激励频段对航天器随机振动载荷的影响

在航天器随机振动等效准静态载荷计算中,高频因对随机振动载荷的贡献较小而可以被截去,但目前截止频率的选择还未有完全确定。为确定随机振动环境下的计算频段,文章设计了不同动态特性的组件进行不同截止频率的随机振动试验,并根据试验数据分析研究了不同特性组件在不同振动频段下应变的变化规律。研究结果认为,对于一般组件,随机振动的计算截止频率可取为组件主频率的1.5倍。针对非均匀输入加速度谱的随机振动载荷计算问题,文章提出分频段的分析方法。按3个基本频段计算随机振动载荷,分析得到了不同频段对总随机振动载荷贡献大小和规律,以及截止频率误差的影响因素和影响大小。算例表明,分频段法可以用于不同状态输入加速度谱的随机振动载荷计算。

The influence of frequency on the random vibration load of spacecraft

For the quasi-static load computation of spacecraft under random vibration environment, the part of high frequencies contributes little to the random vibration load and could be cut off in computations. However, the selection of the cut-off frequency has to be determined. For that purpose, the assemblies with different dynamic characteristics are designed, and the random vibration tests are carried out on the assemblies with different cut-off frequencies. Based on the test data, the variations of the strain of the assemblies in different excitation frequency bands are analyzed. It is shown that, for general assemblies, the cut-off computation frequency is supposed to be 1.5 times of the main frequency of the assembly. For the uneven acceleration power spectrum input, we have no direct computation method, therefore, the frequency band method is proposed to calculate the random vibration load, and the contributions from different frequencies are analyzed, to determine the influencing factors of the cut-off frequency. The computation example indicates that the frequency band method could be used to correctly calculate the random vibration load.