Reliability-Based Performance Assessment of Damaged Ships

摘要

Failure of ship hulls may be a result of a combination of various factors. Residual stress caused by welding of the stiffeners on to the steel plates is one of the contributing factors to the failure. This study was completed for a more in-depth look at the residual stress distribution found at a typical weld-stiffener connection of ship hulls. Six small specimens were built and the sizing of the specimens was designed so that they could be accommodated in the test facility available at the Canadian Neutron Beam Centre in the Chalk River Laboratories. The specimens were made out of 9.53 mm thick plate of 350 WT grade structural steel stiffened by L127x76.2x9.53 angle stiffeners. The non-destructive neutron diffraction method was used to collect strain data at locations within the volume of the specimens. The method of neutron diffraction uses the crystal lattice of the sample material as an internal strain gauge. The test results were analyzed to determine the distribution of all the three components of the residual stress in the parent steel plate and in the stiffened plate specimens. The spacing between two stiffeners and the welding heat input were varied to examine the effect these variables on the residual stress levels. A shortened stiffener specimen was also built to investigate the residual stresses in and around the termination of the stiffener in the parent plate.