Seokbong Kim

Stress evaluation with numerical integration schemes in finite element analysis of elasto-plastic bending

The paper is concerned with evaluation of stress components in elasto-plastic bending for each increment step in finite element analysis using a four-node isoparameteric quadrilateral element. It demonstrates the effect of the integration scheme on the accuracy of a solution with stress evaluation. It is noted that conventional integration schemes cause inaccurate evaluation and oscillatory behaviour of stress components while a reduced integration scheme with hourglass control yields accurate evaluation. As a benchmark problem, elasto-plastic bending is investigated for calculation of the stress and strain. The results fully demonstrate that finite element simulation in the usual way is sometimes very dangerous since it could lead to a fatal pitfall and the selection of the integration scheme should be carefully done for specific problems.

Scale Effects of Warhead on Concrete Penetration

This paper deals with the scale effects of warhead on concrete penetration. We investigated the scale effects using finite element analysis and Young’s penetration equation. As the scale of penetration test decreases, the strain rate effects of target increases, and then strength of concrete target increases. This means the residual velocity and penetration depth of warhead decreases as the test model size decreases. Young’s penetration equations are transformed with various penetrator mass and scale cases as a function of scale ratio. Penetration distance and residual velocity are not simply changed by the geometric scaling law.

Optimum Finite Element for Simulation of Elasto-Plastic Bending of Sheet Metal

This paper concerns the optimum condition of finite elements in simulation of elasto-plastic bending. The effect of the integration scheme and the number of finite element layers on calculation of the stress and the strain is thoroughly investigated and some remedies are suggested. As a benchmark problem, an elasto-plastic bending problem is studied for the calculation of the stress and the strain. The calculation directly estimates stress and strain distribution along the thickness direction and shows the oscillatory behavior ol the stress and the incompatible behavior of the strain. The results tully demonstrate that the finite: element simulation in the usual way is sometimes very dangerous since it could lead to a fatal pitfall. This study proposes the optimum condition of finite elements especially in simulation of elasto-plastic bending with a proper integration scheme.