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Chen, Cai, Yan Beygelzimer, Roman Kulagin y Oleksandr Davydenko. "Construction of tensile stress-strain curves for solid bars pre-deformed by gradient shear strain". Обробка матеріалів тиском, n.º 1(50) (31 de marzo de 2020): 114–18. http://dx.doi.org/10.37142/2076-2151/2020-1(50)114.
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Cai Chen, Beygelzimer Y., Kulagin R., Davydenko O. Construction of tensile stress-strain curves for solid bars pre-deformed by gradient shear strain. Material working by pressure. 2020. № 1 (50). P. 114-118.
Strain hardening curves were derived for the first time for tension of cylindrical solid bars in the presence of a linear strain gradient produced by severely pre-straining by torsion. An analytical formula was obtained, which enables constructing the local stress-strain curve. Data obtained for pure copper samples pre-twisted to different levels of shear strain were used. A saturation stage not known hitherto was found for large strains.
One particularity of the present results is that for low tensile strains the tensile flow stress after torsion agrees well with the flow stress in monotonic tension.
Another particularity of the results is that the tensile flow stress is constant after torsion at large strains, starting from about 1.5 strain. This effect was observed for the first time because the present technique is the first one to provide access to tensile flow stress after large strain torsion.
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Shuaiquan, Zhao, Chang Yuping, Yang Yadie, Zhang Minglonghai, Hasan Kamrul y Hu Hong. "Auxetic behavior of warp knitted fabric under repeating tension". Textile Research Journal 91, n.º 15-16 (25 de enero de 2021): 1732–41. http://dx.doi.org/10.1177/0040517521989277.
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In our previous study, a novel class of auxetic warp knitted fabrics were developed and their auxetic behaviors were studied under a single tensile test. However, during daily use, the fabrics are usually subjected to repeating tension rather than single tension. Therefore, the durability of the fabrics’ auxetic performance is of great importance. So far, the auxetic behavior of fabrics under repeating tension has not systematically been investigated. In this paper, we report a study on the auxetic behavior of warp knitted fabrics under repeating tension. All the fabric samples were subjected to a repeating tensile test within a tensile strain of 25% until 100 tensile cycles. The results show that the fabrics can keep their auxetic effect in both course and wale testing directions after 100 tensile cycles, and the auxetic effect in the wale direction is retained longer under higher tensile strains than that under lower tensile strains with the increase of tensile cycles. The results also indicate that auxetic stability in the course direction is much better than that in the wale direction. We hope that this study can offer useful information to improve the auxetic stability of auxetic fabrics for practical use.
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Kim, Seung-Gyu, Yeong-Seong Park y Yong-Hak Lee. "Comparison of Concrete Creep in Compression, Tension, and Bending under Drying Condition". Materials 12, n.º 20 (15 de octubre de 2019): 3357. http://dx.doi.org/10.3390/ma12203357.
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Three types of creep experiments of compression, tension, and bending were implemented to identify quantitative relations among the three types of creep under drying atmospheric conditions. In case of the bending creep experiment, two types of unreinforced concrete beams with similar dimensions were cast for use in the beam creep and shrinkage tests. The variations in the shrinkage strain within the beam depth were measured to evaluate the effect of the shrinkage variations on the bending creep strain. The beam creep strain measured within the beam depth was composed of uniform and skewed parts. The skewed parts of the creep strain were found to be dominant whereas the uniform parts were small enough to be neglected in the bending creep evaluation. This indicated that the compressive bending creep at the top surface was close to the tensile bending creep at the bottom surface. The ratios of tensile and bending creep strains to compressive creep strain were approximately 2.9 and 2.3, respectively, and the ratio of bending creep strain to tensile creep strain was approximately 0.8. Particular attention is laid on the close agreement between tensile and compressive bending creep strains even if the creep in tension is 2.9 times larger than the creep strain in compression.
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Hidayati, Sri y Sholihun Sholihun. "Strain Effects on the Band Structures of Monolayer GaN from the Density Functional Theory". Materials Science Forum 1066 (13 de julio de 2022): 144–49. http://dx.doi.org/10.4028/p-d647l2.
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We perform the density functional theory calculations (DFT) to study the effect of biaxial strain on the band structures of monolayer GaN. We apply compressive and tensile strains up to 10%. There is no change of bandgap for the applied tensile strains below 8%. The compressive strains have a constant bandgap which is slightly smaller than that of the zero strain. We find that the applied tensile strain above 8% affects its electronic structure and decreases its bandgap energy by about 0.05 eV while the compressive strain above 4% decreases its bandgap about 0.22 eV.
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Khalsa, Partap S., Robert H. Lamotte y Peter Grigg. "Tensile and Compressive Responses of Nociceptors in Rat Hairy Skin". Journal of Neurophysiology 78, n.º 1 (1 de julio de 1997): 492–505. http://dx.doi.org/10.1152/jn.1997.78.1.492.
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Khalsa, Partap S., Robert H. LaMotte, and Peter Grigg. Tensive and compressive responses of nociceptors in rat hairy skin. J. Neurophysiol. 78: 492–505, 1997. Mechanically sensitive nociceptor afferents were studied in a preparation of isolated skin from rat leg. Each neuron was studied while the skin was subjected to tensile and compressive loading. The experiment was designed to create highly uniform states of stress in both tension and compression. Tensile loads were applied by pulling on the edges of the sample. Applied loads were used to determine the tensile stresses. Surface displacements were used to determine tensile strains. Compressive loads were applied by indenting the surface of the skin with flat indenter tips applied under force control. The skin was supported by a flat, hard substrate. Compressive stresses were determined from the applied loads and tip geometry. Compressive strains were determined from skin thickness and tip excursions. All nociceptors were activated by both tensile and compressive loading. There was no interaction between the responses to compressive and tensile stimuli (i.e., the responses were simply additive). Responses of nociceptors were better related to tensile and compressive stresses than to strains. Nociceptors responded better to tensile loading than to compressive loading. Response thresholds were lower and sensitivities were higher for tensile stress than for compressive stress. The response to compression was better related to compressive stress than to other stimulus parameters (i.e., load/circumference or simply load). Indentations of intact skin over a soft substrate such as muscle would be expected to cause widespread activation of nociceptors because of tensile stresses.
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Jiang, Yin Fang, Zhen Zhou Tang, Zhi Fei Li y Lei Fang. "Research on the Forming Limit Diagram Based on Laser Shock Forming". Applied Mechanics and Materials 44-47 (diciembre de 2010): 148–52. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.148.
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Laser shock forming (LSF) of sheet metal is a novel technology in plastic deformation. It is necessary to correctly predict the Forming Limit Diagram (FLD) based on LSF. New failure maximum thickness reduction rate criterion is used to determine the forming limit based on the numerical system during LSF. The relationship model between maximum thickness reduction rate and the strain path is built. In addition, the effects of strain path and strain-hardening exponent on forming limit are considered. The maximum thickness reduction rate under equi-biaxial tensile strain path can be determined easily during LSF and the expression of the criterion is determined finally. Then the limit strains under other strain paths between uniaxial tension to equi-biaxial tension can be determined by the criterion combined with numerical simulation of forming process. The criterion can predict forming limits for sheet metal exactly and makes it possible to determine forming limit strains under different strain paths only through equi-biaxial tensile test during LSF.
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Gallage, Chaminda y Chamara Jayalath. "Use of Particle Image Velocimetry (PIV) technique to measure strains in geogrids". E3S Web of Conferences 92 (2019): 12007. http://dx.doi.org/10.1051/e3sconf/20199212007.
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Geosynthetics are widely used in Geotechnical Engineering to reinforce soil/gravel in pavements, retaining wall backfills, and embankments. It is important to measure strains in geogrids in the determination of their strength parameters such as tensile strength and secant stiffness, and in evaluating their performances in geogrid-reinforced structures. Strain gauges are commonly used in measuring strains in geogrids. However, it is important to verify the strains measured by strain gauges as these strains are affected by the data logging device, gauge factors, quality of bonding between grain gauge and geogrid, and temperature. Therefore, this study was conducted to verify the performance of strain gauges attached to Geogrids and also to investigate the possibility of using PIV technique and GeoPIV-RG software to measure the local strains developed in a geogrid specimen under tensile testing in the laboratory. In the experimental program of this study, six composite geogrid specimens were tested for tensile strength (wide-width tensile tests) while measuring/calculating its tensile strain by using strain gauges attached to the specimens, Geo-PIV-RG analysis and crosshead movements of Instron apparatus. Good agreement between the strains obtained from strain gauges and geoPIV-RG analysis was observed for all the tests conducted. These results suggest that the PIV technique along with geoPIV-RG program can effectively be used to measure the local strain of geogrids in the laboratory tests. It was also able to verify that properly installed strain gauges are able to measure strain in the geogrids which are used in the field applications.
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Yu, Tianbo, Yan Du, Guohua Fan, Rozaliya Barabash, Dorte Juul Jensen y Yubin Zhang. "In Situ Synchrotron X-ray Micro-Diffraction Investigation of Elastic Strains in Laminated Ti-Al Composites". Metals 11, n.º 4 (19 de abril de 2021): 668. http://dx.doi.org/10.3390/met11040668.
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Spatially resolved elastic strains in the bulk interior of a laminated Ti-Al metal composite were studied during in situ tensile loading at strains up to 1.66% by a synchrotron-based micro-diffraction technique, namely differential aperture X-ray microscopy (DAXM). For both Al and Ti grains, deviatoric elastic strains were estimated based on polychromatic X-ray microbeam diffraction, while lattice strains along the normal direction of the tensile sample were directly measured using monochromatic X-ray microbeam diffraction. The estimated deviatoric strains show large spatial variations, and the mean values are consistent with the external loading conditions, i.e., increasing tensile strain along the tensile direction and increasing compressive strain along the sample normal with increasing loading. The directly measured lattice strains also show large spatial variations, although the magnitude of this variation is smaller than that for the estimated deviatoric strain. The directly measured lattice strains in Ti grains are largely consistent with the external loading, whereas those in Al grains are in contradiction with the external loading. The causes of the experimental results are discussed and related to both the laminated microstructure of the composite material and the limitations of the techniques.
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TAKAHASHI, Y., M. DAIMARUYA, H. KOBAYASHI, H. TSUDA y H. FUJIKI. "IMPACT TENSILE PROPERTIES OF YAG LASER WELDED BUTT JOINTS MADE BY DIFFERENT STEEL SHEETS FOR VEHICLES". International Journal of Modern Physics B 22, n.º 09n11 (30 de abril de 2008): 1712–17. http://dx.doi.org/10.1142/s0217979208047304.
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The tensile properties of YAG laser welded butt joints using different high strength steel sheets with a tensile strength of 270 MPa, 590 MPa and 980 MPa (denoted HR270, HR590 and HR980, respectively) were investigated at static and dynamic rates, together with the three kinds of laser welded joints made by the same steel sheets. The impact tensile tests were performed by using the vertical type of split Hopkinson tension bar apparatus, while the static tensile tests were carried out using a universal testing machine INSTRON5586. The impact tensile strengths were significantly increased in comparison with the static ones due to the effect of strain rate, which might be the contribution of the part of HR270 base metal. And in both of static and impact tests, the fracture strains of HR270-HR590 joint, HR270-HR980 joint and HR590-HR980 joint were about one half of the fracture strains observed in the same steel welded joints of HR270-HR270, HR270-HR270 and HR590-HR590, respectively.
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Wu, W. C., Z. M. Ao, C. H. Yang, S. Li, G. X. Wang, C. M. Li y S. Li. "Hydrogenation of silicene with tensile strains". Journal of Materials Chemistry C 3, n.º 11 (2015): 2593–602. http://dx.doi.org/10.1039/c4tc02095b.
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The energy barrier for hydrogenation of silicene decreases as the strains increase, and the barrier reduces from 1.71 to 0.24 eV when the strain reaches the critical value of 12%. In this way, the reaction time for the hydrogenation of silicene can accelerate significantly from 8.06 × 1016 to 1.68 × 10−8 s.
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Thuillier, Sandrine. "Influence of a Tensile Pre-Strain on Bending of Aluminium Alloy". Key Engineering Materials 611-612 (mayo de 2014): 1742–49. http://dx.doi.org/10.4028/www.scientific.net/kem.611-612.1742.
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The mechanical behavior of thin sheets of aluminium alloy 6016, of thickness 1.14 mm, was investigated in unconstrained bending, with or without a tensile pre-strain. In the case of bending without pre-strain, no rupture was observed. Therefore, a tensile pre-strain, ranging from 0.19 up to 0.45 (longitudinal strain), was applied prior to bending. The highest pre-strain values were reached within the necking area. Tensile tests on rectangular samples were performed, then reduced samples were cut out and submitted to bending. A Digital Image Correlation (DIC) system was used to measure the maximum local strains reached during both tests. The evolution of the applied load on the bending tool versus its displacement showed that a rupture in bending was obtained for tensile pre-strains higher than 0.25, as evidenced by a load drop. These results showed that very high strains can be reached in bending, which is consistent with previously obtained numerical results.
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de Melo Pereira, Alexandre, Marcelo Costa Cardoso y Luciano Pessanha Moreira. "Effects of Strain-Rate and Deformation Mode on Strain-Induced Martensite Transformation of AISI 304L Steel Sheet". Applied Mechanics and Materials 835 (mayo de 2016): 216–21. http://dx.doi.org/10.4028/www.scientific.net/amm.835.216.
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Metastable austenitic stainless steels are prone to strain-induced martensitic transformation (SIMT) during deformation at room temperature, as in the case of sheet metal forming processes. SIMT is influenced by chemical composition, grain size, temperature, deformation mode or stress state and strain-rate effects. In this work, uniaxial and plane-strain tension tests were performed in AISI 304L sheet to evaluate the SIMT as a function of strain-rate. Feritscope and temperature in-situ measurements were performed during the uniaxial tensile testing. Digital image correlation (DIC) technique was employed to determine the in-plane surface strains of the plane-strain tension specimen. From the uniaxial tensile and plane-strain tension results, the yield stress increased with the strain-rate in the small strain range whereas a cross-effect in the stress-strain curve is exhibited in the large strain domain. This effect is attributed to the specimen heat generation, which inhibits the SIMT phenomenon. Conversely, plane-strain deformation mode displayed a higher SIMT rate and an improved work-hardening behavior in comparison to the uniaxial tensile straining.
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Natesan, Elanghovan, Johan Ahlström, Stefan Eriksson y Christer Persson. "Effects of Temperature on the Evolution of Yield Surface and Stress Asymmetry in A356–T7 Cast Aluminium Alloy". Materials 14, n.º 24 (20 de diciembre de 2021): 7898. http://dx.doi.org/10.3390/ma14247898.
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As the electrification of vehicle powertrains takes prominence to meet stringent emission norms, parts of internal combustion engines like cylinder heads are subjected to an increased number of thermal load cycles. The cost-effective design of such structures subjected to cyclic thermo-mechanical loads relies on the development of accurate material models capable of describing the continuum deformation behaviour of the material. This study investigates the effect of temperature on the evolution of flow stress under cyclic loading in A356-T7 + 0.5% Cu cast aluminium alloy commonly used in modern internal combustion engine cylinder heads. The material exhibits peak stress and flow stress asymmetry with the stress response and flow stress of the material under compressive loading higher than under tension. This peak and flow stress asymmetry decrease with an increase in temperature. To compare this stress asymmetry against conventional steel, cyclic strain-controlled fatigue tests are run on fully pearlitic R260 railway steel material. To study the effect of mean strain on the cyclic mean stress evolution and fatigue behaviour of the alloy, tests with tensile and compressive mean strains of +0.2% and −0.2% are compared against fully reversed (Rε = −1) strain-controlled tests. The material exhibits greater stress asymmetry between the peak tensile and peak compressive stresses for the strain-controlled tests with a compressive mean strain than the tests with an identical magnitude tensile mean strain. The material exhibits mean stress relaxation at all temperatures. Reduced durability of the material is observed for the tests with tensile mean strains at lower test temperatures of up to 150 °C. The tensile mean strains at elevated temperatures do not exhibit such a detrimental effect on the endurance limit of the material.
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van Ruijven, L. J., E. B. W. Giesen y T. M. G. J. van Eijden. "Mechanical Significance of the Trabecular Microstructure of the Human Mandibular Condyle". Journal of Dental Research 81, n.º 10 (octubre de 2002): 706–10. http://dx.doi.org/10.1177/154405910208101010.
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The human mandibular condyle has a parasagittal plate-like trabecular structure. We tested the hypothesis that this structure reflects the mechanical loading of the condyle. We developed a finite element model of the condyle to analyze the strains occurring during static compressive loading. The principal strains in the trabecular bone were primarily oriented in the sagittal plane. The first component was compressive and oriented supero-inferiorly. The second component was negligibly small and oriented medio-laterally. The third component was tensile, oriented antero-posteriorly, and almost equal to the compressive strain. This tensile strain was caused by antero-posterior bulging of the cortex. This means that the trabecular structure is also subjected to significant tensile forces. The orientation of the parasagittal strains followed the direction of the applied load. It was concluded that the trabecular structure of the mandibular condyle is optimal in resisting the compressive and tensile strains to which it is subjected.
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Themelis, G. y J. Weertman. "Stereoimaging of tensile plastic strains". Scripta Metallurgica et Materialia 24, n.º 9 (septiembre de 1990): 1719–24. http://dx.doi.org/10.1016/0956-716x(90)90535-o.
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Rizzone, Katherine, Grace E. Weyand, Michael S. Richards, Catherine K. Kuo y Mark R. Buckley. "MAPPING COMPRESSIVE AND TENSILE STRAINS OF THE PATELLAR TENDON IN OSGOOD-SCHLATTER DISEASE USING ULTRASOUND ELASTOGRAPHY". Orthopaedic Journal of Sports Medicine 7, n.º 3_suppl (1 de marzo de 2019): 2325967119S0002. http://dx.doi.org/10.1177/2325967119s00024.
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Background Osgood-Schlatter Disease (OSD) impacts millions of young athletes every year, yet its biomechanical etiology remains unclear. It’s been postulated that increased growth velocity in children elevates tension within the patellar tendon, placing distal strain on the tibial tubercle, causing anterior knee pain, but this process has not been previously elucidated. The purpose of this study was to evaluate axial tensile and transverse compressive strains in adolescent patellar tendons during exercise to identify differences between those with and without OSD using a cumulative strain, ultrasound elastography measurement method [REF: Chimenti et al 2016]. Methods Axial tensile and transverse compressive strains of the patellar tendon in eight adolescents with OSD and ten adolescents without OSD were quantified from ultrasound elastography images. Multiaxial strains of the patellar tendon were assessed as the participant performed two different exercises: 1) participant seated with leg fully extended, participant bends knee, followed by a return to initial extended position; (2) participant standing performs a squat and then returns to initial standing position. Participants’ disease severity was clinically assessed using the VISA-P and Cincinnati knee scale. Results Mean age was 13.1 years (+/- 2.7), 39% were male (63% of OSD group). There was no statistically significant difference in patellar tendon tensile strains during the seated knee flexion and squat positions between groups (p = 0.99, p = 0.83 respectively). The OSD group had significantly less tendon compression compared to the non-OSD group during both the knee flexion (p <0.01), and squat exercises (p <0.05). Conclusions/Significance Adolescents with OSD had lower transverse compressive strains in the patellar tendon as compared to adolescents without OSD. In contrast, tensile strains were not increased in children with OSD. These findings appear to contradict the tension hypothesis postulating that OSD is caused by increased patellar tendon axial tension associated with rapid bone growth, Instead, impingement from the tibia leading to transverse tendon compression may lead to an adaptive stiffing the patellar tendon, However, further research is needed to confirm this hypothesis. While OSD is a common cause of knee pain in growing athletes that frequently leads to loss in participation, its etiology is unclear, making development of effective treatment approaches difficult. This study highlights differences in multiaxial patellar tendon strains in adolescents with OSD which may help direct future research on management strategies.
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Naseem, S., E. S. Perdahcıoğlu, H. J. M. Geijselaers y A. H. van den Boogaard. "A New in-Plane Bending Test to Determine Flow Curves for Materials with Low Uniform Elongation". Experimental Mechanics 60, n.º 9 (17 de agosto de 2020): 1225–38. http://dx.doi.org/10.1007/s11340-020-00621-5.
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Abstract Background Flow curves can easily be obtained by uniaxial tensile tests, but strains are then limited by diffuse necking. For many applications, the flow stress must be known above this limit. Objective The main objective of this paper is to obtain flow curves for material with low uniform elongation to relatively high strains compared to a uniaxial tensile test. Method A novel in-plane sheet bending experiment and stress evaluation procedure is presented. The developed bending device can be mounted in a tensile test machine and can produce very high bending curvatures compared to previously proposed pure bending setups. The bending angle and curvature are obtained by image processing and the bending moment is calculated directly from the force measured from the tensile test machine and the bending angle. The moment–curvature relation is used to determine the uniaxial stress–strain relation using an analytical approach, without presuming any hardening model. The bending process and the analytical procedure are validated by a numerical simulation as well as by experiments. Results The numerical validation shows good agreement between the stress–strain curve obtained from the bending process and that of the uniaxial input flow curve up to 12% strain. Experimentally the model is validated by comparing the stress–strain curve obtained from the bending test with the results directly obtained from a tensile test for mild steel. Good agreement is observed up to 12% strain. As an application example, bending tests were performed on a martensitic steel (MS) with low uniform strain (less than 3%). For this material, flow curves could be obtained up to relatively high strains (~12%), compared to a tensile test. Conclusion This bending test setup allows to study materials with low uniform elongation up to significantly higher strains than are readily obtained in a tensile test.
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Butcher, Cliff y Armin Abedini. "On Phenomenological Failure Loci of Metals under Constant Stress States of Combined Tension and Shear: Issues of Coaxiality and Non-Uniqueness". Metals 9, n.º 10 (28 de septiembre de 2019): 1052. http://dx.doi.org/10.3390/met9101052.
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The present study investigates how the choice of characterization test and the composition of the stress state in terms of tension and shear can produce a non-unique failure locus in terms of stress triaxiality under plane stress conditions. Stress states that are composed of tensile and simple shear loadings result in a loss of proportionality between the cumulative strain and stress such that the principal frames become non-coaxial despite a constant stress triaxiality. Consequently, it is shown that the conventional interpretation of a failure locus in plane stress is based upon an implicit assumption of proportional coaxial loading. The use of simple shear tests along with traditional in-plane tensile tests for fracture characterization is only one “path” that can be taken in terms of the stress triaxiality, which may produce a bifurcation at uniaxial tension while the tension–torsion path does not. In general, the failure locus in terms of the equivalent strain is a failure surface and must consider the composition of the stress state that produces a given triaxiality. A comprehensive review of phenomenological fracture loci within a modified Mohr-Coulomb (MMC) framework is performed to highlight how the choice of stress states obtained using different characterization tests can change the apparent fracture locus of a material. The finite strain solutions for the work conjugate equivalent strain are derived for various loading paths that produce the same stress triaxiality. It is then shown that accounting for non-coaxiality leads to equivalent failure strains that are even higher than previously reported in tension–torsion tests within the literature. The equivalent plastic strains integrated from finite-element simulations are work-conjugate by definition. The equivalent strains estimated from the cumulative principal strains using DIC strain measurement depend upon a coaxial or non-coaxial assumption. Finally, an analytical solution for the onset of diffuse necking that accounts for the stabilizing influence of shear loading against a tensile instability is considered. Even under plane stress conditions, a failure surface arises in terms of the equivalent strain at necking, the stress triaxiality, and the severity of shear loading.
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Tang, Ping Ying, Bi Yu Tang, Li Ming Peng y Wen Jiang Ding. "Effect of Y and Zn Substitution on Tensile Properties of 6H-Type LPSO Phase in Mg97Zn1Y2 Alloy". Advanced Materials Research 476-478 (febrero de 2012): 2469–75. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.2469.
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The effect of Y and Zn substitution on tensile properties of 6H-type ABCBCB LPSO phase in Mg97Zn1Y2alloy has been studied from first principles calculations. From obtained tensile stress-strain relations, at small strains anisotropy of Young’s modulus for Mg95Zn is larger than that for Mg95Y, whereas at lager strains anisotropy of peak tensile stress for Mg95Zn is smaller than that for Mg95Y. The ideal tensile strengths for both Mg95Y and Mg95Zn phases occur in direction, and the ideal tensile strength is increased with single Zn atom substitution. The detailed electronic structure investigations show that the hybridization between Mg and Y (or Zn) atoms is obvious, and the directional bonding between Mg and Y (or Zn) atoms would lead to large anisotropy of tensile stress-strain relations. As the strain increase, the directional bonding between Mg and Y (or Zn) atoms is weakened, the stability would be lowered, and the phases are finally fractured.
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Liu, Keming, Xiaochun Sheng, Qingpeng Li, Mengcheng Zhang, Ningle Han, Guangyu He, Jin Zou, Wei Chen y Andrej Atrens. "Microstructure and Strengthening Model of Cu–Fe In-Situ Composites". Materials 13, n.º 16 (6 de agosto de 2020): 3464. http://dx.doi.org/10.3390/ma13163464.
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The tensile strength evolution and strengthening mechanism of Cu–Fe in-situ composites were investigated using both experiments and theoretical analysis. Experimentally, the tensile strength evolution of the in-situ composites with a cold deformation strain was studied using the model alloys Cu–11Fe, Cu–14Fe, and Cu–17Fe, and the effect of the strain on the matrix of the in-situ composites was studied using the model alloys Cu–3Fe and Cu–4.3Fe. The tensile strength was related to the microstructure and to the theoretical strengthening mechanisms. Based on these experimental data and theoretical insights, a mathematical model was established for the dependence of the tensile strength on the cold deformation strain. For low cold deformation strains, the strengthening mechanism was mainly work hardening, solid solution, and precipitation strengthening. Tensile strength can be estimated using an improved rule of mixtures. For high cold deformation strains, the strengthening mechanism was mainly filament strengthening. Tensile strength can be estimated using an improved Hall–Petch relation.
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Jin, Li, Qinzhi Fang, Xingwei Yan y Qinwei Hu. "Biaxial Tensile Mechanical Properties of HTPB Solid Propellant". International Journal of Aerospace Engineering 2023 (6 de octubre de 2023): 1–18. http://dx.doi.org/10.1155/2023/2407730.
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The purpose of this work is to study the effects of different loading rate ratios and loading speeds on the biaxial tension of hydroxyl-terminated polybutadiene (HTPB) solid propellant. A proper kind of biaxial tensile specimen with which the stresses in its central part can be obtained with the loads acted on each loading direction is designed and used in the study, and the strains in its central parts are obtained with the digital image correlation (DIC) method. The stress and strain relationship at each direction can be obtained by experiments. The uniaxial stress vs. strain curves and the biaxial stress vs. strain curves were obtained, and it was found that the loading speed remarkably influenced the biaxial tensile behaviors of HTPB propellant. The Mises equivalent stress and strain could be used to describe the biaxial tension stress and strain state, and the exponential constitutive model obtained in the study could be used to predict the stress vs. strain curve under different test conditions.
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Ridge, I. M. L., J. Zheng y C. R. Chaplin. "Measurement of cyclic bending strains in steel wire rope". Journal of Strain Analysis for Engineering Design 35, n.º 6 (1 de agosto de 2000): 545–58. http://dx.doi.org/10.1243/0309324001514288.
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This paper reports strain gauge measurements of cyclic bending strain in the wires of a six-strand right-handed Lang's lay steel wire rope running on and off a pulley. The paper describes the measurement procedures and presents the results for the two tests conducted which had different gauge configurations along and around the sample. It was found that the strain waveforms observed had some similarities with those reported elsewhere and the magnitudes of strains matched theoretical predictions. However, in contrast with behaviour reported for fluctuating tension, the initial differences between and along wires rapidly attenuated. This observation helps to explain reported similarities in bending fatigue performance of ropes from different sources which contrasts with the very significant differences in characteristics found in tensile fatigue. The dependence of wire strain amplitude on rope bending deformation further contrasts with tensile fatigue in which wire strain range is dependent on the local sharing of axial load.
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Kim, D. G., J. B. Brunski y D. P. Nicolella. "Microstrain fields for cortical bone in uniaxial tension: Optical analysis method". Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 219, n.º 2 (1 de febrero de 2005): 119–28. http://dx.doi.org/10.1243/095441105x9291.
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This study employed an optical strain measurement method, called microdisplacements by machine vision photogrammetry (DISMAP), to measure both the global and local strain fields in microtensile specimens of cortical bone subjected to controlled uniaxial tension. The variation of local maximum principal strains was measured within the gauge region of samples as a function of applied tensile stress during testing. High gradients of local strain appeared around microstructural features in stressed bone even while the global strain for the entire gauge region showed a strong linear correlation with increasing tensile stress (r2 = 0.98, p < 0.0001). The highest local strain around micro-structural features in bone was 11.5-79.5 times higher than the global strain.
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Zhang, Yingbo, Kaare Höeg, Weibiao Wang y Yue Zhu. "Watertightness, cracking resistance, and self-healing of asphalt concrete used as a water barrier in dams". Canadian Geotechnical Journal 50, n.º 3 (marzo de 2013): 275–87. http://dx.doi.org/10.1139/cgj-2011-0443.
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The coefficient of permeability of hydraulic asphalt concrete is in the range 10−8–10−10 cm/s. Laboratory test results show that triaxial specimens in axial compression can undergo axial strains up to 18% without any significant increase in permeability until approaching the compressive strength. For temperatures between 5 and 20 °C and strain rates between 2 × 10−3%/s and 5 × 10−3%/s, conventional hydraulic asphalt concrete can tolerate 1%–3% tensile strains before cracking in direct tension tests and strains up to 3%–4% in bending. At 20 °C the tensile and bending strains at cracking are 2–4 times higher than those at 0 °C, and at −20 °C they are approximately 0.2% and 0.8%, respectively. Asphalt concrete possesses pronounced crack self-healing properties. In the experiments, the crack leakage rate dropped 1–4 orders of magnitude within a few hours and the cracked specimens regained 55% of the intact tensile strength after only 1 day of self-healing. In summary, the comprehensive series of laboratory tests documents that asphalt concrete has characteristics that make the material extremely well suited for use in impervious barriers in dams, and the test results reported herein can be of great use in barrier design.
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Costa Cardoso, Marcelo, Alexandre de Melo Pereira, Fabiane Roberta Freitas da Silva y Luciano Pessanha Moreira. "Experimental Analysis of Forming Limits and Thickness Strains of DP600-800 Steels". Applied Mechanics and Materials 835 (mayo de 2016): 230–35. http://dx.doi.org/10.4028/www.scientific.net/amm.835.230.
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In this work, the plastic behavior of cold-rolled zinc coated dual-phase steel sheets DP600 and DP800 grades is firstly investigated by means of uniaxial tensile and Forming Limit Curve (FLC) testing. The uniaxial tensile tests were carried out at 0o, 45o and 90o angular orientations with respect to the rolling direction to evaluate the mechanical properties and the plastic anisotropy Lankford r-values. The forming limit strains are defined according to Nakajima’s procedure. Thickness measurements of tested Nakajima’s samples cut perpendicular to the fracture allowed to identify a rapid decrease of the strain, which governs the plastic instability that preceded the fracture in the drawing region of the FLC. Optical metallographic and scanning electron microscopy techniques helped to characterize and distinguish the orientation of rotated grains and flat fractured surface (ductile shear failure in blank specimens close to plane-strain tension) from no grain rotations and rough fractured surface (ductile tensile fracture in blank geometries in the biaxial stretching domain).
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Henderson, James H., Randall P. Nacamuli, Betty Zhao, Michael T. Longaker y Dennis R. Carter. "Age-dependent residual tensile strains are present in the dura mater of rats". Journal of The Royal Society Interface 2, n.º 3 (10 de mayo de 2005): 159–67. http://dx.doi.org/10.1098/rsif.2005.0035.
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The objectives of this study were to determine whether residual tensile strains exist in the dura mater of mammals in vivo , and whether the strains are age-dependent. We made incisions in the parietal dura mater of immature and mature rats, and measured the retraction of the dura mater from each incision. We then used a finite-element model to calculate the strain present in the parietal dura mater of each rat. We found that age-dependent residual tensile strains are present in the dura mater of rats. The mean average residual strain of the immature rats was significantly larger than that of the mature rats (4.96±1.54% (s.d.) versus 0.39±0.13%, p <0.0001), with the mean strain calculated in the mature rats of the order of the minimum measurement that could be made using our experimental approach. In addition, in the immature rats mean residual strain in the longitudinal direction was significantly larger than mean residual strain in the transverse direction (6.11±3.62% versus 3.82±2.64%, p =0.0218). Our findings show that age-dependent residual tensile strains exist in the dura mater of rats. We speculate that these strains may reflect the rate and direction of cranial growth and may also influence cranial healing.
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Wang, Min, C. L. Au, P. K. Lai y William Bonfield. "Tensile and Compressive Behaviours and Properties of a Bone Analogue Biomaterial". Key Engineering Materials 284-286 (abril de 2005): 693–96. http://dx.doi.org/10.4028/www.scientific.net/kem.284-286.693.
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For the purpose of mimicking the structure and matching mechanical properties of human cortical bone, a natural composite material, hydroxyapatite (HA) reinforced high density polyethylene (HDPE) has been developed as a bioactive, analogue material for bone replacement. This synthetic composite material is now in clinical use. To understand the deformation behaviour and determine mechanical properties of HA/HDPE composite under different loading modes and loading conditions, tensile and compression tests were performed in the current investigation. It was observed that under tension, HA/HDPE composite exhibited two types of deformation behaviour: ductile and brittle. Under compression, the composite deformed in a ductile manner and did not fracture at high compressive strains. It was found that an increase in HA content resulted in increases in Young’s modulus, compressive modulus, tensile strength and compressive yield strength of the composite. A higher strain rate led to higher modulus and strength values and lower tensile fracture strains of the composite.
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Urriolagoitia-Sosa, G., J. F. Durodola, A. Lopez-Castro y N. A. Fellows. "A method for the simultaneous derivation of tensile and compressive behaviour of materials under Bauschinger effect using bend tests". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 220, n.º 10 (1 de octubre de 2006): 1509–18. http://dx.doi.org/10.1243/09544062jmes180.
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Some materials exhibit Bauschinger effect as a consequence of strain hardening. The effect leads to asymmetric tensile and compressive stress-strain behaviour. If the hardening behaviour in either tension or compression is known, combined isotropic/kinematic hardening rules can be used to estimate the hardening behaviour in the other. These rules are, however, only approximate empirical relationships that are derived from the analysis of separate tensile and compressive test results. This article presents a method for the simultaneous derivation of tensile and compressive stress-strain behaviour from bending tests only. The information required is strains at the top and bottom surfaces of beams and moment as load is incrementally applied. The derivation of the method is based on the application of tensile and moment equilibrium conditions. The proposed method is tested on theoretical data obtained from finite-element analysis and as well as on data from actual experimental testing. The agreement between the results obtained is very good.
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Su, S. C., J. G. Skedros, K. N. Bachus y R. D. Bloebaum. "Loading conditions and cortical bone construction of an artiodactyl calcaneus". Journal of Experimental Biology 202, n.º 22 (15 de noviembre de 1999): 3239–54. http://dx.doi.org/10.1242/jeb.202.22.3239.
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Customary nonuniform distributions of physiological bone strains are thought to evoke heterogeneous material adaptation in diaphyseal cortices of some limb bones. Recent studies of artiodactyl calcanei have suggested that the regional prevalence of specific mechanical strain features such as mode and magnitude correlate with specific variations in cortical bone ultrastructure, microstructure and mineralization. These data are also consistent with predictions of current algorithms of mechanically induced bone adaptation. However, detailed characterization of the customary functional strain environment of these bones is needed to understand better the mechanisms of these adaptations. An in vitro loading method and rosette strain gauges were used to record principal strains, maximum shear strains and principal strain angles at multiple locations on ten calcanei of adult male mule deer (Odocoileus hemionus hemionus). Each hind limb was fixed in an apparatus to mimic the mid-support phase of the gait and loaded via the Achilles tendon over a broad range of functional loads (0 to 2943 N). Strains were recorded on the craniolateral, craniomedial, caudal, medial and lateral cortices at mid-diaphysis. Loading variations included the progressive elimination of the ligament and tendon along the caudal calcaneus. The results showed that the cranial cortex experiences longitudinal compressive strains that are nearly equal to the principal minimum strains and that the caudal cortex receives longitudinal tensile strains that are nearly equal to the principal maximum strains. With a 981 N load, the mean principal compressive strain on the cranial cortex was −636+/−344 micro(ε) (mean +/− s.d., N=9) and the mean principal tensile strain on the caudal cortex was 1112+/−68 micro;(ε)x (N=9). In contrast to the cranial and caudal cortices, principal strains in the medial and lateral cortices displayed relatively large deviations from the longitudinal axis (medial, 24 degrees cranial; lateral, 27 degrees caudal). Although shear strains predominated at all gauge sites, variations in maximum shear strains showed no apparent regional pattern or consistent regional predominance. The plantar ligament and tendon of the superficial digital flexor muscle were shown to have important load-sharing functions. These results demonstrate that the functionally loaded artiodactyl calcaneus generally behaves like a cantilevered beam with longitudinal compression and tension strains predominating in opposing cranial and caudal cortices, respectively. Differences in osteon remodeling rates, osteon morphology and mineral content reported previously between the cranial and caudal cortices correlate, in part, with the magnitudes of the principal compressive and tensile strains, respectively. However, material differences that distinguish the medial and lateral cortices from the cranial and caudal cortices could not be primarily attributed to locally increased shear strains as previously suggested. Variations in osteon and/or collagen fiber orientation may correlate more strongly with principal strain direction.
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Yoshihara, Shintaro y Hideto Yanagihara. "Magnetoelastic constant of thin films determined by a four-point bending apparatus". Japanese Journal of Applied Physics 61, n.º 3 (25 de febrero de 2022): 036502. http://dx.doi.org/10.35848/1347-4065/ac4928.
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Abstract We have developed a method to variably induce lattice strains and to quantitatively evaluate the induced magnetic anisotropy. Both tensile and compressive strains were introduced into epitaxial films of cobalt ferrite (CFO) grown on a single crystal MgO(001) substrate using a four-point bending apparatus made of a plastic material fabricated by a 3D printer. The change in magnetic anisotropy due to bending strain can be measured quantitatively by using the conventional magneto-torque meter. The strain-induced magnetic anisotropy increased with the tensile strain and decreased with the compressive strain as expected from a phenomenological magnetoelastic theory. The magnetoelastic constant obtained from the changes in bending strains shows quantitatively good agreement with that of the CFO films with a uniaxial epitaxial strain. This signifies that the magnetoelastic constant can be evaluated by measuring only one film sample with strains applied by using the bending apparatus.
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Yu, Ziruo, Zhiguang Li, Yuran Jiang y Yue Wang. "Mechanical Behavior of Reactive Powder Concrete Subjected to Biaxial Loading". Advances in Civil Engineering 2022 (1 de julio de 2022): 1–11. http://dx.doi.org/10.1155/2022/9246692.
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To investigate the biaxial mechanical characteristics of reactive powder concrete (RPC), RPC plate specimens and bone-shaped specimens were tested under compression-compression and compression-tension loadings, respectively. The strengths and strains of the specimens were recorded, and the crack patterns and failure modes in various stress states were examined. Based on the test data, the characteristics of biaxial strength were analyzed, and a biaxial failure criterion was established. The characteristics of major stress-strain curves and failure modes in different biaxial stress states were determined. The results show that the ratio between the biaxial compression strength and the uniaxial compression strength was 1.44–1.58 for RPC. When the stress ratio under compression-tension was −0.05, the tensile strength decreased by 48%. Under compression-compression, the proportional limit of RPC was about 95%, and its peak strain was high. Under compression-tension, as the compressive stress increased, the elastic modulus decreased, and the peak strain in the tensile direction increased. When the RPC specimens were under compression-compression, the failure mode of RPC was splitting failure. Under compression-tension, the failure mode changed from single-crack tensile failure to multicrack compressive failure with increasing confining stress.
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Kumar, Nilesh, Rajneesh Chaurasiya y Ambesh Dixit. "Strain tailored thermodynamic stability, electronic transitions, and optoelectronic properties of III (In, Ga and Al)-nitride monolayers". Nanotechnology 33, n.º 4 (5 de noviembre de 2021): 045202. http://dx.doi.org/10.1088/1361-6528/ac31ea.
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Abstract The thermodynamic stability of III-nitride monolayers is calculated using the phonon band structure. Electronic properties are computed using the generalized gradient approximation-Perdew–Burke–Ernzerhof exchange-correlation potentials, which show the semiconducting behavior with bandgap 0.59 eV, 2.034 eV, and 2.906 eV for InN, GaN, and AlN monolayers, respectively. The biaxial tensile and compressive strains are used as external stimuli to understand their impact on the optoelectronic properties of these monolayers. The thermodynamic stability of strained monolayers is investigated to explore the maximum possible strains, i.e. flexibility limit, these monolayers can sustain. These monolayers are more sensitive to compressive strains, showing thermodynamic instability even at 1% compressive strain for all the considered monolayers. Further, the III-nitride monolayers are more robust with the tensile strain. InN, GaN, and AlN monolayers can sustain up to 4%, 16%, and 18% tensile strain, respectively. More interestingly, the electronic transitions, such as direct to indirect and semiconducting to metallic, are noticed with strain in the considered monolayers. The optical properties also exhibit strong strain dependency at the different transition points.
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Kashin, Oleg, Konstantin Krukovskii, Aleksandr Lotkov y Victor Grishkov. "Effect of True Strains in Isothermal abc Pressing on Mechanical Properties of Ti49.8Ni50.2 Alloy". Metals 10, n.º 10 (30 de septiembre de 2020): 1313. http://dx.doi.org/10.3390/met10101313.
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The paper analyzes the microstructure and mechanical properties of Ti49.8Ni50.2 alloy (at.%) under uniaxial tension at room temperature after isothermal abc pressing to true strains e = 0.29 − 8.44 at T = 723 K. The analysis shows that as the true strain e is increased, the grain–subgrain structure of the alloy is gradually refined. This leads to an increase in its yield stress σy and strain hardening coefficient θ = dσ/dε at linear stage III of its tensile stress–strain curve according to the Hall–Petch relation. However, the ultimate tensile strength remains invariant to such refinement. The possible mechanism is proposed to explain why the ultimate tensile strength can remain invariant to the average grains size (dav). It is assumed that the sharp increase of the ultimate tensile strength σUTS begins when (dav) is less than the critical average grain size (dav)cr. In our opinion, for the investigated alloy (dav)cr ≈ 0.5 µm. In our study, the attained average grain size is larger the critical one. The main idea of the mechanism is next. In alloys with an average grain size (dav) less than the critical one, a higher external stress is required for the nucleation and propagation of the main crack.
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Chang, Zue Chin, C. B. Lin, Wen Hua Yang y Jin Shin Ho. "Effect of Tensile Strain and Gold Thickness on the Micropattern Topography of Gold Thin Coatings Deposited on Polydimethylsiloxane". Applied Mechanics and Materials 117-119 (octubre de 2011): 743–46. http://dx.doi.org/10.4028/www.scientific.net/amm.117-119.743.
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Abstract: The polydimethylsiloxane (PDMS) film was applied a tensile strain, next the following steps was should be done: fixing the tensile strain, sputtering the gold film on the surface of PDMS film, and then releasing the tensile strain, a large-scale area ripple structure was formed. The ripple dislocations, the cracks and the oriented surface cracks appeared simultaneously during the forming of the ripple structure. This study also discussed the wavelengths of ripple structures resulted from the amount of tensile strain (30%, 50%, 70%, 90% and 110%) and gold thickness (4Å and 10Å). The wavelengths of ripple structures decreased as the tensile strains increased and gold thickness decreased.
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He, Shixin, Haibo Bai y Zhiwei Xu. "Evaluation on Tensile Behavior Characteristics of Undisturbed Loess". Energies 11, n.º 8 (30 de julio de 2018): 1974. http://dx.doi.org/10.3390/en11081974.
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Tensile strength is one significant parameter involved in tensile fracture in soil mechanics. In this paper, a stress-controlled, uniaxial, direct-tension test apparatus was developed to investigate the tensile properties of soils. A limited number of investigations have examined the impact of anisotropy and loading interval on the tensile strength of undisturbed loess. The deformation and strains generated were also examined during the tests. It was revealed that anisotropy was an important factor affecting tensile strength of undisturbed loess, and the effect of loading interval on tensile strength significantly depended on water content. It was negligible while the water content was below the plastic limit. However, when the water content was above the plastic limit, the loading interval not only affected the tensile strength, but also the failure displacement and stiffness response of the soil. Two patterns of tensile fracture were summarized and discussed. Moreover, an empirical constitutive relation was proposed to describe the stress-strain relationship of undisturbed loess and its robustness was validated by the experimental data.
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Sasaki, Katsuhiko, Ken-ichi Ohguchi y Hiromasa Ishikawa. "Viscoplastic Deformation of 40 Pb/60Sn Solder Alloys—Experiments and Constitutive Modeling". Journal of Electronic Packaging 123, n.º 4 (24 de agosto de 1999): 379–87. http://dx.doi.org/10.1115/1.1371927.
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This study first proposes a simple constitutive model for viscoplasticity, which includes the elastic, plastic, and creep strains independently. The plastic strain is evaluated by the flow rule employing back stresses evolved with a Ziegler type of hardening rule. The creep strain is evaluated by the modified Norton’s law. The applicability of this constitutive model is evaluated with pure tensile tests, creep tests and cyclic tension-compression loading tests, to demonstrate the progress of viscoplastic deformation of 40Pb/60Sn solder alloys. The tests were conducted over both several temperature ranges and strain rates. As a result, it was found that the material constants used in the constitutive model could be determined by simple tests such as pure tensile and cyclic tension-compression loading tests. The simulation by the constitutive model explains accurately the viscoplastic deformation of the 40Pb/60Sn solder alloys.
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Park, Seonghun y Gerard A. Ateshian. "Dynamic Response of Immature Bovine Articular Cartilage in Tension and Compression, and Nonlinear Viscoelastic Modeling of the Tensile Response". Journal of Biomechanical Engineering 128, n.º 4 (4 de enero de 2006): 623–30. http://dx.doi.org/10.1115/1.2206201.
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Very limited information is currently available on the constitutive modeling of the tensile response of articular cartilage and its dynamic modulus at various loading frequencies. The objectives of this study were to (1) formulate and experimentally validate a constitutive model for the intrinsic viscoelasticity of cartilage in tension, (2) confirm the hypothesis that energy dissipation in tension is less than in compression at various loading frequencies, and (3) test the hypothesis that the dynamic modulus of cartilage in unconfined compression is dependent upon the dynamic tensile modulus. Experiment 1: Immature bovine articular cartilage samples were tested in tensile stress relaxation and cyclical loading. A proposed reduced relaxation function was fitted to the stress-relaxation response and the resulting material coefficients were used to predict the response to cyclical loading. Adjoining tissue samples were tested in unconfined compression stress relaxation and cyclical loading. Experiment 2: Tensile stress relaxation experiments were performed at varying strains to explore the strain-dependence of the viscoelastic response. The proposed relaxation function successfully fit the experimental tensile stress-relaxation response, with R2=0.970±0.019 at 1% strain and R2=0.992±0.007 at 2% strain. The predicted cyclical response agreed well with experimental measurements, particularly for the dynamic modulus at various frequencies. The relaxation function, measured from 2% to 10% strain, was found to be strain dependent, indicating that cartilage is nonlinearly viscoelastic in tension. Under dynamic loading, the tensile modulus at 10Hz was ∼2.3 times the value of the equilibrium modulus. In contrast, the dynamic stiffening ratio in unconfined compression was ∼24. The energy dissipation in tension was found to be significantly smaller than in compression (dynamic phase angle of 16.7±7.4deg versus 53.5±12.8deg at 10−3Hz). A very strong linear correlation was observed between the dynamic tensile and dynamic compressive moduli at various frequencies (R2=0.908±0.100). The tensile response of cartilage is nonlinearly viscoelastic, with the relaxation response varying with strain. A proposed constitutive relation for the tensile response was successfully validated. The frequency response of the tensile modulus of cartilage was reported for the first time. Results emphasize that fluid-flow dependent viscoelasticity dominates the compressive response of cartilage, whereas intrinsic solid matrix viscoelasticity dominates the tensile response. Yet the dynamic compressive modulus of cartilage is critically dependent upon elevated values of the dynamic tensile modulus.
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Tian, Hao, Shuqi Cui, Long Fu, Hongwei Zhang, Chenggang Li, Yingqi Cui y Aijie Mao. "Strain-Induced Structural Phase Transitions in Epitaxial (001) BiCoO3 Films: A First-Principles Study". Nanomaterials 13, n.º 16 (15 de agosto de 2023): 2342. http://dx.doi.org/10.3390/nano13162342.
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We have simulated BiCoO3 films epitaxially grown along (001) direction with density functional theory computations. Leading candidates for the lowest-energy phases have been identified. The tensile strains induce magnetic phase transition in the ground state (P4mm symmetry) from a C-type antiferromagnetic order to a G-type order for the in-plane lattice parameter above 3.922 Å. The G-type antiferromagnetic order will be maintained with larger tensile strains; however, a continuous structural phase transition will occur, combining the ferroelectric and antiferrodistortive modes. In particular, the larger tensile strain allows an isostructural transition, the so-called Cowley’s ‘‘Type Zero’’ phase transitions, from Cc-(I) to Cc-(II), with a slight volume collapse. The orientation of ferroelectric polarization changes from the out-of-plane direction in the P4mm to the in-plane direction in the Pmc21 state under epitaxial tensile strain; meanwhile, the magnetic ordering temperature TN can be strikingly affected by the variation of misfit strain.
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Oliver, E. C., Mark R. Daymond y Philip J. Withers. "Neutron Diffraction Study of Extruded Magnesium during Cyclic and Elevated Temperature Loading". Materials Science Forum 490-491 (julio de 2005): 257–62. http://dx.doi.org/10.4028/www.scientific.net/msf.490-491.257.
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Neutron diffraction has been used to study the progress of deformation twinning and intergranular strain evolution in extruded magnesium during cyclic and monotonic loading at two temperatures. Differences in the intergranular strains generated during tensile and compressive tests are attributed to the operation of twinning in compression. Twinning activity is reduced relative to slip at higher temperature, leading to greater similarities between tension and compression. During cyclic loading, a distinct Bauschinger effect is observed after each compressive loading stage. The origin of this effect is identified as the reversal of twinning during unloading and subsequent tensile loading.
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Santos, Rafael O., Luciano P. Moreira, Marilena C. Butuc, Gabriela Vincze y António B. Pereira. "Damage Analysis of Third-Generation Advanced High-Strength Steel Based on the Gurson–Tvergaard–Needleman (GTN) Model". Metals 12, n.º 2 (24 de enero de 2022): 214. http://dx.doi.org/10.3390/met12020214.
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The third generation of advanced high-strength steels (AHSS) brought attention to the steel and automotive industries due to its good compromise between formability and production costs. This work evaluated a third-generation AHSS (USS CR980XG3TM) through microstructural and X-ray diffraction (XRD) analyses, uniaxial tensile and plane-strain tension testing, and numerical simulations. The damage behavior of this steel is described with the Gurson–Tvergaard–Needleman (GTN) model using an identification procedure based on the uniaxial tensile and initial microvoids data. The microstructure of the CR980XG3TM steel is composed of ferrite, martensite–austenite islands, and retained austenite with a volume fraction of 12.2%. The global formability of the CR980XG3TM steel, namely the product of the uniaxial tensile strength and total elongation values, is 24.3 GPa%. The Lankford coefficient shows a weak initial plastic anisotropy of the CR980XG3TM steel with the in-plane anisotropy close to zero (−0.079) and the normal anisotropy close to unity (0.917). The identified GTN parameters for the CR980XG3TM steel provided a good forecast for the limit strains defined according to ISO 12004-2 standard from the uniaxial tensile and plane-strain tension data.
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Tang, Xiaochao, Angelica M. Palomino y Shelley M. Stoffels. "Reinforcement Tensile Behavior under Cyclic Moving Wheel Loads". Transportation Research Record: Journal of the Transportation Research Board 2363, n.º 1 (enero de 2013): 113–21. http://dx.doi.org/10.3141/2363-13.
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Numerous studies have revealed the benefits of using geogrids in a flexible pavement, especially for reducing permanent deformation. One of the questions that remain about the effectiveness of a geogrid in reinforcing of pavement is the extent to which the geogrid is engaged and mobilized throughout its service. This paper presents results of a laboratory study on various geogrid products embedded in flexible-pavement sections. The laboratory-scale pavement sections were subjected to cyclic moving wheel loads by using reduced-scale accelerated pavement testing (APT). During the APT, strains that developed in the geogrids were measured at intervals of loading applications by strain gauges installed in pairs on the upper and lower surfaces of the geogrid ribs. Permanent deformation of the subgrade was also measured at the same intervals of loading applications. The measurements of geogrid strains throughout the construction process indicated that the construction resulted in a considerable prestressing effect on the geogrids. Measurements from the individual strain gauges in pairs showed that the gauges installed on the upper surfaces of the ribs were in compression while those on the lower surfaces were in tension; the situation suggested a significant effect on the flexural deflection of the ribs on the tensile strain measurements from the strain gauges. Furthermore, it was observed that geogrid ribs in the longitudinal direction of traffic loading were not mobilized, while considerable strains were developed in geogrid ribs in the direction transverse to traffic loading. A clear correlation was found between the reinforcing forces developed in the geogrids and the performance of the reinforced subgrade in relation to resisting permanent deformation.
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Yu, Yan y R. Kerry Rowe. "Modelling deformation and strains induced by waste settlement in a centrifuge test". Canadian Geotechnical Journal 55, n.º 8 (agosto de 2018): 1116–29. http://dx.doi.org/10.1139/cgj-2017-0558.
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A numerical model to estimate the tensile strains (loads) of the geomembrane liner in the waste containment facility due to waste settlement is presented. A centrifuge test of the geomembrane-lined landfill is used to validate the numerical model. The calculated surface settlement at the centre of the landfill and the geomembrane tensile strains on intermediate benches are generally in good agreement with the measured data. Parametric analyses associated with foundation shear strength as well as interface shear strength and stiffness are performed. The influence of geometric nonlinearity on the geomembrane tensile strains is also examined. The numerical analyses indicate that the maximum geomembrane tensile strain occurs at the crest of the side slope near the intermediate bench for the cases and conditions examined. The lessons learned are likely to be useful to landfill design engineers using numerical models to aid in the design of the geosynthetic liner system for the waste containment facilities.
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Lu, Aizhong, Ning Zhang y Guisen Zeng. "An Extension Failure Criterion for Brittle Rock". Advances in Civil Engineering 2020 (27 de octubre de 2020): 1–12. http://dx.doi.org/10.1155/2020/8891248.
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Under the triaxial compressive state, the compressive strain is supposed to happen in the direction of the maximum principal stress, but tensile strain happens in the direction of the minimum principal stress. Moreover, as the intermediate principal stress is not too high, the corresponding strain can also be tensile. If the brittle rock is assumed as linear elastic in the prefailure stage, a new strength criterion based on the sum of the two tensile strains was presented. The new criterion considers the differences in mechanical parameters (i.e., elastic modulus and Poisson’s ratio) under tension and compression. The parameters of the criterion only include Poisson’s ratio and uniaxial strength. And the effect of the intermediate principal stress σ 2 can be reflected. Certain featured failure phenomenon of rock material can be explained well by the proposed criterion. The results of conventional and true triaxial tests can verify the criterion well. Finally, the criterion is compared with the Mohr–Coulomb and Drucker–Prager criteria.
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Mills, N. J. y A. Gilchrist. "High Strain Extension of Open-Cell Foams". Journal of Engineering Materials and Technology 122, n.º 1 (22 de abril de 1999): 67–73. http://dx.doi.org/10.1115/1.482767.
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The high strain tensile deformation of open-cell foams is analyzed, using a Kelvin foam lattice model. The stretching, bending, and twisting of elastic cell edges is analyzed, and the deformed cell shapes predicted. The stress-strain relation and Poisson’s ratio are predicted for strains up to 40% for tension in the [100] and [111] directions of the BCC lattice. The latter prediction is closest to stress-strain curves for polyurethane foams, especially when the cell shape anisotropy is taken into account. The change from edge bending to extension as the main deformation mechanisms, for strains exceeding 20% increases the slope of the stress-strain curve. A comparison is made with irregular cell structure models. [S0094-4289(00)01001-X]
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Oleksik, Mihaela, Nicolae Cofaru y Valentin Oleksik. "Experimental Studies Regarding Mechanical Behaviour of Textile Reinforcements Laminated Composite Materials". Applied Mechanics and Materials 371 (agosto de 2013): 348–52. http://dx.doi.org/10.4028/www.scientific.net/amm.371.348.
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The aim of this paper is to determine the mechanical properties of textile reinforcements laminated composite material and to establish the influence of thickness about these properties. The composite material used for this is a laminated sheet of HGW 2082. In order to study the mechanical behaviour of these kinds of materials we select two experimental tests: uniaxial test and bending test. For the uniaxial test we have measured the maximum load, the maximum extension, the maximum tensile stress and the maximum tensile strain. Also, using an optical extensometer we measured the major and the minor strains. For the bending test we measured the maximum load and the maximum bending deflection and the major and minor strains. After the uniaxial tension tests we can draw that we obtained the following results: the maximum value of the local major strain and equivalent strain decreases with the increase of the specimen thickness. After the bending test we can draw the following conclusions: the maximum value of the bending deflection decreases with the increase of the specimen thickness while the maximum value of the local major strain increases with the increase of the specimen thickness.
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Huang, Shan, Yanping Wang, Yawen Fan, Jinjiao Feng, Hui Zhao y Yang Zhang. "First principle studies on the structures, electronic properties and Raman spectrums of monolayer WX2 (X = S, Se, Te) under strain condition". Modern Physics Letters B 35, n.º 08 (22 de febrero de 2021): 2150135. http://dx.doi.org/10.1142/s0217984921501359.
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The two-dimensional transition-metal dichalcogenides (2D TMDs) WX2 (S, Se, Te) have received extensive attention and research since they have excellent physical properties and have been widely used in the fields of photoelectronics. Monolayer (ML) WX2 has excellent physical properties and can be modified by simple strain. Using the first principles based on density functional theory (DFT), this paper mainly studies the electronic properties of ML WS2, WSe2 and Wte2. We also study the stabilities of three ML structures, the changes of Raman spectra and the movement of Raman peaks under biaxial tensile and compressive strains. Under the control of strain not only does the bandgap changes, but also the band properties shift between the direct bandgap and the indirect bandgap. With the increase of strain, bond length and bond angle change in the opposite trend. At the same time, we also studied the phonon dispersion relations of WX2 under different strains. We found that three structures showed good thermodynamic stabilities under the tensile strain (1–10%). When the compressive strain is 2%, one of the acoustic modes of WS2 or Wse2 becomes imaginary at [Formula: see text] point, which indicates the structural instability. When tensile strain Raman summit blueshifts and when compressive strains, the redshift occurs.
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Alkaissi, Zainab Ahmed, Yasir M. Al-Badran y Najwa Wasif. "Theoretical Analysis on the Effect of Surface Horizontal Traction on Top-Down Cracking of Flexible Pavement". Association of Arab Universities Journal of Engineering Sciences 26, n.º 1 (31 de marzo de 2019): 170–74. http://dx.doi.org/10.33261/jaaru.2019.26.1.022.
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Fatigue cracking of flexible pavement is one of the most important elements that should be considered due to the damage occurs in asphalt layer under the effect of wheel load repetitions. This research demonstrated theoretical study on top-down fatigue crackingusing the finite element method. A three- dimensional finite elastic structural element is used to modal pavement using (ABAQUS ver. 6.12.1) program. The results obtained from this studydemonstrated that maximum value of tensile strain developed at the surface of asphalt layer for flexible pavement due to the horizontal traction generated from wheel load application at contact area. Also, the horizontal tensile strain ( ) at surface of asphalt layer is increasing rapidly with load repetitions with values greater than that generated at bottom by (94%) at failure. This prescribed the basic or inherent features of top crack initiation and down propagates within asphalt layer in flexible pavement. The top horizontal tensile strains obtained from the finite element model is higher than the empirical relations by (20%); since the finite element analysis of flexible pavement considered the surface horizontal tensile strains due to contact traction force at tire pavement interface. Finally, according to the results of this study the horizontal tensile strains at the top of asphalt surface significantly increase the damage intensity of fatigue failure for flexible pavement.
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Hedström, Peter, Jonathan Almer, Ulrich Lienert y Magnus Odén. "Evolution of Residual Strains in Metastable Austenitic Stainless Steels and the Accompanying Strain Induced Martensitic Transformation". Materials Science Forum 524-525 (septiembre de 2006): 821–26. http://dx.doi.org/10.4028/www.scientific.net/msf.524-525.821.
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The deformation behavior of metastable austenitic stainless steel AISI 301, suffering different initial cold rolling reduction, has been investigated during uniaxial tensile loading. In situ highenergy x-ray diffraction was employed to characterize the residual strain evolution and the strain induced martensitic transformation. Moreover, the 3DXRD technique was employed to characterize the deformation behavior of individual austenite grains during elastic and early plastic deformation. The cold rolling reduction was found to induce compressive residual strains in the austenite along rolling direction and balancing tensile residual strains in the ά-martensite. The opposite residual strain state was found in the transverse direction. The residual strain states of five individual austenite grains in the bulk of a sample suffering 2% cold rolling reduction was found to be divergent. The difference among the grains, considering both the residual strains and the evolution of these, could not be solely explained by elastic and plastic anisotropy. The strain states of the five austenite grains are also a consequence of the local neighborhood.
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Heilmeier, Florian, Robert Koos, Michael Singer, Constantin Bauer, Peter Hornberger, Jochen Hiller y Wolfram Volk. "Evaluation of Strain Transition Properties between Cast-In Fibre Bragg Gratings and Cast Aluminium during Uniaxial Straining". Sensors 20, n.º 21 (4 de noviembre de 2020): 6276. http://dx.doi.org/10.3390/s20216276.
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Current testing methods are capable of measuring strain near the surface on structural parts, for example by using strain gauges. However, stress peaks often occur within the material and can only be approximated. An alternative strain measurement incorporates fibre-optical strain sensors (Fiber Bragg Gratings, FBG) which are able to determine strains within the material. The principle has already been verified by using embedded FBGs in tensile specimens. The transition area between fibre and aluminium, however, is not yet properly investigated. Therefore, strains in tensile specimens containing FBGs were measured by neutron diffraction in gauge volumes of two different sizes around the Bragg grating. As a result, it is possible to identify and decouple elastic and plastic strains affecting the FBGs and to transfer the findings into a fully descriptive FE-model of the strain transition area.We thus accomplished closing the gap between the external load and internal straining obtained from cast-in FBG and generating valuable information about the mechanisms within the strain transition area.It was found that the porosity within the casting has a significant impact on the stiffness of the tensile specimen, the generation of excess microscopic tensions and thus the formation of permanent plastic strains, which are well recognized by the FBG. The knowledge that FBG as internal strain sensors function just as well as common external strain sensors will now allow for the application of FBG in actual structural parts and measurements under real load conditions. In the future, applications for long-term monitoring of cast parts will also be enabled and are currently under development.
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Corning, WR y AA Biewener. "In vivo strains in pigeon flight feather shafts: implications for structural design". Journal of Experimental Biology 201, n.º 22 (1 de noviembre de 1998): 3057–65. http://dx.doi.org/10.1242/jeb.201.22.3057.
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To evaluate the safety factor for flight feather shafts, in vivo strains were recorded during free flight from the dorsal surface of a variety of flight feathers of captive pigeons (Columba livia) using metal foil strain gauges. Strains recorded while the birds flew at a slow speed (approximately 5-6 m s-1) were used to calculate functional stresses on the basis of published values for the elastic modulus of feather keratin. These stresses were then compared with measurements of the failure stress obtained from four-point bending tests of whole sections of the rachis at a similar location. Recorded strains followed an oscillatory pattern, changing from tensile strain during the upstroke to compressive strain during the downstroke. Peak compressive strains were 2.2+/-0. 9 times (mean +/- s.d.) greater than peak tensile strains. Tensile strain peaks were generally not as large in more proximal flight feathers. Maximal compressive strains averaged -0.0033+/-0.0012 and occurred late in the downstroke. Bending tests demonstrated that feather shafts are most likely to fail through local buckling of their compact keratin cortex. A comparison of the mean (8.3 MPa) and maximum (15.7 MPa) peak stresses calculated from the in vivo strain recordings with the mean failure stress measured in four-point bending (137 MPa) yields a safety factor of between 9 and 17. Under more strenuous flight conditions, feather stresses are estimated to be 1.4-fold higher, reducing their safety factor to the range 6-12. These values seem high, considering that the safety factor of the humerus of pigeons has been estimated to be between 1.9 and 3.5. Several hypotheses explaining this difference in safety factor are considered, but the most reasonable explanation appears to be that flexural stiffness is more critical than strength to feather shaft performance.