15th May 2015 by David Mason
Last week we reviewed the 2014 Altair Enlighten Award entry from Shiloh who developed an innovative new body panel process which allows weight reduction with significant NVH performance gains. This week, I wanted to take a look at the first of two entries from material and adhesives specialists, Dow Automotive System.
Dow’s entry concerned the use of adhesives and centered on the BETAMATE™ Crash Durable Adhesive (CDA), Dow’s structural adhesive that can replace welds and mechanical fasteners, helping reduce fatigue and failure commonly found around spot welds and fasteners. It provides a reliable joining solution for multi-material designs enabling OEM’s to use advanced ultra-lightweight materials to reduce weight.
As an example of BETAMATE’s use on a production vehicle, Dow presented the benefits that Chevrolet had seen since adopting the adhesive. The new 2014 Chevrolet Corvette uses continuous aluminum hydro-formed main frame rails with the main rails each featuring five aluminum segments, including extrusions at each end, a center main rail section and hollow-cast nodes at the suspension interface points. All rails consist of as-received aluminum, chemically treated aluminum and cast aluminum chassis.
Choosing aluminum over steel for the frame and utilizing the adhesive bond line meant that the stresses on the frame could be distributed over a continuous area, something that would not be possible with a more traditional welded structure. In addition, Dow noted that the load bearing capability, static and dynamic stiffness were all improved leading to improved safety and crash behavior, reduced vibrations and noise, optimized ride, driving and handling characteristics; all as a direct result of using BETAMATE.
The all-aluminum, adhesive bonded frame is 99 pounds (45kg) lighter and 57% stiffer than the previous steel hydro-formed rail-based frame. Use of adhesive and mechanical fasteners eliminated significant arc welding content and concerns about heat effect zones and thermal distortion.
Dow’s entry proved to be an intriguing one for our judging panel. As vehicle designs become more multi-material, traditional joining methods are no longer applicable. The great load bearing capability of the CDA adhesive bond, allows very aggressive use of lightweight materials. Dow’s nomination demonstrated that innovation in almost every element of a vehicle’s construction can lead to weight savings opportunities. With the advent of more and more multi-material vehicles where reliable and cost efficient joining methods can be a considerable challenge, we will no doubt see an increased use of structural adhesives in the cars we drive.