ABSTRACT
For the incremental excitation-response relations studied are assumed that the loading of the structure is sufficiently slow in order to prevent the development of any appreciable inertial forces in the structure. The dynamic equilibrium equations of the nodes can be expressed only in terms of independent nodal deflections ξ and its time derivatives by eliminating s from the first partition of equations as is commonly done in the displacement method of analysis. Inertial forces are present at every mass point in motion. Although the mass points attached to the nodes of a discrete parameter structure do not create any particular problem since there are only a finite number of nodal points, the mass points of the structural elements pose a difficult problem since they are infinitely many. According to the experiments on structural materials the frictional forces are proportional to the particle's velocity.
