Discrete Element Modelling of the Unloading and Failure of Green Compacts

摘要

The modelling of powder processes needs to take into account the particulate nature of the materials involved. The Discrete Element Method (DEM) is well suited for such a task. It allows the behaviour of a set of particles to be calculated from the contact forces generated during the process. Theoretical progresses on contact laws and the increase in computing power allow practical situations in powder metallurgy to be tackled with DEM. We present simulations on the important problem of unloading after cold compaction. The elastic springback of unloaded compacts is calculated from the elastic and plastic properties of the particles and from their strain history. Following unloading, the failure of the green compact is considered. In particular the role of particle size on the strength of the compact is quantitatively assessed. The effect of the presence of hard (elastic) particles is also analysed in order to treat the case of composites.