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Showing papers on "Strain rate published in 2012"


Journal ArticleDOI
TL;DR: The histological investigation concluded that there is a definite correlation between the orientation of the Langer lines and the preferred orientation of collagen fibres in the dermis and the data obtained will provide essential information for those wishing to model the skin using a structural constitutive model.
Abstract: The mechanical properties of skin are important for a number of applications including surgery, dermatology, impact biomechanics and forensic science. In this study, we have investigated the influence of location and orientation on the deformation characteristics of 56 samples of excised human skin. Uniaxial tensile tests were carried out at a strain rate of 0.012 s(-1) on skin from the back. Digital Image Correlation was used for 2D strain measurement and a histological examination of the dermis was also performed. The mean ultimate tensile strength (UTS) was 21.6±8.4 MPa, the mean failure strain 54%±17%, the mean initial slope 1.18±0.88 MPa, the mean elastic modulus 83.3±34.9 MPa and the mean strain energy was 3.6±1.6 MJ/m(3). A multivariate analysis of variance has shown that these mechanical properties of skin are dependent upon the orientation of the Langer lines (P<0.0001-P=0.046). The location of specimens on the back was also found to have a significant effect on the UTS (P=0.0002), the elastic modulus (P=0.001) and the strain energy (P=0.0052). The histological investigation concluded that there is a definite correlation between the orientation of the Langer lines and the preferred orientation of collagen fibres in the dermis (P<0.001). The data obtained in this study will provide essential information for those wishing to model the skin using a structural constitutive model.

562 citations


Journal ArticleDOI
TL;DR: In this article, the properties of a refractory multi-component alloy, Ta20Nb20Hf20Zr20Ti20, were determined in the temperature range of 296-1473 K and strain rate range of 10−1-10−5 s−1.
Abstract: Compression properties of a refractory multi-component alloy, Ta20Nb20Hf20Zr20Ti20, were determined in the temperature range of 296–1473 K and strain rate range of 10−1–10−5 s−1. The properties were correlated with the microstructure developed during compression testing. The alloy was produced by vacuum arc melting, and it was hot isostatically pressed (HIPd) and homogenized at 1473 K for 24 h prior to testing. It had a single-phase body-centered cubic structure with the lattice parameter a = 340.4 pm. The grain size was in the range of 100–200 μm. During compression at a strain rate of έ = 10−3 s−1, the alloy had the yield strength of 929 MPa at 296 K, 790 MPa at 673 K, 675 MPa at 873 K, 535 MPa at 1073 K, 295 MPa at 1273 K and 92 MPa at 1473 K. Continuous strain hardening and good ductility (e ≥ 50%) were observed in the temperature range from 296 to 873 K. Deformation at T = 1073 K and έ ≥ 10−3 s−1 was accompanied by intergranular cracking and cavitation, which was explained by insufficient dislocation and diffusion mobility to accommodate grain boundary sliding activated at this temperature. The intergranular cracking and cavitation disappeared with an increase in the deformation temperature to 1273 and 1473 K or a decrease in the strain rate to ~10−5 s−1. At these high temperatures and/or low-strain rates the alloy deformed homogeneously and showed steady-state flow at a nearly constant flow stress. Partial dynamic recrystallization, leading to formation of fine equiaxed grains near grain boundaries, was observed in the specimens deformed at 1073 and 1273 K and completed dynamic recrystallization was observed at 1473 K.

547 citations


Journal ArticleDOI
TL;DR: The microstructure characteristics and deformation behavior of 304L stainless steel during tensile deformation at two different strain rates have been investigated by means of interrupted tensile tests, electron-backscatter-diffraction and transmission electron microscopy (TEM) techniques as discussed by the authors.
Abstract: The microstructure characteristics and deformation behavior of 304L stainless steel during tensile deformation at two different strain rates have been investigated by means of interrupted tensile tests, electron-backscatter-diffraction (EBSD) and transmission electron microscopy (TEM) techniques. The volume fractions of transformed martensite and deformation twins at different stages of the deformation process were measured using X-ray diffraction method and TEM observations. It is found that the volume fraction of martensite monotonically increases with increasing strain but decreases with increasing strain rate. On the other hand, the volume fraction of twins increases with increasing strain for strain level less than 57%. Beyond that, the volume fraction of twins decreases with increasing strain. Careful TEM observations show that stacking faults (SFs) and twins preferentially occur before the nucleation of martensite. Meanwhile, both ɛ-martensite and α′-martensite are observed in the deformation microstructures, indicating the co-existence of stress-induced-transformation and strain-induced-transformation. We also discussed the effects of twinning and martensite transformation on work-hardening as well as the relationship between stacking faults, twinning and martensite transformation.

389 citations


Journal ArticleDOI
TL;DR: The influence of increasing strain rate on the mechanical behavior and deformation substructures in metals and alloys that deform predominately by slip is very similar to that seen following quasi-static deformation at increasingly lower temperatures or due to a decrease in stacking-fault energy (γsf) as mentioned in this paper.
Abstract: The influence of increasing strain rate on the mechanical behavior and deformation substructures in metals and alloys that deform predominately by slip is very similar to that seen following quasi-static deformation at increasingly lower temperatures or due to a decrease in stacking-fault energy (γsf). Deformation at higher rates (a) produces more uniform dislocation distributions for the same amount of strain, (b) hinders the formation of discrete dislocation cells, (c) decreases cell size, and (d) increases misorientation, with more dislocations trapped within cell interiors. The suppression of thermally activated dislocation processes in this regime can lead to stresses high enough to activate and grow deformation twins even in high-stacking-fault-energy, face-centered-cubic metals. In this review, examples of the high-strain-rate mechanical behavior and the deformation substructure evolution observed in a range of materials following high and shock-loading strain rates are presented and compared with ...

261 citations


Journal ArticleDOI
TL;DR: Preliminary results provide preliminary confirmation that model-predicted strain and strain rate in the CC correlate with changes in indices of white matter integrity.
Abstract: On-field monitoring of head impacts, combined with finite element (FE) biomechanical simulation, allow for predictions of regional strain associated with a diagnosed concussion. However, attempts to correlate these predictions with in vivo measures of brain injury have not been published. This article reports an approach to and preliminary results from the correlation of subject-specific FE model-predicted regions of high strain associated with diagnosed concussion and diffusion tensor imaging to assess changes in white matter integrity in the corpus callosum (CC). Ten football and ice hockey players who wore instrumented helmets to record head impacts sustained during play completed high field magnetic resonance imaging preseason and within 10 days of a diagnosed concussion. The Dartmouth Subject-Specific FE Head model was used to generate regional predictions of strain and strain rate following each impact associated with concussion. Maps of change in fractional anisotropy (FA) and median diffusivity (MD) were generated for the CC of each athlete to correlate strain with change in FA and MD. Mean and maximum strain rate correlated with change in FA (Spearman ρ = 0.77, p = 0.01; 0.70, p = 0.031), and there was a similar trend for mean and maximum strain (0.56, p = 0.10; 0.6, p = 0.07), as well as for maximum strain with change in MD (−0.63, p = 0.07). Change in MD correlated with injury-to-imaging interval (ρ = −0.80, p = 0.006) but change in FA did not (ρ = 0.18, p = 0.62). These results provide preliminary confirmation that model-predicted strain and strain rate in the CC correlate with changes in indices of white matter integrity.

223 citations


Journal ArticleDOI
TL;DR: Multilevel regression analyses suggest no evidence of any discontinuity in the progression of the relationships between peak dynamic load and three‐dimensional measures of bone mass/strength in both cortical and cancellous regions.
Abstract: There is a widely held view that the relationship between mechanical loading history and adult bone mass/strength includes an adapted state or “lazy zone” where the bone mass/strength remains constant over a wide range of strain magnitudes. Evidence to support this theory is circumstantial. We investigated the possibility that the “lazy zone” is an artifact and that, across the range of normal strain experience, features of bone architecture associated with strength are linearly related in size to their strain experience. Skeletally mature female C57BL/6 mice were right sciatic neurectomized to minimize natural loading in their right tibiae. From the fifth day, these tibiae were subjected to a single period of external axial loading (40, 10-second rest interrupted cycles) on alternate days for 2 weeks, with a peak dynamic load magnitude ranging from 0 to 14 N (peak strain magnitude: 0–5000 µe) and a constant loading rate of 500 N/s (maximum strain rate: 75,000 µe/s). The left tibiae were used as internal controls. Multilevel regression analyses suggest no evidence of any discontinuity in the progression of the relationships between peak dynamic load and three-dimensional measures of bone mass/strength in both cortical and cancellous regions. These are essentially linear between the low-peak locomotor strains associated with disuse (∼300 µe) and the high-peak strains derived from artificial loading and associated with the lamellar/woven bone transition (∼5000 µe). The strain:response relationship and minimum effective strain are site-specific, probably related to differences in the mismatch in strain distribution between normal and artificial loading at the locations investigated. © 2012 American Society for Bone and Mineral Research.

190 citations


Journal ArticleDOI
TL;DR: In this article, a commercial purity (99.8%) magnesium single crystals were subjected to plane strain compression (PSC) along the c-axis at 200 and 370 degrees C and a constant strain rate of 10(-3) s(-1).

185 citations


Journal ArticleDOI
TL;DR: In this article, the effect of initial texture on the mechanical properties and strain hardening behavior of AZ31 magnesium alloy has been investigated, and the results indicate that the yield strength and the strain-hardening rate are highly anisotropic with respect to the initial texture.
Abstract: The effect of initial texture on the mechanical properties and strain hardening behavior of AZ31 magnesium alloy has been investigated. Cylindrical specimens of extruded and hot rolled AZ31 are compressed along different directions, with the compression axis (C) perpendicular or parallel to the extrusion direction (ED) or the sheet normal direction (ND), referred to as C⊥ED, C//ED, C⊥ND and C//ND specimen, respectively. The compression tests are conducted at room temperature with a strain rate of 0.01 s−1. The results indicate that the yield strength and the strain hardening rate are highly anisotropic with respect to the initial texture. The significant yield behavior can be induced by only a small volume of twins. When the initial grain orientations are unfavorable for { 10 1 ¯ 2 } twinning, the strain hardening rate decreases gradually. When the initial grain orientations are favorable for { 10 1 ¯ 2 } twinning, the strain hardening behavior exhibits three distinct stages. The main contribution to increasing strain hardening rate (corresponding to the stage II) results from texture strengthening, which rotates grain orientations into hard orientations by the { 10 1 ¯ 2 } twinning. The length of the stage II is predominantly related to the volume fraction of grains which are favorable for { 10 1 ¯ 2 } twinning.

170 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of relative density, strain rate, and honeycomb cell size on the mechanical properties of honeycombs were studied and it was demonstrated that the mean plateau force was linearly related to the specimen dimensions.

170 citations


Journal ArticleDOI
TL;DR: In this paper, a unified constitutive model is proposed to describe the fcc crystalline plasticity at the extreme strain rate beyond which the material sensitivity to strain rate increases dramatically, and an optimization method is used to obtain globally optimal parameters in the model.

159 citations


Journal ArticleDOI
TL;DR: In this paper, the authors provide a micromechanical model describing time dependent brittle deformation of water-saturated rocks under triaxial stress conditions. But their model is based on the sliding wing crack model of Ashby and Sammis [1990], and the crack length evolution is computed from Charles' law.
Abstract: In the upper crust, the chemical infuence of pore water promotes time dependent brittle deformation through sub-critical crack growth. Sub-critical crack growth allows rocks to deform and fail at stresses well below their short-term failure strength, and even at constant applied stress (\brittle creep"). Here we provide a micromechanical model describing time dependent brittle creep of water-saturated rocks under triaxial stress conditions. Macroscopic brittle creep is modeled on the basis of microcrack extension under compressive stresses due to sub-critical crack growth. The incremental strains due to the growth of cracks in compression are derived from the sliding wing crack model of Ashby and Sammis [1990], and the crack length evolution is computed from Charles' law. The macroscopic strains and strain rates computed from the model are non linear, and compare well with experimental results obtained on granite, low porosity sandstone and basalt rock samples. Primary creep (decelerating strain) corresponds to decelerating crack growth, due to an initial decrease in stress intensity factor with increasing crack length in compression. Tertiary creep (accelerating strain as failure is approached) corresponds to an increase in crack growth rate due to crack interactions. Secondary creep with apparently constant strain rate arises as an inflexion between those two end-member phases. The minimum strain rate at the inflexion point can be estimated analytically as a function of model parameters, e ective con ning pressure and temperature, which provides an approximate creep law for the process. The creep law is used to infer the long term strain rate as a function of depth in the upper crust due to the action of the applied stresses: in this way, sub-critical cracking reduces the failure stress in a manner equivalent to a decrease in cohesion. We also investigate the competition with pressure solution in porous rocks, and show that the transition from sub-critical cracking to pressure solution dominated creep occurs with increasing depth and decreasing strain rates.

Journal ArticleDOI
TL;DR: In this article, a set of isothermal hot compression tests were carried out in the temperature range of 400-540 ÂC and strain rates of 0.001, 0.01 and 0.1 Â s −1 up to a true strain of 6.6.
Abstract: The flow stress behavior of cast A356 aluminum alloy has been studied by a set of isothermal hot compression tests. The compression tests were carried out in the temperature range of 400–540 °C and strain rates of 0.001, 0.01 and 0.1 s −1 up to a true strain of 0.6. The effects of temperature and strain rate on deformation behavior were represented by Zener–Hollomon parameter in an exponent type equation. Employing an Arrhenius-type constitutive equation, the influence of strain has been incorporated by considering the related materials’ constants as functions of strain. The accuracy of the developed constitutive equations has been evaluated using standard statistical parameters such as correlation coefficient and average absolute relative error. The results indicate that the strain-dependent constitutive equation can lead to a good agreement between the calculated and measured flow stresses in the relevant temperature range.

Journal ArticleDOI
TL;DR: Based on the extensive new experimental results, a yield criterion is proposed to describe the anisotropic yield behavior and tension compression asymmetry characteristics of an electron beam single melt Ti-6Al-4V alloy as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this paper, the coupling between precipitation and plasticity has been systematically investigated in an Al-Zn-Mg-Cu alloy using in situ small-angle X-ray scattering measurements during thermomechanical tests.

Journal ArticleDOI
TL;DR: In this paper, a new uncoupled anisotropic fracture criterion based on the magnitude of stress vector (MSV) was proposed to simulate the ductile fracture of Al2024-T351 alloy.

Journal ArticleDOI
TL;DR: In this paper, the dynamic recrystallization behavior of 42CrMo steel was investigated by hot compression tests and the effects of deformation temperature, strain rate, and initial austenite grain size on the dynamic re-stallization behaviour were discussed.
Abstract: The dynamic recrystallization behavior in 42CrMo steel was investigated by hot compression tests. The effects of deformation temperature, strain rate, and initial austenite grain size on the dynamic recrystallization behavior were discussed. Based on the experimental results, the kinetic equations for the dynamic recrystallization behavior of 42CrMo steel were proposed. Results indicate that the effects of the deformation temperature, strain rate and initial austenitic grain size on the dynamic recrystallization behavior in 42CrMo are significant. The dynamic recrystallization in 42CrMo steel easily occurs at high deformation temperature, low strain rate and fine initial austenitic grain. A good agreement between the experimental and predicted results shows that the proposed kinetic equations can give an accurate estimate of the dynamic recrystallization behavior in hot deformed 42CrMo steel.

Journal ArticleDOI
TL;DR: In this article, the effect of high strain rate on compressive behavior of plain and fiber-reinforced high-strength concrete (FRHSC) with strength between 80 and 90 MPa was investigated.

Journal ArticleDOI
TL;DR: In this article, isothermal hot compression tests were conducted at the deformation temperatures varying from 350 to 500 ÂC and strain rates ranging from 0.005 to 0.5 Â s−1.
Abstract: In order to study the high-temperature flow stress of commercial purity aluminum (AA1070), isothermal hot compression tests were conducted at the deformation temperatures varying from 350 to 500 °C and strain rates ranging from 0.005 to 0.5 s−1. The results showed that the flow stress of AA1070 was evidently affected by both the deformation temperature and strain rate. The influence of strain was also incorporated in the constitutive equation by considering the effects of strain on material constants which are consist of β, α, n, A and activation energy Q. The predicted flow stress curves using the proposed constitutive equations well agree with the experimental results of the flow stress for AA1070.

Journal ArticleDOI
TL;DR: In this article, a phenomenological constitutive model is proposed to predict the mechanical behavior of the alloy over wide ranges of strain rate and temperature, which is very close to the observed responses.

Journal ArticleDOI
TL;DR: In this article, the capability of artificial neural network (ANN) has been evaluated to describe and to predict the high temperature flow behavior of a cast AZ81 magnesium alloy, and a feed-forward back propagation ANN with single hidden layer was established to investigate the flow behaviour of the material.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the flow behavior of 7050 aluminum alloy by means of isothermal compression tests and established the constitutive equations for characterizing flow behavior during the whole deformation process.
Abstract: The flow behavior of 7050 aluminum alloy was investigated by means of isothermal compression tests. Isothermal compression of 7050 aluminum alloy was carried out on a Gleeble-1500 thermal simulation machine at the deformation temperatures ranging from 593 K to 743 K, the strain rates ranging from 0.01 s−1 to 20.0 s−1, and the height reductions of 30%, 50% and 70%. The characteristics of stress–strain curves are determined by the interaction of work hardening, dynamic recovery and dynamic recrystallization. The flow stress decreases with the increasing of deformation temperature and the decreasing of strain rate. The relationship between microstructure and processing parameters was analyzed. The constitutive equations for characterizing the flow behavior during the whole deformation process had been established, based on the experimental results and the kinetic analysis. The average relative error between the calculated and the experimental flow stress is 5.73%, which indicates that the constitutive equations can be used to predict the flow behavior of 7050 aluminum alloy accurately during high temperature deformation.

Journal ArticleDOI
TL;DR: In this article, a mesoscale numerical simulation of concrete specimens under high strain rate compression is presented, where the influence of the material heterogeneity on the dynamic increase factor (DIF) is discussed.

Journal ArticleDOI
TL;DR: Strain rate is a more robust measure of contractility that is less influenced by changes in cardiac load and structure than either radial or circumferential strain rate, and is the more relevant parameter to assess myocardial contractile function noninvasively.
Abstract: It is well accepted that strain and strain rate deformation parameters are not only a measure of intrinsic myocardial contractility but are also influenced by changes in cardiac load and structure....

Journal ArticleDOI
TL;DR: In this paper, a constitutive analysis has been conducted on the AZ81 magnesium alloy employing experimental stress-strain data obtained from isothermal hot compression tests, where the effects of the temperature and strain rate on hot deformation behavior have been expressed in terms of an exponent-type Zener-Hollomon equation.

Journal ArticleDOI
TL;DR: In this article, boron steel sheet metal blanks were austenized and quenched at five different cooling rates ranging from 14 to 50°C/s, which resulted in as-quenched microstructures that ranged from bainitic to martensitic respectively.

Journal ArticleDOI
TL;DR: In this article, the role of twinning on dynamic recrystallization and microstructural evolution during moderate to high strain rate (0.1 to 100 s−1) hot deformation in a Ti-modified austenitic stainless steel (alloy D9) was discussed.
Abstract: This article discusses the role of twinning on dynamic recrystallization (DRX) and microstructural evolution during moderate to high strain rate (0.1 to 100 s−1) hot deformation (1173 to 1373 K (900 to 1100 °C) range) in a Ti-modified austenitic stainless steel (alloy D9). The extent of DRX increased with increasing strain rate and temperature in the range of hot working parameters employed in the present study. The acceleration of DRX with strain rate is attributed to increased rate of dislocation accumulation during high strain rate deformation as well as adiabatic temperature rise. The DRX grains were found to be twinned and a linear relationship was observed between the area fraction of DRX grains and the fraction of Σ3 boundaries. Analysis of misorientations revealed that the majority of these Σ3 boundaries are newly formed coherent twin boundaries during DRX. Interaction of pre-existing Σ3 boundaries that may regenerate new Σ3 boundaries did not seem to occur frequently during DRX. The majority of the twin boundaries are found within the DRX grains, signifying that these annealing twins are mainly formed by “growth accidents” during the expansion of the DRX grains. It is suggested that annealing twins play an important role during nucleation and subsequent expansion of the DRX process in alloy D9.

Journal ArticleDOI
TL;DR: Based on the measured stress-strain data, a phenomenological constitutive model, which considers the coupled effects of strain, strain rate and forming temperature on the flow behavior of alloy, was proposed to describe the compressive behavior of the studied Al-Cu-Mg alloy as discussed by the authors.
Abstract: The high-temperature flow behavior of Al–Cu–Mg alloy is studied by the hot compressive tests over wide range of strain rate and forming temperature. Considering the negative effects of the interfacial friction on the heterogeneous deformation of specimen, the measured flow stress was corrected. The effects of processing parameters on material flow behavior are discussed. Based on the measured stress–strain data, a phenomenological constitutive model, which considers the coupled effects of strain, strain rate and forming temperature on the flow behavior of alloy, was proposed to describe the compressive behavior of the studied Al–Cu–Mg alloy. The proposed constitutive model correlates well with the experimental results, which confirms that the proposed model can give an accurate and precise estimate of flow stress for the studied Al–Cu–Mg alloy.

Journal ArticleDOI
TL;DR: In this paper, a series of high-strain torsion experiments on thin-walled cylinders of iron-rich olivine aggregates were conducted in a gas-medium apparatus at 1200°C and constant strain rate.
Abstract: [1] Although microstructural evolution is critical to strain-dependent processes in Earth's mantle, flow laws for dunite have only been calibrated with low-strain experiments. Therefore, we conducted a series of high-strain torsion experiments on thin-walled cylinders of iron-rich olivine aggregates. Experiments were performed in a gas-medium apparatus at 1200°C and constant strain rate. In our experiments, each at a different strain rate, a peak stress was observed followed by significant strain weakening. We first deformed samples to high enough strain that a steady state microstructure was achieved and then conducted strain rate stepping tests to characterize the creep behavior of each sample with constant microstructure. A global fit to the data yields a stress exponent of 4.1 and a grain-size exponent of 0.73, values which agree well with those from previous small-strain experiments conducted on olivine in the dislocation-accommodated grain-boundary sliding (GBS) regime. Strong crystallographic preferred orientations provide support for GBS accommodated by movement of (010)[100] dislocations. The observed strain weakening is not entirely explained by grain-size reduction; thus, we propose that the remaining 30% reduction in stress is related to CPO development. To incorporate microstructural evolution in a constitutive description of GBS in olivine, we (1) derive a flow law for high-strain deformation with steady state microstructure, which results in an apparent stress exponent of 5.0, and (2) present a system of evolution equations that recreate the observed strain weakening. Our results corroborate flow-law parameters and microstructural observations from low-strain experiments and provide a means for incorporating strain weakening into geodynamic simulations.

Journal Article
TL;DR: From data obtained, the invariance of the dissipative action in the strong shock regime is validated, and by comparing with data obtained at much lower strain rates show that this invariance is observed over at least 5 orders of magnitude in the strain rate.
Abstract: We have directly resolved shock structures in pure aluminum in the first few hundred picoseconds subsequent to a dynamic load at peak stresses up to 43 GPa and strain rates in excess of ${10}^{10}\text{ }\text{ }{\mathrm{s}}^{\ensuremath{-}1}$. For strong shocks we obtain peak stresses, strain rates, and rise times. From these data, we directly validate the invariance of the dissipative action in the strong shock regime, and by comparing with data obtained at much lower strain rates show that this invariance is observed over at least 5 orders of magnitude in the strain rate. Over the same range, we similarly validate the fourth-power scaling of the strain rate with the peak stress (the Swegle-Grady relation).

Journal ArticleDOI
TL;DR: In this paper, a modification of the finite-strain elasto-viscoplastic EGP model is proposed to enable an accurate description of the mechanical response of solid polymers in the transition range.
Abstract: It is demonstrated that a large number of solid poly- mers (PMMA, PLLA, iPP, PS) display a pronounced change in kinetics (strain-rate and temperature dependence) after yield. The phenomenon finds its origin in the fact that, in specific ranges of temperature and strain rate, two different molecular processes may contribute to the yield stress. Because of strain softening, the post-yield response is only controlled by one of the two, resulting in a strain-rate dependence of the yield drop. The universality of the phenomenon is discussed in connection to the alleged influ- ence of secondary transitions on the impact response of polymer glasses. A modification of the finite-strain elasto-viscoplastic EGP-model is proposed to enable an accurate description of the mechanical response of solid polymers in the transition range. The versatility of the model is demonstrated on the temperature and strain-rate dependence of the intrinsic mechanical behav- ior of PMMA, iPP, PS, and PLLA. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 1757-1771, 2012 INTRODUCTION Structural failure in static or dynamic (impact) loading conditions is a major concern in the applica- tion of polymers in load-bearing components. 1 Hence, under- standing of the fundamental causes leading to that process, and, ideally, identification of the role of details in the molec- ular architecture, is of critical importance. Likewise, the need for quantitative predictive modeling tools for failure phenom- ena is of extreme relevance and importance in the design and optimization of reliable load-bearing polymer components. The short-term failure of polymers is known to originate in usually rapid development of localized irreversible (plastic) strain, 2, 3 as manifested in moderate localization in shear bands and/or necks, 4, 5 or in extreme localizations in crazes that lead to cracks. 6, 7 A loss of structural integrity of the product results, and product failure can therefore be either ductile, involving the development of large localized plastic deformation zones accompanied by (more stable) tearing phenomena, or brittle, which gives fragmentation of the part. Changing the tempera- ture or loading rate can cause the failure mode to switch: the so-called brittle-to-ductile (B-D) or ductile-to-brittle (D-B) transitions. 8, 9