Coupling analysis of vibration and crack propagation for a cracked beam at resonant state

As an exploration of damage tolerance lifetime analysis for a cracked stator blade, coupling effect of vibration and fatigue crack propagation for a cracked beam was studied by using contact FEM. Cracked beam is discretized by 2-D plane elements and stiffness changes of breathing crack during opening and closing process are described by contact model. The first resonant frequency was calculated by analytical method and transient response frequency sweeping. Linear fracture mechanics theory was used to calculate the stress intensity factor in vibration analysis. Two numerical examples were calculated to investigate coupling effects at resonant state: crack arrest problem and crack unstable propagation problem. The stability of crack propagation was predicted and crack propagation lifetime was calculated. Based on the Campbell diagram, the judgment of resonance was analyzed according to the conclusions from the numerical tests.