Journal articles: 'Local strain rate'

1

Tseng, Ampere A., Shi R. Wang, and A. C. W. Lau. "Local Variations of Strain and Strain Rate in Roll Bite Region During Rolling of Steels." Journal of Engineering Materials and Technology 120, no. 1 (January 1, 1998): 86–96. http://dx.doi.org/10.1115/1.2806843.

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A combined experimental-numerical approach has been developed to quantify the strain rate variation of the workpiece in the roll bite region. In this approach, cold rolling experiments at a production mill were conducted first. Then tensile and microhardness tests were performed on workpieces before and after cold rolling to establish the relationship between the microhardness and plastic strain of the material. Microhardness measurements were also conducted in the roll bite region on a partially cold rolled workpiece. A finite element rolling simulation was performed to predict the spatial variations of the strain and strain rate. Through microhardness matching, it was found that the finite-element predicted strains agree very well with those actually existing in the rolled workpiece. Consequently, the finite-element predicted strain rates, whose time-accumulation directly gave strains which matched the actual strains, were verified. Finally, a finite-element simulation of both cold and hot rolling was conducted to assess the effect of several major rolling parameters on the strain rate variation in the bite region. Results show that the spatial variations of strain rate in the roll bite region are extremely nonuniform for both cold and hot rolling.

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Best, T. M., J. H. McElhaney, W. E. Garrett, and B. S. Myers. "Axial Strain Measurements in Skeletal Muscle at Various Strain Rates." Journal of Biomechanical Engineering 117, no. 3 (August 1, 1995): 262–65. http://dx.doi.org/10.1115/1.2794179.

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A noncontact optical system using high speed image analysis to measure local tissue deformations and axial strains along skeletal muscle is described. The spatial resolution of the system was 20 pixels/cm and the accuracy was ±0.125mm. In order to minimize the error associated with discrete data used to characterize a continuous strain field, the displacement data were fitted with a third order polynomial and the fitted data differentiated to measure surface strains using a Lagrangian finite strain formulation. The distribution of axial strain along the muscle-tendon unit was nonuniform and rate dependent. Despite a variation in local strain distribution with strain rate, the maximum axial strain, Exx = 0.614 ± 0.045 mm/mm, was rate insensitive and occurred at the failure site for all tests. The frequency response of the video system (1000 Hz) and the measurement of a continuous strain field along the entire length of the structure improve upon previous noncontact optical systems for measurement of surface strains in soft tissues.

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Komeili, Amin, Ziad Abusara, Salvatore Federico, and Walter Herzog. "Effect of strain rate on transient local strain variations in articular cartilage." Journal of the Mechanical Behavior of Biomedical Materials 95 (July 2019): 60–66. http://dx.doi.org/10.1016/j.jmbbm.2019.03.022.

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Er-Raiy, Aimad, Radouan Boukharfane, Linda Alzaben, and Matteo Parsani. "Assessment of local and non–local turbulent flow components on turbulence–flame interaction." Journal of Physics: Conference Series 2116, no. 1 (November 1, 2021): 012015. http://dx.doi.org/10.1088/1742-6596/2116/1/012015.

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Abstract In the framework of turbulence-flame interaction, the flame is characterized by the gradient of a reactive scalar such as the progress variable, whereas the turbulence is represented by the vorticity and the strain rate. Quantitative assessment of this interaction is performed trough the study of the coupled transport between these quantities that are subject to the effects of heat release and chemical reactions. The present analysis aims at improving the understanding of the small scale turbulence – flame interaction properties, through the introduction of an additive decomposition of the strain rate and vorticity fields into their local and non-local components. The respective role of the local and non-local effects is studied for a broad range of Karlovitz numbers, by virtue of direct numerical simulations (DNS) of turbulent, premixed, lean, and statistically planar flames of methane-air. In the conditions of the present study, the alignment between flame front normals and the strain rate is found to be dominated by the local contribution from the strain rate tensor.

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Musa, Ahmed M., Elnuman B. Mohammed, Afra A. Abd Alla, Wael M. Alfatih, and Abdelgadir M. Manofal. "Evaluation Study on the Growth Performance of Four Local Strains of Nile Tilabia (Oreochromis niloticus) in Sudan." Aquatic Science and Technology 9, no. 2 (January 4, 2021): 1. http://dx.doi.org/10.5296/ast.v9i2.18152.

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The study was conducted at the fish farm of the Department of Fish Sciences, Faculty of Agricultural Technology and Fish Sciences, Al-Neelain University. The purpose of the study is to compare the growth performance of different local strains of Nile tilapia (Oreochromis niloticus) to provide the necessary information for conducting research leading to genetic improvement of the locally farmed Nile tilapia. Fish fry used in the study were spawned by brooders collected from, Jebel Aulia Dam Reservoir (White Nile strain A) , Sennar Dam Reservoir (Sennar strain B), Lake Nubia (Halfa strain C) and khashm elgirba reservoier( Khashm elgirba strain D). The study was conducted for six weeks in twelve happas, each stocked with 30 fry in three replicates for each strain, averaging 5 g. Fish were fed by diet with a protein level of 35%. Statistical analysis showed Sennar strain was the best growth rate with a percent weight gain of 1529%, followed by white nile strain with a percent weight gain of 1114%, followed by khashm elgerba strain with a percent weight gain of 993% and finally Halfa strain with a percent weight gain of 829%. Daily Growth Rate gain was 0.9g/day for sennar strain, followed by other strain with no significant(≥0.05). Food Conversion Ratios (FCR) were best in sennar and white nile strain ,survival rate with the same no significant(≥0.05) between treatments. finally results indicated that there is significant( ≤ 0.05) between treatments so sennar and white nile strains is better than two strains in this study.

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Lee, Min-Su, Yong-Taek Hyun, and Tea-Sung Jun. "Global and local strain rate sensitivity of commercially pure titanium." Journal of Alloys and Compounds 803 (September 2019): 711–20. http://dx.doi.org/10.1016/j.jallcom.2019.06.319.

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Maier, Verena, Karsten Durst, Johannes Mueller, Björn Backes, Heinz Werner Höppel, and Mathias Göken. "Nanoindentation strain-rate jump tests for determining the local strain-rate sensitivity in nanocrystalline Ni and ultrafine-grained Al." Journal of Materials Research 26, no. 11 (June 2, 2011): 1421–30. http://dx.doi.org/10.1557/jmr.2011.156.

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Pun, Lalit, Guilherme Corrêa Soares, Suprit Bhusare, Matti Isakov, and Mikko Hokka. "Microscale Strain Localizations and Strain-Induced Martensitic Phase Transformation in Austenitic Steel 301LN at Different Strain Rates." Metals 13, no. 2 (January 20, 2023): 207. http://dx.doi.org/10.3390/met13020207.

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Microscopic strain and strain-induced phase transformation during plastic deformation in metastable austenitic steel were investigated at different strain rates. Quasi in-situ tension tests were performed sequentially with well-defined elongation intervals at room temperature at strain rates of 10−3 s−1 and 10−1 s−1. The tests were monitored by high-resolution optical imaging with a microscopic lens at a resolution of 0.23 µm/pixel. The macroscopic temperature was also measured with an infrared (IR) camera. The microstructure-level strain localizations were observed on the surface of the etched specimens by means of microscale digital image correlation (µDIC). Additionally, the microstructure was characterized by electron backscatter diffraction (EBSD) at the same location before and after deformation. The results of the study indicated that microscopic strain localizations favored the formation of α′-martensite particles. At the lower strain rate, high local strain concentrations formed at several locations in the microstructure, correlating with the areas where the formation of large martensite islands occurred. Martensite particles of various sizes formed nearby each other at the lower strain rate, whereas at the higher strain rate, martensite islands remained small and isolated. Although the macroscopic increase in temperature at both the studied strain rates was very low, at the higher strain rate, local heating on the microscopic scale could take place at the newly nucleated martensite embryos. This inhibited the further growth of the martensite particles, and local strain distribution also remained more homogeneous than at the lower strain rate.

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He, Zhubin, Zhibiao Wang, Yanli Lin, and Xiaobo Fan. "Hot Deformation Behavior of a 2024 Aluminum Alloy Sheet and its Modeling by Fields-Backofen Model Considering Strain Rate Evolution." Metals 9, no. 2 (February 18, 2019): 243. http://dx.doi.org/10.3390/met9020243.

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The deformation behavior of a 2024 aluminum alloy sheet at elevated temperatures was studied by uniaxial hot tensile tests over the nominal initial strain rate range of 0.001–0.1 s−1 and temperature range of 375–450 °C. In order to analyze the deformation behavior with higher accuracy, a digital image correlation (DIC) system was applied to determine the strain distribution during hot tensile tests. Local stress-strain curves for different local points on the specimens were calculated. The strain rate evolution of each point during the tensile tests was investigated under different deformation conditions. Then, an improved Fields–Backofen (FB) model, taking into account the local strain rate evolution instead of the fixed strain rate, was proposed to describe the constitutive behaviors. It has been found that obvious non-uniform strain distribution occurred when the true strain was larger than 0.3 during hot tensile tests. The strain rate distribution during deformation was also non-uniform. It showed increasing, steady, and decreasing variation tendencies for different points with the increasing of strain, which led to the local flow stress being different at different local points. The flow stresses predicted by the improved FB model showed good agreement with experimental results when the strain rate evolutions of local points during tensile tests were considered. The prediction accuracy was higher than that of traditional FB models.

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Bekar, I., M. S. H. Fatt, and J. Padovan. "Deformation and Fracture of Rubber under Tensile Impact Loading." Tire Science and Technology 30, no. 1 (January 1, 2002): 45–58. http://dx.doi.org/10.2346/1.2135247.

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Abstract An impact experiment is designed to obtain the deformation and fracture characteristics of SBR specimens under tensile impact loading. The experimental apparatus is capable of achieving very large strains (about 300%) and high strain rates (between 10 and 1000 s−1) in the specimen. Dynamic stress-strain curves reveal that SBR goes through several phases of deformation and fracture as the strain rate increases in the specimen. In the first phase, the initial modulus, yield stress, tensile strength, and fracture strain increase, while the final modulus remains fairly constant with increasing strain rate. Increases in the initial modulus, tensile strength, and strain at fracture with increasing strain rate are due to a lack of stress relaxation in constituents that have longer relaxation times than the load duration. Local scale relaxation times are shorter than the load duration in this phase so that the final modulus is almost insensitive to strain rate. In the second phase, the initial modulus and the yield stress remain roughly constant while the final modulus increases with increasing strain rate. The tensile strength also increases, but the fracture strain decreases as the strain rate increases. Increases in the final modulus and tensile strength are due to a lack of relaxation on a local scale. The tensile fracture strain decreases because convolutions do not have sufficient time to slip completely. In the third phase, all stress-strain curves follow a master curve, but both the tensile strength and fracture strain decrease with increasing strain rate. The decrease in tensile strength as the strain rate increases could be due to stress concentration at the tip of microcracks within the SBR.

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11

Zhang, Longhui, David Townsend, Nik Petrinic, and Antonio Pellegrino. "Strain rate and temperature dependent strain localization of dynamically stretched lightweight bars: from metal to polymer." EPJ Web of Conferences 250 (2021): 05001. http://dx.doi.org/10.1051/epjconf/202125005001.

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This work studies the dynamic strain localization and constitutive relationship of a Ti3Al2.5V alloy in jet engine containment system and a transparent polycarbonate conceived for aircraft canopy application by Digital Image Correlation (DIC) technique from quasi-static condition to high strain rates at different temperatures. The responses of two materials show significant strain rate and temperature sensitivities. Observations of Ti3Al2.5V alloy show that the dynamic local strain rate can reach values up to 1000 % of the nominal strain rate in the necking zone. However, dynamic local strain rate of polycarbonate soars up during strain softening then decreases rapidly with necking propagation, and eventually becomes 20 % of the nominal strain rate until fracture. Appropriate viscoplastic constitutive models are determined for both materials, which are incorporated in finite element simulations to reveal the trend of dynamic local strain rate evolution in dynamic tensile tests. The present work shows two different kinds of strain localization in typical lightweight materials, which should be addressed carefully from Split Hopkinson Tension Bar (SHTB) tests.

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12

Toribio, J. "Local strain rate at crack tip: implications in stress corrosion cracking." British Corrosion Journal 32, no. 1 (January 1997): 41–48. http://dx.doi.org/10.1179/bcj.1997.32.1.41.

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13

Vachhani, Shraddha J., Carl Trujillo, Nathan Mara, Veronica Livescu, Curt Bronkhorst, George T. Gray, and Ellen Cerreta. "Local Mechanical Property Evolution During High Strain-Rate Deformation of Tantalum." Journal of Dynamic Behavior of Materials 2, no. 4 (November 10, 2016): 511–20. http://dx.doi.org/10.1007/s40870-016-0085-z.

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14

Mizuguchi, Takashi, Rintaro Ueji, Hayato Miyagawa, Yasuhiro Tanaka, and Kazunari Shinagawa. "Fracture Behavior Transition by Change of Strain Rate in Dislocation-Induced Si Steels." Materials Science Forum 706-709 (January 2012): 2187–92. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2187.

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The fracture behavior transition due to the change of strain rate in 5%Si magnetic steel with dislocation microstructures was studied. The Si steel was multi-passed rolled at 800°C to a various reductions up to 50%. The room temperature tensile deformation was conducted at various strain rates from 10-5/s to 100/s. All rolled steels were fractured in ductile manners with local elongation (necking) at slower strain rate. When strain rate was faster, the local elongation disappeared and the fracture manner was turned to brittle. The strain rate at which fracture mechanism changed from ductile to brittle increased with the increasing of the reduction. On the other hand, the almost fully recrystallized Si steel was fractured in the brittle manner at any strain rate and the transition strain rate was not found. The fractured tensile specimen with no local elongations contains deformation twins; whereas these deformation twins were not observed in the fractured specimen with local elongations. This result indicates that dislocation structure evolved during rolling suppressed the twinning and that the dislocation structure is effective for the enhancement of toughness in Si steel.

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15

Daniel, I. M., G. Yaniv, and G. Peimanidis. "Hygrothermal and Strain Rate Effects on Properties of Graphite/Epoxy Composites." Journal of Engineering Materials and Technology 110, no. 2 (April 1, 1988): 169–73. http://dx.doi.org/10.1115/1.3226026.

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A unidirectional graphite/epoxy material was characterized at strain rates ranging from 5 × 10−6 to 5 s−1 under various hygrothermal conditions. A time-temperature-moisture equivalence principle was applied to obtain master curves for the longitudinal, transverse and in-plane shear moduli and corresponding strengths and ultimate strains of the unidirectional graphite/epoxy. It was found that, except for the longitudinal modulus which shows a slight increase with strain rate, temperature and moisture, all other longitudinal properties in general remain unchanged. All matrix dominated properties, i.e., transverse and intralaminar properties, decrease with increasing temperature and moisture content for a fixed strain rate. The transverse and in-plane shear moduli increase with strain rate. Transverse ultimate properties show a trend reversal with a local maximum. The in-plane shear strength increases noticeably, but the ultimate shear strain decreases slightly with strain rate. The time-temperature-moisture shift function is expressed as a function of two variables, temperature and moisture, allowing interchangeability of the three parameters, time, temperature and moisture content.

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Butler, D. L., M. Y. Sheh, D. C. Stouffer, V. A. Samaranayake, and M. S. Levy. "Surface Strain Variation in Human Patellar Tendon and Knee Cruciate Ligaments." Journal of Biomechanical Engineering 112, no. 1 (February 1, 1990): 38–45. http://dx.doi.org/10.1115/1.2891124.

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Local surface strains in bone-fascicle-bone subunits from human patellar tendon and anterior and posterior cruciate ligaments were measured between markers using low-speed photography during low rate subfailure testing. A simple stress-strain relationship of the power form was found to describe the bone-to-bone responses up to four percent strain for all three tissue types examined. The regional material behavior were best fit using an inverted strain-stress relationship, however. The power model, fitted to the experimental data, conformed to the expected stress-strain relationship better than either the quadratic or cubic models. With few exceptions, for a given stress, the strains near the proximal and distal bone ends were not significantly different from each other, but were significantly higher than the strains in the tissue midregions. Local strain patterns generally varied among subunits from the same tissue.

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Putra, Ramadhani Eka, and Gunadi Trinuroni. "Effect of Water Temperature to Survival and Development of Larvae of Two Local Aedes Aegypti Strains." Jurnal Biodjati 4, no. 1 (May 28, 2019): 40–49. http://dx.doi.org/10.15575/biodjati.v4i1.3843.

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Global warming has been reported in last decades. Chang-es in average Earth’s temperature may affect the physiology of many insect species, especially the ones which act as a human disease vec-tor, like Aedes aegypti. In this study, the effect of increasing water temperature on physiological components related to development period, sex ratio, and body size of two distinctively strains, VCRU (Vector Control Research Unit) and Pangandaran. Thirty larvae of each strain kept inside distilled water with the temperature of 25°C, 27°C, 30°C, 33°C, 35°C, 40°C which replicated three times. Observa-tions were conducted until all larvae metamorphed into adults or all larvae dead. Development rate and time were analyzed by frequency dependent mean. The result showed that the optimum temperature for larvae development of VCRU strain was 27-30°C with a survival rate of 84% while it was 30°C for Pangandaran strain, with the surviv-al rate of 83%. Larvae of both strains showed 100% mortality rate when kept inside a container with water temperature exceed 33°C. Both strains showed the highest and the lowest male:female ratio at similar water temperature which were 33°C and 30°C, respec-tivelly. Highest and lowest ratio of VCRU was 1.25 and 0.6, respec-tively, while it was 1.4 and 0.6 for Pangandaran. In general, larvae lived in increasing water temperature showed reducing wing width.

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Tanaka, Yukimi, Koichiro Hattori, and Yoshihisa Harada. "Evaluating local strain rate sensitivity of titanium alloy using dynamic nanoindentation testing." Measurement: Sensors 18 (December 2021): 100094. http://dx.doi.org/10.1016/j.measen.2021.100094.

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Zhang, J., C. Soutis, and J. Fan. "Strain energy release rate associated with local delamination in cracked composite laminates." Composites 25, no. 9 (October 1994): 851–62. http://dx.doi.org/10.1016/0010-4361(94)90026-4.

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Toribio,, J. "Local Strain Rate At A Notch Tip: Implications in Environmentally Assisted Fracture." Journal of the Mechanical Behavior of Materials 9, no. 3 (September 1998): 177–204. http://dx.doi.org/10.1515/jmbm.1998.9.3.177.

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21

Jun, Tea-Sung. "Local strain rate sensitivity of α+β phases within dual-phase Ti alloys." Journal of Physics: Conference Series 2169, no. 1 (January 1, 2022): 012040. http://dx.doi.org/10.1088/1742-6596/2169/1/012040.

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Abstract Using in-situ micropillar compression, the local strain rate sensitivity in Ti6242 and Ti6246 has been investigated to strengthen our understanding on the rate- and slip system-sensitive deformation of dual-phase Ti alloys. Electron backscatter diffraction (EBSD) was used to find target grains anticipating basal and primatic slip activities under compression test. Micropillars with similar α orientation and incomparable β morphology were made by a focused ion beam (FIB). Strain rate sensitivity (SRS) was determined based on the constant strain rate method (CSRM). The marked difference of SRS is found in the α+β of both alloys such that in Ti6242 the SRS in the basal slip is considerably higher than that in the prism whilst both slips in Ti6246 show somewhat similar SRS, inferring that either local chemical effects or the β morphology could affect rate-sensitive deformation behaviour.

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Mentes, Gyula, and Márta Kiszely. "Local tectonic deformations measured by extensometer at the eastern foothills of the Alps at the Sopronbánfalva Geodynamic Observatory, Hungary." Contributions to Geophysics and Geodesy 49, no. 3 (September 1, 2019): 373–90. http://dx.doi.org/10.2478/congeo-2019-0019.

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Abstract In Hungary, at the foot of the Eastern Alps, in the Sopronbánfalva Geodynamic Observatory (SGO), a quartz-tube extensometer has been used for recording the Earth’s tides and local tectonic deformations since 1991. The 27-year long strain record (1991–2017) shows a continuous compression of the rock with changing rate. The relations between the measured local deformation and present-day tectonics in the region of the observatory were investigated. The local strain rate variations were also compared with the temporal and spatial distribution as well as with the magnitudes of earthquakes occurred within 200 km from the observatory in two sectors around the azimuth of the extensometer (116°): 116°±15° and 296°±15°. Our investigations show that earthquakes can also influence the strain rate. Earthquakes to the west of SGO generally increase the compressive strain rate, while earthquakes in the Pannonian Basin, with some exceptions, have no significant effect on the local strain rate variations measured in the SGO. It has been found that the recorded compressive strain is in good accordance with the recent tectonic processes in the region of the SGO determined by Global Navigation Satellite System (GNSS) technology and geophysical measurements. From the results it can be concluded that the uplift of the Alps, tectonic processes in the East Alpine region and in the Pannonian Basin play the most important role in the changing local compressive strain rate.

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Mueller, Johannes, Karsten Durst, Dorothea Amberger, and Matthias Göken. "Local Investigations of the Mechanical Properties of Ultrafine Grained Metals by Nanoindentations." Materials Science Forum 503-504 (January 2006): 31–36. http://dx.doi.org/10.4028/www.scientific.net/msf.503-504.31.

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The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.

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Nishimura, Satoshi, Shota Okajima, Jinyuan Wang, and Bhakta Raj Joshi. "Small-strain deformation behaviour of a clay at frozen and unfrozen states: A comparative study." E3S Web of Conferences 92 (2019): 04001. http://dx.doi.org/10.1051/e3sconf/20199204001.

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The small-strain deformation behaviour of frozen high-plasticity clay, and the factors influencing it were investigated through parallel tests at frozen and unfrozen states. The first and second series involved temperature-controlled triaxial compression tests on unfrozen and frozen samples, respectively, with accurate strain measurement with local displacement sensors, fully calibrated for cold environment. The small-strain loading was conducted at different axial strain rates and temperatures. At pre-yield small strains in order of 0.001%, Young's modulus was independent of the strain rate, in a same manner as in unfrozen soils. The strain rate only affected the onset of small-scale yielding and the degradation of stiffness after that. The elastic strain range was greater at lower temperature, but the degree of stress-strain non-linearity seen at small strains remained on the whole similar between frozen and unfrozen states. An interesting feature of the frozen clay's stiffness, also confirmed by third test series adopting bender elements, is that it decreases when the soil is frozen from higher effective stress. A simple model was proposed to explain this feature.

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Wang, Jing Jing, and Jian Hua Xiao. "Fatigue-Fracture Solution of Iron Wire under Pseudo-Periodic Strain." Applied Mechanics and Materials 750 (April 2015): 69–75. http://dx.doi.org/10.4028/www.scientific.net/amm.750.69.

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Under pseudo-periodic strain, the thermo-effect plays an important role in the fatigue fracture of material. How to construct the related mechanics model is a practical issue. For simple bending of iron wire under pseudo-periodic, based on local rotation concept, the deformation is described by the local rotation angle. Then, the related motion equations are used to obtain the theoretical form of life-strain rate relation. The results show that: (1) The local rotation angle rate can represent thermo-effects well; (2) The fatigue fracture is nucleated at the position of maximum local rotation angle; (3) The intrinsic mechanism of fatigue fracture of the material is the local rotation.

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Situ, Q., Mukesh K. Jain, and M. Bruhis. "A Suitable Criterion for Precise Determination of Incipient Necking in Sheet Materials." Materials Science Forum 519-521 (July 2006): 111–16. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.111.

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Forming limit diagram (FLD) is a measure of the formability of a sheet material. The major-minor strain pairs that are closest to the neck on multiple specimens of various strain paths are utilized to construct a boundary between safe and unsafe zones. The challenge to obtain the FLD is the determination of incipient necking. Three approaches to determine the limit strains have been investigated and compared in this research in order to establish the optimal one for implementation: (1) commonly used Bragard criterion ( 1)e Br with periodic grids; (2) tracking the region of large local strains from strain history to locate the instance when critical major strain ( 1)e cr happens; (3) post-processing of strain history to locate the inflection in the major strain rate curve 1 max (e&&) at the onset of localization. The last criterion of inflection in strain rate 1 max (e&&) carries both a numerical and a physical meaning towards developing an understanding of flow localization, formability and fracture.

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Krumphals, Friedrich, Zeng Gao, Hassan Zamani, Stefan Mitsche, Norbert Enzinger, and Christof Sommitsch. "Physical and Numerical Simulations of the Microstructure Evolution in AA6082 during Friction Stir Processing by Means of Hot Torsion and FEM." Materials Science Forum 762 (July 2013): 590–95. http://dx.doi.org/10.4028/www.scientific.net/msf.762.590.

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A reproduction of the conditions occurring during friction stir processing, where a fine grained structure according to the process parameters rpm, transverse speed and pressure develops is the main focus in the present work. To physically simulate such a friction stir process, hot torsion tests at constant temperatures were carried out in a Gleeble ® 3800 machine at different strains and strain rates. The specimens were immediately water quenched after hot deformation to avoid any static recrystallization. The microstructure was investigated to characterize the grain size evolution and misorientation as a function of the local strain, strain rate and temperature. Dynamic recovery was observed followed by continuous dynamic recrystallization at large deformations. By means of DEFORMTM3D the occurring strain, strain rate and temperature distributions, which are decisive for the observed microstructure evolution, were evaluated.

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Mizuguchi, Takashi, Ryota Oouchi, Rintaro Ueji, Yasuhiro Tanaka, and Kazunari Shinagawa. "Effect of Si Content on Fracture Behaviour Change by Strain Rate in Si Steels." Materials Science Forum 654-656 (June 2010): 1303–6. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1303.

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Fracture behaviour transitions due to change in the strain rate in steels with various Si content ranging from 2% to 5 wt% were studied. Room-temperature tensile tests were conducted over wide range of strain rates ranging from 10-3 s-1 to 103 s-1. Concerning of the steels with low Si content (no more than 3%), the nominal stress - nominal strain curves represented both uniform and local elongations at all strain rates. On the other hand, in 4% Si steel at a strain rate higher than 101 s-1, the tensile sample broke down without local elongation (necking). The stress at breaking was found to be nearly equal to its work hardening rate. The strain rate at which fracture behaviour transition took place in 5% Si steel (10-1s-1) was lower than that in 4% Si steel. TEM observations clarified the existence of deformation twins in the sample that fractured without necking. These results indicated that Si addition is subject to the brittle fractures and that the fracture mechanism transition is closely related with the deformation twinning behaviour.

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Vachhani, Shraddha J., Nathan Mara, Veronica Livescu, and Ellen Cerreta. "Microstructure and local mechanical property evolution during high strain-rate deformation of tantalum." EPJ Web of Conferences 94 (2015): 02023. http://dx.doi.org/10.1051/epjconf/20159402023.

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30

Jun, Tea-Sung, David E. J. Armstrong, and T. Benjamin Britton. "A nanoindentation investigation of local strain rate sensitivity in dual-phase Ti alloys." Journal of Alloys and Compounds 672 (July 2016): 282–91. http://dx.doi.org/10.1016/j.jallcom.2016.02.146.

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North, T. H., G. J. Bendzsak, A. Gerlich, P. Su, and G. Cingara. "Transient Local Melting in Al 7075-T6 Friction Stir Spot Welds." Materials Science Forum 539-543 (March 2007): 3826–31. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.3826.

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Transient local melting can account for the remarkable decrease in the strain rate when the tool rotational speed, heating rate and cycle time produce temperatures exceeding the 475 °C in Al 7075-T6 spot welds. The calculated strain rate is about 20 s-1 in Al 7075-T6 spot welds produced using tool rotational speeds from 1500 RPM to 3000 RPM and dwell time of 4 s. However, the peak temperature is less than less than 475 °C when a low tool rotational speed setting (1000 RPM) is used; transient local melting and tool slippage are precluded and the calculated strain rate is high (about 650 s-1). It is proposed that transient local melted films directly influence formation of the stir zone microstructure in Al 7075- T6 spot welds. It is suggested that the stir zone microstructure in spot welds made using high tool rotational speed settings are determined by a combination of grain boundary sliding and the limitation of cavity interlinkages when transient local melted films form.

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Dewi, Raden Roro Sri Pudji Sinarni, and Evi Tahapari. "EFEK SELEKSI TERHADAP PERTUMBUHAN, SINTASAN, EFISIENSI KONVERSI PAKAN, RASIO RNA/DNA DAN BIOEKONOMI IKAN LELE AFRIKA (Clarias gariepinus)." Media Akuakultur 12, no. 1 (August 15, 2017): 11. http://dx.doi.org/10.15578/ma.12.1.2017.11-17.

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Peningkatan produksi ikan lele perlu didukung oleh ketersediaan benih berkualitas baik. Pada penelitian ini dilakukan pengujian penggunaan benih unggul ikan lele hasil seleksi (strain Mutiara) dengan tujuan untuk mendapatkan informasi mengenai performa hasil seleksi terhadap pertumbuhan, sintasan, konversi pakan, rasio RNA/DNA, dan nilai bioekonominya. Pengujian dilakukan di sentra budidaya ikan lele di Kabupaten Sleman. Hasil pengujian pertumbuhan pada kolam tembok berukuran 12,5 m2 menunjukkan bahwa strain Mutiara menunjukkan bobot akhir, sintasan, dan biomassa panen yang lebih tinggi (P<0,1) dibandingkan strain lokal. Strain Mutiara lebih efisien dalam memanfaatkan pakan dibandingkan strain lokal yang ditunjukkan dengan nilai FCR yang lebih rendah. Pertumbuhan strain Mutiara yang lebih cepat didukung oleh peningkatan rasio RNA/DNA yang lebih tinggi dibandingkan strain lokal. Berdasarkan analisis nilai bioekonomi, biaya yang dikeluarkan untuk menghasilkan 1 kg ikan lele strain Mutiara lebih murah (Rp 12.576,-) dibandingkan strain lokal (Rp 15.105,-). Nilai BCR pada budidaya ikan lele strain Mutiara (1,3) lebih tinggi dibandingkan strain lokal (1,1), yang menunjukkan bahwa budidaya ikan lele strain Mutiara lebih menguntungkan dibandingkan strain lokal. Keuntungan yang diperoleh pada budidaya ikan lele strain Mutiara (31,2) mencapai tiga kali lebih tinggi dibandingkan strain lokal (9,9), berdasarkan nilai pengembalian modal (ROI). Masa pengembalian modal (PP) pada budidaya ikan lele strain Mutiara (3,2 siklus) adalah 3 kali lebih singkat daripada strain lokal (9,9 siklus).The effort to increase African catfish production should be supported by the availability of good quality seed. In this study, we evaluated the performance of superior African catfish seed (Mutiara strain) that was resulted through selection program on growth, survival rate, feed conversion ratio, RNA/DNA ratio, and bioeconomic paramaters. The experiment was conducted at the center of catfish farming in Sleman District. Fish were cultivated in 12.5 m2 concrete pond. The result showed that the use of Mutiara strain could significantly increase growth, survival rate, and biomass harvest (P<0.1)). Mutiara strain were more efficient at utilizing feed than that of local strains which was indicated by low FCR value. The fast growth of Mutiara strain correlated with the increase of RNA/DNA ratio. Based on the analysis of bioeconomic value, the cost for producing 1 kg of Mutiara strain (IDR 12,576) was lower than that of local strain (IDR 15,105). The BCR value for Mutiara strain farming (1.3) was higher than that of local strain (1.1), indicated that Mutiara strain farming was more beneficial than that of local strain. The value of return of investment (ROI) for Mutiara strain (31.2) was three times higher than that of local strain (9.9). The payback period (PP) on the Mutiara strain farming (3.2 cycles) was shorter than that of local strain (9.9 cycles).

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Xu, Qinhua, Zhixian Peng, Jianxin Zhu, Mingyang Li, Yong Zong, Lei Yan, Chaoqun Li, Ke Peng, Zhaoyang Cheng, and Jing Liu. "The Effect of Drawing Deformation Rate Induced Inhomogeneous Local Distortion on Phase Transformation of 304H Stainless Wire." Metals 10, no. 10 (September 29, 2020): 1304. http://dx.doi.org/10.3390/met10101304.

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The micro/macro magnetic properties, local element distribution, martensite transformation, and mechanical properties of 304H stainless wires are determined for two cold drawing chains. Finite element simulations are used to analyse the local strain and heat generation. The results show that there is obvious inhomogeneity in the magnetic properties, strain/stress relationship, and strain-induced heat within the drawn wires. Comparing wires with the same total strain, a larger area reduction of previous drawing processes contributes to a higher volume of the martensite phase, while a smaller area reduction of the first process results in an inhibited phase transformation. A higher single strain in the first drawing process leads to additional heat generation at the subsurface of the wire, which would eventually retard the martensite transformation. The inhomogeneous deformation-induced differences in the grain size affect the stability of austenite and transform the final martensite.

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Wang, En Yang, and Masaki Omiya. "A Microscopic Study on Local Strain Rate Sensitivity of Polypropylene Syntactic Foam with Microballoons." Advanced Materials Research 160-162 (November 2010): 1280–84. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.1280.

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Ossenbrink, R., H. Wohlfahrt, and V. Michailov. "Numerical simulation of welding stresses and distortions under consideration of temporal and local changes of strain rate." Journal de Physique IV 120 (December 2004): 169–75. http://dx.doi.org/10.1051/jp4:2004120019.

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As a result of high temperature changing rates in the heat affected zone (HAZ) the elevated strain rates during welding may have a high influence of the yield stresses. Higher yield stresses as a result of high strain rates can be observed in hot tensile tests for several materials. A model has been developed and integrated in a multi-purpose FEA-program (ANSYS®) to investigate strain rate effects in numerical welding simulation. The routine calculates the current yield stress as a function of the local strain rates. The influence of the resulting stresses and distortions has been analyzed in comparative numerical welding simulations.

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Liu, Wei-Dong, Kai-Xin Liu, Xing-Xiang Xia, and Wei-Hua Wang. "The failure stress of bulk metallic glasses under very high strain rate." Journal of Materials Research 25, no. 7 (July 2010): 1230–34. http://dx.doi.org/10.1557/jmr.2010.0176.

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The dynamic uniaxial compressive behavior of Zr-based metallic glasses under a wide high strain rate was studied by a miniaturized split Hopkinson pressure bar, including high strain rate up to 104 s−1. Experimental results indicate that the uniaxial compressive failure stress would decrease suddenly and then tend to hold steady with increasing strain rate. This phenomenon provides a generalized perspective for understanding the effect of local heat generation on the deformation of metallic glasses under dynamic loads.

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Khokhlov, A. V. "THE CHARACTERISTIC OF THE STRAIN RATE SENSITIVITY OF STRESS-STRAIN CURVES IN THE LINEAR VISCOELASTICITY THEORY AND ITS INTERRELATION WITH RELAXATION MODULUS." Problems of strenght and plasticity 81, no. 4 (2019): 519–34. http://dx.doi.org/10.32326/1814-9146-2019-81-4-519-534.

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Properties of the stress-strain curves family generated by the Boltzmann-Volterra linear viscoelasticity constitutive equation under uni-axial loadings at constant strain rates are studied analytically. Assuming relaxation modulus is arbitrary, the general expression for strain rate sensitivity index as the function of strain and strain rate is derived and analyzed. It is found out (within the framework of the linear viscoelasticity theory) that the strain rate sensitivity index depends only on the single argument that is the ratio of strain to strain rate. So defined function of one real variable is termed “the strain rate sensitivity function” and it may be regarded as a material function since it is interconvertible with relaxation modulus. It is found out that this function can be increasing or decreasing or non-monotone or can have local maximum or minimum without any complex restrictions imposed on the relaxation modulus. It is proved that the strain rate sensitivity value is confined in the interval from zero to unity (the upper bound of strain rate sensitivity index for pseudoplastic media) whatever strain and strain rate magnitudes are and its values may be close to unity (even for the standard linear solid model). It means that the linear viscoelasticity theory is able to produce high values of strain rate sensitivity index and to provide existence of the strain rate sensitivity index local maximum with respect to strain rate (for any fixed strain). These properties are the most distinctive features of superplastic deformation regime observed in numerous materials tests. The explicit integral expression for relaxation modulus via the strain rate sensitivity function is derived. It enables one to restore relaxation modulus assuming a strain rate sensitivity function is given. The restrictions on the strain rate sensitivity function are obtained to provide decrease and convexity down of the resulting relaxation modulus as a function of time, i.e. to provide necessary properties of a relaxation modulus in the linear viscoelasticity. Thus, the technique is developed to evaluate relaxation modulus using test data for strain rate sensitivity, in particular, using piecewise smooth approximations (by splines, for example) of an experimental strain rate sensitivity function.

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Khokhlov, A. V. "THE CHARACTERISTIC OF THE STRAIN RATE SENSITIVITY OF STRESS-STRAIN CURVES IN THE LINEAR VISCOELASTICITY THEORY AND ITS INTERRELATION WITH RELAXATION MODULUS." Problems of strenght and plasticity 81, no. 4 (2019): 521–36. http://dx.doi.org/10.32326/1814-9146-2019-81-4-521-536.

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Properties of the stress-strain curves family generated by the Boltzmann-Volterra linear viscoelasticity constitutive equation under uni-axial loadings at constant strain rates are studied analytically. Assuming relaxation modulus is arbitrary, the general expression for strain rate sensitivity index as the function of strain and strain rate is derived and analyzed. It is found out (within the framework of the linear viscoelasticity theory) that the strain rate sensitivity index depends only on the single argument that is the ratio of strain to strain rate. So defined function of one real variable is termed “the strain rate sensitivity function” and it may be regarded as a material function since it is interconvertible with relaxation modulus. It is found out that this function can be increasing or decreasing or non-monotone or can have local maximum or minimum without any complex restrictions imposed on the relaxation modulus. It is proved that the strain rate sensitivity value is confined in the interval from zero to unity (the upper bound of strain rate sensitivity index for pseudoplastic media) whatever strain and strain rate magnitudes are and its values may be close to unity (even for the standard linear solid model). It means that the linear viscoelasticity theory is able to produce high values of strain rate sensitivity index and to provide existence of the strain rate sensitivity index local maximum with respect to strain rate (for any fixed strain). These properties are the most distinctive features of superplastic deformation regime observed in numerous materials tests. The explicit integral expression for relaxation modulus via the strain rate sensitivity function is derived. It enables one to restore relaxation modulus assuming a strain rate sensitivity function is given. The restrictions on the strain rate sensitivity function are obtained to provide decrease and convexity down of the resulting relaxation modulus as a function of time, i.e. to provide necessary properties of a relaxation modulus in the linear viscoelasticity. Thus, the technique is developed to evaluate relaxation modulus using test data for strain rate sensitivity, in particular, using piecewise smooth approximations (by splines, for example) of an experimental strain rate sensitivity function.

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Durbin, P. A., and C. G. Speziale. "Local Anisotropy in Strained Turbulence at High Reynolds Numbers." Journal of Fluids Engineering 113, no. 4 (December 1, 1991): 707–9. http://dx.doi.org/10.1115/1.2926540.

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It is shown that the hypothesis of local isotropy is implausible in the presence of significant mean rates of strain. In fact, it appears that in uniform shear flow near equilibrium, local isotropy can never constitute a systematic approximation, even in the limit of infinite Reynolds number. An estimate of the level of mean strain rate for which local isotropy is formally a good approximation is provided.

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Chang, Chao Cheng. "Influences of Strain Rate on Copper Nanowire in Tension." Key Engineering Materials 450 (November 2010): 153–56. http://dx.doi.org/10.4028/www.scientific.net/kem.450.153.

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This study uses molecular dynamics simulations with an embedded-atom method (EAM) potential to investigate the effects of strain rate on a copper wire in tension at the nanoscale. By averaging the atomic stresses over the entire system, the stress-strain curves for the nanowire were predicted. The results show that an elastic region clearly exists in the early deformation of the copper nanowire and the elastic modulus is about two times of the value measured at the macroscale. The yield stress of the nanowire increases with the strain rate. Moreover, the evolution of the crystal structure was investigated in terms of the radial distribution function and the local atomic order was also examined by the common neighbour analysis. The dislocations and recrystallization processes inside the nanowire have been observed. The simulated results reveal the process of the fracture of copper nanowire in tension.

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TAMURA, ATSUTAKA, SADAYUKI HAYASHI, and TAKEO MATSUMOTO. "EFFECT OF LOADING RATE ON VISCOELASTIC PROPERTIES AND LOCAL MECHANICAL HETEROGENEITY OF FRESHLY ISOLATED MUSCLE FIBER BUNDLES SUBJECTED TO UNIAXIAL STRETCHING." Journal of Mechanics in Medicine and Biology 16, no. 06 (September 2016): 1650086. http://dx.doi.org/10.1142/s021951941650086x.

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To investigate the effect of viscoelastic behavior on instantaneous muscle mechanics, the passive mechanical properties for the range of physiologically relevant rates should be clarified. Therefore, a series of uniaxial extension tests were conducted at various stretching rates using the muscle fiber bundles, which contained extracellular matrix (ECM) and interfibrillar microstructural components. We revealed that the tensile strength is strain rate-sensitive over the examined range, i.e., the muscle fiber bundle failed at 109[Formula: see text][Formula: see text][Formula: see text]34, 122[Formula: see text][Formula: see text][Formula: see text]44, and 179[Formula: see text][Formula: see text][Formula: see text]61[Formula: see text]kPa (mean[Formula: see text][Formula: see text][Formula: see text]SD) for strain rates of 0.02, 0.1, and 0.5[Formula: see text]s[Formula: see text], respectively. Moreover, we found that the applied stretch was not distributed uniformly even in relaxed conditions; the ratio between maximum and minimum local strains within a specimen was 2–3 on average during stretching and increased up to approximately four just before failure, indicating local mechanical heterogeneity along a fiber bundle and its exaggeration by stretching. Macroscopically, however, the tensile strain at failure was almost constant, [Formula: see text]50%. The local heterogeneity of muscle strain distribution can lead to unstable oscillation in a computational model. Thus, in addition to the intrinsic viscous effects of the muscle fiber itself, those of ECM and interfibrillar microstructural components should be considered in mathematical modeling of skeletal muscle.

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Kermouche, G., F. Grange, and C. Langlade. "Local identification of the stress–strain curves of metals at a high strain rate using repeated micro-impact testing." Materials Science and Engineering: A 569 (May 2013): 71–77. http://dx.doi.org/10.1016/j.msea.2013.01.020.

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Durban, David, and Omri Rand. "Singular Fields in Plane-Strain Penetration." Journal of Applied Mechanics 58, no. 4 (December 1, 1991): 910–15. http://dx.doi.org/10.1115/1.2897707.

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Local singular fields are investigated in the vicinity of the vertex of a sharp wedge that penetrates a viscous solid. Material behavior is modeled by the usual powerlaw constitutive relation. Wall friction is accounted for by imposing friction factors along the walls of the wedge. The case of a Newtonian fluid is investigated analytically, and sample numerical results are presented for nonlinear strain rate hardening. It is shown that the exponent of strain rate singularity increases as the wedge becomes sharper and smoother. Increasing the hardening parameter also results in a stronger strain rate singularity. High levels of wall friction induce an intensive shear boundary layer near the wall.

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Kirane, Kedar, Yewang Su, and Zdeněk P. Bažant. "Strain-rate-dependent microplane model for high-rate comminution of concrete under impact based on kinetic energy release theory." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, no. 2182 (October 2015): 20150535. http://dx.doi.org/10.1098/rspa.2015.0535.

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The apparent increase of strength of concrete at very high strain rates experienced in projectile impact (10 s −1 to 10 6 s −1 ), called ‘dynamic overstress’, has recently been explained by the theory of release of local kinetic energy of shear strain rate in finite size particles about to form. This theory gives the particle size and the additional kinetic energy density that must be dissipated in finite-element codes. In previous research, it was dissipated by additional viscosity, in a model partly analogous to turbulence theory. Here it is dissipated by scaling up the material strength. Microplane model M7 is used and its stress–strain boundaries are scaled up by factors proportional to the −4/3rd power of the effective deviatoric strain rate and its time derivative. The crack band model with a random tetrahedral mesh is used and all the artificial damping is eliminated. The scaled M7 model is seen to predict the crater shapes and exit velocities of projectiles penetrating concrete walls of different thicknesses as closely as the previous models. The choice of the finite strain threshold for element deletion criterion, which can have a big effect, is also studied. It is proposed to use the highest threshold above which a further increase has a negligible effect.

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Makarov, P. V. "Relaxation model of dynamic deformation of elastic-plastic media." Izvestiya vysshikh uchebnykh zavedenii. Fizika, no. 11 (2020): 36–43. http://dx.doi.org/10.17223/00213411/63/11/36.

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A variant is considered for the relaxation model of a loaded elastic-plastic medium with dislocation kinetics of plastic shearing. The model is formulated in rates and includes two independent strain rates: total strain rate, which corresponds to the rate of external action, and local rate of plastic response of the material, which represents the ability of the medium to generate strain-induced defects. This makes it possible to describe both local relaxation processes in the elastic-plastic medium and average relaxation of stresses in a loaded specimen. The model being developed amounts to microscopic ones. All model parameters are determined from independent experiments for the evolution of the dislocation continuum during loading of macroscopic specimens. The model provides an adequate description of the dynamic effects of the macroscopic response of materials depending on the strain rate: the upper and lower yield points (yield drop, yield plateau), subsequent strain hardening as well as features of cyclic and alternating loading, ideal and nonideal Bauschinger effect.

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Gao, Y., N. Chakraborty, and N. Swaminathan. "Local Strain Rate and Curvature Dependences of Scalar Dissipation Rate Transport in Turbulent Premixed Flames: A Direct Numerical Simulation Analysis." Journal of Combustion 2014 (2014): 1–29. http://dx.doi.org/10.1155/2014/280671.

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The statistical behaviours of the instantaneous scalar dissipation rateNcof reaction progress variablecin turbulent premixed flames have been analysed based on three-dimensional direct numerical simulation data of freely propagating statistically planar flame and V-flame configurations with different turbulent Reynolds numberRet. The statistical behaviours ofNcand different terms of its transport equation for planar and V-flames are found to be qualitatively similar. The mean contribution of the density-variation termT1is positive, whereas the molecular dissipation term(-D2)acts as a leading order sink. The mean contribution of the strain rate termT2is predominantly negative for the cases considered here. The mean reaction rate contributionT3is positive (negative) towards the unburned (burned) gas side of the flame, whereas the mean contribution of the diffusivity gradient term(D)assumes negative (positive) values towards the unburned (burned) gas side. The local statistical behaviours ofNc,T1,T2,T3,(-D2), andf(D)have been analysed in terms of their marginal probability density functions (pdfs) and their joint pdfs with local tangential strain rateaTand curvaturekm. Detailed physical explanations have been provided for the observed behaviour.

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Felton, Samuel M., Terry A. Gaige, Thomas Benner, Ruopeng Wang, Timothy G. Reese, Van J. Wedeen, and Richard J. Gilbert. "Associating the mesoscale fiber organization of the tongue with local strain rate during swallowing." Journal of Biomechanics 41, no. 8 (2008): 1782–89. http://dx.doi.org/10.1016/j.jbiomech.2008.01.030.

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Toribio, J., and M. Elices. "The role of local strain rate in the hydrogen embrittlement of round-notched samples." Corrosion Science 33, no. 9 (September 1992): 1387–95. http://dx.doi.org/10.1016/0010-938x(92)90179-7.

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Jun, Tea-Sung, Zhen Zhang, Giorgio Sernicola, Fionn P. E. Dunne, and T. Benjamin Britton. "Local strain rate sensitivity of single α phase within a dual-phase Ti alloy." Acta Materialia 107 (April 2016): 298–309. http://dx.doi.org/10.1016/j.actamat.2016.01.057.

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Lyamina, Elena, Sergei Alexandrov, Yeau Ren Jeng, and Yeong-Maw Hwang. "Modelling of Damage Evolution in the Vicinity of Frictional Interfaces in Metal Forming." Advanced Materials Research 579 (October 2012): 124–33. http://dx.doi.org/10.4028/www.scientific.net/amr.579.124.

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Conventional ductile fracture criteria are not applicable in the vicinity of maximum friction surfaces for several rigid plastic material models because the equivalent strain rate (second invariant of the strain rate tensor) approaches infinity near such surfaces. In the present paper, a non-local ductile fracture criterion generalizing the modified Cockroft-Latham ductile fracture criterion is proposed to overcome this difficulty with the use of conventional local ductile fracture criteria. The final form of the new ductile fracture criterion involves the strain rate intensity factor which is the coefficient of the principal singular term in a series expansion of the equivalent strain rate in the vicinity of maximum friction surfaces. When the velocity field is not singular, the new ductile fracture criterion reduces to the modified Cockroft-Latham criterion. The strain rate intensity factor cannot be found by means of commercial finite element packages since the corresponding velocity field is singular. In the present paper, the new fracture criterion is illustrated with the use of an approximate semi-analytical solution for plane strain drawing. It is shown that the prediction is in qualitative agreement with physical expectations.

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Journal articles on the topic 'Local strain rate'

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