Speaker
Description
LS-DYNA is a multiphysics simulation software package. It targets a wide range of industrial applications, such as modal analysis problems. These are solved with a variety of homegrown eigensolvers, tailored over decades to industrial models. In this talk, we will focus our attention on the quadratic eigenvalue problem underlying the rotational dynamics' framework of the Jeffcott Rotor model. LS-DYNA currently relies on the implementation of IRAM within ARPACK to target this problem. As an alternative, we have developed an in-house extension of the Locally Optimal Block Preconditioned Conjugate Gradient (LOBPCG) method to the complex case, known as the Generalized Preconditioned Locally Harmonic Residual (GPLHR) method. We present our studies on the numerical behavior and performance of GPLHR, including strong-scaling results (with comparisons to LOBPCG where applicable), sensitivity to tolerances and subspace dimension size, and convergence bottlenecks that trade off preconditioner cost against orthogonalization. Finally, we verify the correctness of the implemented damping contributions by isolating various damping terms in the equation of motion, demonstrating consistent eigenvalue behavior across these cases.