ELASTIC-BRITTLE-PLASTIC UNIFIED SOLUTIONS OF LIMIT INTERNAL PRESSURE FOR DOUBLE-LAYERED COMBINED THICK-WALLED CYLINDER

With the consideration of brittle softening and intermediate principal stress, the elastic-brittle-plastic unified solutions of limit internal pressure for double-layered combined thick-walled cylinder are presented based on both the triple-shear unified strength criterion and the elastic-brittle-plastic softening model. The effects of the cohesion, internal friction angle, radius ratio, strength theory parameter and the intermediate principal stress coefficient on the unified solutions are discussed. The new unified solutions overcome the shortages of the existing elastic-perfectly plastic solutions based on the Tresca yield criterion, Mises yield criterion or twin shear strength theory. It is shown that the influence of intermediate principal stress, material model and brittle softening on the limit internal pressure is significant. The unified solutions obtained in this paper have a wide applicability and theoretical significance, which can be naturally degraded to the existing formula and can get a series of new solutions. Therefore, the unified solutions have an important practical value for the optimum design and engineering application of combined thick-walled cylinder.