Abstract
Spot-welded joints are widely used in the construction of vehicle structures and frequently become critical locations for fatigue failure. Hence, it is essential to have reliable fatigue life prediction method for the spot-welded joints during vehicle structure design. In this paper, a new notch stress approach is developed for fatigue life prediction of the spot-welded joints. Currently, structural stress methods are widely used in automotive industry for fatigue life prediction of spot-welded joints. However, these methods are not well considering local geometry information. This paper introduces a notch stress based method to overcome the limitation of the structural stress methods. In the notch stress method, stress concentration factors for spot-welded joints are calculated from stress intensity factor equations. Then, the notch stress method is validated with fatigue test results of lap-shear and coach peel specimens.
Highlights
Spot-welded joints in thin-sheet materials are a common joining method in the structural components of automobiles: car body, chassis components, truck cab, and van box
Since about 90% of cracks occurrent in car bodies in service are originated from spot-welded joints [1], the evaluation methods of fatigue failure of spot-welded joints are very important during vehicle structure design processes
It is known that the notch stress is directly related to the stress intensity factors (SIF) around the crack tip
Summary
Spot-welded joints in thin-sheet materials are a common joining method in the structural components of automobiles: car body, chassis components, truck cab, and van box. Many researchers [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19] had proposed the fatigue life prediction methods for spot-welded joints It is a very well-known factor that stress values in finite element analysis (FEA) depend on the mesh sizes. Structural stress approaches [2,3,4,5,6,7,8,9,10,11,12] were introduced to predict fatigue life of spot-welded joints These methods calculate the stress at/around the spot-welded joints from the forces and moments obtained from coarse-meshed FEA. The notch stress approach showed better correlation without any adjustment of empirical parameters
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