干摩擦双层梁的工作模态实验方法

Experimental Method of Operating Modal Analysis on Double Beam Model with Dry Friction

采用模态实验方法,针对具有干摩擦的双层梁结构,基于LMS Test.lab 9A软件及采集仪,研究出一种有效的工作模态实验方法。将模型安置振动台上,在独立的垂向和横向随机激励工况下,分别拾取模型的响应信号,采用Polymax方法识别两种工况的模态参数,获得系统模态参数。同时分析了参考方向、采样时间、采样点数等参数对实验方法的影响规律。实验结果表明:参考方向应与激励方向保持一致,采样时间应足够长,识取的系统模态参数与采用锤击法模态实验得到的结果具有一致性。

The valid operating modal analysis(OMA)method using LMS Test.lab 9Asoftware to a double beam model with dry friction is studied.The model is fixed on the surface of vibrostand before the response signal of experimental model respectively is collected under the ambient excitation of vertical and lengthways,meanwhile the modal parameters of system are obtained by employing the OMA method of Polymax to obtain modal parameters of the double beam with the two kinds of excitation.The effect of experimental method is influenced by the parameter of the reference direction sampling time and the number of samples,possessing certain regularity.The experimental results show that the reference direction should be accordance with the excitation direction,and the sampling time should be long enough thatthe modal parameters identified with the proposed method are outstanding accordance with the result of impact modal analysis method.