Wheels matter

So what is a good efficient wheel design? Need we look no further than F1?

The IMechE has a very thorough MX manufacturing award scheme that no doubt takes considerable resources to administrate. I am wondering if it might take on another possibly simpler one that might attract beneficial publicity and even improve automobile engineering.

Back in the early years of PC based FEA I attended a demonstration of one such system. The demonstrator showed how easy it was to create a model of an car’s alloy wheel. It was based on a real case. A pertinent comment from one attendee was “Those holes are completely in the wrong place”. The demonstrator explained that the holes were demanded by the style department!

Ever since I have viewed alloy wheels with considerable scepticism and an analytical eye with years of stress calculation experience. First I see a car component quite critical to the performance of the car and its suspension. I see alloy substituted for pressed steel plate, lighter but more prone to fatigue failure. Then I might see nice substantial structural lines suitable for the load paths or I see structural lines bearing little respect for efficient load paths, so demanding more material, cost and weight. Whatever the structural lines, I also see corner radii so small that I conclude that either the stresses there are near the maximum allowed for fatigue or that the other generous regions are grossly oversized. So what is a good efficient wheel design? Need we look no further than F1? They seem attractive enough to my eyes so why all the inefficient shapes we see so often on the roads today with either excess material and weight or dodgy corner radii?

I am sure most of these wheels are proven safe enough to market, they just seem to be so inefficiently designed.

I am therefore wondering if the IMechE might issue both awards and wooden spoons by assessing and making public the most efficient and inefficient alloy wheels to appear each year? I hope this will bring its work further into public respect and perhaps make those stylists think more carefully!

Denis Oglesby, Bingley, West Yorkshire

Next letter: Raising the IMechE profile