Additive Schwarz preconditioners for C-0 interior penalty methods for the obstacle problem of clamped Kirchhoff plates

The discrete variational inequalities resulting from C0 interior penalty methods for the obstacle problem of clamped Kirchhoff plates can be solved by the primal-dual active set algorithm. We develop and analyze additive Schwarz preconditioners for the auxiliary systems that appear in each iteration of the primal-dual active set algorithm. Numerical results corroborate our theoretical estimates.