Correlating simulation result to pressure sensor

[Anonymous]

Hello there,

I am just trying to brainstorm some analysis steps for my simulation results. I know there is the stress result that I can probe to a particular point. For non-linear simulation, if I am trying to correlate how much pressure at a certain area after the forces are applied, I am wondering how to design those pressure sensors and how to correlate the simulated results to the sensors (to help to select commercial pressure sensors for example). 

Thanks in advance!

[Anonymous]

Could I interpret interrupt the contact pressure in non-linear model as the pressure "being feel" by the model?

[Anonymous]

Anyone? 😞

[Anonymous]

??

[John_Holtz]

Hi @Anonymous 

I do not fully understand your arrangement, in part because I am not sure what a pressure sensor is or what it is doing. 🤔

If you have two parts of an assembly that contact each other, and the pressure sensor measures the force (or pressure) due to the contact between the parts, then you are correct that the "Contact Pressure" result is the item that you want to use. The alternative is to use the stress in the direction perpendicular to the contact face. Those two results should be equal (but analytically, the two results are probably approximately the same.) If the perpendicular direction is in the global X, Y, or Z direction, the stress tensor result (XX, YY, ZZ) is easy to view. 

If my understanding is incorrect, please attach a sketch, image, drawing to help clarify the geometry and where you want to measure the pressure.

[Anonymous]

Hi @John_Holtz 

Thank so much for the response. I think you did explain what I tried to achieve with the simulation. But I am attaching a picture here to give you a better sense. 

As you can see in the picture, I am hoping to relate the simulation result to the pressure sensor datasheet and to predict what would happen to the sensors. 

 After the simulation, could I just say the estimated pressure of the sensors (with the use of the point probe) will be the contacting area between the column and the plate (the yellow area)?

Is there a better way to estimate that area ?? 

 

[John_Holtz · Accepted solution]

Thanks @Anonymous . I agree with your approach: define contact between the parts, and use the contact pressure result to choose the proper pressure sensor.

I suggest a relatively fine mesh on the contacting surfaces, and then make an average of the pressure over the area. The reason to do both of these is because there are variations in the results due to the approximation of the mesh. More elements (a finer mesh) will help to smooth out any "hot spots", and averaging the result over many nodes will further reduce the variations.

Fusion does not have any tools to average results over an area (unless they have "slipped" something in that I have not found yet), so you will need to do it manually.

Let us know if you have any other questions.

[Anonymous]

Hi @John_Holtz 

Thanks for the response. That makes sense. Just want to clarify a bit regarding "finer mesh". Do you mean that let's say I should try 10% in the simulation? (I am a bit new to defining mesh for the model) I thought I learned that the higher mash should give a more accurate result (correct me if I am wrong). Please see the attached picture.

Also, in my case, I think it might be easier for me to just estimate the area of the cylinder as the contact area( since I know the dimension)? Do you have any suggestions?

Thanks for your time 

[John_Holtz]

Sorry, it can be confusing when talking about mesh size (finer, smaller, larger) and the number of elements (fewer, larger), and so on.

I was suggesting that you use a smaller mesh size on the bottom of the cylinder and the top of the plate. Those are the two surfaces that are in contact. A smaller mesh size will result in more elements on the contacting faces, and this gives a smoother result.

On the Mesh Settings dialog you included in your image, 10% indicates to make larger size elements, and therefore fewer element in the model. 1% indicates to make smaller elements which results in more elements in the model. The results are more accurate when you have smaller elements = larger number of elements in the model.

In your example, it may be easy and not change the time it takes to run the analysis by too much by decreasing the mesh size in the entire model. That is, move the slider down to 5% or 3%. In more complex models, you may not want to increase the number of elements in the entire model when you really only want smaller elements (= more elements) on the two contacting faces. Instead of using the slide to change the mesh size in the entire model, use "Manage > Local Mesh Control" and use a smaller mesh size on the two contact faces.

I hope this helps.