Finite element simulation of the Portevin-LeChatelier effect

The phenomenon of the Portevin-LeChatelier effect is described on the basis of a constitutive model of dynamic strain ageing, which was implemented in three-dimensional finite element analysis. The simulation of the deformation behaviour of Al–Cu alloys is performed, using the constitutive parameters as required by the model. The simulations confirm the occurrence of propagative zones of localized deformation bands and provide insight into the strain rate distribution in the zones, characterized by a sharp strain rate peak. The influence of the applied strain rate on the localized deformation behaviour of a plane specimen is also analysed and the resulting stress–strain curves are calculated for each case. It is found, that the higher the applied strain rate, the faster the deformation band propagation and the smaller the amplitude of the stress–strain serrations. It is observed that macrosteps on the stress–strain curve match the reflection of the band at a specimen end. The propagative deformation bands in flat strip specimens are inclined with respect to the tensile axis from 45° to 53°, which is in good agreement with experimental findings.