ABOUT THE NONSMOOTH GENERALIZED-α METHOD AND CONTACT CONSTRAINTS AT ACCELERATION LEVEL

ALBERTO CARDONA; ALEJANDRO COSIMO; BRÜLS, OLIVIER; CAVALIERI, FEDERICO J.

Congreso; 14th World Congress on Computational Mechanics (WCCM), ECCOMAS Congress 2020; 2020

The adoption of nonsmooth techniques for the study of the dynamics of flexible multibody systems subject to contacts and impacts brings many advantages when compared to smooth alternatives as shown by Brüls et al. in [1]. In that work, the nonsmooth generalized-α (NSGA) time integration scheme is presented. It is an event-capturing technique based on the splitting of the involved fields into a smooth and a (nonsmooth) impulsive contribution, where the former is integrated with second order accuracy by means of the generalized-α scheme and the latter with first-order accuracy. The resulting scheme offers an effective control of the numerical dissipation and it does not present any drift of the bilateral and unilateral constraints at the position and velocity levels.The robustness of the NSGA time integrator for problems involving nonlinear bilateral constraints and flexible elements was improved by Cosimo et al. [2]. The main difference with its predecessor is that the definition of the splitting is modified in order to ensure the decoupling of the smooth, the position correction and the velocity jump sub-problems. However, in that work no constraints at acceleration level were considered. Brüls et al. [3] presented a variation of the NSGA in which the contact constraints at acceleration level were incorporated; nonetheless, they did not exploit any decoupling. In this work, we investigate the incorporation of unilateral constraints at acceleration level in the decoupled version of the NSGA. Several numerical examples are solved with the aim of determining the robustness and the performance of the proposed algorithm.