8th May 2015 by David Mason
Last week we looked back at Grede’s 2014 Altair Enlighten Award entry where the company had developed a new material to take weight out of vehicle body panels. This week I wanted to continue to look at body panels with the entry from materials specialist, Shiloh.
Noise and vibration experienced by drivers and passengers is more and more becoming a significant criterion in consumer purchases. As such, OEMs are working very hard to differentiate their vehicles in this area. Lightweighting with all its benefits for fuel efficiency and emissions can potentially have a negative influence on noise and vibration performance if not managed correctly. It is common in today’s vehicles to use damping treatments on body panels at specific locations to reduce the noise and vibrations. But damping treatments add mass / cost and complexity back in to the manufacturing process.
ShilohCore Acoustic Panel Laminate (APL) provides maximum damping performance for minimum weight by engineering the constraining layer to only the areas of NVH concern. The ShilohCore patch can be stamped along with the main panel, eliminating many additional operations and ensuring a quality part with consistent performance. The constraining laminated steel layer can be extended to the edge of holes and weld studs plus other attachments can be applied directly on top of the laminate without degrading performance.
Shiloh has overcome several challenges in making this new process work. Controlling the metal flow during the stamping operation is critical and that the stresses on the adhesive are controlled throughout manufacture. Highly accurate formability simulations are necessary to guarantee the consistent and precise location of the patch on the finished stamping.
The weight saving potential of the solutions impressed the judging panel. Using a dash panel as an example, Shiloh estimating a saving of between 1 and 2kg (2.2 and 4.4 lbs) was possible depending on the alternative damping treatments that are being replaced.
We spend a lot of time as engineers trying to reduce base architecture metal thicknesses in our designs. What interested me about this entry was the reminder that we must optimize for all required criteria. It does no good to reduce panel weight if we then need to add damping materials to manage the vibro-acoustic energy. Saving weight is a vitally important strategy for car makers today, but few manufacturers would be willing to do this by sacrificing something as central as driver and passenger comfort. Shiloh’s entry shows that, with the right materials and simulation knowledge, reducing weight does not have to mean reducing performance.