模态综合法计算双转子临界转速研究

Study of Twin-Rotor Critical Speed by Mode Synthesis

采用模态综合法计算了双转子临界转速 ,子结构模态由传递矩阵法求得 ,并着重研究了对接条件、模态数及子振形拟合多项式等因素对双转子临界转速影响。改进了双转子临界转速传递矩阵法并以传递矩阵法算得系统临界转速为准 ,评定了各种条件下模态综合法的计算精度。结果表明 :取一阶为平动模态 ,其余模态由传递矩阵法求得 ,拆分为子系统时采用自由子系统法 ,采用位移协调对接条件、子振形取 4次拟合多项式、仅取 4阶模态求得了具有一定精度的 1～ 3阶临界转速。

Twin rotor critical speed is calculated by mode synthesis, the mode of sub structure is obtained by using transmission matrix method (TMM). It is important to study the influence of abutting joint condition, the number of mode and sub vibration type fit quantic on twin rotor critical speed, the result of TMM is used to judge the calculation precision of mode synthesis in all conditions. Results show that one order mode is translation mode, and other modes were obtained by TMM. Sub system is divided by free sub system method. The first three order critical speeds were calculated by using displacement harmonization abutting joint condition, sub vibration type with four order fit quantic and four order modes. Some instructive conclusions are obtained in developing mode synthesis.