摘要
分析了大型空间结构密集频率产生的问题，指出了传统模态分析所用矩阵摄动法的缺陷，提出了一种新的密集模态平均化摄动法．算例表明本文方法正确有效、精度较高，具有实用价值．
In engineering design ) we often try to avoid but still meet structures with close frequencies. When such design calls for small changes, we in P. R. China need a simple method thatrequires only standard software for quickly modifying dynamic characteristics. We now present such a method.Our perturbation method is simpler than that of Chen et al [2] in that close frequenciesare averaged and treated as repeated frequencies. Mathematically, averaging is done with eq.(7). For repeated frequencies, standard softwares can be u'sed in conjunction with eqs. (14)and (15). We take a simple example. Its six frequencies and corresponding modes are given inTable 1. λ5and λ6 are close frequencies. Tables 2, 3, and 4 are for three different perturbation conditions with perturbation increasing from condition Ⅰ to condition Ⅲ, correspondingto increasing changes in design. In Tables 2, 3, and 4, the left two columns give relSults obtainable with method of Chen et al [2]. The center two columns give results obtained withtraditional perturbation method without giving special attention to close frequencies. Theright two columns give results obtained with our method. It can be seen that as perturbationgets larger, traditional method gives unsatisfsctory results, whereas the results of our simple method remains quite close to those obtainable with method of Chen et al [2].
出处
《西北工业大学学报》
EI
CAS
CSCD
北大核心
1996年第1期95-99,共5页
Journal of Northwestern Polytechnical University
基金
国家自然科学基金
航空自选课题
