On Reliability Evaluation of a Diaphragm in a Light Touch Switch( Reliability Engineering in Materials and Structures)

Abstract

Fatigue characteristics of a metal diaphragm in a light touch switch are evaluated with experimental approach considering cyclic load acting on it. The approach consumes much time and costs for evaluation. In previous paper, we have described that the mechanical properties of stainless steel have anisotropy and the fatigue characteristics must be discussed considering the large scatter of material properties induced by the anisotropy. Therefore, the purpose of this study is to establish a simple method to evaluate the reliability of diaphragms with the consideration of anisotropy. The proposed approach consists of three procedures. Firstly, residual stress after press forming is evaluated by finite element method (FEM), and response curves when the pushing load is applied on the diaphragm are also analyzed. And, the stress amplitude and the mean stress at every point on the diaphragm can be calculated. Secondly, the experimental database about S-N curve and Goodman diagram considering the effect of anisotropy have been prepared. Finally, the fatigue lives considering failure probabilities on the diaphragm can be estimated by comparison of Goodman diagram with numerical results. Obtained results revealed that the proposed approach is very useful for the reliability evaluation of the diaphragm.