A study of bi-metal coins by the finite element method

A two-dimensional finite-element program, based on a rigid-plastic formulation has been used to simulate the joint of a bi-metal coin. Several geometric joint profiles have been analyzed and theoretical predictions of the joining load, the deformed grid patterns, the velocity field and the strain field are presented. The strength of the joint has been checked experimentally by measuring the separating load. Experiments have been performed on prototypes with different joint profiles in order to obtain the load necessary to separate the center of the coin from the outer ring. The results obtained have been compared with those found for two bi-metal coins currently produced, and show that the joint profiles proposed presently are suitable for industrial purposes.