A FULLY EDGE-BASED SMOOTHED FINITE ELEMENT METHOD FOR UPPER-BOUND LIMIT ANALYSIS OF AXISYMMETRIC STRUCTURES

Based on the kinematic theorem of limit analysis, a fully smoothed edge-based finite element method is developed for upper bound limit analysis of axisymmetric structures. In order to completely avoid the complex coordinate mapping and calculation of Jacobian matrix, the partial derivative and non-partial derivative of shape functions are treated respectively by the smoothing strain technique and the quasi-weak form of smoothed integral. As a result, all the smoothed domain integrals can be converted into boundary integrals in the smoothing domains, which are relatively simpler. The plastic incompressibility can be introduced conveniently by the penalty function. By distinguishing the rigid zones from the plastic zones generally and by modifying the objective function accordingly at each iteration, the difficulties caused by a non-smoothness objective function can be easily overcome. Numerical examples show that the method proposed has some advantages such as simple formulation, high efficiency and fast convergence. In addition, high computational accuracy can also be obtained even though the extremely irregular elements are employed.