Measuring chassis stiffness

[singlecoil]

One of the aims, when producing a chassis, as I understand it, is to achieve a satisfactory level of stiffness.

Can anyone suggest a good method by which the stiffness of a chassis might tested, and what would be a good figure to aim for?

I assume the basic idea is to rigidly secure one end of the chassis, then to subject the other end to a measured torsional force, and measure the deflection, presumably with a dial test indicator.

[singlecoil]

p1doc said:

i tend to get fat bloke to sit on end of car if it breaks not strong lol
i know regarding the murtaya they did loads of research to keep chassis strong but not too sure how they did it,once load is applied can you not use x-rays etc to show potential cracks as with metal but for grp not sure of best method
martin

Engineers (I'm not one myself) draw a distinction between stiffness and strength, and I think what you are talking about there is strength. Stregth is good, of course, but I'm not going to be able to measure it unless I can actually break the chassis.

[singlecoil]

Sam_68 said:

It's not perfect, but it'll give you an adequately accurate indication of the torsional stiffness.

I was thinking something along those lines, so thanks.

Any thoughts as to what numbers should be aimed for?