Limit analysis problem, coupled with finite element method and mathematical programming method, is a direct method to predict the load bearing capacity of solids and structures. Many work have been devoted to isotropic structures based on von Mises yield criterion. This paper turns to consider the orthotropic structures. Based on Hill's yield criterion [1], a numerical method is presented for the static limit analysis of 3-D orthotropic structures, where the temperature parameter method is used to construct the self-equilibrium stresses.The application of this method is listed. First, the lower bound of the punch problem is studied and compared with the upper bound got by Capsoni et al [2], who obtained it by using kinemetic limit theory. The comparison illustrates that this method releases the severe constraints of Hill's yield criterion imposed on the kinematic method and avoids the limitation of the upper bound method. Next, the cylindrical-conical- cylindrical combined shell under internal pressure are solved, and compared with the upper bound. The lower bound limit loads of orthotropic pipeline under internal pressure, axial tension and bending moment are calculated, and the interactive curves are plotted. Numerical results show the applicability of this method.
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