薄壁圆管空间结构的热疲劳可靠性分析

针对薄壁圆管的空间结构，分析其在交变热载荷下的疲劳可靠性问题。为同时考虑由截面平均温度和截面温差造成的疲劳损伤，提出了综合利用剩余强度和疲劳累积损伤模型的分析方法。首先根据疲劳累积损伤相等原理，将截面温差造成的多级扰动应力载荷作用频次等效为平均温度下的常幅应力载荷作用次数，从而将两者产生的热应力载荷统一为一常幅载荷，再利用剩余强度模型基于动态应力-强度干涉理论对疲劳可靠度进行分析，得到了结构在综合考虑两种热疲劳状态下的动态可靠度。本方法可避免直接利用疲劳累积损伤理论临界损伤值难以确定的问题，且能体现金属疲劳损伤的真实情况。最后以哈勃望远镜为例，分析了其主梁随疲劳热载荷循环作用下的动态可靠度，得出了一些有意义的结论。

THERMAL FATIGUE RELIABILITY ANALYSIS FOR SPACE STRUCTURES COMPOSED OF THIN-WALLED TUBE

The fatigue reliability of space structures composed of thin-walled tube element has been analyzed under alternating thermal load. Taking into account the fatigue damage due to both average temperature and temperature difference in cross section, an analytical method is proposed by using the models of residual strength and fatigue cumulative damage. First of all, according to the principle of fatigue cumulative damage equal, the frequency of multi-level disturbance stress load caused by temperature difference in cross section is equivalent to the times of constant amplitude stress load action under average temperature, thus both thermal stress loads will be unified for a constant amplitude load, then fatigue reliability can be analyzed by applying the residual strength model based on the theory of dynamic stress-strength interference, finally, the dynamic reliability of the structure in the comprehensive consideration of both thermal fatigue state is obtained. This method not only avoids the direct use of the critical damage value of the cumulated fatigue damage theory which is difficult to determine the problem, but also reflect the real situation of fatigue damage of metal. In the end, take Hubble Space Telescope as an example ,the dynamic reliability of the main beam with the role of cycle fatigue thermal load is analyzed ,and some meaningful conclusions are drawed.