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Aerospace engineer here, weighing in... I have two areas of expertise on this matter. First, I was on UW-Madison's competition-winning FutureTruck team about 10 years ago. We were, IIRC, the only team of about 15 other universities that replaced our competition car's (a Ford Excursion) entire frame with aluminum. In addition to replacing many other steel parts/assemblies with aluminum equivalents, we managed to bring the newly parallel hybrid SUV under stock weight... despite adding a large battery pack and motor. The thing I learned from this experience was: even though aluminum has about 1/3 the density of steel, your parts end up being about 50–55% of the steel weight because you need to add more aluminum to maintain equivalent strength. Basically, given the same tensile strength properties of a part, an aluminum one will be about half as heavy. Second, I worked as a payload mechanical engineer for a number of spaceflight systems. Suffice to say, our base material for consideration was aluminum. Sure, we deferred to steel for certain applications (e.g., ball bearings, rat cage bars, fasteners, etc) and to myriad materials in others, aluminum was the standard. It has a tremendous strength/weight ratio, can be alloyed in many different ways to get different characteristics, is non-magnetic, is relatively cheap, and can have a number of interesting surface coatings applied. About the only major systemic problem aluminum has is that it is difficult to weld. Not impossible, as my FutureTruck experience tells me, but difficult. It didn't matter to us, though, since NASA generally frowns upon welded joints anyway. Too much strength variation due to heat stress and potential for FOD if not ground properly. Anyway, I've been waiting for the auto industry to catch up to a bunch of college students for 10 years now. Nice to see one of the Big Four finally getting it. And cheers to the smaller car companies that have been doing it for years. |