Space bus

 

I'm pretty sure he means vertical G's, aka going over potholes and such.

 

Confirmed, 11G vertical spike over pavement 'irregularities'. We're only sustaining 4G lateral in turns.

 

very interesting topic.. so far I'm getting to understand how the concept works but my question is how will this matter take affect on non-forged materials vs forged materials, steel for instance. since the mass of a forged item will be greater than a non forged. Also, I'm pretty sure Honda used top of the line materials to make an open top car THIS rigid.

 

Density of forged steel is pretty much the same as cast or rolled or whatever other process, ~0.283 lb/in^3, forged parts aren't more massive. Modulus of elasticity (i.e., stiffness) is also the same, ~29x10^6 psi. Strength properties of steel will, however, vary greatly depending on alloy, temper, and forming process.

What gives the S2000's steel frame its stiffness is the design/shape/layout, not what kind of steel was used.

 

Bingo. ZDan is exactly correct. It's the cross-sectional dimensions that dictate the stiffness of the S2k chassis. Features like the tall transmission tunnel increase the front to rear bending stiffness.

Good discussion, everyone.

 

Also, to generalize, forged parts usually have longer fatigue lives than cast parts. A lot if this is due to the surface; forged parts typically will have compressive residual surface stresses and a smooth surface. The improvement in fatigue life/performance is thought to be because precracks are harder to form in a smooth surface with compressive residual stresses when compared to precrack formation in a rough, discontinuous surface that may have tensile residual stresses.

The longer fatigue life can also be traded for performance: the better part could instead have an equal fatigue life with slightly increased loads. But with metal fatigue, a load increase on the order of 10% might cut the predicted mean lifespan by a factor on the order of 2.


But again, that's strength, not rigidity.

OTOH, composites will lose rigidity as they fatigue. Typically carbon FRP loses on the order of 10% of its modulus before total failure. This is because during fatigue, fibers are broken and no longer transfer loads.