Abstract: Ultrahigh pressure tubular reactor is the key equipment of tube-type ultrahigh pressure polyethylene, its end is usually the shrink-fit structure composed of jacket and reaction tube. Stress field of end structure of the ultrahigh pressure polyethylene tubular reactor, in which fatigue fracture occurred, is experimentally studied by measuring electric resistance strain. And the local stress field after shrink-fit is obtained based on stress release method. In terms of experimental results, ANSYS FEM is built and the simulation results compared with experimental data. The results show that a large tensile axial stress appeared on the location at the edge of the shrink-fit and it’s larger than hoop stress, and the local stress level increases with the increase of shrink-fit range; the influence of contact stiffness on simulation results is significant, and in order to improve the simulation accuracy, the combination of contact stiffness and convergence has to be optimized; the FEM simulation results is consistent well with the experimental data. The study results can provide some insight into subsequent numerical simulation and failure analysis of the end structure.

Key words: dimensional analysis, massive on-site data, mechanical model, residual analysis, total thrust, ultrahigh pressure tubular reactor;stress release method;shrink-fit;contact stiffness