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Since the access to the liner is difficult, it is assumed that after the auto-frettage process with 5% plastic deformation, there is a possibility that cracks have been introduced in the material as deep as 95% through the thickness. 17 shows the part through crack that is almost becoming a through crack as the result of plastic deformation. In the analysis, it is assumed the crack has initiated in the weld region. The weld will locally bulge when the applied load (causing the 5% plastic deformation) is removed, resulting in the induced residual compressive stresses through the liner.

In all the above-mentioned cases, both the fracture toughness and the fatigue crack growth rate properties have lower values and must be reevaluated through testing. This is where virtual testing proves to be a valuable tool to implement in order to avoid costly and time-consuming tests. As mentioned previously, the fatigue crack growth rate, as well as the fracture toughness tests, requires specimen preparation and pre-cracking that are time consuming. It can delay life assessment analysis for weeks.

14, which is an indication that the fracture toughness value after the auto-frettage process is lower. For this reason the analyst must use the correct value of Kc in the safe-life analysis assessment. Not considering this fact, the analysis results can be overestimated, which can result in catastrophic failure of liner and loss of the space vehicle during its service usage. Under this situation, the new fracture allowables can best be obtained through the virtual testing technique. Using this approach will help analysts to perform safelife analysis in a short time without compromising the safety of the structure.