Elastic-Plastic Analysis of Cylindrical Pressure Vessels with Variable Thickness Heads

The present paper examines elastic-plastic analysis of pressure vessels with variable thickness heads under internal pressure. the vessels consist of a cylindrical body and spherical, elliptical or torispherical heads. thickness of heads is variable and in some cases a nozzle is set up on the heads. the material behavior is considered to be elastic-perfectly plastic and the limit pressure is determined by elastic-plastic analysis using the finite element method. the upper and lower limit loads are obtained by upper and lower bound theorems along with elastic compensation method. the results of the above-mentioned methods will be compared to each other. moreover, the effect of parameters such as type of heads, thickness of heads and presence of nozzle is investigated on first yield and plastic limit pressure. finally, a simple optimization process is performed aiming at decreasing the amount of consumed material and a practical curve is proposed.