Composites Manufacturing Magazine

A Shelter from the Sea

When the U.S. Navy needs to transport a large number of sailors at the same time, they often use a hovercraft. However, that presents a challenge. “You can’t go on the hovercraft deck while it’s flying across the water, so you have to put a portable building on the deck to accommodate up to 180 people,” says Rob Banerjee, president of NexGen Composites LLC in Franklin, Ohio. “That’s where we come in.”

NexGen supplies the U.S. Navy with 21 x 42-foot personal transport modular (PTM) shelters made from composites. The shelters are constructed from individual panels measuring approximately 7 x 7 feet that connect mechanically. Once assembled on the hovercraft deck, the PTM shelter is anchored to the deck with chains. “Everything for the shelter fits in one 20-foot ISO container. It’s basically a building in a box,” says Banerjee. “You can put up the building with four people in about six hours with simple hand tools and without crane or forklift.”

Composite panels for the PTM shelter are stacked and ready for shipment in an ISO container to the U.S. Navy. Photo Credit: NexGen Composites

In 2015, NexGen delivered a prototype shelter system, including panels, frames, doors, seats, lights, ventilation fans, electrical control panels and tools. It was deployed immediately and has served several missions, says Banerjee. NexGen received a production contract from the U.S. Navy last year for up to 10 shelters. The company delivered the first production shelter in March 2017 and is scheduled to deliver another one in October.

The panels, which are approximately 2 inches thick, feature balsa core and fiberglass phenolic facings and aluminum edges. They are produced using NexGen Composites’ proprietary vacuum assisted resin transfer molding (VARTM) process, then cured at temperatures ranging from 150 F to 220 F for several hours.

While constructing square panels may sound simple, they needed to meet several requirements. “The building is designed to take a very high load while traveling at up to 60 knots in high sea conditions, including waves coming over the bow and hitting the shelter,” says Banerjee. “Beyond the structural issues, the biggest challenge was ensuring the panels passed the fire test.”

The U.S. Navy requires a very high fire rating for its PTM shelters, so the shelter had to pass the ISO 9705 full-scale room corner fire test. Prior to that testing, NexGen did a lot of coupon level testing on 3 x 3-inch and 4 x 4-inch samples. “You can learn a lot from those tests about fire behavior, but there is no substitute for starting a full-blown fire in an 8 x 8 x 12-foot room and watching it burn,” says Banerjee.

Based on the coupon testing, NexGen tweaked the phenolic resin chemistry and curing profiles. Moving from coupon testing to the room corner test was “a big leap of faith,” says Banerjee. “There’s a real need in the composites industry to come up with an intermediate test method between small coupon level testing and the full-scale room fire test.”

In 2011, NexGen’s panels passed the ISO 9075 fire test at the Southwest Research Institute in San Antonio. “To the best of our knowledge, this is the only composite modular building that has passed the full-scale room corner fire test,” says Banerjee.

In addition to the military, the fire-resistant composite panels are well suited for other industries where users need a portable building in a fire-critical application, such as oil and gas. “The intention is to move into industrial and commercial applications to compete with standard metal panels,” says Banerjee. “Obviously, pricing is a challenge there, but we believe we can offer a better value proposition.”

NexGen’s standard panels are 8 x 20 feet and can be cut into smaller sizes, like they are for PTM shelters. The panels are typically four inches thick, but can range from two to eight inches. Aside from panels, NexGen also manufactures fire-resistant composite plates, channels and other shapes.

“I think we will move into other niches,” says Banerjee. “We continue to increase our capacity in terms of making larger panels, reducing the costs, improving product performance and getting the word out. At the same time, we look for niche market applications where we can provide tangible value.”

Save the Date: Transportation Fly In

If your company is looking for greater traction in the transportation and defense markets, join ACMA and its members on Capitol Hill, Oct. 31 – Nov. 1. The event will present opportunities to foster relationships with members of Congress representing your plant locations, as well as decision makers from federal agencies like DARPA, the Department of Energy, NASA, the Federal Aviation Administration, the Environmental Protection Agency and the National Highway Transportation Safety Administration. For more information, contact Brooke Wickham at bwickham@acmanet.org.