18-DOF Triangular Quasi-Conforming Element for Couple Stress Theory

The basic idea of quasi-conforming method is that the strain-dis- placement equations are weakened as well as the equilibrium equations. In this paper, an 18-DOF triangular element for couple stress theory is proposed within the framework of quasi-conforming technique. The formulation starts from truncated Taylor expansion of strains and appropriate interpolation functions are chosen to calculate strain integration. This element satisfies C-0 continuity with second order accuracy and weak C-1 continuity simultaneously. Numerical examples demonstrate that the proposed model can pass the C0-1 patch test and has high accuracy. The element does not exhibit extra zero energy modes and can capture the scale effects of microstructure.