Mayi Guo, Gang Zhao, Wei Wang^*, Xiaoxiao Du, Ran Zhang, Jiaming Yang

CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.2, pp. 821-843, 2020, DOI:10.32604/cmes.2020.09898

Abstract Nonlinear behaviors are commonplace in many complex engineering applications, e.g., metal forming, vehicle crash test and so on. This paper focuses on the T-spline based isogeometric analysis of two-dimensional nonlinear problems including general large deformation hyperelastic problems and small deformation elastoplastic problems, to reveal the advantages of local refinement property of T-splines in describing nonlinear behavior of materials. By applying the adaptive refinement capability of T-splines during the iteration process of analysis, the numerical simulation accuracy of the nonlinear model could be increased dramatically. The Bézier extraction of the T-splines provides an element structure for isogeometric analysis that can be… More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.3, pp. 231-258, 2005, DOI:10.3970/cmes.2005.008.231

Abstract Using a group-theoretical approach in the Minkowski space we explore kinematic hardening rules from a viewpoint of the Poincaré group. The resultant models possess two intrinsic times q₀^a and q₀^b; the first q₀^a controls the on/off switch of plasticity, and the second q₀^b controls the pace of back stress during plastic deformation. We find that some existent kinematic hardening rules, including the modifications from the Armstrong-Frederick kinematic hardening rule, can be categorized into type I, type II and type III, which correspond respectively to q₀^b = 0, q₀^b = q₀^a and q₀^b… More >

Igor Karšaj¹, Carlo Sansour², Jurica Sorić¹

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.1, pp. 45-60, 2005, DOI:10.3970/cmes.2005.008.045

Abstract In this paper, a free energy-based formulation incorporating the effect of kinematic hardening is proposed. The formulation is able to reproduce symmetric expressions for the back stress while incorporating the multiplicative decomposition of the deformation gradient. Kinematic hardening is combined with isotropic hardening where an associative flow rule and von Mises yield criterion are applied. An accurate and trivial wise objective integration algorithm employing the exponential map is developed. In order to ensure a high convergence rate in the global iteration approach, an algorithmic tangent operator is derived. The computational algorithm is implemented and applied to a shell finite element… More >

L.S. Miers, J.C.F. Telles¹

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.5, pp. 431-440, 2004, DOI:10.3970/cmes.2004.006.431

Abstract Most formulations involving the use of the so-called consistent elastoplastic tangent operator procedure, in boundary element analysis, have been presented taking in consideration only a J₂-type yield criterion, like von Mises. The present paper aims at bringing a general consistency concept to tangent operators obtained without yield criterion particularization, ready to be used in implicit schemes for elastoplastic BEM analysis. The ideas follows much of the second author's physically nonlinear implicit BEM solution procedures introduced in the 80's and is based on a Taylor series expansion of the true effective stress around an equivalent stress corresponding to the accumulated true… More >

Marwa Abida^1,2, Jamel Mars^3,*, Florian Gehring¹, Alexandre Vivet¹, Fakhreddine Dammak³

Journal of Renewable Materials, Vol.6, No.5, pp. 464-476, 2018, DOI:10.32604/JRM.2018.01897

Abstract Based on experimental test results, flax fiber reinforced polymer composites are characterized by nonlinear visco-elastoplastic behavior. The aim of this work is to model the quasi-unidirectional flax fiber reinforced composite behavior through a three dimensional formulation with orthotropic elasticity and orthotropic plasticity using Hill criterion. The isotropic hardening and Johnson Cook parameters are identified from unidirectional tensile tests at different strain rates. The adjustment of Hill’s yield criterion is developed based on yield stresses obtained in tensile tests at different directions. The numerical integration of the constitutive equations is implemented in a user-defined material, UMAT subroutines for the commercial finite… More >

Yoshihiro OCHIAI¹

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.2, pp. 83-102, 2011, DOI:10.3970/cmes.2011.079.083

Abstract In general, internal cells are required to solve unsteady thermo-elasto -plastic problems using a conventional boundary element method (BEM). However, in this case, the merit of BEM, which is the easy preparation of data, is lost. The conventional multiple-reciprocity boundary element method (MRBEM) cannot be used to solve thermo-elastoplastic problems, because the distribution of initial stress cannot be determined analytically. In this paper, it is shown that two-dimensional unsteady thermo-elastoplastic problems can be solved without the use of internal cells by using the triple-reciprocity BEM and a thin plate spline. The initial stress formulation is adopted and the initial stress… More >

K.I. Silva¹, J.C.F. Telles², F.C. Araújo³

CMES-Computer Modeling in Engineering & Sciences, Vol.78, No.3&4, pp. 209-224, 2011, DOI:10.3970/cmes.2011.078.209

Abstract In this work the boundary element method is applied to solve 2D elastoplastic problems. In elastoplastic boundary element analysis, domain integrals have to be calculated to introduce the contribution of yielded zones. Traditionally, the use of internal integration cells have been adopted to evaluate such domain integrals. The present work, however, proposes an alternative cell free strategy based on the OMLS (Orthogonal Moving Least Squares) interpolation, typically adopted in meshless methods. In this approach the definition of points to compute the interpolated value of a function at a given location only depends on their relative distance, without need to define… More >

A. Owatsiriwong¹, B. Phansri¹, K.H. Park^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.31, No.1, pp. 37-60, 2008, DOI:10.3970/cmes.2008.031.037

Abstract This study deals with the particular integral formulation for two (2D) and three (3D) dimensional elastoplastic analyses. The elastostatic equation is used for the complementary solution. The particular integrals for displacement, stress and traction rates are derived by introducing the concept of global shape function to approximate an initial stress rate term of the inhomogeneous equation. The Newton-Raphson algorithm for the plastic multiplier is used to solve the system equation. The developed program is integrated with the pre- and post-processor. The collapse analyses of the smooth flexible strip, square and circular footings are given by comparing the numerical results of… More >

Zdenko Tonković¹, Jurica Sorić^1,2, Ivica Skozrit¹

CMES-Computer Modeling in Engineering & Sciences, Vol.26, No.2, pp. 75-90, 2008, DOI:10.3970/cmes.2008.026.075

Abstract An efficient numerical algorithm for modeling of cyclic elastoplastic deformation of shell structures is derived. The constitutive model includes highly nonlinear multi-component forms of kinematic and isotropic hardening functions in conjunction with von Mises yield criterion. Therein, the closest point projection algorithm employing the Reissner-Mindlin type kinematic model, completely formulated in tensor notation, is applied. A consistent elastoplastic tangent modulus ensures high convergence rates in the global iteration approach. The integration algorithm has been implemented into a layered assumed strain isoparametric finite shell element, which is capable of geometrical nonlinearities including finite rotations. Numerical examples, considering the symmetric and nonsymmetric… More >

S. Ozaki¹, K. Hashiguchi², T. Okayasu², D.H. Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.2, pp. 101-120, 2007, DOI:10.3970/cmes.2007.018.101

Abstract In order to analyze precisely not only the elastoplastic deformation phenomenon of saturated particle assembly such as soils, grains, powdered and tablet medicines or three dimensional cellular materials, but also the frictional sliding phenomenon between saturated particle assembly and other bodies, a particle assembly-water coupled finite element program, that incorporates both the subloading surface and the subloading-friction models, is developed. Subsequently, simulations of the compaction behavior of saturated particle assembly under strain rate control are performed. It is revealed by the numerical experiment adopting the finite element program that the frictional sliding behavior of the contact boundary influences both the… More >