Dynamic load identification on nonlinear damping structure using positive deduction approach

Linear and time-invariant hypotheses are the basic requirements to identify dynamic load in frequency-domain by the traditional dynamic identification method. However, these hypotheses for avoiding the ill-posed problem of inverse transfer function matrix might bring about large errors of identification. To this problem, a novel dynamic load identification method is proposed using positive deduction approach for nonlinear damping structure in this paper. This method starts with predetermined dynamic excited forces to solve the dynamic response of sampling site and the frequency response functions (FRFs), and the obtained FRFs in previous step and dynamic response by experiments will be re-used for further modifying excited forces and FRFs, until the dynamic response errors reach the fulfilling requirements of identification precision. For intuitively descripting this method, a fixed plate attached particle dampers are employed to compose a nonlinear damping structure and to demonstrate the process of load identification. In addition, the identification precision of proposed method is compared with the traditional method. It is worthwhile to indicate that the identification method developed in this paper can accurately identify the dynamic load in a nonlinear damping structure, as a result of avoiding the inverse calculation and revision for the transfer function matrix by the traditional method.