Optimization of plastic conical shells of piece-wise constant thickness

Thin-walled conical shells subjected to uniformly distributed external pres sure loading are considered assuming that the thickness of the shells is pi ece-wise constant. Minimum weight designs are established under the conditi on that the load carrying capacity of the optimized shell coincides with th at of the reference shell of constant thickness. The material of the shell is assumed to obey Tresca's yield condition and the associated flow law. Th e exact yield surface in the space of generalized stresses corresponding to the Tresca condition is approximated with the squares on the planes of mem brane forces and moments, respectively.