Tension in Non - linear springs - How do I measure it?
I am modeling ligament structures in the knee joint finite element model with non-linear springs and I am successfully getting non-linear displacement curve.
My only problem is with the calculation of tension in the springs. I have a set of non-linear springs representing a particular ligament in the joint, which is having an elongation when I apply the forces on the joint. I am giving pre-load to the springs so that they do not have any slack in them before the analysis. I am also specifying the stiffness of the springs (corresponding to the stiffness of the ligament material). I cannot use connector elements. In the post-processing,I am trying to check the S11 of the nonlinear springs and all I could see is a decrease in the value i.e. a value less than the pre-load I specify.
If the springs are having elongation, then they should have tension in them. Where can I check this tension?:confused::confused::