An efficient adaptive polygonal finite element method for plastic collapse analysis of solids

Abstract: We propose an adaptive polygonal finite element formulation for collapse plastic analysis of solids. The article contributes into four crucial points: 1) Wachspress shape functions at vertex and bubble nodes handled at a primal-mesh level; 2) plastic strain rates and dissipation performed over a dual-mesh level; 3) a new adaptive primal-mesh strategy driven by the L^2 -norm-based indicator of strain rates; and 4) a spatial decomposition structure obtained from a so-called polytree mesh scheme. We investigate both purely cohesive and cohesive-frictional materials. We prove numerically that the present method performs well for volumetric locking problem. In addition, the optimization formulation of limit analysis is written by the form of second-order cone programming (SOCP) in order to exploit the high efficiency of interior-point solvers. The present method retains a low number of optimization variables. This convenient approach allows us to design and solve the large-scale optimization problems effectively. Numerical validations show the excellent performance of the proposed method.