Pressure tube ballooning experiments analysis

Three computer codes, namely, PTDFORM, PTSTRAIN, and AECBALL were used to simulate the experiments on pressure tube ballooning and analyze the observed effects. The results calculated by the codes for strain rates and time of failure are close to each other but the codes largely underpredict the creep rate and failure strains. This disagreement between theory and experiment can be attributed to the nonlinearity of the straining. Other sources of nonlinearity include the localized heat generation due to the deformation work done on the pressure tube, particularly around the location of failure. The simple mechanistic models incorporated into the codes could not account for ballooning and straining in the plastic deformation.