基于随机激励的某机匣模态实验与分析

用模态实验的方法对某型飞机发动机机匣的模态参数进行了识别。考虑噪声对频响函数的影响,在功率谱分析时,导出了噪声影响情况下的功率谱表达式,利用这个表达式计算了频响函数并最终用来提取模态参数。引入预实验方法用于机匣模态参数的探测中,以确定机匣上各个测点和激振器激振点的合理布置。考虑到实际工作时的激励情况,在实验台上用白噪声随机激励来模拟环境激励,对机匣进行了模态实验。与计算模态相比,用实验模态方法提取模态参数,避免了复杂的有限元建模与仿真,并能用相干函数来检验测得的实验数据的有效性。实验模态分析表明,得到的模态参数对于进一步改进机匣设计、分析其振动、疲劳寿命特性等具有重要的意义。 

Modal Experiment and Analysis of an Engine Casing Based on Stochastic Excitation

An engine casing modal experiment and modal parameters extraction have been introduced in the paper.In the power spectrum analysis,the effect of noise was considered.Power spectrum expression mixed with noise was proposed,and it was used to calculate the power spectrum function and finally modal parameters were extracted.The pre-experiment was introduced to determine the approximate scope of the modal frequency,so that we could determine the locations of transducers and excitation point of the vibro-machine.Considering the practical working condition,the white-noise stochastic excitation has been used to simulate the stochastic excitation during the modal experiment.Compared with the computational model,the means of extracting parameter with modal experiment can avoid complicated finite element modeling and simulation.Correlation function was used to checkout the reliability of the experimental data.Modal experiment shows that the parameters of the engine casing are of great importance in improving the structural design of the engine casing,vibration fault analysis,and fatigue life analysis and so on.