Solution Verification of Frictional Contact Problems in Explicit Transient Dynamics

Abstract

Contact is a commonly used capability i n explicit transient dynamics codes. Yet the quality of the solution to these problems is often unknown. Typically, users are left to determine if they “look acceptable.” In this talk we present the solution verification efforts underway for frictional con tact problems in PRESTO, a massively parallel large deformation transient dynamics code developed at Sandia National Laboratories. It is common practice in explicit transient dynamics to seek a balance between computational efficiency and accuracy (especia lly on massively parallel computers). In this presentation, the constrained set of fully discretized equations of motion is examined and various approaches for verifying solution accuracy of them are discussed. A set of frictional contact verification prob lems will be presented that give results of our investigations, including solution and mesh converge studies. I. Introduction HIS paper describes ongoing efforts in the verification and validation of frictional contact in large deformation solid mechanics problems with dynamic effects. Such explicit codes are now commonly used for a variety of applications, especially those involving contact/impact, contact with sliding, and contact with frictional sliding using some interface response (typically Coulomb f riction). Central difference time integration is the time integrator of choice for most of thee problems because of its simplicity and efficiency. Over the many years that explicit transient dynamics codes have been used, their efficiency has been the domi nant focus. It is common practice to seek a balance between computational efficiency and accuracy, especially on massively parallel computers. Here, we wish to explore the quality of explicit solutions, particularly those involving frictional contact. Spe cifically, in this paper we present the solution verification efforts underway (and challenges) for frictional contact problems in Presto, a massively parallel large deformation transient dynamics code developed at Sandia National Laboratories. We begin with an examination of the fully discretized equations of motion and then look at various approaches for verifying solution accuracy of them. Finally, we conclude with a set of frictional contact verification problems used to present the results of our ong oing investigation, including solution and mesh convergence studies.