Brittle Failure of the Liberty Ships Amy O’Connell Benjamin Toomey Niall Minihan Rónán Dillon Murphy 4A6(1) - Structures

Contents: History The Design Failure Preventing Brittle Failure Conclusions Questions

History Built During WW2 by US 2700 produced ( ) 1 st All Welded Construction significant failure by catastrophic fracture –30% of early ships –Failure occurred mostly during winter months –Both at sea and in port

Normally ductile steels can become brittle under certain conditions. The Design Failure Three basic factors contribute to a brittle-cleavage type of fracture a triaxial state of stress a low temperature a high strain rate or rapid rate of loading Effect of stress concentrations due to notched and cracks

Temperature Effects

Preventing Brittle Failure Hull plate and weld metal impact toughness control Eliminate sharp changes in cross section Material used : adequate toughness for anticipated loading and low temperature

Conclusions New understanding of this brittle phenomenon New test techniques were found Previsions were put in place to prevent failure again

Any Questions? Amy O’Connell Benjamin Toomey Niall Minihann Rónán Dillon Murphy 4A6(1) - Structures Thank You