T. Fujimoto¹ and T. Nishioka¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.2, pp. 91-102, 2006, DOI:10.3970/cmes.2006.011.091

Abstract In the dynamic fracture of metallic material, some cracks propagate with the incidence of plastic deformation, and distinct plastic strain remains near the post-propagation area. In order to elucidate these dynamic nonlinear fracture processes, the moving finite element method is developed for nonlinear crack propagation. The T* integral is used as the parameter to estimate crack tip condition. First, the effect of material viscosity and crack propagation velocity have been discussed based on the numerical results for fracture under pure mode I high speed loading. Under mixed mode loading, numerical simulations for fracture path prediction More >

G.P. Nikishkov¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.2, pp. 81-90, 2006, DOI:10.3970/cmes.2006.011.081

Abstract This paper presents the object oriented approach to programming the finite element method using the Java language. The developed finite element code consists of ten Java packages. Three main methods are related to generation of finite element models, solution of elastic and elastic-plastic boundary value problems, and visualization of models and solution results. Object-oriented model of the code is described. It is demonstrated that Java 1.5 new features are useful in development of the finite element code. Java 3D is used for visualization of models and results. More >

G. Mishuris¹, A. Öchsner², G. Kuhn³

CMC-Computers, Materials & Continua, Vol.4, No.3, pp. 137-152, 2006, DOI:10.3970/cmc.2006.004.137

Abstract Nonclassical transmission conditions for dissimilar elastic structures with imperfect interfaces are investigated. The thin interface zone is assumed to be soft or stiff in comparison with the bonded materials and the transmission conditions for stiff interfaces are evaluated based on asymptotic analysis. The accuracy of the transmission conditions is clarified not only in terms of asymptotic estimate, but, which is especially important for users, also in values by accurate FEM calculations. The ranges of applicability of the conditions are discussed. More >

T. Nishioka¹, S. Tchouikov¹, T. Fujimoto¹

CMC-Computers, Materials & Continua, Vol.3, No.3, pp. 147-154, 2006, DOI:10.3970/cmc.2006.003.147

Abstract In this study, phenomena of multiple branching of dynamically propagating crack are investigated numerically. The complicated paths of cracks propagating in a material are simulated by moving finite element method based on Delaunay automatic triangulation (MFEM BODAT), which was extended for such problems. For evaluation of fracture parameters for propagating and branching cracks switching method of the path independent dynamic J integral was used. Using these techniques the generation phase simulation of multiple dynamic crack branching was performed. Various dynamic fracture parameters, which are almost impossible to obtain by experimental technique alone, were accurately evaluated. More >

Lingfei Gao¹, Xiaoping Zheng^1,2, Zhenhan Yao¹

CMC-Computers, Materials & Continua, Vol.3, No.1, pp. 25-36, 2006, DOI:10.3970/cmc.2007.003.025

Abstract A general numerical approach is developed to model the elastic behaviours and failure processes of heterogeneous materials. The heterogeneous material body is assumed composed of a large number of convex polygon lattices with different phases. These phases are locally isotropic and elastic-brittle with the different lattices displaying variable material parameters and a Weibull-type statistical distribution. When the effective strain exceeds a local fracture criterion, the full lattice exhibits failure uniformly, and this is modelled by assuming a very small Young modulus value. An auto-select loading method is employed to model the failure process. The proposed More >

I. Smojver¹, J. Sorić²

CMC-Computers, Materials & Continua, Vol.3, No.1, pp. 13-24, 2006, DOI:10.3970/cmc.2007.003.013

Abstract The paper addresses the problem of impact on layered fibre composites. The behaviour of composite laminates under impact loading is dependent not only on the velocity but also on the mass and geometry of the impactor. Using micromechanical Mori-Tanaka approach, mechanical properties of the laminate have been calculated utilizing the material constants of the fibre and matrix. General purpose FEM software ABAQUS has been modified by means of user written subroutines for modelling of composite laminate and rigid impactor. The kinematics of the impact has been simulated using transient dynamic analysis. Employing user defined multi More >

M. S. Alam¹, M.A. Wahab^1,2

Structural Durability & Health Monitoring, Vol.1, No.3, pp. 171-184, 2005, DOI:10.3970/sdhm.2005.001.171

Abstract Fatigue life of curved structural joints in ship structures under constant amplitude cyclic loading has been studied in this research. A new approach for the simulation of fatigue crack growth in welded joints has been developed and the concept has been applied to welded curved butt-joints. The phenomena of crack propagation and interface debonding can be regarded as the formation of new surfaces. Thus, it is possible to model these problems by introducing the mechanism of surface formation. In the proposed method, the formation of new surface is represented by interface element based on the… More >

G.S. Palani¹, Nagesh R. Iyer¹, B. Dattaguru²

Structural Durability & Health Monitoring, Vol.1, No.2, pp. 107-120, 2005, DOI:10.3970/sdhm.2005.001.107

Abstract A posteriori error estimation and adaptive refinement technique for 2-D/3-D crack problems is the state-of-the-art. In this paper a new a posteriori error estimator based on strain energy release rate (SERR) or stress intensity factor (SIF) at the crack tip region has been proposed and used along with the stress based error estimator for reliable fracture analysis of 2-D crack problems. The proposed a posteriori error estimator is called the K-S error estimator. Further, h-adaptive mesh refinement strategy which can be used with K-S error estimator has been proposed for fracture analysis of 2-D crack problems. The performance More >

S. N. Atluri¹

Structural Durability & Health Monitoring, Vol.1, No.1, pp. 1-20, 2005, DOI:10.3970/sdhm.2005.001.001

Abstract The solution of three-dimensional cracks (arbitrary surfaces of discontinuity) in solids and structures is considered. The BEM, developed based on the symmetric Galerkin BIEs, is used for obtaining the fracture solutions at the arbitrary crack-front. The finite element method is used to model the uncracked global (built-up) structure for obtaining the stresses in an otherwise uncracked body. The solution for the cracked structural component is obtained in an iteration procedure, which alternates between FEM solution for the uncracked body, and the SGBEM solution for the crack in the local finite-sized subdomain. In addition, some crack… More >

L. Nasdala¹, G. Ernst¹, M. Lengnick¹, H. Rothert¹

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.3, pp. 293-304, 2005, DOI:10.3970/cmes.2005.007.293

Abstract Like any other geometric structure or building, carbon nanotubes may break down due to either material failure or structural failure. In this paper, it is shown that the failure mechanism of carbon nanotubes not only depends on the type and direction of loading but also on the location and number of defects. For the finite element simulations we use a new 4-node finite element without rotational degrees of freedom based on the force field method. For the examples shown here, mainly a single-walled (10,10) armchair nanotube with different Stone-Wales defects, the material parameters are directly… More >