A Numerical Implementation of Linear Matching Method for the Limit Analysis

ANSYS UserMat and its corresponding special MACRO are developed for implementing the linear matching method (LMM) for the limit analysis by using ANSYS. By this, pre and post-processing for the limit analysis can be done in the sole ANSYS circumstance without a help of any additional programs. Once user creates the FE model and enters the parameters for the LMM analysis by using ANSYS interface, ANSYS then will evaluate the upper and lower bound of limit load automatically. In order to overcome the drawback of LMM which does not give the reliable lower bound of limit load, the elastic compensation method (ECM) for the computation of lower bound of limit load is combined with the LMM so that the converged upper and lower bound of limit load is obtained, respectively. Moreover, a simple method is proposed in order to overcome the numerical difficulty of LMM due to the high gradient of stress state. Some numerical examples were given to validate the proposed method and the corresponding computational system and the reliable stability was shown, as expected.