Motoharu Taneda

Crack Initiation and Extension under Penetration of Thin Metal Sheet.

Quasi-static and dynamic penetration tests were conducted using thin metal sheets of extra-super duralumin, corrosion-resistant aluminum alloy and cold-rolled carbon steel. The phenomenon before crack initiation differed from that after the initiation. Therefore, formulae for estimating the energy-absorbing capacity were proposed for before and after crack initiation. By comparing the estimated values with the experimental ones, it was clarified that the proposed formulae were valid for the assessment of the energy-absorbing capacity of a thin metal sheet under penetration.

A new iterative method for the elastic-plastic stress analysis by the finite element method.

This report proposes a new iterative method for the elastic-plastic stress analysis by the finite element method (FEM), of which scheme simultaneously satisfies the normality condition of plastic strain increments and two other conditions : the conditions that the stress point must move on the yield surface during plastic deformation and that the plastic strain increments relate to the hardening parameters. The combined hardening rule is used in this FEM program. In order to evaluate the accuracy and the computational time for the proposed new iterative method, we analyze an axisymmetric problem that is a round bar with a U groove loaded in the uni-axial direction. Good accuracy is obtained by using the incremental displacement (load) which produces the equivalent plastic strain increment within 0.01 in each step.