Abstract
In this paper, fatigue life evaluation of spot-welded joint under two steps multi variable amplitude load was investigated. Fatigue tests under two steps multi variable amplitude load in combination with the loading below the fatigue limit and above it were carried out, using a single spot-welded tensile shear and peel, bend specimens. As a result, the loading below the fatigue limit contributes to the fatigue damage of the spot-welded joints under variable amplitude load. Also, modified Miner's rule using nominal structural stress - number of cycle to failure curve could systematically estimate the fatigue life of the spot-welded joint under variable amplitude load, regardless of the joint form and sheet thickness.
