Dynamic Analysis of Vehicles

I'll bump this up for you.

By the way, center of gravity is found on aircraft by dividing total moment by total weight. Moment being weight times distance from some designated reference point. Reference datum point, sadly, is designated by the manufactorer

I know a bit about vehicle dynamics, but im not sure I understand your question. Different riders would mean different centers of gravity, yes?

Yes, both riders would have different centers of gravity. I have by this point worked through the analyses I mentioned earlier, including finding the center of gravity; it would be very helpful to me now if you had any ideas on performing analysis of a situation where I wanted to quantify the effects of stress on the combined frame (specifically, on the crossbeams) if one and only one of the front wheels collided with an immovable object.

Thanks a lot!

If one half or the vehicle stopped suddenly (hit an immovable object) the effect would be more shear than bending on the crossbeams. This means that any failure would be more apt to occur at the root (point of attachment) rather than the midsections (stress failure).

There are some interesting early 19th century applications of the vehicle you're constructing. They were designed to ride railroad rails through great parts of the American west. Their major failure mode; however, was a collision with a large moving object.

Rap

lol, im not familiar with the physics making vehicles collide with things (thats generally bad :-)).
I would imagine i would do a nodal analysis of the structure with the external force applied by the object countered in. The peak force in the collision (which is different based on speed and collision time) would differ, and be the key factor to failure (this would need to be measured using a digital accelerometer instrument or what ever).
raprap is right however, in general collisions are not well received by vehicles.
If you are performing a dynamic analysis would you not need to do experiments as to when it will slide or roll and what sort of slide etc.