Simple Shear Behavior Research Articles

Role of Tangential Displacement Amplitude in 3D Cyclic Simple Shear Behavior of Gravel–Steel Interface

Role of Tangential Displacement Amplitude in 3D Cyclic Simple Shear Behavior of Gravel–Steel Interface

Modified SANISAND‐F model for simple shear path

AbstractSimple shear behavior of sand is representative in geotechnical engineering with potential failure occurred along a thin shear zone. The strength and deformation of sand under simple shear are accompanied with principal stress rotation (PSR). This study proposes a modified SANISAND‐F model to capture the simple shear behavior of sand with PSR. A new plastic flow rule along with a kinematic hardening modulus is proposed to consider the evolution of the PSR and intermediate stress ratio. The developed model, with thirteen parameters, can reasonably the capture the stress‐strain and PSR of sand under simple shear.

Application of droplet migration scaling behavior to microchannel flow measurements.

In confined channels in low Reynolds number flow, droplets drift perpendicular to the flow, moving across streamlines. The phenomenon has proven useful for understanding microfluidic droplet separation, drug delivery vehicle optimization, and single-cell genomic amplification. Particles or droplets undergo several migration mechanisms including wall migration, hydrodynamic diffusion, and migration down gradients of shear. In simple shear flow only wall migration and hydrodynamic diffusion are present. In parabolic flow, droplets also move down gradients of shear. The resulting separation depends on parameters including particle size and stiffness, concentration, and flow rate. Computational methods can incorporate these effects in an exact manner to predict margination phenomena for specific systems, but do not generate a descriptive parametric dependence. In this paper, we present a scaling model that elucidates the parametric dependence of margination on emulsion droplet size, volume fraction, shear rate and suspending fluid viscosity. We experimentally measure the droplet depletion layer of silicone oil droplets and compare the results to theoretical scaling behavior that includes hydrodynamic diffusion and wall migration with and without an added shear-gradient migration. Results demonstrate the viability and limitations of applying a simple scaling behavior to experimental systems to describe parametric dependence. Our conclusions open the possibility for parametric descriptions of migration with broad applicability to particle and droplet systems.

Cyclic simple shear behavior of a tropical alluvial soil

Tropical alluvial soil has distinctive physical characteristics when compared to common sedimentary soils. Ignoring such distinctive characteristics might lead to geotechnical problems that require a thorough re-investigation. Foundation failures have been identified along some river banks of tropical alluvial soil deposits in Sarawak, Malaysia, which were speculated to be due to cyclic loading effects. This paper presents preliminary results on tropical alluvial soil engineering behaviors from simple shear cyclic loading tests. Specimens measuring 50 mm in diameter and 16 mm in height were obtained from three undisturbed samples. They were sheared using an Electro-Mechanical Dynamic Cyclic Simple Shear (EMDCSS) for thirty cycles at three different target displacements. The results showed hysteresis loops, where the shear stress decreases as the cycle increases. Excess pore water pressures develop during shearing, which correspond to the target displacement levels. The damping ratio increases as the shear strain increases but decreases as the cycle increases. The normalized shear modulus decreases as both the shear strain and loading cycle increase. A comparison with previous literature on cohesive soils shows that the tropical alluvial soil has a lower damping ratio and normalized shear modulus, which range from 3.3% to 9% and 0.0004 to 0.01, respectively. The findings indicate that the tropical alluvial soil has a potential reduction in strength when subjected to continuous cyclic loading. The paper provides a better understanding for academics and engineering professionals before conducting design or remedial work in the tropical alluvial soil environment.

Cyclic simple shear behaviour of saturated and moist sandy soils

ABSTRACT Liquefaction and settlement of sandy soils cause significant damage during earthquakes. In this research, cohesionless soils of Kutch region with history of large earthquakes are explored. Twenty-six soil samples were collected from different locations of Kutch region and tested under saturated and moist conditions by performing two series of Electromechanical Dynamic Cyclic Simple Shear (EMDCSS) tests. In series I, the liquefaction characteristics of saturated samples were observed to be dependent on fines content and plasticity index. Kutch soils with non-plastic fines exhibited low liquefaction resistance and showed increased resistance at higher FC; however, for sands with plastic fines, PI rather than FC controlled the cyclic degradation. Saturated sandy soils with non-plastic fines exhibited lower shear stress mobilisation, higher pore pressure and larger degradation as compared to sands with clay content. In series II, the settlement characteristics of moist samples at constant normal stress revealed decreased axial deformation and increased mobilised shear stress with increased FC and PI. Silty-sands exhibited higher deformations and larger strength as compared to clayey-sands. The EMDCSS tests at saturated and moist conditions revealed Kutch soils to be prone to liquefaction and large settlements, respectively.

Oldroyd's model and the foundation of modern rheology of yield stress fluids

• Oldroyd's 1946 paper was ahead of its time. • Pre- and post-yielded regimes are described in a tensorial manner with a von Mises yield criterion. • Modern formulations of yield stress fluids are still heavily influenced by Oldroyd's paper. • Many experimental studies have probed the assumptions and implications of Oldroyd's model. Oldroyd's 1946 formulation of the constitutive equation of yield stress fluids laid the foundation of modern rheology of yield stress fluids, by considering not just the simple shear behavior of yield-stress fluids in the plastic regime, but also by prescribing a simple expression for how they behave prior to yielding and a 3D expression for how they behave beyond yielding. We discuss the implications of Oldroyd's model, and the ways in which researchers have tested and refined his ideas. We also review the experimental methods that have been employed to test these implications, and to determine the rheological parameters it lays out. We finally discuss the impact of Oldroyd's model, and the future of investigations into what happens prior to yielding.

Simple shear behavior of 2024-T351 aluminum alloy over a wide range of strain rates and temperatures: Experiments and constitutive modeling

A recently developed single shear specimen (SSS) was used to investigate the thermo-viscoplastic behavior of 2024-T351 aluminum alloy (AA2024-T351) under simple shear stress state. Shear stress-shear strain relations over a wide range of strain rates, covering low (0.001 and 0.1 s−1), medium (10 s−1), high (3000 and 6000 s−1) and very high (14000-49000 s−1) regimes and at initial temperatures from 293 to 573 K were obtained experimentally. The results show that: (1) at 293 K, AA2024-T351 exhibited negligible strain rate sensitivity at strain rates below 6000 s−1, and the effect of strain rate became obvious at strain rates above 14000 s−1; (2) dynamic strain aging (DSA) occurred at temperatures between 373 and 573 K and strain rates below 6000 s−1; (3) strain rate sensitivity of the material was strongly affected by DSA, and bell-shaped strain rate sensitivity curves were observed; (4) with an increase in temperature, peak values of the bell-shaped strain rate sensitivity curves shifted to higher strain rates. A constitutive model taking the advantages of Johnson-Cook model, Khan-Huang-Liang model, Nemat-Nasser-Li model and Wang-Guo-Gao model was developed for deformation behavior description, with the effects of viscous drag on dislocation motion and DSA considered. The experimental flow stress curves were compared to the model predictions, and a good agreement was observed. To validate the constitutive model independently of the experiments used for the identification of the model parameters, numerical simulations of Taylor impact tests were performed. A good agreement between experimental and numerical post-test specimens, in terms of mushroom shaped specimen head and reduced specimen length, was observed. According to the numerical results, strain rates varied largely between 103 and 106 s−1 during Taylor impact tests. Besides, numerical simulations of Taylor impact tests were performed again using the constitutive model excluding the viscous drag component, and less accurate numerical results were obtained. It implies that for precise computations of engineering applications, the actual strain rate should be considered in the establishment of constitutive models.

Simple shear behavior and constitutive modeling of 304 stainless steel over a wide range of strain rates and temperatures

A novel single shear specimen (SSS) together with a correction coefficient method is used to study the deformation behavior of a 304 stainless steel under shear loadings. Shear stress-shear strain relations over a wide range of shear strain rates (0.001 to 39000 s−1) at three initial temperatures (77 to 473 K) are obtained experimentally. The effects of strain rate and temperature on the flow stress curves are determined. With increasing strain rate or temperature, the strain hardening rate decreases continuously. At the maximum strain rate of 39000 s−1, negative strain hardening rates are observed. At very high strain rates above 13000 s−1, a sharp increase in flow stress is observed, indicating a rapid rise in strain rate sensitivity. The fracture morphology of post-mortem specimens is analyzed and no well-developed adiabatic shear bands are observed. This may be due to the shear-tension stress state without hydrostatic pressure in the fracture process. Based on the experimentally obtained shear stress-shear strain curves, parameters of a modified Johnson-Cook (MJC) model are determined. A good agreement between experiments and model predictions is found, with an average error of 3.9%. Using finite element analysis, distributions of stress and strain components in the specimen shear zone is analyzed. It is found that the shear stress and shear strain play dominant roles, and a simple shear stress state with low stress triaxiality (0.015) and Lode angle parameter (0.014) is obtained.

Modelling the simple shear behaviour of clay considering principal stress rotation

Simple shear deformation is prevailing in geotechnical problems. One of its salient features is the rotation of the principal stress axes. Early numerical modelling of soil simple shear behaviour usually neglects the plastic deformation induced by principal stress rotation. Recent attempts at accurately modelling the sand simple shear behaviour have accounted for this loading mechanism, but those for the clay simple shear modelling are rare. To fill the gap, this paper presents a simple constitutive model for the simulation of clay simple shear behaviour with consideration of the effect of the principal stress rotation. The model uses a non-associative flow rule and incorporates an additional mechanism associated with the principal stress rotation. The new mechanism caters for the soil non-coaxiality and plastic volumetric response under pure rotation of principal stress axes. Stress–strain incremental linearity is maintained in the proposed model. Comparisons of simulations with clay simple shear test data justify the importance of the principal stress rotation. The model satisfactorily captures the undrained shear strength. The soil non-coaxial behaviour is also well reproduced.

Macro and micro investigation of gravel content on simple shear behavior of sand-gravel mixture

The gravel content (GC) may influence the mechanical properties of sand-gravel mixture (SGM) used in earth structures and may compromise the stability of such structures. The purpose of this paper is to present a macro and micro study on the effect of GC on simple shear behavior of SGM using experimental and numerical approaches. Firstly a series of large-scale simple shear tests on SGM with different gravel contents under different normal stresses were conducted. The test results demonstrate that GC affects the shear strength and friction angle of SGM according to the change of void ratio at macro-scale. The variations of dilatancy and initial modulus with GC were also discussed. Then a 3D discrete element model was established for numerical simulations, in which the grading distributions of particles had similar shapes with the simple shear tests, but the particle size was 5 times scaled. The Herts-Mindlin model was used for contact, and the rolling resistance was taken into account. The numerical results showed a fairly good agreement with the experimental results. After that the micro mechanism of gravel content effect was investigated according to the analysis of micro force chain topology and contact force distributions. In summary, the experimental and numerical investigations provide valuable insights into the gravel content effect of SGM at both macro- and micro- scales.

Cyclic and postcyclic simple shear behavior of binary sand-gravel mixtures with various gravel contents

The effect of gravel contents on the cyclic and post-cyclic monotonic simple shear behavior of gravelly soils during seismic events has significant implications for civil infrastructure. Large-scale cyclic simple shear tests and post-cyclic monotonic simple shear tests were performed on gravelly soils with different levels of gravel content (GC) and loading conditions. The test results indicated that the GC of a sand-gravel mixture (SGM) profoundly influences the mixture's cyclic simple shear characteristics. The SGM specimen with the lowest GC had the broadest hysteresis loops. The shear modulus of the SGM specimens differing in GC was found to increase with increasing cyclic number. The increase in shear modulus was more pronounced during the first 10 cycles. The damping ratio of the SGM decreased to some extent as the cyclic loadings increased. Overall, the results suggested a modified relationship between the damping ratio and shear modulus. The modified function accurately represented the relationship between the normalized damping ratio and the normalized secant shear modulus for SGMs varying in GC. Shear strain obviously decreased with the number of cycles during the initial cyclic loadings, when loading frequency was low. However, at a higher loading frequency, shear strain was less affected by the number of cycles. In general, the inclusion of gravel particles slightly reduced the post-cyclic monotonic shear resistance.

Two-way approach for deformation analysis of non-crimp fabrics in uniaxial bias extension tests based on pure and simple shear assumption

In-plane shear is considered as the main deformation mechanism during the forming of fabrics on double curved geometries. Non-Crimp Fabrics (NCFs) are more and more used in the industry thanks to their high mechanical performances. The uniaxial bias extension (UBE) test is commonly used for characterizing the in-plane shear behavior of fabrics. However, presence of slippages calls the reliability of this test into question for NCF material. These slippages lead to a macroscopic kinematic which does not respect the fundamental hypotheses of UBE test theory. The variety of NCF architectures is usually pointed while the lack of standardized experimental methods is seldom discussed. The first section of this paper presents a two-way approach to detect slippage on an NCF. This approach is based on two kinematical descriptions of the UBE test. The first one assumes a pure shear behavior whereas the second one assumes a simple shear behavior. These behaviors correspond respectively to the rotation of fibers and to the slippage of fibers from a macroscopic point of view. In the second section, the two-way approach is used to analyze experimental UBE tests. This investigation highlights the influence of the sample width on the deformation mode during a UBE test. More precisely, it is shown that increasing the sample width of NCF specimens improves the UBE test reliability.

Interpretation of coarse effect in simple shear behavior of binary sand-gravel mixture by DEM with authentic particle shape

The sand-gravel mixture is a binary geotechnical material widely used in construction. Its shear behavior is a significant factor influencing the relevant structure safety or slope stability. In this study, a large-scale direct simple shear test was used to study the effect of gravel content on the shear behavior of the mixture. From the experimental results, macro-mechanical properties of the mixture were acquired with various gravel contents and compression stresses. However, the deeper understanding of the shear behavior of the mixture requires a profound microscopic investigation on the specimens. Based on the experimental tests, a series of three dimensional (3D) discrete element model (DEM) analyses of simple shear tests were carried out. The 3D DEM analysis results agree well with the experimental results. The particle generation process and shear stress calculation method have been improved in this model. Moreover, the gravel particle with authentic particle shape scanned by CT system was used in the simulation. The load transformation of the contact force and the evolution of the force network automatically recorded by the DEM program contribute to further understanding the significant role of the gravel content. In summary, both the micro- and macroscopic analyses were utilized to investigate the shear behavior of the sand-gravel mixture. The findings acquired from this study are expected to help researchers to better understand the role of the gravel content in the shear behavior of sand-gravel mixture and the particle-to-particle interaction mechanism.

A Simple Approach to Performing Large Strain Cyclic Simple Shear Tests: Methodology and Experimental Results

Abstract A simple and efficient methodology has been proposed for characterizing the large strain cyclic simple shear behavior of engineering materials. The proposed methodology includes the use of a modified test specimen coupled with a digital image correlation system to measure the evolution of shear strains during cyclic simple shear deformation. The effectiveness and simplicity of the proposed testing procedure for cyclic simple shear testing lie in the fact that it does not require any custom test apparatus or fixtures to conduct cyclic simple shear tests. The proposed test sample for cyclic simple shear testing makes use of conventional tensile machine with standard grips to conduct the tests. Furthermore, the coupling of the digital image correlation system allows for full-field surface strain mapping, enabling measurement of shear strain evolution throughout the cyclic shear deformation, avoiding any complications associated with shear strain measurements using conventional extensometry techniques. The proposed methodology is successfully applied to characterize the large strain cyclic simple shear behavior of extruded aluminum alloy AA6063 in both T4 and T6 tempered conditions. The obtained cyclic simple shear results are further discussed in light of microstructure evolution during cyclic simple shear deformation.

A general approach to model interfaces using existing soil constitutive models application to hypoplasticity

The modelling of interfaces is important for the holistic simulation of geotechnical structures (e.g. piles, tunnels and geogrids). For this reason, advanced constitutive interface models and numerical techniques are needed. There are few user-friendly models, and these are rarely implemented. In this paper, a new approach for advanced interface models is proposed. This is based on the assumption that the fully rough interface can be modelled considering simple-shear behaviour at the interface. A 3D soil model is used as a constitutive driver for a frictional subroutine. This minimises the effort required, and advanced interface models are available with less effort. Two different hypoplastic models are used with the new approach. The approach was verified for several aspects (e.g. mesh size dependence), and the volumetric behaviour was studied. The user-friendliness and absence of additional parameters led to more realistic simulation results. The proposed method can be extended to other modelling techniques and will improve the modelling of contacts in soil-structure interaction analysis.

A DEM investigation on simple shear behavior of dense granular assemblies

A micromechanical investigation on simple shear behavior of dense granular assemblies was carried out by discrete element method. Three series of numerical tests were performed to examine the effects of initial porosity, vertical stress and particle shape on simple shear behavior of the samples, respectively. It was found that during simple shear the directions of principal stress and principal strain increment rotate differently with shear strain level. The non-coaxiality between the two directions decreases with strain level and may greatly affect the shear behavior of the assemblies, especially their peak friction angles. The numerical modelling also reveals that the rotation of the principal direction of fabric anisotropy lags behind that of the major principal stress direction during simple shear, which is described as fabric hyteresis effect. The degrees of fabric and interparticle contact force anisotropies increase as particle angularity increases, whereas the orientations of these anisotropies have not been significantly influenced by particle shape. An extended stress-dilatancy relationship based on ROWE-DAVIS framework was proposed to consider the non-coaxiality effect under principal stress rotation. The model was validated by present numerical results as well as some published physical test and numerical modelled data.

STUDY ON EXCESS PORE WATER PRESSURE CHANGES OF SATURATED SOFT CLAY SUBJECTED TO UNDRAINED UNI-DIRECTIONAL AND MULTI-DIRECTIONAL CYCLIC SIMPLE SHEARS

In this paper, normally consolidated specimens of kaolinite clay were tested under undrained uni-directional and multi-directional cyclic simple shears. It is shown from the test results that shear strain amplitude (γ), cyclic shear direction (phase difference (θ)) and the number of cycles (n) have significant effects on the changes of excess pore water pressure during cyclic shearing. However, the effect of cyclic shear direction on the excess pore water pressure can be eliminated by using a new parameter - cumulative shear strain (G*). Conventional estimation method of excess ore water pressure can not be used for the case of multi-directional cyclic shear with the number of cycles larger than 50 (n > 50). Consequently, a new estimation method, which is a function of cumulative shear strain was proposed. This method can be applied to various experimental conditions including uni-directional and multi-directional cyclic simples shear with different shear strain amplitudes and number of cycles.ReferencesAnsal, A., Iyisan, R. and Yildirim, H., 2001. “The cyclic behavior of soils and effects of geotechnical factors in microzonation”, Soil Dynamics and Earthquake Engineering, Vol. 21, No. 5, pp. 445-452.DeGroot, D. J., Ladd, C. C. and Germaine, J. T., 1996. Undrained multidirectional direct simple shear behavior of cohesive soil, J. Geotechnical Eng., ASCE, Vol. 122, No. 2, pp.91-98.Fukutake, K. and Matsuoka, H. A., 1989. “Unified law for dilatancy under multi-directional simple shearing”, Journal of JSCE Division C, JSCE, Vol. (412/III-1), pp. 143-151 (tiếng Nhật).Hyodo, M., Yamamoto, Y. and Sugiyama, M., 1994. “Undrained cyclic shear behaviour of normally consolidated clay subjected to initial static shear stress”, Soils and Foundations, Vol. 34, No. 4, pp.1-11.Matsuda, H., 1997. “Estimation of postearthquake settlement-time relations of clay layers”, Journal of JSCE Division C, JSCE, Vol. 568(III-39), pp. 41-48 (tiếng Nhật).Matsuda, H. and Ohara, S., 1989. “Threshold strain of clay for pore pressure buildup”, Proc. of 12h World Conf. on Soil Mechanics and Foundation Engineering, Rio De Janeiro, pp. 127-130.Matsuda, H. and Nagira, H., 2000. “Decrease in effective stress and reconsolidation of saturated clay induced by cyclic shear”, Journal of JSCE Division C, JSCE, Vol. 659(III-52), pp. 63- 75 (tiếng Nhật).Matsuda, H., Shinozaki, H., Okada, N., Takamiya, K. and Shinyama, K., 2004. “Effects of multi-directional cyclic shear on the postearthquake settlement of ground”, Proc. of 13th World Conf. on Earthquake Engineering, Vancouver, B.C., Canada, Paper No. 2890.Matsuda, H., Andre, P. H., Ishikura, R. and Kawahara, S., 2011. “Effective stress change and post-earthquake settlement properties of granular materials subjected to multi-directional cyclic simple shear”, Soils and Foundations, Vol. 51, No. 5, pp. 873-884.Ohara, S., Matsuda, H. and Kondo, Y., 1984. “Cyclic simple shear tests on saturated clay with drainage”, Journal of JSCE Division C, JSCE, Vol. (352/III-2), pp. 149-158 (tiếng Nhật).Ohara, S. and Matsuda, H., 1988. “Study on the settlement of saturated clay layer induced by cyclic shear”, Soils and Foundations, Vol. 28, No. 3, pp. 103-113.Ohmachi, T., Kawamura, M., Yasuda, S., 159 Mimura, C. and Nakamura, Y., 1988. “Damage due to the 1985 Mexico Earthquake and the ground conditions”, Soils and Foundations, Vol. 28, No. 3, pp. 149-159.Yasuhara, K. and Andersen, K. H., 1991. “Recompression of normally consolidated clay after cyclic loading”, Soils and Foundations, Vol. 31, No. 1, pp. 83-94.Yildirim, H. and Ersan, H., 2007. “Settlements under consecutive series of cyclic loading”, Soil Dynamics and Earthquake Engineering, Vol. 27, No. 6, pp. 577-585.

A comparison of material characterizations in frequently used constitutive models of ligaments

Longitudinal tensile and simple shear stress-strain curves of human medial collateral ligaments (MCL) were fitted by six frequently used constitutive relations of ligaments using two different fitting methods for determining which was the best fitting method and the most preferable constitutive model for describing the ligament properties. According to the results of fitting goodness, two typical constitutive models were further analyzed by FEM to investigate the effect of the variation in MCL constitutive models under some physiological loads (i.e., 4.5 Nm external tibial and 10 Nm valgus tibial torques). It was found that different fitting methods induced great variations in describing the simple shear behavior whereas no obvious difference in the longitudinal tensile behavior. The most accurate description of both the longitudinal tensile and simple shear behaviors was obtained from the constitutive model with ground substance defined by an exponential function when the parameters were fitted by the two test data, respectively. Although the distributions of maximal principal stress were almost the same, the variation in MCL constitutive models affected the highest value of the stress greatly when MCL was under the complex physiological loads.

Discrete element modelling of material non‐coaxiality in simple shear flows

SUMMARYWe investigate the quasi‐static simple shear flow of a two‐dimensional assembly of cohesionless particles using discrete element method (DEM) simulations. We focus on the unsteady flow regime where the solid would experience significant evolution of stresses, mobilised shear strength and dilation. We construct the DEM model using a discretised‐wall confined granular cell where the apparent boundary is allowed to dilate or contract synchronously with the confined solid. A rather uniform simple shear field is achieved across the whole assembly, which benefits rheological studies in generalising constitutive laws for continuum methods. We examine two aspects of the simple shear behaviour: macroscopic stress and strain rate evolution, particularly the non‐coaxiality between the principal directions of the two; and micromechanics such as evolution of fabric. For an initially anisotropic specimen sheared under constant normal pressure, the direction of principal stress rotates towards that of the principal strain rate, gradually reducing the degree of non‐coaxiality from about 45° to fluctuating around 0°. The rate in approaching coaxiality is slower in samples with larger initial porosity, stress ratio and mean stress. Generally, a faster rate in approaching coaxiality in simple shear is observed in a more dilatant sample, which often shows a larger degree of mobilised fabric anisotropy, suggesting the possible important role of instantaneous internal friction angle. The evolution of principal fabric direction resembles that of the principal stress direction. © 2013 The Authors. International Journal for Numerical and Analytical Methods in Geomechanics published by John Wiley & Sons, Ltd.

A temperature-dependent elasto-plastic constitutive model for magnesium alloy AZ31 sheets

For warm forming simulations of magnesium alloy sheets, a constitutive model is proposed for describing the temperature-dependent asymmetric cyclic behavior of magnesium alloy sheets. The asymmetric hardening behavior is classified into three modes − twinning (T), untwinning (U), and slip (S) − depending on the corresponding dominant deformation mode. The yield criterion uses two separate yield functions that correspond to the twinning/untwinning and slip dominant deformation modes. Though this model is phenomenological, it adopts the concept of the deformation mechanism as magnesium alloy sheets exhibits significantly different behavior by the active deformation mechanisms for a wide range of temperatures. To obtain the model parameters, the constitutive model requires cyclic behavior at room temperature and tensile behavior at high temperatures. A numerical algorithm for efficiently integrating the constitutive equations is presented for switching deformation paths and active deformation modes. For verification, the predictions by the proposed constitutive model are compared with measurements for the simple shear behavior and the high temperature cyclic behavior.