Engineering news
Developed and patented by Professor Ray Gamache and former graduate student Major Chris Phifer at the US Naval Postgraduate School (NPS) in California, the technology was designed for use in military vehicles.
“We’re not just a physics department, we’re the applied physics department,” said Professor Gamache. “While we’re doing things that involve fundamental research, what we’re ultimately doing is pursuing applied solutions with our military students that are important to the warfighter.”
Major Phifer, of the US Marine Corps, developed and tested multiple prototypes to arrive at the right design for a ‘heterogeneous elastomer system’ for a pressurised fuel line, which immediately snaps back into position after being damaged.
“It was a process to build, test, learn until we got it right,” said Major Phifer. “The challenge was that I had to worry about both entry and exit points, so we created multiple 8-inch lengths of hose made from the polymers we selected, sealed on one side and a pressure fixture on the other, and found certain properties performed better on sealing the entry wound and others performed better sealing the exit wound.
“It was during the second phase of this process that we decided to incorporate multi-layered polymers with opposing material characteristics, and discovered through trial and error that too many layers reduced the performance – but the design with two different composites was able to self-seal.”
Self-sealing technology has existed since the First World War, but old systems relied on interactions with specific fossil fuels, and have therefore become obsolete as new types of fuel were introduced.
The researchers found that polyureas and polythioureas worked best. Capable of 300% elongation – “rubber on steroids,” according to Professor Gamache – the materials immediately snap back after being pierced by .50 calibre bullets, which are used to penetrate armoured vehicles.
“It isn’t rocket science,” said Professor Gamache. “You simply need a material that has elongation and strength to it so that it has a memory of what it used to be like. When the bullet pokes a hole through it, it just goes back and pushes everything to where it used to be.”
While the research was initially conceived for aerospace applications, the technology could apply beyond fuel lines.
“It can be any kind of line,” said Professor Gamache. “It’s a technology that gives you self-sealing and – most importantly – instantaneous self-sealing. There’s a lot being published on self-healing, ie. closing up over time, but you don’t want self-healing on a fuel line, because you’re going to be out of gas before long. Self-sealing is what we are after, and elastomeric materials do that.”
The technology could protect equipment, lengthen ‘loiter times’ and cut maintenance demands, the researchers said.
The self-sealing hose is available for licensing through the NPS Technology Transfer Programme.
Want the best engineering stories delivered straight to your inbox? The Professional Engineering newsletter gives you vital updates on the most cutting-edge engineering and exciting new job opportunities. To sign up, click here.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.