New formulation for vibration analysis

In this study, a dynamic model that determines exact vibration mqdes and frequencies for trusses is formulated. This model, based on the exact representation of element inertia forces, represents the rod vibration problem quasistatically through use of equivalent loads. Thereby, the need to iteratively form and decompose the stiffhess matrix in solving the vibration eigenproblem is eliminated without introducing discretization error. The effectiveness of this formulation is illustrated in numerical examples and tested against the current models available for vibration analysis of trusses. Exact solutions of the first and second modes of a plane truss are assessed with respect to computational efficiency for a given solution accuracy. The study leads to the conclusion that exact eigendata pairs can be evaluated using simpler representations and requiring less computer resources than with the conventional finite element or exact displacement model formulations.