阶跃激励下网架结构的动力响应扩展及其误差分析

Dynamic response expansion and its error analysis of space truss structures under step excitation

为了增加单次动力测试的可用测试信息,提出一种考虑阶跃激励作用的网架结构动力响应扩展方法。由阶跃激励引起的结构自由振动响应在任意时刻均可近似表达为少数贡献模态的线性组合。在此基础上,构造一种优选测点位置的迭代策略,以无偏估计各个时刻的贡献模态组合系数(即广义坐标),从而实现动力响应由少数测点向全自由度空间的扩展。解释了动力响应扩展的误差机理,并提出一种相关系数指标来筛选高精度非测点。以某560杆的网架结构为例进行数值分析。结果表明,该方法能方便地实现网架结构的动力响应扩展,并筛选出较多数量的高精度非测点,有利于提高网架结构动力测试的效率。

Here,to increase available test information of single dynamic testing,a dynamic response expansion method of space truss structure under step excitation was proposed.Structural free vibration response caused by step excitation could be approximately expressed as a linear combination of a few contribution modes at any moment.On this basis,an iterative strategy for optimizing location of measuring points was constructed to unbiasedly estimate each contribution mode’s combination coefficient,i.e.,generalized coordinate at any moment,and realize dynamic response expansion from a few measuring points to the full DOF space.The error mechanism of dynamic response expansion was explained,and a correlation coefficient index was proposed to screen high-precision non-measuring points.A certain grid structure with 560 members was taken as an example to perform numerical analysis.The results showed that the proposed method can conveniently expand dynamic response of space truss structure,and select larger number of high-precision non-measuring points,so as to be beneficial to improve dynamic testing efficiency of space truss structure.