Multiaxial Fatigue Analysis in a High-speed Microgenerator Rotor Shaft

Fatigue evaluation is one of the most concerning issue in the design of mechanical parts subject to alternative forces. Fatigue life estimation is more complicated when loads act on different axes. This paper shows the stress analysis result of the steel shaft of a high-speed microgenerator rotor with 47750 rpm and 100kW which has been carried out with analytical stress formulation. The shaft is subjected to alternative torsional and bending stresses. First, Mean and alternative components of stresses have been calculated; then, using a MATLAB code, multiaxial fatigue life has been calculated with equivalent static yield criteria and Sines method. Having considered five potential critical points on the shaft, fatigue life calculation is done in each critical point. Using different criteria, it is possible to compare results and decide about the fatigue strength of different sections. Consideration of the mean and alternative stresses effects with different axes is the major attempt in this paper.