary file systems at intracanal temperature. Int Dent Res 2021;11(3):158-64. https://doi.org/10.5577/intdentres.2021.vol11.no3.4
 
 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.
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Chen, Chun-Feng, Chun-Ming Chen, Han-Sheng Chen, et al. "The Use of Customized Three-Dimensionally Printed Mandible Prostheses with a Pressure-Reducing Device: A Finite Element Analysis in Different Chewing Positions, Biomechanical Testing, and In Vivo Animal Study Using Lanyu Pigs." BioMed Research International 2022 (March 16, 2022): 1–31. http://dx.doi.org/10.1155/2022/9880454.
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Segmental bony defects of the mandible constitute a complete loss of the regional part of the mandible. Although several types of customized three-dimension-printed mandible prostheses (CMPs) have been developed, this technique has yet to be widely used. We used CMP with a pressure-reducing device (PRD) to investigate its clinical applicability. First, we used the finite element analysis (FEA). We designed four models of CMP (P1 to P4), and the result showed that CMP with posterior PRD deployment (P4 group) had the maximum total deformation in the protrusion and right excursion positions, and in clenching and left excursion positions, posterior screws had the minimum von Mises stress. Second, the P4 CMP-PRD was produced using LaserCUSING from titanium alloy (Ti-6Al-4V). The fracture test result revealed that the maximum static pressure that could be withstood was 189 N, and a fatigue test was conducted for 5,000,000 cycles. Third, animal study was conducted on five male 4-month-old Lanyu pigs. Four animals completed the experiment. Two animals had CMP exposure in the oral cavity, but there was no significant inflammation, and one animal had a rear wing fracture. According to a CT scan, the lingual cortex of the mandible crawled along the CMP surface, and a bony front-to-back connection was noted in one animal. A histological examination indicated that CMP was significantly less reactive than control materials ( p = 0.0170 ). Adequate PRD deployment in CMP may solve a challenge associated with CMP, thus promoting its use in clinical practice.
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Deviatnikova, V. G., and T. N. Manak. "Experimental study of factors affecting the failure of the cyclical nature of rotary endodontic instruments." Endodontics Today 18, no. 1 (2020): 4–14. http://dx.doi.org/10.36377/1683-2981-2020-18-1-4-14.
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Relevance. The properties of shape memory, superelasticity and plasticity in nickel-titanium tools make the visual prediction of breakage as difficult as possible. Therefore, an important role is given to research, the purpose of which is to predict the time of their work and to identify the main factors affecting the probability of a fracture.Aim. Comparison of cyclic fatigue resistance of Ni-Ti rotary endodontic instruments of various manufacturers.Materials and methods. The influence of the autoclaving procedure and the angle of bending of the root canal on the resistance of a rotating endodontic instrument to cyclic loads was studied using an author's patented device that simulates the rotation of an instrument in a real channel; the number of cycles completed by each instrument before its fracture was recorded. The morphology of fractures, the microstructure of specimens under fractures, and the microhardness of specimens of endodontic instruments after testing were studied.Results. It has been established that resistance to fatigue fractures of instruments of various endodontic systems decreases with an increase in the bending angle of the root canal. For Endostar E3 Basic Rotary System tools, the number of cycles decreased by 1.2 times, for Protaper Universal tools by 2.9 times. The tools of the Protaper Next system reduced the number of cycles at a bending angle of the artificial root canal of 60 degrees by 1.5 times compared with the number of cycles at a bending angle of 45 degrees. At the same time, statistical data and the study of the microstructure of samples of new and past 6 cycles of autoclave tools did not show a connection between the autoclaving procedure and a decrease in their resistance to cyclic loads.Conclusions. When working in complex bent over 45 degrees channels, it is rational to choose an endodontic instrument that has undergone heat treatment at the production stage (in the framework of this study, it was Protaper Next 25/06 M-Wire alloy). This will reduce the likelihood of a file fracture and associated dangerous complications of endodontic treatment.
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Wu, T. W. "Microscratch and load relaxation tests for ultra-thin films." Journal of Materials Research 6, no. 2 (1991): 407–26. http://dx.doi.org/10.1557/jmr.1991.0407.
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The microindenter has proven to be a powerful device in the characterization of the mechanical properties of thin films. The machine has both high resolution in the applied load and penetration depth measurements, as well as the versatility to perform different types of testing. The former provides the capability to deal with extremely thin films, while the latter allows for other mechanical properties, in addition to hardness, to be acquired. Four types of tests, namely indentation, scratch, load relaxation, and indentation fatigue tests can currently be conducted using the microindenter via different operating procedures. Only the scratch and load relaxation techniques will be covered in this paper. In a microscratch test, the normal load, tangential load, scratch length, and acoustic emission are monitored simultaneously during an entire scratch process for the purposes of measuring the critical load and studying the failure mechanisms of the deposited films. The adhesion strength, scratch hardness, fracture toughness, and friction are the mechanical properties which are possible to obtain by using this technique. Results from aluminum, carbon, and zirconia coatings will be discussed. The load relaxation test provides information on the creep properties of the films and results in an empirical constitutive relation between the applied stress and plastic strain rate. The creep properties of DC sputtered Al films will be used as an illustration of this.
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Srikrishnan, Anand, and Katie Tran. "0973 HGNS Sensing Lead Damage After 3D Mammogram Requiring HGNS IPG and Lead Re-Implantation." SLEEP 46, Supplement_1 (2023): A429—A430. http://dx.doi.org/10.1093/sleep/zsad077.0973.
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Abstract Introduction Obstructive sleep apnea (OSA) is associated with excessive daytime sleepiness, nocturnal hypoxemia, and daytime fatigue. Standard therapy is with positive airway pressure (PAP) therapy. If this is unsuccessful or poorly tolerated, a hypoglossal nerve stimulator (HGNS) can be surgically implanted for treatment. The goal of HGNS treatment is to advance the tongue with each respiration during sleep to relieve oropharyngeal obstruction causing OSA. This therapy has been shown to be efficacious and well tolerated for moderate to severe sleep apnea with a low complication rate. Report of case(s) A 61 year-old female with history of obesity and severe OSA presented to the sleep clinic with complaint of excessive daytime sleepiness and persistently elevated apnea-hypopnea index (AHI) of 42 events/hour despite adequate usage of CPAP therapy. She underwent an HGNS placement for treatment. Following HGNS activation she used it nightly and three months after implantation underwent an HGNS titration study which was successful (AHI 5.7) and the patient was started on optimal treatment settings with resulting resolution of OSA symptoms. After a period of successful device usage, she presented for follow up and reported complaints of excessive fatigue and sleepiness that was sudden. She attributed these changes to a 3D mammography study she underwent for breast cancer surveillance. Repeat home sleep apnea testing showed sudden worsening of her AHI to 50.6. During a thorough investigation of her device, HGNS sensing waveforms indicated possible sensing lead fracture. The patient was taken to the operating room for implanted pulse generator removal and replacement with new sensing and stimulation leads. Intra-operatively, it was noted that the distal sensing lead had several tears of the polyurethane insulation near the hub of the sensor. Following successful re-implantation sensing returned to normal and she has continued HGNS treatment. Conclusion We present a case of an unusual complication of HGNS sensing lead damage following a 3D mammography study. This led to surgical exploration with removal of a torn sensing lead and re-implantation of the HGNS generator and leads. Attention should be brought to patients and providers in the future regarding this rare, but potentially serious complication. Support (if any)
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Di Nardo, Dario, Alessio Zanza, Marco Seracchiani, Orlando Donfrancesco, Gianluca Gambarini, and Luca Testarelli. "Angle of Insertion and Torsional Resistance of Nickel–Titanium Rotary Instruments." Materials 14, no. 13 (2021): 3744. http://dx.doi.org/10.3390/ma14133744.
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Previously published studies have investigated the influence of instrument access on cyclic fatigue resistance. However, no studies have evaluated the relationship between angulated access and torsional resistance. The aim of this study was to investigate the influence of the angle of access on the torsional resistance of endodontic instruments. One hundred and eighty instruments were selected: 90 F-One Blue 25/04 and 90 HeroShaper 25/04 instruments. Three subgroups (n = 30) for each instrument type (A and B) were established according to the angle of insertion of the instruments inside the artificial canal (0°, 10° and 20°). The tests were performed using a custom-made device consisting of the following: a motor that can record torque values of 0.1 s; interchangeable stainless-steel canals with different curvature (0°, 10° and 20°) that allow the instrument’s angulated insertion and keep it flexed during testing procedures; and a vise used to secure the instrument at 3 mm from the tip. Torque limit was set to 5.5 Ncm, and each instrument was rotated at 500 rpm until fracture occurred. Torque to fracture (TtF) was registered by the endodontic motor, and the fragment length (FL) was measured with a digital caliper. Fractographic analysis was performed using a scanning electron microscopy (SEM) evaluation to confirm the cause of failure. TtF values and fragment length (FL) values were statistically analyzed using one-way analysis of variance (ANOVA) test and the Bonferroni correction for multiple comparisons across the groups with significance set to a 95% confidence level. Regarding the F-One Blue instruments, the results showed a higher TtF for group A3 (20°) than for group A1 (0°) and group A2 (10°), with a statistically significant difference between group A3 and the other two groups (p < 0.05), whereas no statistically significant difference was found between group A1 and group A2 (p > 0.05). Regarding the HeroShaper instrument, the results showed the highest TtF for group B3, with a statistically significant difference between the three subgroups B1, B2 and B3 (p < 0.05). The results showed that the torsional resistance increases as the angle of instrument access increases with a varying intensity, according to the crystallographic phase of the instrument selected.
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Krella, Alicja Krystyna. "Degradation and Protection of Materials from Cavitation Erosion: A Review." Materials 16, no. 5 (2023): 2058. http://dx.doi.org/10.3390/ma16052058.
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The phenomena of cavitation and cavitation erosion affect hydraulic machines, increasing their maintenance costs. Both these phenomena and also the methods of preventing the destruction of materials are presented. The compressive stress in the surface layer created from the implosion of cavitation bubbles depends on the aggressiveness of the cavitation, which in turn depends on the test device and test conditions, and also affects the erosion rate. Comparing the erosion rates of different materials tested using different tests devices, the correlation with material hardness was confirmed. However, no one simple correlation was obtained but rather several were achieved. This indicates that in addition to hardness, cavitation erosion resistance is also affected by other properties, such as ductility, fatigue strength and fracture toughness. Various methods such as plasma nitriding, shot peening, deep rolling and coating deposition used to increase resistance to cavitation erosion by increasing the hardness of the material surface are presented. It is shown that the improvement depends on the substrate, coating material and test conditions, but even using the same materials and test conditions large differences in the improvement can be sometimes gained. Moreover, sometimes a slight change in the manufacturing conditions of the protective layer or coating component can even contribute to a deterioration in resistance compared with the untreated material. Plasma nitriding can improve resistance by even 20 times, but in most cases, the improvement was about two-fold. Shot peening or friction stir processing can improve erosion resistance up to five times. However, such treatment introduces compressive stresses into the surface layer, which reduces corrosion resistance. Testing in a 3.5% NaCl solution showed a deterioration of resistance. Other effective treatments were laser treatment (an improvement from 1.15 times to about 7 times), the deposition of PVD coatings (an improvement of up to 40 times) and HVOF coatings or HVAF coatings (an improvement of up to 6.5 times). It is shown that the ratio of the coating hardness to the hardness of the substrate is also very important, and for a value greater than the threshold value, the improvement in resistance decreases. A thick, hard and brittle coating or alloyed layer may impair the resistance compared to the untreated substrate material.
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Sun, Xiaoyuan, Yongliang He, Tingxu Jin, Jianlin Xie, Chuantian Li, and Jiewen Pang. "Microseismic Signal Characteristics of the Coal Failure Process under Weak-Energy and Low-Frequency Disturbance." Sustainability 15, no. 19 (2023): 14387. http://dx.doi.org/10.3390/su151914387.
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In deep mining, “critical static stress + slight disturbance” is an important inducing form of coal mine rockburst disasters. In previous studies, the critical static stress has been shown to be consistent with the loading direction of a slight disturbance but cannot reflect all types of rockbursts. In addition, the research that uses microseismic (MS) signals to reflect the overall process and critical stages of coal failure and instability under weak-energy and low-frequency disturbance conditions is immature, and more information, such as the critical state, has not been fully revealed. The aims of this paper are to further elucidate the important role of weak-energy and low-frequency disturbances in the occurrence of rockburst disasters. First, briquette samples were prepared from the Tashan Coal Mine, which is severely affected by rockbursts, and their homogeneity was verified using ultrasonic longitudinal wave velocity. Second, the natural frequency of the coal sample specimens was measured using a testing system. Then, based on the self-developed static pressure loading system, dynamic and static combined loading test system and MS signal monitoring device, the MS signal characteristics during the process of coal body failure and instability were comprehensively analysed. Finally, a comparison was made between weak-energy and low-frequency disturbances and impact disturbances. The results are summarized as follows. (1) The longitudinal wave velocity test results reflect that the briquette samples prepared in the experiment have high homogeneity. The smaller the particle size is, the higher the density and moulding pressure, and the denser the sample. (2) The natural frequency of the briquette samples is between 30.79 Hz and 43.34 Hz, and most of them fluctuate at approximately 35 Hz. (3) During the static loading stage, the occurrence of more than three MS signals of larger magnitude in a continuous cluster is an important criterion for the critical failure of the samples. (4) The weak-energy and low-frequency disturbance actually leads to fatigue damage, and the briquette sample experiences three stages: the near-threshold stage, the high-speed expansion stage and the final fracture stage. The smaller the particle size of the coal sample, the denser the specimen, the stronger the amplitude and energy of the single effective MS signal formed during the destruction process, the longer the time duration of crack expansion from the near-threshold stage to the high-speed expansion stage, and the stronger the ability of the coal sample to resist weak-energy and low-frequency disturbances. This study may contribute to a more comprehensive understanding of the destabilization mechanism of coal bodies and MS signal characteristics under weak-energy and low-frequency disturbances and provide a reference for further research and discussion.
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Mohammad, Reza Zamani Kouhpanji. "Designing and Analyzing Sensor and Actuator of a Nano/Micro-System for Fatigue and Fracture Characterization of Nanomaterials." September 2, 2017. https://doi.org/10.5281/zenodo.1132467.
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This paper presents a MEMS/NEMS device for fatigue and fracture characterization of nanomaterials. This device can apply static loads, cyclic loads, and their combinations in nanomechanical experiments. It is based on the electromagnetic force induced between paired parallel wires carrying electrical currents. Using this concept, the actuator and sensor parts of the device were designed and analyzed while considering the practical limitations. Since the PWCC device only uses two wires for actuation part and sensing part, its fabrication process is extremely easier than the available MEMS/NEMS devices. The total gain and phase shift of the MEMS/NEMS device were calculated and investigated. Furthermore, the maximum gain and sensitivity of the MEMS/NEMS device were studied to demonstrate the capability and usability of the device for wide range of nanomaterials samples. This device can be readily integrated into SEM/TEM instruments to provide real time study of the mechanical behaviors of nanomaterials as well as their fatigue and fracture properties, softening or hardening behaviors, and initiation and propagation of nanocracks.
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Mohammad, Reza Zamani Kouhpanji. "Studying the Dynamical Response of Nano-Microelectromechanical Devices for Nanomechanical Testing of Nanostructures." International Journal of Mechanical, Industrial and Aerospace Sciences 10.0, no. 11 (2017). https://doi.org/10.5281/zenodo.1314465.
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Characterizing the fatigue and fracture properties of nanostructures is one of the most challenging tasks in nanoscience and nanotechnology due to lack of a MEMS/NEMS device for generating uniform cyclic loadings at high frequencies. Here, the dynamic response of a recently proposed MEMS/NEMS device under different inputs signals is completely investigated. This MEMS/NEMS device is designed and modeled based on the electromagnetic force induced between paired parallel wires carrying electrical currents, known as Ampere’s Force Law (AFL). Since this MEMS/NEMS device only uses two paired wires for actuation part and sensing part, it represents highly sensitive and linear response for nanostructures with any stiffness and shapes (single or arrays of nanowires, nanotubes, nanosheets or nanowalls). In addition to studying the maximum gains at different resonance frequencies of the MEMS/NEMS device, its dynamical responses are investigated for different inputs and nanostructure properties to demonstrate the capability, usability, and reliability of the device for wide range of nanostructures. This MEMS/NEMS device can be readily integrated into SEM/TEM instruments to provide real time study of the fatigue and fracture properties of nanostructures as well as their softening or hardening behaviors, and initiation and/or propagation of nanocracks in them.
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Mohammad, Reza Zamani Kouhpanji. "Studying the Dynamical Response of Nano-Microelectromechanical Devices for Nanomechanical Testing of Nanostructures." October 1, 2017. https://doi.org/10.5281/zenodo.1132793.
Full textAbstract:
Characterizing the fatigue and fracture properties of nanostructures is one of the most challenging tasks in nanoscience and nanotechnology due to lack of a MEMS/NEMS device for generating uniform cyclic loadings at high frequencies. Here, the dynamic response of a recently proposed MEMS/NEMS device under different inputs signals is completely investigated. This MEMS/NEMS device is designed and modeled based on the electromagnetic force induced between paired parallel wires carrying electrical currents, known as Ampere’s Force Law (AFL). Since this MEMS/NEMS device only uses two paired wires for actuation part and sensing part, it represents highly sensitive and linear response for nanostructures with any stiffness and shapes (single or arrays of nanowires, nanotubes, nanosheets or nanowalls). In addition to studying the maximum gains at different resonance frequencies of the MEMS/NEMS device, its dynamical responses are investigated for different inputs and nanostructure properties to demonstrate the capability, usability, and reliability of the device for wide range of nanostructures. This MEMS/NEMS device can be readily integrated into SEM/TEM instruments to provide real time study of the fatigue and fracture properties of nanostructures as well as their softening or hardening behaviors, and initiation and/or propagation of nanocracks in them.
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Vladimir Oborin, Mikhail Bannikov, Oleg Naimark, Mikhail Sokovikov, and Dmitry Bilalov. "Multiscale study of fracture in aluminum-magnesium alloy under fatigue and dynamic loading." Frattura ed Integrità Strutturale, no. 34 (September 28, 2015). http://dx.doi.org/10.3221/igf-esis.34.47.
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In this paper we investigated the influence of consecutive dynamic and gigacycle fatigue loads on the lifetime of aluminum-magnesium alloy AlMg6. Preloading of samples was achieved during dynamic tensile tests in the split-Hopkinson bar device. Fatigue tests were conducted on Shimadzu USF-2000 ultrasonic fatigue testing machine. This machine provides 109-1010 loading cycles with the amplitude from 1 to several dozens of microns and frequency of 20 kHz, which reduces dramatically the testing time in the comparison to the classical fatigue testing machines. The New-View 5010 interferometer–profiler of high structural resolution (resolution of 0.1 nm) was used for qualitative fracture surface analysis, which provided the data allowing us to find correlation between mechanical properties and scale-invariant characteristics of damage induced roughness formed under dynamic and gigacycle fatigue loading conditions. Original form of the kinetic equation was proposed, which links the rate of the fatigue crack growth and the stress intensity factor using the scale invariant parameters of fracture surface roughness. The scale invariance characterizes the correlated behavior of multiscale damage provides the link of crack growth kinetics and the power exponent of the modified Paris law.
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Ismail, Amira Galal, Manar Galal, and Nehal Nabil Roshdy. "Assessment of cyclic fatigue resistance of Protaper Next and WaveOne Gold in different kinematics." Bulletin of the National Research Centre 44, no. 1 (2020). http://dx.doi.org/10.1186/s42269-020-00421-w.
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Abstract Background The purpose of the current study was to inspect and compare the influence of applying continuous rotation and reciprocation motions on the cyclic fatigue resistance of Protaper Next (PTN) file (X2) and WaveOne Gold (WOG) Primary file in simulated canals. Twenty Protaper Next files(X2) and 20 WaveOne Gold Primary files were included in this study. A cyclic fatigue testing device was employed to test the cyclic resistance of each file in different motions. The testing device has an artificial custom-made stainless-steel canal with a 60° angle of curvature and a 2-mm radius of curvature. The files were randomly divided into 4 groups; group 1: PTN in continuous rotation, group 2: PTN in reciprocation, group 3: WOG in continuous rotation and group 4: WOG in reciprocation. All the instruments were rotated until fracture occurred, and the time to fracture was recorded in seconds using a digital chronometer. The number of cycles to fracture (NCF) was calculated. The data were analyzed statistically (p < .05). Results Results represented that when using either continuous rotation motion or reciprocating motion, WOG files showed a significantly longer time until failure than PTN files (p < 0.001). The time till fracture increased significantly, when using both types of files with a reciprocating filing motion. Conclusion Within the confinement of this study, WOG file in reciprocation showed higher cyclic fatigue resistance than PTN in both continuous rotation and reciprocating motion. The reciprocating motion enhances both files behavior in terms of cyclic fatigue resistance.
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Cortelli, Giorgio, Tobias Cramer, Luca Patruno, Beatrice Fraboni, and Stefano de Miranda. "In Situ Nanomechanical Characterization Techniques for Soft Bioelectronic Interfaces and Their Building Blocks." Advanced Materials Technologies, October 16, 2023. http://dx.doi.org/10.1002/admt.202300931.
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AbstractSoft bioelectronic interfaces constitute a paradigm shift for biomedical devices. High‐resolution monitoring and stimulation of physiological processes in vivo are becoming possible with minimally invasive devices operated without inflicting tissue damage or discomfort over prolonged timescales. However, the development and commercialization of such interfaces still must address significant challenges. Biological tissue is subjected to continuous motion and the related device deformations can easily trigger fracture or delamination of the device components, putting long‐term durability of soft implants at risk. In this review, an overview of experimental techniques for testing mechanical properties and failure mechanisms of soft bioelectronic devices at the nanoscale while the deformation takes place (in situ) is provided. Through the tensile test, bending test, nanoindentation, and micropillar compression test, precise measurements of the mechanical properties of individual building blocks and the interfaces themselves can be obtained. Such parameters are crucial to design, model, and optimize the device's performance. Then, recent examples of how this information guides design and optimization of soft bioelectronic interfaces and devices for healthcare, robotics, and human–machine interfaces is provided. Last of all, future research that is needed to fully achieve long‐term soft bioelectronic interfaces for integration with the human body is discussed.
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Ballarini, R., R. L. Mullen, H. Kahn, and A. H. Heuer. "The Fracture Toughness of Polysilicon Microdevices." MRS Proceedings 518 (1998). http://dx.doi.org/10.1557/proc-518-137.
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AbstractThe development of polysilicon fracture mechanics specimens with characteristic dimensions comparable to those of typical microelectromechanical systems (MEMS) devices is presented. The notched cantilever specimens are fully integrated with a simultaneously microfabricated electrostatic actuator, which allows on-chip testing of the specimens without the need of an external loading device, and without any possible influences from external sources. Under monotonic loading, the average maximum tensile stress (strength) and average nominal fracture toughness were measured as 4.2 GPa and 3.5 MPa-m½ for boron-doped specimens, and 5.0 GPa and 4.0 MPa-m½ for undoped specimens. An average modulus of rupture of 3.3 GPa and average nominal toughness of 2.7 MPa-m½ were measured for specimens cracked under cyclic resonance loading. The differences between the monotonic loading and cyclic loading data are attributed to fatigue initiation of a sharp crack from the 1 ýtm radius notch. The experimental data is consistent with a critical flaw size in the fabricated devices, a, that is related to the fracture toughness Klc by Klc/a1/2=4600 MPa.