Development of a Life Assessment Method for Bonded and Weld-Bonded Automotive Structures

This paper gives an overview of an ongoing program of work aimed at developing a new life assessment methodology for bonded and weld bonded automotive structures. The approach involves the integration of three key requirements: environmental resistance, fatigue behavior in fracture mechanics terms and finite element analysis of joint design.

A relatively simple laboratory fatigue test, suitable for typical automotive sheet materials, has been developed to assess the interaction of fatigue loading with environmental effects. From this, data are derived to: (a) compare the effects of various environmental conditions on adhesive systems, and (b) provide fundamental fracture mechanics data that can be used in the analysis of structures. The required fracture mechanics parameters for structures are obtained using finite element analysis (FEA). Validation of the method has been carried out by correlating the measured fatigue life of model automotive structures with the predicted behavior.