Correlating cryogenic fracture strength using a modified two-parameter method

Damage tolerant approaches have been employed increasingly in the design of critical engineering components. In these approaches, one has to assess the residual strength of a component with an assumed pre-existing crack. In other cases, cracks may be detected during service. Then, there is a need to evaluate the residual strength of the cracked components in order to decide whether they can be continued safely or repair and replacement are imperative. A modified two-parameter fracture criterion is applied to correlate fracture data from tensile cracked plates made of aluminium alloys, titanium alloys and stainless steel at cryogenic temperatures. Fracture parameters to generate the failure assessment diagram are determined for the materials considered in the present study. An attempt is made to correlate the fracture data on pressure vessels tested at cryogenic temperatures. The fracture parameters obtained from the fracture data of tensile cracked plates and pressure vessels were found to be closely matching with each other. Failure pressure estimates were found to be in good agreement with test results. This study indicates that the failure assessment diagram of a material generated from tensile fracture plate configurations can be applied for failure pressure estimations of flawed pressure vessels.