Numerical schemes for time integration are the cornerstone of dynamical simulations for deformable solids. The most popular time integrators for isotropic distortion energies rely on nonlinear root-finding solvers, most prominently, Newton's method. These solvers are computationally expensive and sensitive to ill-conditioned Hessians and poor initial guesses; these difficulties can particularly hamper the effectiveness of variational integrators, whose momentum conservation properties require reliable root-finding. To tackle these difficulties, this paper shows how to express variational time integration for a large class of elastic energies as an optimization problem with a ''hidden'' convex substructure. This hidden convexity suggests uses of optimization techniques with rigorous convergence analysis, guaranteed inversion-free elements, and conservation of physical invariants up to tolerance/numerical precision. In particular, we propose an Alternating Direction Method of Multipliers (ADMM) algorithm combined with a proximal operator step to solve our formulation. Empirically, our integrator improves the performance of elastic simulation tasks, as we demonstrate in a number of examples.
@inproceedings{mattosdasilva2025variational, author = {Mattos Da Silva, Leticia and Sell\'{a}n, Silvia and Pacheco-Tallaj, Natalia and Solomon, Justin}, title = {Variational Elastodynamic Simulation}, booktitle = {SIGGRAPH Conference Papers ’25}, year = {2025}, location = {Vancouver, BC, Canada}, doi = {10.1145/3721238.3730726} }
Leticia Mattos Da Silva acknowledges the support of the MathWorks Engineering Fellowship. The MIT Geometric Data Processing Group acknowledges support from ARO (W911NF2010168, W911NF2110293), NSF (IIS-2335492), CSAIL Future of Data program, MIT–IBM Watson AI Lab, Wistron Corporation, and the Toyota–CSAIL Joint Research Center. Natalia Pacheco-Tallaj was supported by NSF grant DGE-2141064.