Abstract
This paper proposes identification method of excitation force of rigid body vibration source by constructing modal model without force signal during preliminary excitation test. If the reworking occurs after the assembly of the prototype in mechanical product, the cost increases due to the retrofit countermeasures and development period extension. Pre-prediction of vibration at the design stage is important to avoid these problems. Prior prediction of vibration needs to grasp the excitation force of the vibration source. As conventional methods, the mount stiffness method and the matrix inversion method have been proposed. However, mount stiffness method calculates the mount transmission force. Therefore, if the development machine changes the structure, preliminary evaluation does not apply. The matrix inversion method can solve this problem. However, when the frequency response function contains a measurement error, the error spreading propagates in inverse matrix calculation. Therefore , in order to avoid the inverse matrix calculation, until now authors have proposed method for identifying excitation force by building a physical model. However, with this method, it was necessary to use the force signal at the preliminary excitation test for identifying the modal parameters for constructing the modal model. For this reason, it is necessary to perform vibration with a vibrator equipped with force measuring device. When the real structure is targeted, there is problem that it is impossible to secure the excitation points due to interference with surrounding equipment. In order to solve this problem we propose identification method of excitation force of rigid body vibration source by constructing modal model without force signal during preliminary excitation test. In this paper, the validity of the method was verified by basic experiment. As a result of study, proposed method shows that a modal model can be constructed without using the force signal at the preliminary excitation test and that the excitation force can be identified accurately.
