空载固体发动机计算与试验模态相关性分析

为了预测空载状态固体火箭发动机动态特性,对其进行了模态试验,并应用MSC.Marc进行了模态计算,然后对比两者的结果,进行了相关性分析和评估。计算得到了发动机250Hz以内的一阶弯曲模态和五阶呼吸模态。试验测得了发动机的三阶呼吸模态和一阶弯曲模态。比较试验测试模态和与之对应的计算模态:固有频率相对误差均在5%以内;振型相关图上的点大都分布在斜率为1(或 1)的直线周围;MAC(模态置信判据)值在0 9左右。说明计算与试验模态有较好的相关性,有限元计算模型比较准确的反映了实际情况。

Correlation between the finite element and testing modal analysis of solid rocket motor

In order to get the modal parameters of an unloaded solid rocket motor,FEM modal analysis with MSC Marc was compared with test modal analysis.Then,correlation between calculated values and measured values were studied.Below 250Hz,one bending mode and five breathing modes are found with FEM.The first bending mode and three breathing modes of computation show excellent agreement with the test results,except that the 3rd and 4th breathing mode were not found with test.The difference of between the test and FEM for all nature frequencies within 5%.Correlation of all mode shapes from test and their correspondent from FEM are evaluated and MAC values are about 0.9.It shows the calculated model can simulate the dynamic characters of actual motor well.