Measurement of the Structural Intensity

本研究的目的是检验双加速度计法测量结构强度的准确性，并探讨该方法在结构噪声和振动问题中的应用，主要研究结果如下：（1）用机械法和电学法检验了阻抗头法测量振动功率的准确性。据观察，振动功率被准确地测量。(2)利用部分覆盖阻尼材料的钢梁对结构强度测量系统的精度进行了测试。具体地，由激励器提供的振动功率由阻抗头测量。基于在梁上测量的结构强度计算振动功率。通过将计算功率与测量功率进行比较，发现测量系统的准确性是足够的。(3)结构强度测量系统的准确性进行了测试，使用一个平坦的钢板部分覆盖阻尼材料。具体地，由激励器提供的振动功率由阻抗头测量。根据测量的结构强度，计算了通过激励点周围的闭合线和横向与板相交的直线的振动功率。通过将计算功率与测量功率进行比较，发现测量系统的准确性是足够的。(4)开发了基于有限元的计算机程序来计算含阻尼材料平板的结构强度。通过比较计算的分布与测量的分布，观察到板上结构强度的测量和计算的足够的精度。此外，阻尼材料的振动功率流的模式的影响进行了检查。(5)讨论了结构强度分布与板弯曲振动节线移动的关系。

The purpose of this study were to test the accuracy of structural intensity measured by the so-called two accelerometer method and to discuss the application of the method to the problems of noise and vibration of structure.Following results were obtained in this study:(1) The accuracy of vibrational power measured by an impedance head was tested by a mechanical method and an electrical one. It was observed that the vibrational power was accurately measured.(2) The accuracy of a structural intensity measuring system was tested using a steel beam partly covered by damping material. Specifically, the vibrational power supplied by the exciter was measured by an impedance head. The vibrational power was calculated based on the structural intensity measured on the beam. The accuracy of the measuring system was found to be sufficient by comparing the calculated power with the measured one.(3) The accuracy of the structural intensity measuring system was tested using a flat steel plate partly covered by damping material. Specifically, the vibrational power supplied by the exciter was measured by an impedance head. The vibrational power passing closed lines encircling the exciting point and straight lines intersecting the plate laterally was calculated based on the structural intensity measured on the lines. The accuracy of the measuring system was found to be sufficient by comparing the calculated power with the measured one.(4) An FEM based computer program was developed to calculate the structural intensity on the flat plate with damping material. The sufficient accuracy of both the measurement and calculation of structural intensity over the plate was observed by comparing the calculated distribution with the measured one. In addition the influence of damping materials on the mode of vibrational power flow was examined.(5) The relation between the structural intensity distribution and the movement of nodal lines of bending vibration of the plate was discussed.