Modal Analysis Methodology for Articulated Machinery and Vehicles

A modal analysis methodology is presented for multi-degree-of-freedom articulated machinery and vehicles. The analytical technique formulates the eigenvalue problem for linearized, constrained dynamical systems during steady-state motion or at a static equilibrium position. The technique is implemented into a computer simulation program to compute the system modal properties. The system eigenvalues and eigenvectors are combined with the system geometrical transformation data to yield the system transfer function ratios for the generalized coordinates and points of interest, as well as the mode shapes. In turn, the frequency response magnitudes and phase angle shifts for a specified frequency range are computed from the system transfer functions. Finally, the system transfer function ratios are combined with the input force and base motion excitations by the mode superposition method to obtain the response of the system generalized coordinates and points of interest in both the frequency- and time-domains. The modal analysis methodology for linearized, constrained dynamical mechanical systems is illustrated with several vehicle models.