Research on Fatigue Life of Lifting Equipment Based on Nonlinear Cumulative Damage Theory

Abstract

Abstract. The lifting equipment is applied more and more extensively with the fast development of economy. The fatigue and safety problems of lifting equipment in service are more and more prominent. This paper presents a nonlinear fatigue damage and life assessment approach for existing lifting equipment and the nonlinear effects of the fatigue damage accumulation due to random dynamic stress spectrum. The stress spectrum monitoring data was analyzed by the modified four peak-valley values fast rain-flow counting method for fatigue analysis. By considering nonlinear effects, the calculation for cumulative damage and prediction for fatigue life of the lifting equipment's hot region were calculated based on the nonlinear damage theory and the nominal stress method. The predicted fatigue damages are different when using the linear and nonlinear fatigue damage rules. According to the engineering application results, the real crack generation time is consistent with that of our estimation method, which demonstrates that our nonlinear prediction model and method for fatigue life are effective. The nonlinear damage theory is recommended for use in fatigue and damage prediction of lifting equipment in service.