M.A. Argenta¹, A.P. Gebert², E.S. Filho³, B.A. Felizari⁴, M.B. Hecke⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.3&4, pp. 159-182, 2011, DOI:10.3970/cmes.2011.079.159

Abstract Various methods in the literature proposesequations to calculate the stiffness as a function of density of bone tissue such as apparent density and ash density among others[Helgason, Perilli, Schileo, Taddei, Brynjolfsson and Viceconti, 2008]. Other ones present a value of an equivalent elasticity modulus, obtained by statistical adjustments of curves generated through mechanical compression tests over various specimens[Chevalier, Pahr, Allmer, Charlebois and Zysset, 2007; Cuppone, Seedhom, Berry and Ostell, 2004]. Bone tissue is a material withdifferent behaviors according to the scale of observation. It has a complex composite hierarchical structure, which is responsible for assign optimal mechanical properties. Its characteristics,… More >

Sheng Yan Li¹, Bin Gang Xu^1,2, Xiao Ming Tao¹, Hong Hu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.77, No.1, pp. 33-56, 2011, DOI:10.3970/cmes.2011.077.033

Abstract Slender yarn structure made from natural fibers, nano-fibers, carbon nanotubes or other types of fibrous materials is all formed by twisting an assembly of short or long fibers and its performance is significantly influenced by the physical behavior of these fibers in the slender yarn forming region - a small triangle area called spinning triangle. In this paper, a new generalized FEM model of spinning triangle has been developed to theoretically analyze the fiber structural and mechanical performance in fabrication of these slender yarn structures. In this proposed model, a geometrical model of spinning triangle is developed and the initial… More >

K. Jayabal¹, A. Menzel^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.2, pp. 183-208, 2011, DOI:10.3970/cmes.2011.073.183

Abstract Naturally evolving Voronoi discretisation of two-dimensional plane domains renders representative microstructures that turn out to be useful for the modelling and simulation of polycrystalline materials. Hybrid finite element approaches are employed on such polygonal discretisations to solve, for instance, mechanical and electromechanical problems within a finite element context. In view of solving mechanical problems, varying order of polynomial functions are suggested in the literature to sufficiently approximate stresses within the polygonal finite elements. These are, in addition to the order of the approximation functions for the displacements, characterised by the number of edges in the polygonal elements. It appears, as… More >

B. Ren^1,2, J. Qian¹, X. Zeng¹, A. K. Jha³, S. Xiao⁴, S. Li^1,5

CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.3, pp. 253-278, 2011, DOI:10.3970/cmes.2011.071.253

Abstract Ductile failure is a complex multi-scale phenomenon evolved from the micro-voids to macro-crack. There are three main failure mechanisms behinds a ductile failure: adiabatic shear band (ASB), spall fracture, and crack. Since this type of thermo-mechanical phenomena involves large deformation and large scale plastic yielding, a meshfree method has intrinsic advantages in solving this kind of problems over the conventional finite element method. In this paper, the numerical methodologies including multi-physics approach for ASB, parametric visibility condition for crack propagation, and multi-scale approach to determine spall strength in simulating ductile failure have been reviewed. A thermo-mechanical coupling algorithm is proposed… More >

H.W. Zhang^1,2, J. Lv¹, Y.G. Zheng¹

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.1, pp. 55-94, 2010, DOI:10.3970/cmes.2010.068.055

Abstract A new multiscale computational method named as extended multiscale finite element method is proposed for the mechanical analysis of closed liquid cell materials. The numerical base functions for both the displacement field and the pressure of the incompressible fluid within the closed cells are employed to establish the relationship between the macroscopic deformation and the microscopic variables such as deformation, stress, strain and fluid pressure. The results show that the extended multiscale finite element method constructed with the conventional four-node quadrilateral coarse-grid elements sometimes will have strong boundary effects and cannot predict well the fluid pressure in the closed cells.… More >

E. Carrera, S. Brischetto¹, M. Cinefra²

CMES-Computer Modeling in Engineering & Sciences, Vol.65, No.3, pp. 259-342, 2010, DOI:10.3970/cmes.2010.065.259

Abstract This paper investigates the problem of free vibrations of multilayered plates and shells embedding anisotropic and thickness polarized piezoelectric layers. Carrera's Unified Formulation (CUF) has been employed to implement a large variety of electro-mechanical plate/shell theories. So-called Equivalent Single Layer and Layer Wise variable descriptions are employed for mechanical and electrical variables;linear to fourth order expansions are used in the thickness direction z in terms of power of z or Legendre polynomials. Various forms are considered for the Principle of Virtual Displacements (PVD) and Reissner's Mixed Variational Theorem (RMVT) to derive consistent differential electro-mechanical governing equations. The effect of electro-mechanical… More >

Xianqiao Wang¹, James D. Lee¹

CMES-Computer Modeling in Engineering & Sciences, Vol.62, No.2, pp. 150-170, 2010, DOI:10.3970/cmes.2010.062.150

Abstract The concurrent methods for coupling molecular dynamics with continuum thermodynamics offer a myriad of challenging problems, mostly related with energy transmission, wave reflection, and damage propagation at the interfaces between the continuum description and the discrete description. In this work, by virtue of the atomistic field theory (AFT), we present an analysis to reconcile the compatibility between atomic region and continuum region and to calculate the matching temperature field of a heat conduction problem in a concurrent atomistic/continuum system. First, formulation of AFT with finite temperature and its corresponding finite element implementation are briefly introduced. Then we develop a new… More >

C. Becker¹, S. Jox², G. Meschke³

CMES-Computer Modeling in Engineering & Sciences, Vol.57, No.3, pp. 245-278, 2010, DOI:10.3970/cmes.2010.057.245

Abstract A three-dimensional numerical model based on the Extended Finite Element Method (X-FEM) is presented for the simulation of cohesive cracks in cementitious materials, such as concrete, in a hygro-mechanical framework. Enhancement functions for the small scale resolution of the displacement jump across cracks in the context of the X-FEM is used in conjunction with a higher order family of hierarchical shape functions for the representation of the large scale displacement field of the investigated structure. Besides the theoretical and computational formulation in a multiphase context, aspects of the implementation, such as integration and crack tracking algorithms, are discussed. Representative numerical… More >

M. Kashtalyan^1,2, Y.A. Zhuk³

CMES-Computer Modeling in Engineering & Sciences, Vol.57, No.1, pp. 1-30, 2010, DOI:10.3970/cmes.2010.057.001

Abstract The paper investigates propagation of stationary plane longitudinal and transverse waves along the layers in adhesively bonded multilayered structures for MEMS applications in the presence of residual stresses. The multilayered structure is assumed to consist of the infinite amount of the periodically recurring layers made of two different materials possessing significantly dissimilar properties: conductive metal layer and insulating adhesive layer. It is assumed that the mechanical behaviour of both materials is nonlinear elastic and can be described with the help of the elastic Murnaghan potential depending on the three invariants of strain tensor. The problem is formulated in the framework… More >

S. Brischetto¹, E. Carrera²

CMES-Computer Modeling in Engineering & Sciences, Vol.56, No.3, pp. 249-302, 2010, DOI:10.3970/cmes.2010.056.249

Abstract This work considers the fully coupled thermo-mechanical analysis of one-layered and multilayered isotropic and composite shells. The temperature is assumed a primary variable as the displacement; it is therefore directly obtained from the model and this feature permits the temperature field to be evaluated through the thickness direction. Three problems are analyzed: - static analysis of shells with imposed temperature on the external surfaces; - static analysis of shells subjected to a mechanical load, with the possibility of considering the temperature field effects; - a free vibration problem, with the evaluation of the temperature field effects. In the first problem,… More >