“…Thus, there are some difficulties to apply these existing methods to complex multibody systems. For example, unlike the numerical method where the stiffness and mass matrices can be formulated separately [9] , almost all existing analytical methods [45][46][47][48][49][50]2,6,13,52,14,15,[22][23][24]26,27,[29][30][31]55,[32][33][34][35][37][38][39][40]42,44,61,62] apply the usual determinant method for non-trivial solution of the eigenvalue problem for which the determinant of the coefficient matrix vanishes. The determinant method needs the evaluation of the determinant numerically for one frequency at a time.…”