Prediction of fracture generated by elastic recoveries of tools in multi-level powder compaction using finite element simulation

Fracture initiated in a compact by the difference between the amounts of el astic recovery of tools during the unloading process of multi-level powder compaction is predicted from calculated results by finite element simulatio n. The loading and unloading processes in the compaction are simulated by t he rigid-plastic and elastic finite element methods, respectively, In these simulations, elastic tools are modelled as springs connected with the noda l points on the interfaces between the powder material and tools. This mode lling leads to simple treatment of coupling of the tools and compact. The i nitiation of fracture is evaluated from the maximum principal stress, and t he critical stress is measured by means of bending and shearing tests. Two- level compaction operations are simulated by the finite element methods to predict the initiation of fracture. The predicted critical values of relati ve density for the occurrence of fracture are in good agreement with the ex perimental ones for iron powder compacts. (C) 1999 Elsevier Science Ltd. Al l rights reserved.