C. Thornton, COEFFICIENT OF RESTITUTION FOR COLLINEAR COLLISIONS OF ELASTIC PERFECTLY PLASTIC SPHERES, Journal of applied mechanics, 64(2), 1997, pp. 383-386
Based on a simplified theoretical model for the normal contact interac
tion of two elastic-perfectly plastic spheres, an analytical solution
is provided for the coefficient of restitution. The solution is expres
sed in terms of the ratio of impact velocity to yield velocity rather
than in terms of material properties such as the yield stress which is
difficult to reliably ascertain for many materials.