A multi-scale fatigue–creep coupled damage model for steel structures under extreme cyclic loading and temperature

In order to compute the process from the damage accumulation to failure of steel structures under extreme cyclic loading and temperature, a multi-scale fatigue–creep damage model has been developed. Based on the balance of micro-crack number density theory, the multi-scale fatigue damage model has been established using generalized self-consistent method. In the fatigue damage model, the scatter of micro-crack length is expressed by two-parameter Weibull distribution and the interaction among micro-cracks has been studied. In turn, the multi-scale fatigue–creep damage model has been developed by considering the nonlinear coupling of fatigue damage and creep damage. The validity of the developed model has been verified by comparing the predicted damage evolution curves with experimental damage data. The developed model enables to more accurately study the fatigue degradation of steel structures than the phenomenological damage models. Fatigue–creep damage analysis on steel turbine blades under different extreme operating condition are performed using the developed model.