Vantare Slide Cutout Structure Reinforcement

[davidbrady]

Here's an FEA on the stock Prevost sidewall loaded up to the same 49 lbs/in and with axle constraints in place:


This model was derived from SpongeBob's Prevost documentation. Here's a view of the sidewall construction from my documents. In this view the front of the bus is to the right; whereas, in my FEA model the front is to the left:


Deflection:
, ,

Tensile Force:
, , , and

Tensile Stress:
, ,
you can see the max stress again is less than 16,000 psi, again well below the fatigue and ultimate tensile strengths of low carbon steel.


Observations:

The max tensile stress is the same in both cases, both the Vantare beam and the Prevost beam exhibit stresses less than 16000 psi. Tensile forces on the Vantare beam chords are higher than those in the Prevost chords, maxing out at 25000 lbs versus Prevost's 13000 lbs. This is to be expected since the Prevost beam is two times as tall as the Vantare. The point to note is that the tensile stresses are the same due to the greater amount of steel in the Vantare beam, both come in less than 16000 psi. So far things are virtually unchanged by Vantare's modifications. Where things differ is in deflection. Because the partial height Vantare beam has a lower moment of inertia we'd expect it to deflect more than the Prevost beam, and this is the case. The Vantare beam's max deflection is 0.34" whereas the Prevost beam's deflection is 0.26". Remember, the loading case presented here is extreme. I'm assuming the full 50,000 lb load is supported solely by the sidewall beams. Clearly this isn't the case. Also, I'm placing all the load over 474 inches, or 40 feet; the full load of the 45 foot bus is imposed on the length made up by the two Vantare beams and the intervening Prevost beam segment. Clearly, my loading configuration is a highly conservative model; even so, the deflections are close and given the alternate load paths within the chassis in the real world I'd expect the deflection differences to be inconsequential. Still, our max stresses are close to a factor of 4 away from the steel's ultimate yield strength and well below the steels fatigue strength!

The Vantare chassis modifications are in line with restoring the 2-slide equipped chassis back to its original strength!