Industry leaders, customers, OEMs and suppliers will gather at the North American Pultrusion Conference in Chicago in May to learn about the latest trends in pultrusion technology. In advance of the conference, Composites Manufacturing presents projects in four market segments highlighting the durability and versatility of pultruded products.
Delivering Safety and Storage
When Toyota sought greater functionality in the seats of its Tundra full-size pickup truck, the automotive manufacturer turned to pultruded composites. The 2022 Tundra is the first interior application using L&L Products’ Continuous Composite Systems™ (CCS) technology with Elastocoat®, BASF’s polyurethane resin system for pultrusion.
CCS is a fiber-reinforced composite carrier with highly engineered sealants and adhesives in a two-dimensional profile. It was overmolded with BASF’s Ultramid® B3ZG7 CR, an impact-modified polyamide 6 (PA6), to create the 3D shape of the 60% seatback. Flex-N-Gate manufactured the seatback, as well as other components for the seating system.
“The seatback had to be thin so Toyota could put storage behind it,” says Hank Richardson, product engineering manager for L&L Products in Romeo, Mich. “We could have made a molded seatback out of nylon that would probably have met the criteria, however it would have been twice as thick because of all the load-carrying requirements.”
The seating system features four composite components—two seatbacks and two seat bottoms—compared to the previous all-steel assembly, which contained 60 stamped and welded parts. The seatback is a complicated mold assembly: all nine of its elements, which include the pultruded profile, steel threaded fasteners and seat anchors, are robotically inserted into the die, then overmolded with the PA6. The in-mold processing reduces scrap, which provides a huge savings for Toyota.
“At the end of the cycle, we were able to achieve a nice, thin seat with storage space below and behind it,” says Richardson. “It met all the criteria, and it was 20% lighter than the metal seatback.” It also was 20% less expensive.
“In automotive, you often talk about how much somebody would pay for a reduced weight per kilo. In this case, it was an overall cost savings as well,” says Richardson.
Convincing Toyota to incorporate pultruded composites into its seatback wasn’t difficult, he says. The OEM had previously used molded seats with fiber and glass-mat reinforced polyamide compounds from BASF in the folding third-row seats on the 2021 Sienna minivan. However, the Tundra had different load requirements.
“We were able to showcase what pultrusion could do – that it’s lighter weight and carries more load than aluminum,” says Richardson. “It wasn’t hard to lead Toyota down the path.”
The project required close collaboration among suppliers to achieve success, especially during the design and simulation phase. All the materials that go into the seatback – GFRP, steel and nylon – have different properties and reactions upon molding.
“The challenges go beyond modeling the part to carry all the loads,” says Richardson. “How do you create the die design to produce a flat seatback that’s the same every time? There was a ton of work in simulating the mold flow to get to the end result.”
While this was L&L Products’ first project with Toyota, the company has provided CCS components to other automotive manufacturers. For instance, it created a cross member for the Ford F-150® Lightning™ all-electric pickup truck. The cross member is the first body-in-white application for CCS featuring BASF’s Elastocoat resin.
Richardson envisions multiple opportunities for pultruded composites in the automotive market – particularly on battery-electric vehicles.
“There are applications where you are trying either to protect the batteries and you need crash load transfer type parts or you are trying to protect the electric drive motors and high voltage systems,” he says. “I get excited when people ask me where the limit is for applications. I don’t think there is one.”
Carrying a heavy load
Applications: Generator Access Platforms
In 2020, at the height of supply chain issues and rising steel prices, a data center in California faced difficulties sourcing galvanized steel materials for a planned exterior generator access platform. With construction schedules looming, the company contracted Frost Engineering & Consulting to provide a pultruded composite alternative.
“We were able to re-evaluate, re-detail, fabricate and install the platform prior to when the first shipment of steel was scheduled to arrive onsite,” says Jake Althouse, PE, structural project manager with Frost.
The two-story, 7,000-square-foot GFRP platform provided other advantages aside from meeting construction deadlines. Unlike galvanized steel, GFRP is non-corrosive, non-conductive and lightweight. It’s easy to maintain and doesn’t require grounding or equipment to erect. Given the project’s resounding success, when the data center owner required a second access platform last year, it opted for pultruded FRP from the outset.
“The first structure was just for maintenance personnel to reach equipment. The 2022 project was designed to support small forklift traffic, which presented unique challenges for the design team,” says Althouse. The weight of the equipment, operator and payload totaled nearly two tons per lift.
The decked area of the more recent one-story platform is approximately 8,000 square feet. The platform framing is made from pultruded GFRP, including the structural members (beams, columns, braces), handrails, stair assemblies and railings. To help support forklift traffic, a large portion of the deck is steel bar grating. The platform weighs 75 tons, with all the FRP components accounting for half the total weight and the steel grating the other half.
One of the main design considerations was supporting the concentrated load – the force applied at any single point in the structure – generated by the equipment navigating the platform. In addition to supporting the gravity loading, Frost also reviewed the impact of lateral loads induced by the equipment in a situation in which the brakes were applied very rapidly.
“We had to justify what we expected the concentrated load to be, then go through the rigorous process of showing that pultruded FRP could adequately support the concentrated loading at any point it might exist,” says Althouse.
Another key design challenge – prying action – can elevate the tensile force between beams, columns and the bolts holding them together. “The current standard for pultruded products – the LRFD pre-standard published in 2010 – has a statement that prying forces need to be considered, but there is currently no guidance on how it should be addressed,” says Althouse. “We explored all available research in other materials, then used that information in conjunction with our understanding of FRP and other orthotropic materials to meld the two into a best practice.”
Frost collaborated with a pultruder to design and experimentally validate a custom beam profile for the platform – a heavy-duty 18-inch-deep, 8-inch-wide I-shape – to support the project’s longest span of 26 feet.