On Establishing Balance and Conservation Laws in Elastodynamics

By placing time on the same level as the space coordinates, governing balance and conservation laws are derived for elastodynamics. Both Lagrangian and Eulerian descriptions are used and the laws mentioned are derived by subjecting the Lagrangian (or its product with the coordinate four-vector) to operations of the gradient, divergence and curl. The 4 x 4 formalism employed leads to balance and conservation laws which are partly well known and partly seemingly novel.