Learning Forum

[Diane]

Hello, nI have a 2 step static structural simulation of a 2D model. In the first step I reposition Body A by applying a displacement load in the X and Y direction (the other bodies in contact with it get deformed accordingly). In the second step I apply a pressure load on my geometry but the repositioned body (body A) is not displaced by the pressure load because it is fixed in the location it was repositioned too. nIs there a way I can make Body A free to be moved by the pressure load without having to deactivate the displacement load and returning the body to it's initial position? I want Body A to be free to be displaced by the pressure load in step 2 from it's new position while keeping the stress and strain resulting from the displacement load applied in step 1. nLet me know if further clarification is needed. nBest, nDiane

[peteroznewman]

nIt seems you expect the pressure load will hold body A in position without the displacement.nIf that is true, try a 3 step solution. Step 1 applies the Displacement, Step 2 applies the Pressure, Step 3 deactivates the Displacement.nI expect body A will move during step 3. You can minimize the movement by adjusting the pressure.nWhat happens if you have a one-step solution with Pressure only? Can you get Body A to move close to the position that you want?nIt would be helpful if you insert an image of the geometry, the displacement and the pressure so I can see what you are working with.n

[Diane]

nIt's not exactly that. The geometry represents the structure of an upper airway as shown in the image below and body A is the selected face that is displaced 5mm in the positive Y direction in Step1. nA negative pressure is applied to the airway walls in step 2 as shown below.nThe movement of body A is an important factor and output in my study. When a pressure is applied at the airway walls, body A usually displaces with the other structures. The total displacement of body A is shown below for a 1 step simulation with the pressure as the only load. nI want to be able to compare the movement of body A when it is in its original position and after it is displaced to a more cranial or caudal position. So after body A is repositioned by the displacement load I want to give it some freedom to move in response to the pressure load. Do you think this is feasible? nThank you for your help!nBest, nDiane n

[peteroznewman]

nProbe the Reaction Force on the Displacement and find out what it is at (0, 5) mm, and call that Fx and Fy.nSuppress the Displacement and add a Force to that face with the X component equal to Fx and the Y component equal to Fy.nNow in Step 1, Body A will move up by 5 mm and be free to move anywhere else in Step 2 when the Pressure is applied. nSince you are holding a Face, there may also be a moment required to replicate what happened in Step 1.nA simpler situation is if you create a Remote Point on that Face and Apply the (0, 5) mm as a Remote Displacement. Then there is zero torque applied because you are moving a point not a face, and the Probe on the Reaction Force will give Fx and Fy that, when applied to the Remote Point as a Remote Force instead of a Remote Displacement, will exactly repeat the position achieved in step 1 with the Remote Displacement.n

[Diane]

It works perfectly, thank you Peter!n