TFP Output

[mkumar3]

I have some problem with TFP element output. My set up is the simplest possible, a two noded structure with both nodes fixed in horizontal direction. One of the nodes is being given cyclic displacement using SP command.

I kept the axial load fixed at 1.5 MN, coefficients of friction at the exterior surfaces 0.8 and for the interior ones, I varied from 0.01 to 0.20. The elastic force should have varied from 15000 N to 300000 N. However, the analysis results are showing a variation from 60700 N to 347500 N. If I subtract 45000 N from each of the numbers, I get what the elastic force should have been.

The problem, I think is the following. It does not ask the user to define a yield displacement. Rather, the yield displacement seems to be defined at about 0.021m, which for a load of 1.5 MN and the effective radii for the interior surface 0.33m (or 13 in), implies a force of about 47000 N in addition to mu.N.

Can you please look into it and let me know if I am interpreting something incorrectly?

Manish

[vesna]

Try not to fix the node in direction in which you assign SP command.

[mkumar3]

But, how does it depend on boundary condition? I have anyway given my code in the other post. Please take a look and let me know if changing the boundary condition will fix the problem.

I feel that as coefficient of friction is increased, the maximum elastic force should increase proportionately.

[vesna]

I looked at your code and saw that you are multiplying displacements defined with SP command by two. With a fixed dof in direction of applied displacement you will achieve the displacements you want.

I do not know much about this element. I suggest you to read Tracy's paper to see how she calculates the forces. If you still have some doubts try contacting her directly.

[mkumar3]

I tried finding her contact yesterday. Can you help me with that?