结构振动阻尼测试的衰减法研究

Decay method for measuring structural vibration damping

使用反向滤波、反向积分、能级平均等技术构建了衰减法阻尼测试的数据处理系统,研究了衰减法阻尼测试结果与统计能量分析意义下的频段阻尼之间的关系,探讨了频段外模态的阻尼对频段阻尼测试结果的影响,最后使用平板的瞬态冲击有限元仿真数据对相关结论进行了验证。研究表明:在所研究的频段内,当各模态的阻尼相差不大时,衰减法测试结果同统计能量分析意义下的频段阻尼一致,反之衰减法测试结果小于统计能量分析意义下的频段阻尼;当频段外含有阻尼较小的模态时,该模态对该频段的频段阻尼测试结果将产生较大的影响;如果各模态的模态阻尼随频率变化平缓,则各频段的频段阻尼测试结果较为准确,反之相关频段的频段阻尼测试结果误差较大。

The techniques of reverse filtering,backward integral and energy level average were used to build a damping measurement data processing system for the decay method.The relationship between the test results with the decay method and the frequency-band damping in the sense of statistical energy analysis was examined and the effect of modal damping outside the frequency band on the frequency-band damping test results was explored.At last,a plate＇s transient impact response data from finite element simulation were used to verify the relevant conclusions.It was shown that if the difference of modal dampings of modes in a frequency-band is small,the results with the decay method are close to the frequency-band damping in the sense of statistical energy analysis;otherwise,the results with the decay method are less than the frequency-band damping in the sense of statistical energy analysis;if there are modes with smaller damping outside the considered frequency-band,the frequency-band damping test results are strongly influenced by these modes;if the modal damping of each mode gently changes with frequency,the frequency-band damping test results for each band are more accurate;otherwise,a larger error appears.