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A R Azami - One of the best experts on this subject based on the ideXlab platform.
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a three invariant cap plasticity model with kinematic Hardening rule for powder materials
Journal of Materials Processing Technology, 2007Co-Authors: A R Khoei, H Dormohammadi, A R AzamiAbstract:Abstract In this paper, a three-invariant cap plasticity with a kinematic Hardening rule is presented for powder materials. A general form is developed for the cap plasticity which can be compared with some common double-surface plasticity models proposed for powders in literature. The constitutive elasto-plastic matrix and its components are derived based on the definition of yield surface, Hardening Parameter and non-linear elastic behavior, as function of relative density of powder. The procedure for determination of powder Parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.
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a single cone cap plasticity with an isotropic Hardening rule for powder materials
International Journal of Mechanical Sciences, 2005Co-Authors: A R Khoei, A R AzamiAbstract:Abstract In this paper, a new single cone-cap plasticity with an isotropic Hardening rule is presented for powder materials. A general form is developed for the cap plasticity, which can be compared with some common double-surface plasticity models proposed for powders in literature. The constitutive elasto-plastic matrix and its components are derived based on the definition of yield surface, Hardening Parameter and nonlinear elastic behavior, as a function of relative density of powder. Different aspects of the model are illustrated and the procedure for determination of powder Parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.
željan Lozina - One of the best experts on this subject based on the ideXlab platform.
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a finite element formulation based on non associated plasticity for sheet metal forming
International Journal of Plasticity, 2008Co-Authors: Vedrana Cvitanic, Frane Vlak, željan LozinaAbstract:Abstract In the present paper, a finite element formulation based on non-associated plasticity is developed. In the constitutive formulation, isotropic Hardening is assumed and an evolution equation for the Hardening Parameter consistent with the principle of plastic work equivalence is introduced. The yield function and plastic potential function are considered as two different functions with functional form as the yield function of Hill [Hill, R., 1948. Theory of yielding and plastic flow of anisotropic metals. Proc. Roy. Soc. A 193, 281–297] or Karafillis–Boyce associated model [Karafillis, A.P. Boyce, M., 1993. A general anisotropic yield criterion using bounds and a transformation weighting tensor. J. Mech. Phys. Solids 41, 1859–1886]. Algorithmic formulations of constitutive models that utilize associated or non-associated flow rule coupled with Hill or Karafillis–Boyce stress functions are derived by application of implicit return mapping procedure. Capabilities in predicting planar anisotropy of the Hill and Karafillis–Boyce stress functions are investigated considering material data of Al2008-T4 and Al2090-T3 sheet samples. The accuracy of the derived stress integration procedures is investigated by calculating iso-error maps. The updated Lagrangian formulation of CBR shell element [Yoon, J.W., Yang, D.Y., Chung, K., 1999. Elasto-plastic finite element method based on incremental deformation theory and continuum based shell elements for planar anisotropic sheet materials. Comp. Meth. Appl. Mech. Eng. 174, 23–56] coupled with the developed constitutive formulations is implemented into the finite element program ADINA 8.1 (2003) via user defined subroutine CUSERG. The results of the cylindrical cup drawing for Al2008-T4 and Al2090-T3 sheet samples are evaluated by comparison with experimental data and predictions of Barlat [Barlat, F. et al., 1997b. Yield function development for aluminum alloy sheets. J. Mech. Phys. Solids 45, 1727–1763] associated model.
S V Kamat - One of the best experts on this subject based on the ideXlab platform.
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room temperature plastic flow behaviour of ti 6 8mo 4 5fe 1 5al and ti 10v 4 5fe 1 5al effect of grain size and strain rate
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: Amit Bhattacharjee, P Ghosal, A K Gogia, S Bhargava, S V KamatAbstract:Abstract The effect of β grain size and strain rate on the plastic flow behaviour of Ti–6.8Mo–4.5Fe–1.5Al (Ti metal LCB) and its equi-molybdenum DMRL alloy Ti–10V–4.5Fe–1.5Al was evaluated and compared. The 0.2% yield strength in both alloys was found to obey the Hall–Petch relation. However, σ 0 (friction stress) was higher and k y (unpinning constant or stress concentration factor) was lower for the Mo containing alloy as compared to the V containing alloy. The strain rate was also found to influence the flow behaviour of both alloys. Flow softening was observed at strain rate of 10 −2 s −1 for the Mo containing alloy at room temperature itself. However, at lower strain rates (10 −4 and 10 −5 s −1 ), there was no flow softening, although no significant work Hardening was seen. The strain Hardening Parameter γ = d σ / σ d ɛ P was calculated to explain the tensile deformation behaviour as a function of strain rate. The effect of strain rate on the flow behaviour was explained on the basis of velocity of mobile dislocation, localized adiabatic heating and planar slip due to the presence of ω-phase.
P K Banerjee - One of the best experts on this subject based on the ideXlab platform.
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an anisotropic Hardening rule for saturated clays
International Journal of Plasticity, 1993Co-Authors: Arvind S Kumbhojkar, P K BanerjeeAbstract:The paper describes a generalized anisotropic Hardening rule that uses d ɛ ij p as a Hardening Parameter. It allows modeling of the change in the degree of anisotropy as a part of updating stress history, as well as inherent and induced anisotropy. The steady state K 0 nc expression based on this rule is a function of 4 soil Parameters: λ, κ, φ’ υ, and its predictions compare well with the K 0 nc measurements reported in the literature.
Dai Okumura - One of the best experts on this subject based on the ideXlab platform.
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thermo mechanical cyclic Hardening behavior of 304 stainless steel at large temperature ranges experiments and simulations
International Journal of Mechanical Sciences, 2017Co-Authors: Nobutada Ohno, Ryohei Yamamoto, Dai OkumuraAbstract:Abstract Thermo-mechanical cyclic experiments on 304 stainless steel were performed at several temperature ranges with T min (minimum temperature) of 150 °C and T max (maximum temperature) ranging from 350 °C to 1000 °C. Corresponding isothermal cyclic experiments were also performed at several temperatures. Temperature-history dependent cyclic Hardening was thus observed to significantly occur under thermo-mechanical cyclic loading when T max was around 600 °C. In contrast, almost no cyclic Hardening occurred when T max was 1000 °C. The observed, thermo-mechanical cyclic Hardening behavior was then simulated using a cyclic viscoplastic constitutive model with a cyclic Hardening Parameter. The simulation focused on the saturated state of cyclic Hardening, leading to the following findings. The saturated thermo-mechanical cyclic hysteresis loops were not predicted well by simply taking into account temperature dependence in the cyclic Hardening Parameter. Then, by assuming the cyclic Hardening Parameter to be dependent on T max , the saturated thermo-mechanical hysteresis loops were simulated well. These mean that the cyclic Hardening Parameter of 304 stainless steel should not change with temperature but depend on T max in the saturated state of cyclic Hardening under thermo-mechanical cyclic loading.
