Problem in Boundary Condition (Modelling of a Lower Prosthetic Leg).

[Fhdak88]

Dear All,

I am working on a problem ‘FEA of a Prosthetic model’. The Model is basically a hinge type model which consist of three parts; Part 1:The Prosthetic foot with a Flange, Part 2: the Monolimb with a Flange, Part 3: Pin. The assembly is; Part 1 and Part 2 are connected coaxially with a Pin. (as shown in the jpeg attached below). Material used for all the tree parts is ‘300 Series Stainless Steel’. The first part of the problem is to apply a pressure at the monolimb in the vertical direction followed with running the simulation. The steps that are created are as follows: Initial, Contact (General Static) & Load (General Static).
Now, I have already configured the interactions by ‘Find Pairs’ and setting the interaction property as frictionless. However, My doubts are related to the Boundary Questions & therefore here are the questions that I am seeking answer for:
1) What kind of boundary conditions I should set for all the three parts?
2) How should I configure the boundary conditions in ‘Boundary Condition Manager” for the simulation.

Please Note: I am applying the load in the vertical direction.

Please Look in the picture attached below for a more clear picture.

Thank you in advance.
Fhd

 

[corus]

Once contact has been made then a restraint on the foot to prevent translational and rotational movement is all you need. The 1st step should therefore to be to set up contact by applying a displacement instead of the pressure and restraining each part. When you have several parts as in this case you may need more than one step to initiate contact, successively restraining each part and allowing the applied displacement to make contact through each part. Then remove all the restraints to initiate contact and apply your pressure.

 

[rstupplebeen]

I would model the floor as a rigid surface. As Corus said a displacement force may be more appropriate since the pressure load will tend to rotate freely because of your frictionless constraint. Wouldn't the pin be press fit or threaded into one side so that it wouldn't rotate or translate with respect to part 1 or 2? I hope this helps.

Rob Stupplebeen

https://sites.google.com/site/robertkstupplebeen/