Effect of Impact Load-induced Stress on Fatigue Life of Structures

Generally, in structures, stresses induced by impact loads are observed to be significantly higher than those caused by static loads, thereby affecting their fatigue life. Considering a practical structure, namely a crane, this study employed finite element analysis to verify the increase in the stress due to impact loads and investigated the effect of this increased stress on the fatigue life of the structure. The fatigue life of the crane, with only the static loads considered was compared with that computed after incorporating the impact loads occurring during the lifting or lowering of loads by the crane. Even with a relatively small increase in the stress from the impact loads, a substantial reduction was confirmed in the fatigue life. Therefore, structures exposed to impact loads must be designed with careful consideration to ensure an adequate fatigue life.