Effect of Cracks on Dynamic Strain Reconstruction of Blades Under Multi-Mode Vibration

To investigate the influence of cracks on dynamic strain reconstruction of blades under multi-mode vibration,this study developed finite element models for cracked blades to conduct modal and transient analysis.It simulated a Blade Tip Timing (BTT) measurement system on the Simulink platform to acquire blade tip vibration displacement signals,and employed the least squares method to decouple the coupled displacement data.The study reconstructed full-field dynamic strain from the decoupled tip displacement using a displacement-strain transmissibility,and validated the proposed method under three crack location scenarios:blade tip,blade body,and blade root.Simulation results indicate that the strain correlation coefficient (SCE) between the reconstructed strain of healthy blades and finite element analysis results attains 0.996,while the SCE values for cracked blades range from 0.874 to 0.932,with all relative errors within acceptable limits.This study provides a reliable numerical simulation approach for dynamic characteristics analysis of cracked blades,offering significant engineering reference value for strain identification and vibration monitoring of aero-engine blades.