Cylindrical shell structures from austenitic stainless steel under meridional compression

The main purpose of the study was to improve the competitiveness of austenitic stainless steel in cylindrical shell structures under meridional compression. Reduction in material costs may be achieved with improved design rules and full exploitation of the material's properties. The main challenge with austenitic stainless steel is nonlinear stress-strain relationship, which affects buckling behaviour. Work-hardening during cold-forming makes the use of actual material properties in the design particularly interesting. First the study reviews different formulations given in the ECCS Recommendations for Buckling of Steel Shells, DIN 18800 and the draft of Eurocode 3 for the design of cylindrical shells under meridional compression. The review also covers the design rules for stiffened cylindrical shells and cylindrical shells with cut-outs and openings presented in the ECCS Recommendations for Buckling of Steel Shells and guideline DASt-Richtlinie 017. The applicability of design rules for cylindrical shells from austenitic stainless steel EN X2CrNiMo18-14-3 (1.4435, AISI 316L) were verified experimentally with a test programme totalling 26 tests. Three cylindrical sections with different r/t ratios were loaded in both concentric and eccentric compression. The effect of initial buckle exceeding allowable tolerances was studied with two tests. Ten specimens with a stiffening arrangement were also tested. Cylindrical shells were equipped with stiffening rings, longitudinal stringer stiffeners, or both. Eight cylindrical shells with circular or rectangular cut-outs were tested both unreinforced and reinforced. Comparison with test results shows that general design rules available for cylindrical shells under meridional compression are also applicable to shells made from austenitic stainless steel. Some additional requirements are however necessary for stiffened cylindrical shells and for cylindrical shells with cut-outs. Work-hardening due to cold-forming does not enhance the strength in dimensions typical of shell structures, i.e. r/t ratios larger than 50. However, the design may be based on actual material properties when initial imperfections are within tolerance limits. The design of a stiffened cylindrical shell is based on the general theory of an orthotropically stiffened shell while ensuring that the requirement for the number of stiffeners is fulfilled. Additional reduction has been found necessary for cylindrical shells with unreinforced cut-outs larger than 40 degrees.