W. Brocks¹, I. Scheider¹

Structural Durability & Health Monitoring, Vol.3, No.2, pp. 69-80, 2007, DOI:10.3970/sdhm.2007.003.069

Abstract Cohesive models are used for numerical crack extension analyses in order to predict the mechanical behavior of structures in cases of crack path bifurcation. Possible applications range from the macroscopic to the microscopic scale. As an example of applications to macroscopic engineering structures, simulations of a stiffened cylindrical shell under internal pressure are presented, where a skin crack may penetrate the rib or deviate. On the micro-scale, unit-cell calculation for a fiber-reinforced material is performed, where the fiber may debond or break. More >

T. Nishioka¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.3, pp. 105-112, 2007, DOI:10.3970/icces.2007.001.105

Abstract This paper summarizes recent discovery for the Governing Condition of Dynamic Crack Bifurcation Phenomena, which were found by the author's laboratory. 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 >

X.G. Yuan^1,2, R.J. Zhang²

CMC-Computers, Materials & Continua, Vol.2, No.3, pp. 201-212, 2005, DOI:10.3970/cmc.2005.002.201

Abstract Cavity formation and growth in a class of incompressible transversely isotropic nonlinearly elastic solid spheres are described as a bifurcation problem, for which the strain energy density is expressed as a nonlinear function of the invariants of the right Cauchy-Green deformation tensor. A bifurcation equation that describes cavity formation and growth is obtained. Some interesting qualitative properties of the bifurcation equation are presented. In particular, cavitated bifurcation is examined for a solid sphere composed of an incompressible anisotropic Gent-Thomas material model with a transversely isotropy about the radial direction. The effect of constitutive parameters on… More >

S. Tchouikov¹, T. Nishioka¹, T. Fujimoto¹

CMC-Computers, Materials & Continua, Vol.1, No.2, pp. 191-204, 2004, DOI:10.3970/cmc.2004.001.191

Abstract Phenomena of dynamic crack branching are investigated numerically from a macroscopic point of view. Repetitive branching phenomena, interaction of cracks after bifurcation and their stability, bifurcation into two and three branches were the objectives of this research. For the analysis of dynamic crack branching, recently we developed moving finite element method based on Delaunay automatic triangulation [Nishioka, Furutuka, Tchouikov and Fujimoto (2002)]. In this study this method was extended to be applicable for complicated crack branching phenomena, such as bifurcation of the propagating crack into more than two branches, multiple crack bifurcation and so on. More >

T. Nishioka¹, J. Furutuka¹, S. Tchouikov¹, T. Fujimoto¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.1, pp. 129-146, 2002, DOI:10.3970/cmes.2002.003.129

Abstract The governing condition of dynamic crack bifurcation phenomena had not been fully elucidated until our recent experimental studies. We found from the experimental results that the energy flux per unit time into a propagating crack tip or into a fracture process zone governs the crack bifurcation. Regarding the numerical simulation of dynamic crack bifurcation, to the authors' knowledge, no accurate simulations have been carried out, due to several unresolved difficulties. In order to overcome the difficulties, for the analysis of dynamic crack bifurcation, we developed a moving finite element method based on Delaunay automatic triangulation. More >

K.Yu. Volokh¹

CMES-Computer Modeling in Engineering & Sciences, Vol.2, No.3, pp. 389-400, 2001, DOI:10.3970/cmes.2001.002.389

Abstract A computational framework is described for modeling pin-jointed structures comprising unilateral cable members and slender struts. The deep postbuckling behavior of struts is considered by means of 'elastica' analytical approximation. Prestressing is allowed. The proposed approach is incorporated into equilibrium path following procedures and illustrated in numerical examples. More >

A. Le van¹, P. Le Grognec¹

CMES-Computer Modeling in Engineering & Sciences, Vol.2, No.1, pp. 63-72, 2001, DOI:10.3970/cmes.2001.002.063

Abstract Necking is a bifurcation phenomenon observed in round bars under tensile loading and has been investigated in numbers of papers. In the present work, it is modeled within the framework of finite rate-independent plasticity. The theory is based on thermodynamic foundations developed for standard materials and results in a total Lagrangian formulation for finite plasticity, where the total strain is decomposed additively according to [Green and Nagdhi 1965)] and the hardening is characterized by a nonlinear isotropic hardening law of the saturation type.
The discretization and consistent linearization of the elastic-plastic equation set using the More >