Considering that there are clearances between the gimbal mount assembly and cross shaft of engine, contact must be defined to simulate these non-linear behaviors in the simulation analysis. However, these non-linear behaviors will be ignored automatically when modal analysis is performed with finite elements software ABAQUS. If the contact is replaced by coupling constraints, the calculated results are not always perfect. Transient dynamic analysis is used to compute the displacement response of engine in time domain about the structure of engine with clearances in this paper. Then we can find the natural frequencies based on the peak of frequency-response curves obtained by fourier transform. We can also find the modes of vibration corresponding to natural frequencies according to the output of key points of the rocked engine.%考虑到火箭发动机常平座轴承与十字轴之间存在间隙,在仿真分析中,必须定义接触来模拟这些非线性行为,而有限元软件ABAQUS在进行模态分析时,会自动忽略非线性行为,如果用耦合约束代替接触,计算得到的结果往往不理想.针对发动机存在的这种间隙结构,采用瞬态动力学方法,计算发动机在时域上的位移响应,通过傅里叶变换给出频域内的频响函数曲线,根据峰值频率从而确定固有频率,输出整机结构的关键点,得到固有频率相对应的振型.
展开▼
