Abstract: Thermal load, acoustic load, vibration load and other load, may result in producing nonlinear large-winding dynamic response and high-cycle fatigue damage of the high-speed aircraft thin-wall structure under the impact of high-speed airflow. Thermoacoustic fatigue experiment of GH188 board fixed thin-walled was carried out in the high-temperature traveling wave tube, and the frequency response, dynamic stress and possible dangerous position and fatigue life were obtained under different temperatures and acoustic loads. According to the coupled FEM/BEM method, the nonlinear response of the thin-walled structure is numerically simulated. The improved rainflow counting method and the theory of Miner liner fatigue accumulative damage are used to estimate the fatigue life of the structure. Compared with the test results， the frequency response error is within 1%, the fundamental frequency stress response error is 1%~3%, and the life value is about 3 times, which verifies the validity of the thermoacoustic fatigue life prediction. Then the thermal-vibration characteristics of the thin-walled structure are analyzed. It is found that under the acoustic load and random vibration load, the fundamental frequency response plays a leading role, and the change trend is similar. When the fundamental frequency dynamic stress level is the same, and the fundamental frequency is studied in the vicinity of fatigue life, thermal shock test can be used instead of thermoacoustic test. When the frequency is wider, the thermal fatigue life is significantly lower than the thermoacoustic fatigue life.

Key words: Thin-walled plates;Thermoacoustic fatigue;Thermal vibration fatigue;Experimental verification

摘要： 高速飞行器薄壁结构在高速气流冲击下，产生的热载荷、声载荷、随机振动载荷会使结构产生非线性大绕度动力学响应和高周疲劳破坏。对3组一端固支GH188薄壁板开展行波管热声疲劳试验，研究了温度和声压级对薄壁板的响应及寿命的影响，得到在热声载荷下薄壁结构的频率和动应力响应以及可能产生破坏的危险位置和疲劳寿命。根据耦合的有限元/边界元法对薄壁结构的非线性响应进行数值仿真，采用改进的雨流计数法和Morrow平均应力模型预估结构的疲劳寿命，与试验结果对比：频率响应误差在1%以内，基频应力响应误差在1%~3%，寿命值在3倍左右，验证了热声疲劳寿命预估模型的有效性。随后分析了薄壁结构的热振特性，分析发现：在声载荷和随机振动载荷下，结果基频响应起主导作用，且变化趋势相似，当基频动应力水平相同且主要研究基频附近疲劳寿命时，可用热振试验代替热声试验；当频率较宽时，热振疲劳寿命明显低于热声疲劳寿命。

关键词: 薄壁板;热声疲劳;热振疲劳;试验验证