ABSTRACT
Free vibration might occur due to a single action of force impulse. There are static and energy approaches to solving the problems of structural dynamics. Both approaches aim to set up the equations of system’s motion in order to bring the problem to dynamic calculation, i.e., to a math problem of solving differential equations. In the presented examples, the structure includes a single lumped mass and has a single degree of freedom. Both the force method and displacement method for setting up the motion equations are based on the d’Alembert principle: a structure is considered in equilibrium under the action of loads and inertia forces. The d’Alembert principle is as follows: the stresses, strains, and displacements of an elastic mechanical system can be determined by taking the inertia forces as the external body forces and assuming the equilibrium of the system.
