ABSTRACT
This chapter talks about the systems that have continuously distributed mass and elasticity. These bodies are assumed to be homogeneous and isotropic, obeying Hooke's law within the elastic limit. To specify the position of every point in the elastic body, an infinite number of coordinates is necessary, and such bodies, therefore, possess an infinite number of degrees of freedom. For the normal mode vibration, every particle of the body performs simple harmonic motion at the frequency corresponding to the particular root of the frequency equation, each particle passing simultaneously through its respective equilibrium position. For the forced vibration of the continuously distributed system, the mode summation method, makes possible its analysis as a system with a finite number of degrees of freedom. Constraints are often treated as additional supports of the structure, and they alter the normal modes of the system.
