I am trying to calculate the rotational stiffness of a front knuckle. I applied three seperate 1Nm torques at the wheel center in X,Y,Z. I constrained the UBJ and LBJ in 1,2,3 and the OTR in 2.
The analysis runs fine, but I am having a hard time determining what the true rotation is to use to calculate the rotational stiffness. My post process gives me rotational vector and magnitude but I am not sure that is the right value to divide into the torque.
Should I use the maximum values of rotation or the rotation only in the plane normal to the induced moment?
Should I use some node that is linked to the wheel center and project it back to a common plane and measure the angle.
Also, the rotation is not about the wheel center because the part is not symmetrical.
The rotational values I am getting are extremely low like 4.5e-5 rad for a 1Nm torison input. It seems very stiff to me for cast iron.
Any help would be appreciated.