FINITE ELEMENT SIMULATION OF THE SIEBEL- SCHWAIGERER TENSILE TEST

Abstract

If the flow curve is only to be determined for low strains, the tensile test is normally preferred because of its simplicity and also because, for this experiment, the conditions of testing have been defined by standards. Numerical simulation of great deformations and high strains including the moment of fracture is a very complex task regardless of which sort of criteria is chosen for convergence. As the calculation is done according to individual nodes and the elements are connected through these nodes, at a certain point some nodes have too high stress and that means that the fracture occurs. In fact, that is the beginning of a micro crevice that develops into a macro crevice and by further propagation the fracture spreads over the whole cross section. At the same time, one node is common to several different elements and without it further calculation is no longer possible. To overcome that, so as to properly exclude not only one or several nodes but also certain elements, and at the same time to insure further calculation without them, i.e. to make numerical simulation possible, is a very demanding undertaking, and commercial software even with a great number of subroutines cannot solve such a task without many interventions and with unpredictable results. This paper presents numerous experimental results and 2D as well as 3D simulation of tensile tests including the moment of fracture, and a comparison between these results for one sort of aluminium alloy using MARC/Mentat commercial software that enables intervention in the program and the creation of its own subroutines based on experimental data and mathematical interpretation of such a complex problem.