Elasto-plastic behavior of cylindrical shells with high strength steel

This paper presents an elasto-plastic finite displacement behavior of imperfect cylindrical shells with high strength steel. For the purpose of the study, developed was an analytical method which is based on the degenerated isoparametric shell element in three dimensional space. Mechanical properties of steel material at the range of strain hardening are assumed on the basis of the material tests which were carried out by one the authors. Von Mises’ yield criterion and Prandtl-Reuss’ flow rule are adopted. In the paper effective conclusions concerning the improvement in ultimate strength and ductility of the cylindrical shells are derived from a parametric study on elasto- plastic collapse behavior of the steel shells under uniaxial compression. The contents of the paper are as follows: Described are a lot of numerical examples for cylindrical steel shells of mild steel with 400 MPa tensile strength and of high strength one with 570 MPa strength. Effects of dominant parameters, which are steel material, diameter-to-thickness ratio, initial imperfections, on ultimate strength and ductility of steel shell are clarified quantitatively. Suggested is how to utilize plastic strength of steel material for improvement in the ultimate strength and ductility of the shells. Finally, this study is expected to contribute to steel properties for improvement in the ultimate strength and ductility of steel pipes.