Prediction of Force-Displacement Relation of Stamped Spring of Copper-based Materials

The reliability of connectors depends on contact force, generated by the spring in terminals of connectors. The springs are commonly formed by stamping from a sheet of the spring material. Therefore, prediction of its force-displacement relation by finite element (FE) simulation is very important for design of terminals. For the simulation, an accurate model of stress-strain (s-s) responses of the material is required. When the material is deformed in forward and following reverse directions, almost all the spring materials show different s-s responses between the two directions, due to the Bauschinger effect. Therefore, contact force-displacement relation cannot be predicted by FE simulation using the linear elastic model, in which the Bauschinger effect is not considered. The authors reported that the mathematical description of s-s responses by Yoshida-Uemori (YU) model had high capability of describing actual s-s responses and of predicting spring shapes after stamping. In this paper, the FE simulation of the spring deformation, using YU model, will be presented. The simulated force-displacement relations of the springs are in good agreement with the corresponding experimental results. Therefore the FE simulation of the stamping process and spring deformation, using YU model, is recommended for the more accurate prediction of force-displacement relation of the spring.