考虑热-结构耦合关系下空间结构动力响应随机性分析

Randomness analysis for dynamic response of a space structure considering thermo-structural coupling

以空间薄壁圆管为研究对象,分析其在持续热流作用下并同时考虑热-结构耦合关系及参数具有随机性时的动力响应问题。为了便于分析由截面温差引起的热振动,将温度场分解为平均温度和扰动温度两部分,在此基础上建立了热-结构耦合动力学有限元模型,并采用时间域内温度场和动力响应交替迭代进行的近似计算方法,其中温度场的求解利用时间差分法和牛顿迭代法,动力响应则利用Newmark积分法。从各响应的求解迭代格式出发,分别使用矩法和随机因子法推导了温度场及动力响应的数字特征表达式,并通过各时间步内对温度场和动力响应的交替迭计算可求得整个时间域内的温度和动力响应均值与方差。最后以哈勃太空望远镜为算例考察了热-结构耦合对其悬臂薄壁圆管梁的热颤振影响以及参数的随机性对响应分散性的影响,并利用Monte-Carlo法验证了该方法的可行性。

The dynamic response of a space structure consisting of thin walled pipes subjected to solar heat flux was analyzed, and then this problem was extended taking thermo-structural coupling into account and the randomness of parameters. For analyzing thermal vibration due to temperature difference in its cross section conveniently, temperature field was divided into two parts including average temperature part and disturbance temperature one, then the dynamic model considering thermo-structural coupling was set up using the finite element method. The model was solved with the approximate calculation method through alternating iterations of temperature field and dynamic response in time domain. The temperature field was solved by using the method was obtained with Newmark integral method Starting of time difference and Newton-iteration, while the dynamic response from the solving iterative forms of each response, the computational expressions for the numerical characteristics of the temperature field and the dynamic response were derived, respectively, with the methods of moments and random factor. Through alternating iterative algorithms in each time step, the mean value and variance of the two responses in whole time domain were obtained. Finally, Hubble Space Telescope was taken as an example. Thermal flutter for a thin-walled cantilever beam due to thermo-structural coupling was showed, and the influence of the randomness of parameters on the dynamic response was also found. Monte Carlo method was used to validata the feasibility of the proposed method.