BASF, L&L Products, and Stellantis have been recognized for lightweighting success on the composite tunnel for the 2021 Jeep Grand Cherokee. The vehicle, which launched in May, just won the prestigious Altair Enlighten Award for achievements in vehicle weight savings.
While researching opportunities to reduce mass and improve durability without compromising safety performance, the transmission mounting system (TMS) was one area of focus. The composite tunnel reinforcement (CTR) is located on the underside of the vehicle and is part of the overall TMS. In the event a vehicle collides slightly with an opposing vehicle, for example, the CTR transfers the energy load from the outer rail to the transmission mount crossmember, improving performance in the field and in the Insurance Institute for Highway Safety (IIHS) standards small offset rigid barrier test.
The use of continuous composite systems (CCS) pultrusion technology along with polyurethane chemistry from BASF were key factors in the success of the CTR. CCS combines a fiber-reinforced pultruded composite carrier with highly engineered sealants and adhesives in a two-dimensional profile. This is a continuous process used to create straight or curved composite profiles reinforced with continuous fibers and mats. The system is designed to provide strength, stiffness, and rigidity to a lightweight structure.
“CCS enabled L&L Products and Stellantis to realize a new design that reduces packaging along with mass and uses the surrounding environment on the vehicle to help transition loads to the CTR. We also made technology improvements to achieve an industry first in processing speeds, as we doubled the typical profile pultrusion output,” said Hank Richardson, Product Engineering Manager, L&L Products.
This was also the first application for L&L Products using its CCS technology and BASF’s Elastocoat 74850 polyurethane pultrusion system.
“Our Elastocoat polyurethane chemistry coupled with continuous glass fiber has a superior strength-to-weight ratio in comparison to ultra-high-strength steel when used in these kinds of applications,” said Chris Korson, Chassis Market Segment Manager, Performance Materials, BASF Corp. “We also developed a new computer simulation methodology using our proprietary CAE modeling software Ultrasim to accurately capture the additional load after failure that a composite provides.”
“We are always looking to improve on the design, function, and efficiency of our vehicles,” said Brian Dwyer, Chassis Engineering Manager, Stellantis. “It’s not easy to find a weight-reduction solution that improves overall performance, but that’s exactly what we have done on the 2021 Jeep Grand Cherokee L composite tunnel.”