Pneumatic Finger Simulation

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  • Last Post 05 March 2019
georgemanarnar posted this 27 February 2019

The only way (that I have found) to simulate the effect of pressurized air inside the finger, is to first select all the surfaces and then deselect the surfaces that will not be under the influence of pressurized air. This way I get to select the inside walls of my finger. Now, I apply collective pressure on the selected surfaces and get my result. This is a very tedious way to do it, and also doesn’t feel like the right way. Is there a way to simulate (pressurized) air going in and out?

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rwoolhou posted this 27 February 2019

I'm not sure I follow. Are you looking at the movement of the air, or the stress/strain the pressure puts on the "finger"? 

peteroznewman posted this 27 February 2019

Is this a Structural model or a CFD model?

If it is a Structural model, you are in the Mechanical program defining the pressure.

If the inside of your finger has a collection of faces that have tangent geometry at the edges, and are not tangent at the edge where the inside ends, then there is a very useful button with a pull-down called Extend to Limits. You would pick one face, then use keyboard shortcut Shift+F2 or the pull-down to have the program automatically select all faces that are tangent to that or each other.

georgemanarnar posted this 27 February 2019

I want to simulate the flow of pressurized air into the finger and consequently observe the deformation, stress, etc., due to that.

This is the video that is used as a reference, but my design is different. Watch from 7: 30 onwards. 

georgemanarnar posted this 27 February 2019

It is currently a Structural model. I do not think a CFD model will give me what I want.

Also, I did not understand the latter part of your post. My apologies.

 

 

peteroznewman posted this 28 February 2019

You could pick all those internal cavities using a single Box Select without having to deselect any outside faces.

rwoolhou posted this 28 February 2019

In CFD we'd model the flow, and you can then pass the pressure over to Mechanical. However, depending on the system you may just need to apply the pressure to the surfaces.  In CFD we need the fluid region to be a volume: ie we mesh all the bits that aren't metal. 

peteroznewman posted this 28 February 2019

When you say, "I want to simulate the flow of pressurized air into the finger" you don't mean that, you mean you want to simulate the effect of pressure increasing and decreasing on cavity faces of the body, right?

georgemanarnar posted this 28 February 2019

Yes, I mean the effect of the pressure. But the air pressure is fixed.

I am adding a picture of my model here.

Finger

The air into this finger. It has chambers, and a channel that connect one chamber to another. The air pressure set at 10psi

peteroznewman posted this 01 March 2019

Do you know how to use the Box Select cursor instead of the Single Pick cursor?

If you draw the box from left to right, any face completely inside the box is selected, if you draw the box fro right to left, any face that crosses the box is selected.

georgemanarnar posted this 01 March 2019

So the thing is, I want to avoid the approach of selecting surfaces and then applying pressure. Your approach might be helpful for easier designs like the photo i posted, but for more complicated designs, unnecessary parts and surfaces will get selected too. And I will have to revert to my original method of deselecting those parts and/or surfaces. 

I want to simulate a scenario where I insert a pipe into the finger, allow air (at a certain pressure) flow into the finger and observe what happens.

peteroznewman posted this 01 March 2019

The other approach is to modify your geometry to make selection easier. Put a blend on the edges of all the cavities so that creates a collection of faces that have tangent conditions at the edges of faces, then there is a very useful button with a pull-down called Extend to Limits. You would pick one inside face, then use keyboard shortcut Shift+F2 or the pull-down to have the program automatically select all faces that are tangent to that or each other.

 

georgemanarnar posted this 03 March 2019

That's the thing. I don't want to use this approach. I want to know if there's any other method.

peteroznewman posted this 05 March 2019

If there are many faces with identical face size, you can pick one face, then type N on the keyboard to open the Named Selection dialog box, then click items with the same area, and it will pick all those faces.  Do that for each uniquely sized face.

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