A study of cavitation instabilities in solids.

摘要

Cavitation instabilities in elastic-plastic solids under spherically-symmetric and axisymmetric loadings were investigated using the finite element method. Both quasi-static and dynamic analyses were used to solve these problems.; In the quasi-static analyses, we investigated a cavitation instability in elastic/perfectly-plastic, linear hardening elastic-plastic, power hardening elasticplastic, and constrained silver materials. Here, when the instability occurs, the cavity expands under no change in remote stresses and strains in all cases. In the case of axisymmetric loading on power hardening elastic-plastic material (ϵ_y = 0.003 and n = 0.25), we found good agreement between our FEA solution and the approximate solution (Hou and Abeyaretne, 1992) only when the remote field remained elastic. In the case of axisymmetric loading on constrained silver, we found good agreement between our FEA solution and the experimental results of Kassner et al. (1998). Moreover, a cavitation instability was found for stress ratios, σ₂/σ₁, beyond the range proposed by Kassner et al. (1998), i.e. as low as σ ₂/σ₁ = 0.5. Unfortunately, when the stress ratio was small, FEA simulations appeared to have difficulty determining the exact cavitation instability state because the mesh along the boundaries deteriorated very fast during the onset of instability.; In the dynamic analyses, we investigated cavity expansion in incompressible and elastic/perfectly-plastic materials. Both inertia and strain-rate hardening effects were considered. For dynamic loads below the critical load required for cavitation in the quasi-static case, the cavity expanded rapidly initially but eventually decelerated and stopped at a finite value. For dynamic loads above this critical value, the cavity expanded rapidly initially and then decelerated and settled into expansion at a constant rate. This observation held for both sphericallysymmetric and axisymmetric loading.