Analysis and comparison of pad reinforcement of pressure vessel by elastic and elastoplastic FEM

Considering reinforcement pad and the cylindrical shell as an integral model and a contact model, stress analysis for opening-reinforcement structures of a cylindrical shell is performed by elastic and elastoplastic FEM. By comparison of two sub-models and two material constitutive relations (elastic and elastoplastic), the stress distribution of cylindrical shell intersections by the contact model is similar to that by the integral model, but there are some differences of the stress at contact surfaces of the shell and the reinforcement pad between by the contact model and by the integral model. In general, the stress analysis of the integral model for pad reinforcement can approximately represent that of the contact model. Finite element analyses for different nozzle diameters and different oblique angles in nozzle and cylinder shell intersections are carried out. The stress distribution and the maximum stress are affected by oblique angle. But the difference of the maximum stress intensity among different diameters is small.