点导纳法的模态密度测试试验

Modal Density Measurement Test Based on Point Admittance Method

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 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 vibration energy of structural systems.Modal density can be obtained experimentally using point admittance method. In this paper, the point admittance method is used to test the modal density of a rectangle aluminum alloy plate. Impulse hammer excitation and sinusoidal sweeping excitation are used respectively to get the results. The test results are modified by considering the additive masses of the sensors. Experimental results show that different excitations have different influences on the accuracy of test results; theinfluences of the additive masses on the corrected results are different under different excitations but the same frequency.The test result under the sinusoidal sweeping excitation agrees well with theoretical value after the additive mass correction.