The chassis frame generally consists of side members, cross beams, and several mounting brackets. Strength and fatigue behaviors of welded joints between members and brackets in a frame are a very complex phenomena, which comes basically due to the structural geometry, non-homogeneous material, and welding residual stresses. Therefore, the prediction of fatigue life for the welded structure is very difficult compared to that for the simple geometry. This paper presents the structural and fatigue analysis results for a body frame and welded joints under system durability loads. In order to fatigue assessment of welded joints, local stress approach is used for its simplicity, which is based on the several empirical S-N curves that are associated with welded joint types and loading modes. The estimated fatigue cycles of the welded areas in a frame were satisfied the target cycles under system load conditions.

• 최복록(Member, Dept. of Mechanical Eng., Gangneung-Wonju National Univ.) | B. L. CHOI Corresponding Author