Vibration response experimental verification and fatigue analysis of thinwalled structures to thermalacoustic loads

Metallic thinwalled structure under thermalacoustic environment shows complex nonlinear vibration response characteristics of large deflection, affecting fatigue performances and life of structure. Thermalacoustic responses of superalloy thinwalled rectangular plates with four edges clamped were calculated by combining finite element method and reduced order modal method. Research showed that buckling structures could exhibit snapthrough motions which were decided by relative strength between thermal loads and acoustic loads, and stress cycle showed a triangular distribution. The Miner linear accumulative damage theory was employed in conjunction with improved rain flow counting method and Morrow mean stress model to calculate thermalacoustic fatigue life. From prebuckling to critical buckling, the damage level of stress cycle increased significantly from 10-5 to 10-4, and with the increase of temperature, the fatigue life showed a trend of decrease at first and then increase. The thermalacoustic experiment of thinwalled structure was carried out to make a comparison between the results of simulation and experiment. Results showed that the deviation of structural modal frequencies was less than 1Hz, and strain responses of calculation and experiment results had a good alignment, validating the effectiveness of calculation method and model to thermalacoustic responses.