Abstract
Fatigue damage accumulation theory is one of the core contents in structure fatigue strength design and life prediction. Among them, the nonlinear damage model can overcome the shortcomings of the linear damage model, which takes the loading sequence effect into account. Besides, the loading interaction cannot be ignored for its profound influence in damage accumulation behavior. In the paper, some commonly-used methods of the linear and nonlinear fatigue damage accumulation theory are investigated. In particular, a modified nonlinear fatigue damage accumulation model which considers the effects of loading sequences as well as loading interactions on fatigue life is developed, and a load interaction parameter is obtained by analyzing damage models which assumes that the load logarithm ratio between adjacent stress levels can characterize this phenomenon. Finally, the modified model is employed to predict the fatigue life of high pressure turbine disc. Moreover, comparison is made between the experimental data as well as the predicted lives using the Miner’s rule, the Ye’s model, and the modified model.
Highlights
Most of the mechanical components are subjected to variable amplitude loadings, i.e., the peak-to-valley values of the loading varies with time
The loading changes are very complex in the actual project, and other deterministic methods require a large number of test results to fit relevant parameters, and their prediction accuracy are generally lower than the Miner rule, the application of linear damage accumulation model is still in common use nowadays [13,14,15]
Nonlinear Fatigue Damage Accumulation Theory Based on Damage Curve Method: The definition of damage nonlinearity was first proposed by Marco and Starkey, which assumed that the damage shows an exponential relation of the cycle ratio, its expression is given as [26]: n where xi is a material parameter related to ith loading level
Summary
Most of the mechanical components are subjected to variable amplitude loadings, i.e., the peak-to-valley values of the loading varies with time. A large amount of test data has been accumulated so that the life data under constant loading can be converted equivalently by employing the fatigue damage accumulation theory, the fatigue life of structures under variable amplitude loading can be evaluated. Based on vast experiments and theoretical analysis, researchers proposed a variety of damage accumulation models. In order to overcome the abovementioned shortcomings, researchers have proposed some nonlinear fatigue accumulative damage theories. The fatigue damage accumulation theory is the core content of structural anti-fatigue design and life prediction. It is very important to study the fatigue damage accumulation theory. A modified nonlinear fatigue damage accumulation model considering load interaction effects is developed
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