3 Point Bending Test of a Carbon/Airex Sandwich Structure on Ansys
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- เผยแพร่เมื่อ 17 ต.ค. 2022
- A quick demonstration of a 3-point bending test of a Sandwich Composite Structure made of carbon fiber and Airex C70.75 foam core.
Material properties and CAD file: bit.ly/3_Point_Bending_Test_D...
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This is truly helpful, I have some questions.
This is really helpful, would you please let me know how can I add honeycomb core instead of solid core in sandwich structure?
Hello @graihan57
Honeycomb core should be defined in the material selection.
If you want to have more realistic results you will have to design you own honeycomb structure but this will make the model way more complicated and can lead to conversion problems.
This is really helpful! But can you please tell me how I can calculate bending stress and max? bending stress? I tried calculating bending stress from solution>insert>stress and bending stress, but I couldn't select the geometry. The Beam tool is not working .....
Bending stress is a function of the bending momentum, momentum of inertia and vertical distance from the neutral axis (section ). We can calculate the bending moment by removing the force reaction from the results and multiply it by the distance you are studying, let's say in the center of the bar L/2 ( m = F * L/2) . Momentum of inertia you can find the formula online for the section you have. And distance from the neutral axis will be also dependent on where you want to study the results? if it is on the outside part it will be c/2 and in the middle is 0.
Hello, thank you for this tutorial.
I tried following your steps but I'm having errors. I need to simulate a composite material that has a sensor inlay. I'm to put the inlay in middle layer and in another test it will be in quarter position close to the support. Experimental results show that the stress in quarter position should be more than that in middle position. When I tried the simulation, I'm getting the opposite. I tried using frictionless and frictional contacts but it didn't solve. The Ansys is 2021 R1 version.
What do you suggest? Or can you make a video showing this? This case study has to do with structural health monitoring of composite structures using sensors.
Hi there @obigwevincent4598,
If you are doing a standard 3-point bending test (following any ASTM or ISO regulation) you should get the highest stress in the center of your specimen. Of corse, I am talking about normal stress. Maybe you are getting shear stress results in your experimental. No?
If this is not your case, the sensors you are using may be defective or not properly calibrated.
I can make a video on Ansys 2021 in the following days, but the results will also be higher in the center center of the specimen.
@@rodrigo_correia thank you for your detailed reply. In various academic investigation it is said that the stress of a composite with a sensor inlay in the middle layer (close to neutral fibre) is less than the stress when the sensor inlay is close to the outer layers. I tried modelling this scenario in Ansys using to support this. The Von mises stress is giving me the opposite. The shear stress on the other hand supports the findings. I expected the normal stress to do same but the normal stress was more in the middle position.
Do you have any possible solution as to why the results don't conform to literatures.
@@obigwevincent4598 No worries!
When you referred to the middle I didn't understand it was the middle layer. I understood that you were talking about the entire middle section of the composite.
In that case, you are correct! Stress increases as a function of the outwards distance to the neutral line. You will have more normal stress in the bottom and top faces being the top one subjected to compression and therefore, the first to fail.
I will record a video on Ansys 2021 with a couple of carbon fiber layers and show you my results for each layer.
@@rodrigo_correia thank you, I look forward to seeing your video.
@@obigwevincent4598 Hello there,
I've just posted a new video regarding your situation.
Hope it helps you :)
I tried using frictionless support but I keep getting errors. Can I work with bonded?
You can work with bonded but you will have additional induced stress by the extra tensioning/compressing of the lower and upper faces respectively, which does not happen in a real three-point bending test.
If frictionless doesn't work, try using a frictional supports with a low friction coefficient of around 0.1 (You can find it when assigning the connection method).
If none of this helps, try using Ansys 2021. I found that it converged a lot more in my case studies 😊
@@rodrigo_correia okay, thank you so much. Your explanation is the best I have seen.
@rodrigo_correia Also, in my analysis I'm expect to use force and not displacement. I replaced your remote displacement with remote force. Is that same with real life scenario?
In real life, you would be applying a force and a displacement would be returned to you (just like you said).
You can use a force, and it is the most correct way, but Ansys doesn't really "like" that approach and normally the simulation never converges.
A solution to that problem is doing an analysis for a high deflection using a force probe ( solution > insert > probe > force) which will give you the reaction force (equal to the force in this case) for that same displacement. You can use steps in the simulation to get lower displacements and find the force reaction you want. A bit like reverse engineering.
@rodrigo_correia thank you so much, will try this.
7:51 Excuse you!