NORMALIZED SMOOTHING FUNCTIONS FOR SPH IMPACT COMPUTATIONS

This paper presents a normalized smoothing function (NSF) algorithm th at can improve the accuracy of smooth particle hydrodynamics (SPH) imp act computations. It is presented specifically for axisymmetric geomet ry, but the principles also apply to plane strain and three-dimensiona l geometry. The approach consists of adjusting the standard smoothing functions for every node (and every cycle) such that the normal strain rates are computed exactly for conditions of constant strain rates (l inear velocity distributions). This, in turn, generally improves accur acy for non-uniform strain rates. This can significantly improve the a ccuracy for free boundaries, for non-uniform arrangements of SPH nodes , and for small smoothing distances. A new smoothing function is also introduced. The NSF algorithm is shown to provide improved accuracy fo r a series of cylinder impact examples that includes two different smo othing functions and two different smoothing distances.