Analysis of elasto-plastic stresses and structural reliability of a multilayer pressure vessel

In this paper, the formulas of elasto-plastic deformation and stresses of a multilayer pressure vessel were deduced in consideration of the linear hardening elasto-plasticity of the material, and the relations between plastic zone and interior pressure and between equivalent stress and interior pressure were obtained for a monolayer vessel. Then, treating the strength problem of a pressure vessel with a fuzzy or random one and based on the principle of the information entropy theory that the information of a variable does not change with its expressed type, the fuzzy variables in the problem were transformed into random ones or the random variables into fuzzy ones. At last, the strength reliability degree of the pressure vessel was solved out by use of the random reliability method and the fuzzy one, respectively. The relative error between the fuzzy and random reliability degrees is 4.08% and the fuzzy reliability degree is closer to the determined one than the random one.