Adaptive Nonlinearity for Collisions in Complex Rod Assemblies

We develop an algorithm for the efficient and stable simulation of large-scale elastic rod assemblies. We observe that the time- integration step is severely restricted by a strong nonlinearity in the response of stretching modes to transversal impact, the degree of this nonlinearity varying greatly with the shape of the rod. Build- ing on these observations, we propose a collision response algo- rithm that adapts its degree of nonlinearity. We illustrate the advan- tages of the resulting algorithm by analyzing simulations involving elastic rod assemblies of varying density and scale, with up to 1.7 million individual contacts per time step.