中文摘要：

目的提高大型复杂结构动力学参数修改的准确性和效率。方法以某大功率发动机的缸盖为对象,首先以实测的固有频率为基准,通过比较有限元计算的固有频率和实测频率,找出误差较大的频率项,接着通过灵敏度分析法找出对该频率较敏感的参数,最后用设计参数修改方法对该参数进行优化设计和修正。结果经过动力学修改后的缸盖的固有频率计算值更接近于试验值,能够满足工程使用要求。结论结合设计参数法和灵敏度分析法修改后的有限元模型能够比较准确地反映结构的动态特性,可提高结构动力学修改的效率。

英文摘要：

The work aims to improve the accuracy and efficiency of dynamic modifications for large complex structures. With the high-power engine cylinder head as an object, first of all, on the basis of the measured natural frequency and by comparing the natural frequency and the measured frequency calculated in finite element method, the frequency with bigger error was found out, and then the sensitive parameters of the frequency were discovered through the sensitivity analysis. Finally, the parameters were optimally designed and modified in design parameter modification method. The calculated value of natural frequency of the cylinder head subject to dynamic modification was closer to the test value and could satisfy the using requirements of the project. The modified finite element model combined with design parameter method and sensitivity analysis method can more accurately reflect the dynamic characteristics of the structure, which can improve the efficiency of the structural dynamic modification.