Engine rigidity (structural member)

[ReadySetGo]

Hey there for all the teams that use their engine as a structural member. How do you justify your engines rigidity when designing your frame? I know the design judges would like to see how you verified that your motor can withstand a certain amount of deflection.

Do you just model a fat chunk of aluminum in your FEA to represent the engine? Any info would be greatful. I'm going to partial stress an f4i on our '05 car. I know this has been done before.

Thanks

[clausen]

I think it would be pretty hard to get some figures for the engine stiffness, unless you had a complete but stuffed one that you could put in a jig and twist the hell out of. Keep in mind that when they're installed in the bikes, they are very much a structural member - there is no frame running underneath the motor in any modern road bike. The loads wont be the same, but I dont think they'd be that far off.

I spoke to a chalmers guy in australia and asked him how they came about deciding to fully stress the donk. He said "well we asked ourselves, do we want to stress the engine?, and then we said, yes,let's stress the engine"

http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Colin]

there is a rumour going around swinburne that our chassie engineers did a hot engine torisional test to compare hot and cold engine stiffness figures.....

[Charlie]

We did a ton of engine torsion testing. Several different tests.

If an engine sees torsional loading in a bike, well lets just say that the engine is probably on its way to being in a FSAE car. http://fsae.com/groupee_common/emoticons/icon_wink.gif

In other words, if you need to justify your engine's rigidity, measure it!

Based on what we went through last year, I will never trust any team that has FEA results from a stressed engine frame that they didn't verify.

[Colin]

This is the third year we'll be running a fully stressed engine and every year we do more testing to justify our design, both static and dynamic. if you haven't got testing results to show the design judges you will get crucified, not only that it's nice to know your not going to lock up a cylinder or crankshaft the first time you take a corner.