H. C. Cheng¹, C. Y. Yu², W. H. Chen³

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.1, pp. 1-18, 2005, DOI:10.3970/cmes.2005.007.001

Abstract In this study, a simple but effective solution methodology that integrates a modified global/local finite element (GLFE) modeling technique and a two-staged constitutive modeling strategy is presented for the thermal-mechanical modeling of solder joints in an area array typed electronic package for characterizing the associated solder joint fatigue life under the JEDEC temperature cycling specification. The effectiveness and applicability of the proposed technique are demonstrated through two case studies, each of which is associated with an area array typed test vehicle. The geometry profile of solder joints in the test vehicle is determined by the Surface Evolver [Brakke (1996)]. For… More >

R. Allena^*,†

Molecular & Cellular Biomechanics, Vol.11, No.3, pp. 185-208, 2014, DOI:10.3970/mcb.2014.011.185

Abstract Confined migration is a crucial phenomenon during embryogenesis, immune response and cancer. Here, a two-dimensional finite element model of a HeLa cell migrating across constricted–curved micro-channels is proposed. The cell is modelled as a continuum with embedded cytoplasm and nucleus, which are described by standard Maxwell viscoelastic models. The decomposition of the deformation gradient is employed to define the cyclic active strains of protrusion and contraction, which are synchronized with the adhesion forces between the cell and the substrate. The micro-channels are represented by two rigid walls and exert an additional viscous force on the cell boundaries. Five configurations have… More >

Yunfa Zhang¹, Zihui Xia^1,2

CMC-Computers, Materials & Continua, Vol.2, No.3, pp. 213-226, 2005, DOI:10.3970/cmc.2005.002.213

Abstract In the present study, the initiation and evolution of the interphase damage and their influences on the global stress-strain relation of composite laminates are predicted by finite element analysis on a micromechanical unit cell model. A thin layer of interphase elements is introduced and its stress-strain relation is derived based on a cohesive law which describes both normal and tangential separations at the interface between the fiber and matrix. In addition, a viscous term is added to the cohesive law to overcome the convergence difficulty induced by the so-called snap-back instability in the numerical analysis. The matrix behavior is described… More >

Leiting Dong¹, Satya N. Atluri1¹

CMC-Computers, Materials & Continua, Vol.30, No.1, pp. 39-82, 2012, DOI:10.3970/cmc.2012.030.039

Abstract In this paper, as an extension to the authors's work in [Dong and Atluri (2011a,b, 2012a,b,c)], three-dimensional Trefftz Voronoi Cells (TVCs) with ellipsoidal voids/inclusions are developed for micromechanical modeling of heterogeneous materials. Several types of TVCs are developed, depending on the types of heterogeneity in each Voronoi Cell(VC). Each TVC can include alternatively an ellipsoidal void, an ellipsoidal elastic inclusion, or an ellipsoidal rigid inclusion. In all of these cases, an inter-VC compatible displacement field is assumed at each surface of the polyhedral VC, with Barycentric coordinates as nodal shape functions. The Trefftz trial displacement fields in each VC are… More >

L. Dong¹, S. N. Atluri¹

CMC-Computers, Materials & Continua, Vol.29, No.2, pp. 169-212, 2012, DOI:10.3970/cmc.2012.029.169

Abstract In this paper, three-dimensionalT-Trefftz Voronoi Cell Finite Elements (VCFEM-TTs) are developed for micromechanical modeling of heterogeneous materials. Several types of VCFEMs are developed, depending on the types of heterogeneity in each element. Each VCFEM can include alternatively a spherical void, a spherical elastic inclusion, a spherical rigid inclusion, or no voids/inclusions at all.In all of these cases, an inter-element compatible displacement field is assumed at each surface of the polyhedral element, with Barycentric coordinates as nodal shape functions.The T-Trefftz trial displacement fields in each element are expressed in terms of the Papkovich-Neuber solution. Spherical harmonics are used as the Papkovich-Neuber… More >

Zhengzheng Cao¹, Feng Du^2,3,4, Zhenhua Li², Qinting Wang¹, Ping Xu¹, Haixiao Lin¹

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.3, pp. 275-293, 2017, DOI:10.3970/cmes.2017.113.287

Abstract The stability of ore pillar in mine is essential for the safe and efficient mining. Based on the energy evolvement rule in ore pillar and roadway roof system, the roadway roof and ore pillar are treated as energy release body and energy dissipation body, respectively. Therefore, the double-block mechanical model is established with energy dissipation body and energy release body, and the energy mechanism of ore pillar instability is obtained, based on the fold catastrophe mathematical theory. The research result indicates that the dynamic instability of ore pillar is a physical instability problem caused by the strain softening property of… More >

Meng Li^1,2, Jixiong Zhang^1,3, Nan Zhou¹, Qiang Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.2, pp. 183-194, 2017, DOI:10.3970/cmes.2017.113.189

Abstract To study the influence of coal mining on the stability of river levees, a mechanical model of mining-induced river levee deformation was established. This was based on the mining-induced deformation characteristics of river levees and the application of a typical surface subsidence function. Meanwhile, a failure criterion was proposed for river levees. Using some examples, the deformation of, and stress distribution through, river levees under the influence of mining were obtained: the maximum tensile stress on the bottom of the river levee was less than the tensile strength, under which circumstance the river levee remained undamaged. Meanwhile, this research analyzed… More >

Isa Ahmadi¹, M.M. Aghdam²

CMES-Computer Modeling in Engineering & Sciences, Vol.108, No.1, pp. 21-48, 2015, DOI:10.3970/cmes.2015.108.021

Abstract In this study, a truly meshless method based on the meshless local Petrov-Galerkin method is formulated for analysis of the elastic-plastic behavior of heterogeneous solid materials. The incremental theory of plasticity is employed for modeling the nonlinearity of the material behavior due to plastic strains. The well-known Prandtl-Reuss flow rule of plasticity is used as the constitutive equation of the material. In the presented method, the computational cost is reduced due to elimination of the domain integration from the formulation. As a practical example, the presented elastic-plastic meshless formulation is employed for micromechanical analysis of the unidirectional composite material. A… More >

X. Wang¹, W.T. Ang^1,2, H. Fan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.107, No.2, pp. 81-101, 2015, DOI:10.3970/cmes.2015.107.081

Abstract A micromechanical model is proposed here for estimating the effective stiffness of a pair of parallel microscopically damaged interfaces in a trimaterial under inplane elastostatic deformations. The trimaterial is made of an orthotropic thin layer sandwiched between two orthotropic half-spaces. The microscopically damaged interfaces are modeled using periodically distributed interfacial micro-cracks. The micromechanical model is formulated and numerically solved in terms of hypersingular boundary integro-differential equations. The effects of the width of the thin layer, the micro-crack densities of the two interfaces and the material constants of the thin layer and the two half-spaces on the effective stiffness coefficients are… More >

A. Ferrari¹, L. Laloui^1,2, Ch. Bonnard^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.52, No.3, pp. 217-236, 2009, DOI:10.3970/cmes.2009.052.217

Abstract A coupled hydro-mechanical formulation is presented for the analysis of landslide motion during crisis episodes. The mathematical formulation is used to model a natural slope affected by a multiple slip surface failure mechanism, in which pore water pressure evolution was identified as the main cause for movement accelerations. An elasto-plastic constitutive model is adopted for the behaviour of slip surfaces. Material parameters are obtained by combining the available laboratory tests and the back analysis of some crisis episodes. After being calibrated and validated, the model is applied to improve the understanding of the physical processes involved and to predict the… More >