I have seen testing on real prototype vehicles in a couple of different automakers lab areas, and that testing is also "quite brutal". But it is real testing on a real road course, with the drivers hitting the salt pool once a lap in most cases. But those failures don't quite match the ones that come from years of exposure. So while there are tests and they do provide results, they don't look like an accurate acceleration as I see them. Sort of close, but not on. And I have neither seen nor heard about any simulation of the airborn road grip effect, so possibly it is either not important or else just too hard to produce in a test environment. Or else nobody cares.
Simulation can indeed be a very useful tool, but like Bob Pease used to tell us, "The results can not be more accurate than the model", and creating an accurate model is a real challenge. Certainly that hold just as true in the mechanical world as it does in electronics. In fact it is probably a lot more challenging to make a model of a fuel tanke and it's support system than a lot of other things. I wonder if any of the modeling experts around have considered that system for modeling. Would anybody who does that care to comment?
@William K. "The other challenge for fuel tanks is the incredibly hostile environment under the car, with not only all kinds of corrosive salt spray but a constant wind driven stream of road grit impacting them. Clearly the life of a fuel tank is not a sweet trip."
Indeed! I am wondering if environmental chambers are used for this type of testing. In the semiconductor industry, we subject our parts to accelerated stresses and then we are able to extrapolate information about their performance over a defined lifetime from this data. I wonder if they do something similar?
This is certainly an interesting posting and it does cover a lot of the complexity of fuel tank design. But there is still the very real challenge of assuring that the tank tested is an accurate copy of what will be produced. That is a hard challenge indeed. And those requirements are very tough, especially the leakage requirements. I used to design production line leak test systems for the auto industry, and the specifications about leakage are quite close to "No leakage at all at any time under any condition", which is a tough standard to check for. The best we could do for the 100% production check was detect as little as 0.002CC/Minute at 18PSI tank pressure. That is about two bubbles 1mm in diameter in a minute, which is a very small part of the volume of a 36 gallon tank.
The other challenge for fuel tanks is the incredibly hostile environment under the car, with not only all kinds of corrosive salt spray but a constant wind driven stream of road grit impacting them. Clearly the life of a fuel tank is not a sweet trip.
Very nice Fons. It's intriguing to see how much complexity is involved even in the simplest of things. The more effective your simulations are, the more time you save in the prototyping phase of production, and thus these simulations would not only reduce cost, but also make the production faster. The additional feature of climate chamber is really interesting and useful, because by introducing this, the designed fuel tank would be much closer to reality. Perhaps one day we would eliminate the outdoor testing completely. A visual sample of the test would be really nice as McDermott suggested.
I agree - I would like to see some images as well. This is a fascinating article that introduced me to the complexities of fuel tank design. It is interesting to see what is happening in so many areas - simulation is becoming a great first step in the prototyping process so that actual testing occurs with a design that is more likely to be successful and will require fewer revisions to reach a final product.
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