On the elastic-plastic behaviors of centrifugal steam compressor impeller under cyclic thermomechanical loading

In this paper, the cyclic elastic-plastic behaviors of the centrifugal steam compressor impeller (CSCI) structure under practical operating conditions are discussed employing the linear matching method (LMM). The three-stage strategy of the LMM is employed to determine the shakedown and ratchet boundaries by conducting a series of iterative direct steady cyclic analysis, and based on this, the load regions corresponding to different types of damage behavior that may occur during the operation are identified. Computational results reveal slight contraction in the structural response diagram when considering actual material constitutive relationships, compared to ideal elastic-plastic models. Meanwhile, by integrating the unified ratchet and fatigue program with fatigue experimental data, a series of constant low-cycle fatigue life curves has been presented for different service conditions. Furthermore, a comparison with detailed step-by-step inelastic analyses confirms the applicability and great efficiency of the LMM in practical engineering problems. The cyclic elastic-plastic behavior of impeller were investigated using the three-stage procedure. The effect of temperature-dependent and strain hardening on structural response of impeller were evaluated. The constant low-cycle life fatigue curves of the impeller structure were generated. The applicability and great efficiency of linear matching method have been confirmed.