点导纳法的模态密度测试试验

模态密度能反映结构系统振动能量的存储能力,是应用统计能量分析法研究中高频动响应问题的重要参数。模态密度的实验获取常采用激励点导纳法。基于点导纳法原理,分别采用脉冲锤击和正弦扫频两种激励形式,测试一矩形铝合金板的模态密度,考虑传感器的附加质量,对测试结果进行修正。结果表明,激励形式对矩形铝合金板的模态密度的测试精度有较大影响;传感器的附加质量在不同激励形式下,相同频段内,对识别结果影响的差异明显;经过附加质量修正后,正弦扫频激励测试结果与理论值吻合性较好。

Modal Density Measurement Test Based on Point Admittance Method

Modal density is an important parameter in statistical energy analysis method when analyzing dynamic response in medium and high frequency bands. It can indicate the storage capacity of vibrating energy of a structural system. Modal density can be got by experiment using driving point admittance method. In this paper, the point admittance method was used to test modal density of a rectangle aluminum alloy plate. Impulse hammer excitations and swept-sine excitations were used respectively to get the result. The test result was modified by concerning the added mass of sensors. Experimental results show that different excitations have influence on the accuracy of test result; the influence of added mass on corrected result differs under different excitations in the same frequency. The test result under swept-sine excitations fits well with theoretical value after added mass correction.