When free vibration is under consideration, the structure is not subjected to any external excitation (force or support motion) and its motion is governed only by the initial conditions. There are occasionally circumstances for which it is necessary to determine the motion of the structure under conditions of free vibration, but this is seldom the case. Nevertheless, the analysis of the structure in free motion provides the most important dynamic properties of the structure which are the natural frequencies and the corresponding modal shapes. We begin by considering both formulations for the equations of motion, namely, the stiffness and the flexibility equations.
KeywordsNormal Mode Modal Shape Mass Matrix Modal Matrix Free Vibration
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