Use of Elastodynamic Reciprocity Theorems for Field Calculations

Reciprocity is a good thing. Something is given and something else, equally or more valuable, is returned. So it is in reciprocity for states of deformation of elastic bodies. What is received in return is the main benefit from the reciprocal relationship. From a solution to one loading case, some important aspects or the complete solution to another loading case are returned. However, the return is not always a complete solution, but sometimes an equation for computing such a solution.