Dynamic Explicit Cell Model Simulations in Porous Ductile Metals

The problem of ductile fracture is a complex phenomenon due to various factors such as inelastic behaviour, large deformations, stress gradient ... and has received considerable attention in recent years. For example, the occurrence of ductile fracture by hole growth and coalescence is the limiting factor in many metal-forming operations and consequently the ability to predict ductile fracture would allow modification of a production process and so to reduce the risk of failure occurring. Detailed micro-mechanical analysis for characteristic cell unit models with known porosity have been an important tool in the understanding of the influence of porosity in ductile materials. Indeed, cell models are usually considered as a structure in microscale within the material and the solutions obtained for the cell model can be used to rationally link microscopic properties and mesoscopic quantities. This approach allows to set up a general macroscale constitutive law for a damaged material in the frame of continuum mechanics. In this context, detailed cell model studies available in literature have ascertained that dilatant plasticity model particularly suitable to model porous ductile metals are the well-known micromechanically based model proposed by Gurson [

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] and phenomenologically extended by Tvergaard and Needleman [

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] [

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].