Door Check Load Durability - Fatigue Life Prediction 2011-01-0790

This paper describes an analytical methodology for predicting the fatigue life of a door system for check load durability cycles. A check stop load durability cycle occurs when a customer opens the door beyond the door detent position with a force applied on the check link or hinge check stops. This method combines Finite Element Analysis (FEA) model and fatigue code to compute the durability requirements. The FEA model consists of Door-in-White (DIW) on body with integrated hinge check link or independent check link. Nonlinear material, geometric and parts contact were considered for the door with body-in-white (BIW). Several door hinge designs, with integrated and independent check links, were investigated. Using the Von Mises stress and plastic strain from the above analysis, the fatigue life was predicted and compared with the test data. Integrating FEA and fatigue allows predicting the threshold total strain value, which is developed, for check load durability requirements. The strain-life plots were developed for both car and track programs to be used at the early design stage to estimate the fatigue life of the structure. Various material hardening models were evaluated. The strain hardened-isotropic hardening and cyclic-combined hardening were compared. This method improves design cycle time and reduces the warranty by producing a product design that comprehends the fatigue damage resultant from the application of check stop load to the door structure.