热声载荷作用下金属薄壁结构的振动响应与试验验证

Vibration responses analysis and experimental verification of metallic thin-walled structures to thermal-acoustic loadings

针对航空航天薄壁结构在热声载荷作用下的非线性振动响应问题,基于声振耦合理论,采用耦合的有限元/边界元法对四边固支高温合金矩形薄壁结构进行了动力学响应计算。重点研究了薄壁结构在行波加载与扩散场加载条件下的振动应力/应变响应规律,讨论了温升对结构振动响应的影响规律,分析了薄壁结构热屈曲(Thermal-buckling)和跳变(Snap-through)响应特性。通过将薄壁结构在不同温度条件下的振动模态以及动态应变响应的仿真结果与热环境下的声激振试验结果进行对比,表明计算的基频量值及随温度的变化关系与试验结果获得较好的一致性,计算的应变响应与试验测试结果量值相当,验证了热声响应计算方法与模型的有效性。该研究提出的金属薄壁结构在热声载荷作用下的非线性振动响应计算方法及分析结论对进一步开展热声疲劳寿命预测及动强度设计提供依据。

For nonlinear vibration response problems of aerospace thin-walled structures under thermal-acoustic excitations,based on the theory of structural-acoustic coupling,the coupled FEM/BEM method was used to calculate dynamic responses of super-alloy thin-wall rectangular plates with four edges clamped. This work mainly focused on the influence of progressive wave and diffused acoustic field on the vibration stress/strain responses of thin-walled structures.the effects of temperature rising on vibration responses of structures were discussed,and the characteristics of thermalbuckling and snap-through of thin-walled structures were analyzed. By comparing simulation results of vibration modals and dynamic strain responses of thin-walled structures in different temperatures with experimental results of thermalacoustic excitations,it shows that fundamental frequencies and changing trend with the increase of temperature of structures keep a preferable consistency with test results,and strain responses of calculation and experimental results have a good alignment,validating the effectiveness of calculation method and model to thermal-acoustic responses. The calculation method of thin-walled structures nonlinear vibration responses and analysis conclusions presented in this paper provide references to future thermal-acoustic fatigue life prediction and the dynamic strength design of thin-walled structures.