Why Form Follows Function in Automotive Lightweighting Trends
“Form follows function” is a maxim credited to early 20th century architect, Louis Sullivan, in relation to architectural and industrial design, inferring that the shape of a building or object should be primarily based upon its intended function or purpose. Form also follows function in vehicle lightweighting.
With 2025 CAFE standards targeting 54.5 mpg per vehicle looming, lightweighting is still critical in the automotive industry. But, as Sullivan made us aware, the design of a vehicle needs to support its function. Take this concept a little deeper, and it also applies to a vehicle’s structural components. For lightweighting, it means using the right adhesive to join disparate lightweight materials incorporated into each vehicle’s unique design.
Joining Disparate Materials
Forward Engineering, Inc. won the 2017 JEC Innovation Award for Automotive Structures for their submission based on a new development of a carbon fiber reinforced composite roof frame that used the resin transfer molding (T-RTM) process. The roof project included several innovation partners, including Henkel, which contributed LOCTITE EA 9065 to adhere the roof frame to the thermoplastic roof shell.
This adhesive can bond to many different substrates, including steel and aluminum, as well as fiber reinforced plastics or thermoplastic composites based on polyamides. It also provides the high shear strength required for joining such important roof parts.
In lightweighting applications like these, adhesives need to have properties that supply the necessary strength, rigidity and/or flexibility to accommodate the curves and 90 degree angles defined by design engineers. The multi-material design concepts also need to consider different thermal expansion properties when bonding substrates.
We see this with aluminum and carbon fiber, two common lightweight materials with different thermal expansion rates. In order to successfully bond them, an adhesive must enable longer elongation. Other lightweight vehicle designs may utilize multiple low-energy surfaces such as plastics, including thermoplastics and polypropylene. These require unique adhesive properties to address thermal sensitivity.
How to Choose
Adhesives are often the most versatile option available as they can provide high performance across a wide range of temperatures and can reduce or eliminate welds. They also offer corrosion benefits by acting as a barrier between two different metals being joined.
With the many benefits that adhesives provide, how do you select the right one for your lightweighting application?