模态选择方法及其在复杂结构振动分析中的应用

Modal Truncation Method and Its Application in Vibration Analysis of Complex Structures

为避免复杂结构动态分析中自由度数目多、求解困难的问题,运用模态分析方法求得结构的特征频率和振型,以结构各阶模态的DC增益作为模态价值的判定准则,对结构模态进行截断,实现模型降阶。利用缩减后的模态信息,建立起保持原系统主要特性的低阶状态空间模型。以某一型号塔吊为例,验证了以DC增益作为模态截断判据的有效性,为复杂结构的动态特性分析提供了一种可行的方法。

In order to avoid time consuming solution of equations in complex structure dynamics analysis,modal truncation method was studied herein. DC gains of the individual modes of vibration were used as the criterion of modal truncation, the relative importance of the contributions of each of the individual modes was obtained and a small state space model was defined. The reduced model can accurately describe the pertinent dynamics of original system. A tower crane was used as an example to demonstrate both the theories and the methods. The results show that it is a feasible method to establish theoretic models of complex structures which can then be used in frequency and transient analysis.