Conjugate gradient type algorithms for frictional multi-contact problems: applications to granular materials

This paper presents gradient type algorithms to solve frictional multi-contact problems written as quasi-optimization problems. A single loop scheme formally close to the classical conjugate gradient method is proposed with some adaptations of the iterate corrections and gradient projections. Since the convergence is difficult to prove, various tests in the field of granular media are performed with comparison with the non-linear Gauss–Seidel scheme.