ship structures

pressure vessel

intensity factor

crack length

crack propagation

mode ii

low cycle

wall thinning

Theoretical and Applied Fracture Mechanics

• Compact crack arrest (CCA) testing was carried out on 80 mm thick EH47 shipbuilding steel. • CCA testing was used successfully to measure brittle crack arrest toughness. • The results show that Pellini NDTT data can give a conservative estimate of CCA results. • The results show that instrumented Charpy data over-estimates the CCA results. • CCA testing gives more conservative results than wide-plate testing methods. It is vitally important to measure the brittle crack arrest properties of shipbuilding steels to ensure that accidental damage will not result in total structural failure. Wide-plate test methods allow for direct measurement of the crack arrest toughness but this kind of testing is incredibly expensive. Therefore, there is a need for cheaper and simpler test methods which are able to measure a material’s brittle crack arrest toughness. In this work, Compact Crack Arrest (CCA) testing, which is standardised in ASTM E1221, has been successfully used to measure the crack arrest toughness of thick sections of EH47 shipbuilding steel. The results from this study have been compared to small-scale test methods. It was found that instrumented Charpy testing gives an overprediction of the CCA results, and nil-ductility transition temperature (NDTT) from Pellini tests gives a conservative estimate. The results presented in this study are discussed in terms of the effectiveness of the CCA test method for measurement of brittle crack arrest toughness and integrity assessment of large-scale structures.

Compact crack arrest testing and analysis of EH47 shipbuilding steel