I have a lever twisting a bar. I have the stiffness of the bar in Nm/rad and the length of the lever, how do I get the rate at the end of the lever in N/m?

Cheers

Your 2 sets of units are comparing eggs with cheese.
Rotational stiffness is the moment (or torque) needed to produce unit angular deflection.
If you want to convert Nm/ radian to Nm/ degree, divide by 57.3, which is 2xpii.

it won't be a linear rate at the end of the lever, but divide the Nm/rad by the length (in m) of your lever and that will give you the force required to deflect the lever 1 radian.

divide the N/rad by the angle (in radians) travelled and that should get you somewhere near.

try make whatever linkage you use rising rate

Adam,

The length of the lever comes in twice.

Firstly for the torque i.e. F x L (where X is the cross product if you want to be precise, but if things are perpendicular its just the multiple)

Then a second time, because low levers cause a smaller change in the deflection angle of the tube.




Matt

Managed to find it in my solid mechanics notes. Shows how much attention i pay to what im taking notes on...

Cheers anyway guys!

Finished