I am doing pressure vessel analysis on Ansys as you told. But while I am modeling a Type-4 pressure vessel with Ansys's engineering data as polyethylene all the analysis ends at 25 MPa whatever I have changed. If I model a type-5 linerless composite tank instead of a type-4 plastic liner tank analysis in Ansys, how would it be realistic in burst pressure? Is it able to predict the burst pressure with a linerless as close as  Type-4 composite pressure vessel?