Laser peening to treat aluminium plates on naval combat ships
Laser Peening firm LSP Technologies is working with maritime engineering consultancy Hepburn and Sons to research and design a new laser peening system to treat aluminium plates on naval combat ships.
The system will be based on LSP’s Procudo peening system, which will be installed with a custom-designed beam deck delivery system on-board a Littoral Combat Ship (LCS) – a lightweight vessel designed for ocean-going operations, near-shore operations, and combat.
The LCS craft use 5xxx series aluminium extensively to make them lighter, stronger, and faster. However, 5xxx series aluminium contains magnesium and other elements that make it vulnerable to corrosion due to sensitisation, a process in which high temperatures and salt water can combine to promote corrosion in some aluminium alloys.
The partners will therefore be looking to demonstrate how laser peening can be used to deter such corrosion and cracking caused by aluminium sensitisation.
Laser peening, also known as laser shock treatment, is a process in which a pulsed laser is used to induce deep, high-magnitude compressive residual stresses inside materials, which increase their hardness and resistance to cracking and fatigue failure. The stress waves in the materials are generated from a rapidly expanding plasma that forms on their surface when struck with the pulsed laser beam.
The process will be delivered by the portable, ‘hardened’ version of the Procudo system currently under development, explained David Lahrman, LSP’s vice president of business development.
‘Typically, our Procudo laser peening systems involve robots manipulating metal parts for the laser peening process,’ he said, ‘but in this case, we will use an articulating arm to manipulate the laser beam delivery to the deck of the ship.’
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The installation of the Procudo system on the LCS vessel will take place at one of the West Coast operations of Vigor Shipyards, with the US’ Naval Surface Warfare Center’s Carderock Division providing technical expertise to support the project.
‘This project promises to be a major step forward in adopting laser peening technology to improve the survivability and reliability of navy vessels,’ said Scott Hepburn, COO of Hepburn & Sons. ‘We will validate the ways in which laser peening can improve the condition of the aluminium on-board the ship, even when the aluminium has been sensitised beyond weld repair levels. This kind of lasting repair is a high priority for the navy.’
The project has received a public investment of $1.78 million from the National Shipbuilding Research Program, which in addition to the private sector team’s investment of $1.96 million, brings the total value of the project to almost $3.8 million. Contractual work on the project began in December.