ABSTRACT
In Chapter 1 we introduced time-independent deformation of a continuous solid. In this chapter we shall see the fundamental time-dependent deformations that can occur in an infinite continuous medium. In Chapter 4 we shall see the characteristic effect of an infinite planar surface upon the deformation dynamics. The fundamental dynamical entities are, of course, waves, whose combinations and interactions are as rich and significant in the field of elastic properties as they are in the field of electromagnetism, and in all other field theories. Amongst the results that we shall obtain is the existence of two distinct speeds of wave propagation. Before any of this, we must discuss in section 2.2 the fact that any vector field in an infinite medium, dropping faster than (distance)1 at large distance, consists of irrotational and shear components. In section 2.3 we derive the equation of motion in the absence of thermal effects. In section 2.4 we determine the propagation speeds of irrotational and shear waves.
