Test The Limits

Exa reshaping the lightweight material debate

By Exa

May 01 2015

As manufacturers seek to strip ever more weight out of vehicles to meet emissions standards, they’ve worked to ensure the thinner panels don’t deform at speed. But what if a certain amount of flex was beneficial aerodynamically? What if they deform in the right way?

We are working on introducing the ability to calculate the structural change of the surface based on air pressure within our simulation software. Today’s cars include a structure underneath the sheet metal that is unrelated to the safety cell but serves mainly to make sure the panel doesn’t deform. If you could remove this structure and just have the sheet steel, aluminum or carbon fibre, you’re opening up a new world of aerodynamic possibilities, as well as saving a lot of weight.

Take the hood as an example – carmakers want this to crumple in a crash, so it doesn’t really need a structure. From an aerodynamic point of view, there’s always a problem of air coming off the hood where it meets the windshield. So if we took some structural steel out, that would allow the air to slightly reshape the surface, creating the possibility of a smoother curve up the windshield.

Another example: the purpose of the front spoiler is to aerodynamically protect all this stuff hanging down from the car, such as the exhaust line – but it’s also an integral part of the design, which might make it bigger than you really need. You could easily take enough weight out so that it bends back at speed. Not so much that it couldn’t still do its job, but in a more aero efficient manner than before. The designers might hate the way it looks, but at high speed who cares? You’ve taken kilograms of weight out and improved aero performance.

Flexible wings have already been explored by racing teams who like certain aero pieces to flatten out on high-speed straights. Racing authorities have clamped down on this practice in series such as Formula 1 and Le Mans, using weights to check the deformability of parts, but of course there’s no such issue in road cars.

Deformable parts are definitely something we’re predicting will come in the near future and we’re making sure that manufacturers can work out in simulation exactly how beneficial they’ll be at speed.