Abstract
A multi-particle finite-element method was proposed to study the elastic-plastic behaviour of ductile powders composed of highly deformable elastic-plastic particles. The focus was put on the study of the uniqueness of the direction of plastic strain increment vectors for a given stress state on the plastic limit, which was assessed using a spherical stress-probing method. Results revealed a non-uniqueness of the direction of plastic flow in a small region of the stress space located in the vicinity of the loading point. The direction of plastic flow was almost unique elsewhere on the plastic limit. The non-uniqueness was explained using a combination of two distinct mechanisms for plastic deformation involving two very different plastic limits.
Highlights
This paper is concerned with the mechanical behaviour of granular assemblies involving highly deformable elasticplastic particles
By studying the response of the numerical sample to such loading paths, insight is given on the mechanical behaviour of such materials
The results indicated a correlation between the nonuniqueness of the direction of plastic strain increments and the particular stress state corresponding to the loading point
Summary
This paper is concerned with the mechanical behaviour of granular assemblies involving highly deformable elasticplastic particles. There is a need for continuummechanics-based constitutive models which would be able to predict the evolution of stress and strain with a reasonable accuracy in localised high-shear zones where cracking is susceptible to happen. To this end, a numerical model involving an assembly of meshed spheres interacting through contact conditions is studied in the framework of the finite-element method; this approach will be named Multi-Particle Finite-Element Method (MPFEM) in the following. By studying the response of the numerical sample (which is considered as a model material for ductile powders) to such loading paths, insight is given on the mechanical behaviour of such materials
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