Experimental and Simulated Springback after Stamping of Copper-Based Spring Materials

Abstract

The reliability of connector is depending on the contact force, generated by the spring in terminals of connectors. The springs are formed by stamping from a strip of spring material. Therefore, the prediction of its springback after stamping and force-displacement relation by the finite element (FE) simulation is important for the design of terminals. The mathematical model of stress-strain (s-s) responses of the materials is required for the simulation. When the materials are deformed in forward and the following reverse directions, almost all the spring materials show different s-s responses between the two directions, due to the Bauschinger effect. This phenomenon makes the simulation difficult because the s-s response depends on the prior deformation. The authors reported that s-s responses of copper-based spring materials under cyclic tension and compression deformations could be expressed accurately by the Yoshida-Uemori model, which is a constitutive model describing the Bauschinger effect. In this paper, experimental and simulated springback after stamping will be presented. The simulation results using Yoshida-Uemori model were good agreements with the experimental. The use of this model for the FE simulation would be recommended for the more accurate prediction of springback.