This thesis considers three problems in the field of elastodynamics. The first concerns small-amplitude elastic disturbances in an infinite cylinder, a problem first investigated by Pochhammer and Chree. Our approach extends the results of Pochhammer and Chree by utilising a method of successive approximation through which the governing equations are solved to produce dispersion relations. The second investigation, recently considered by Eringen and Suhubi, is of the propagation of elastic waves in a prestressed body, with particular reference to the circular cylinder and the half-space. The governing equations are again solved via successive approximation to give new and detailed results describing the wave motion. The final investigation is of a compressible strain-energy function which is an extension of the Ko model. The model is examined in the light of various a priori inequalities, and is then used to obtain solutions to the problem of vibrations in a stressed plate.