Test The Limits

The Battle for the A-pillar

By Steve Remondi

February 10 2015

A-pillars used to be a simple strip of metal holding up the roof and providing a fixing point for the windscreen. Now they’ve become one of the most fiercely contested battlegrounds in the development of a car.

The list of engineers wanting a say in its design is long. The crash structure team need to ensure the impact load paths up the pillar don’t deform the door aperture (a no-no in your typical crash test procedure).

The visibility team need to make sure the ever-chunkier post doesn’t breach blind-spot regulations.

And then you’ve got the war between the aero, noise and water management.

For aerodynamicists tasked with improving fuel economy, getting the A-pillar right is vital. If you can get the wind flow to accelerate round the corner you produce suction which actually pulls the car forward, reducing drag.

But if the vortex coming off the A-pillar isn’t properly managed from a noise point of view, it’ll quickly become a sore point with consumers, as it has a huge impact on interior acoustics.

Then you need to manage the water flow off the windscreen, making sure rain doesn’t cascade down the side windows. That requires a channel up the column, creating drag and noise. It’s for this reason that vehicle engineers in water flow management often come into conflict with their colleagues from aerodynamics and acoustics.

But the needs of all these departments pale next to the demands of one of the most important of all: styling. The rake, the amount of metal and the look of the pillar, whether chunkier for a 4×4 or slimmer for a sports car, is dictated by the designers and traditionally, once the styling has been frozen, it’s generally up to the engineers to work round it.

If you don’t want the cost of adding, as an example, triple-thickness door-seals to cure noise issues for a mid-life facelift, then it’s important to resolve these issues early. Small changes on the A-pillar can make a huge difference. With the right information serving as a guide at the beginning of the design process, engineers can work with the studio to find a desirable outcome.

And this information can only be discovered through simulation, which predicts real-world performance early in the design process. The result? The ability to evaluate many potential solutions to craft the optimum A-pillar design, reducing compromise and encouraging collaboration between battle-worn colleagues.