On Damage Failure and Erosion Modelling and Simulation in Dynamics: the Bounded Rate Constitutive Model Concept

Abstract eng:
In today industrial environment, due to the lack of robustness of failure model, important numerical parameters such as the mesh density are fixed in order to calibrate the model with respect to some reference test. Industries involved in such calculations are more and more aware of the problem and seek for adapted solutions. This fundamental problem has been studied since more of thirty years now and is well understood and analyzed. The more widespread approach to overcome the lack of consistency of material model with respect to failure is the one of non-local approach. A huge literature has been devoted to non-local model with variants from non-local integral approaches to explicit and implicit gradient approaches or Cosserat models [1]. Despite of all this studies the development of these approaches in an industrial context is still seldom. The main reason is probably the fact that non-locality implies many and non-obvious code developments, identification practices are also an issue. That is why we have sought for another, even if maybe less general, possibility, to overcome the difficulty, the use of rate dependent models. Needleman was possibly the first to discuss how, in statics, the use of viscosity can help to conserve the elliptic property of the incremental equilibrium equations and, thus, eliminate pathological mesh-sensitivity [2]. For example a rate-dependent model of the Johnson-Cook type has been carefully studied in [3] and it is conclude that spurious localization is not circumvent. That is why we have proposed in [4] the concept of bounded damage rate model, which has been extended latter for other type of phenomenon such as ductile failure. A physical interpretation of the model is that a continuous damage variable results from a complex averaging process of micro flaws each of which having a finite propagation velocity, leading thus to a bounded damage rate. After a short analysis of the problem several examples will serve to illustrate the main property of bounded rate dependent model and their identification: (i) ductile failure of metallic material, (ii) dynamic delamination[5], failure and erosion of laminates submitted to high velocity impact.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket