An in situ modal-based method for structural dynamic joint parameter identification

The present paper proposes an in situ modal parameter-based method for determining the dynamic joint characteristics of mechanical systems. The proposed method uses the mass, damping and stiffness matrices of the structure, calculated by the finite element method (FEM), along with measured eigenvectors and eigenvalues of the actual system. While the modal parameters at the joint must be known in order to identify the structural joint dynamic characteristics, it is often impossible to measure the response of the system directly at the joint location. To overcome this problem and eliminate the errors associated with using measurements close to the joints, an alternative indirect estimation scheme is used to determine the complete set of eigenvectors, and thus the eigenvector component corresponding to the joint location is extracted. Therefore, the proposed method allows in sifts joint parameter identification. The efficiency of this method is validated by simulations with different mechanical systems, and the robustness is also demonstrated with errors introduced into the estimated eigenvectors. Finally, the method is implemented for experimental identification of the joint parameters of an actual spindle system.