Unified Solutions on Plastic Limit Internal Pressure for Metallic Elbows

Abstract

With consideration of the intermediate principal stress and different strength values in tension and compression, the plastic analysis of metallic elbows under internal pressure is conducted based on the unified strength theory. The unified solutions for elbows with constant and variable wall thickness values, and those with a local thinning are derived. Parametric studies are carried out to investigate the dependence between the unified strength theory parameter, tension-compression ratio, bending coefficient, and wall thickness. Comparing the theoretical results and the experimental data, a good agreement was observed. The results obtained show that the unified solutions are versatile in the theoretical analysis of metallic elbows and can be reduced to many existing results. The latent potentialities of metallic elbows are fully achieved due to considering the intermediate principal stress. The unified solutions have an important practical value for the optimum design and engineering application of metallic elbows.