Dynamic load localization using the quasi-frequency response function

In this paper, a novel concept of quasi-frequency response function (Q-FRF) is proposed and applied to dynamic load localization. Aiming to avoid the ill-posed problem in FRF matrix inversion and improve the identification accuracy and calculation efficiency, a new method for fast load localization is developed based on the proposed Q-FRF. In the application of this new method no FRF matrix inversion is required. By utilizing the measured vibration response and the origin real FRF, the virtual loads at possible load application locations can be obtained. Then, the cross point Q-FRF for each measurement point are obtained using the virtual loads and measured response. Finally, the correlation coefficient between the cross point real FRF and the cross point Q-FRF is used to indicate the dynamic load location. The feasibility and effectiveness of the proposed method are validated by case studies on typical engineering structures: a fixed-support beam and a cantilever support stiffened panel. The objects are subjected to random loads and impact loads beforehand. Both types of loads can be well located by the proposed method using Q-FRF. Furthermore, noise resistance and robustness of proposed method were also tested in the present study.