月球探测器加速度响应预测的时域子结构方法

航天器结构的日益复杂和庞大为全系统级的动力学仿真带来了更大的困难和挑战,目前主要采用动态子结构法来提高分析求解效率,并解决不同设计部门之间的模型共享和技术保护问题。月球探测器软着陆阶段的冲击力学环境一般由加速度冲击响应谱描述,由于高阶振型对结构加速度响应的影响要比对位移响应的影响大得多,所以在小阻尼情况下,经典的基于模态的子结构方法在相同截断频率下对加速度响应的预测精度远低于位移响应。为解决这一问题,引进基于脉冲响应函数的时域子结构(IBS)方法,提出了一种适用于预测加速度响应的降阶形式的迭代求解格式。利用探测器着陆数值模拟试验中测得的缓冲机构作用力作为激励,分别采用固定界面模态综合(CB)法和IBS方法分析了月球探测器的加速度响应。数值算例表明,后者在计算精度和求解效率方面均高于前者,并说明基于脉冲响应函数的子结构方法适于对月球探测器加速度响应进行高精度快速预测。

Acceleration response prediction for lunar lander using time-domain substructure methods

The remarkable increase in the complexity and size of spacecraft has inflicted unprecedented difficulties and challenges on system level dynamics simulation. At present, dynamic substructure method is mainly adopted to improve the solution efficiency and protect the proprietary technologies in model sharing among different project groups. The acceleration shock response spectrum is commonly used to describe the impact dynamic environment during the soft landing phase. It is acknowledged that the effects of high order modes on acceleration responses are more significant than those on displacement responses, so under the condition of small damping, the acceleration prediction accuracy is far lower than the prediction accuracy of displacement obtained by classical substructure methods based on modal with identical cut-off frequency. To solve this problem, a recently proposed novel method called impulse based substructuring (IBS) method is applied and its reduced-order form of iterative solution format used to predict acceleration is presented. Based on the buffer load measured from the soft landing numerical experiment, the acceleration response of the lunar lander is respectively calculated through the Craig-Bampton (CB) method and the IBS method. A numerical example shows that the IBS method has higher accuracy and efficiency than CB method, and it is suitable for rapid prediction for acceleration of the lunar lander with high accuracy.