How are they going to loosen at all? Rivets form a tight compression joint between one more more layers of sheets and the rivet itself.
Unless you are stretching the rivet components to failure, in which you are doomed anyway, you will not be loosening anything.
I'd like to have you perform a thought experiment.
Imagine two soup cans, one is slightly smaller than the other. You then attempt to crush the soup cans by stepping on their side walls. Note that both cans crush together.
Now, take a single soup can, and crush in the same way. It still smashes the same as double soup cans.
Dammed if you do, dammed if you don't.
Look at the size of the bus body, and the thickness between the outer skin and the inner skin. In order to cause the combination of inner and outer skin with crossbeam elements to create a boxed structure, there needs to be a favorable ratio of space to the transverse box elements.
When you only have a tiny piece of hat channel or space between the two, the actual additional strength formed is very little. Sure, the inner skin helps - but it's more about manufacturing aesthetics, physical thickness to install things such as lights, speakers, and other components, as well as comfort issues such as thermal load and reducing exposure to condensation.
It just happens that riveting an interior set of panels is convenient because the factory is already working with steel for one, and two you DO gain a small amount of strength, which makes sense since we're constructing big steel boxes to carry children around.
Which vehicle is an entity going to purchase with safety and durability the #1 choice:
The vehicle with the steel exterior and plush composite interior that while nice, is slightly less strong than that other guy's steel box, requires special attention to take care of the finish, and can get destroyed by children.
The vehicle with the steel exterior and steel interior, that isn't quite as nice, but is a little stronger than that other guy's steel box, requires zero to very little attention to take care of the finish, and is nearly indestructible to children.
Id wager that most steel interiors in school buses is more about economy and durability of it's cargo, than anything to do directly with strength.
Originally Posted by kennythebus
So my dad is still upset about this. He said that the outside rivets will loosen more quickly without the interior skins. Did anyone experience that?