RESIDUAL LIFE OF TURBINE DISK WITH DAMAGE IN CRITICAL ZONE

摘要

This study is concerned with assessing the integrity of cracked steam turbine disk which operates under low-cycle conditions. Damage accumulation and growth for turbine disk took place on the slot fillets of the key. Full-size three-dimensional finite element (FE) stress-strain analysis of turbine disk is represented for different stages of lifetime under considering loading conditions. As a result accumulated damages in critical zones of turbine disk depending on time of loading are determined. The nonlinear fracture mechanics parameters that are found numerically are used to characterize the local stress-strain fields at any instant around the crack tip in the turbine disk subjected to biaxial cyclic loading. Elastic-plastic stress intensity factors are obtained for different forms and sizes of part-through quarter-elliptical cracks. Approximate estimations of residual life are presented for different stress-strain states of steam turbine disk in the operation.