*work in progress*
Intro
This page will show the simulation results for a 3-point bend test on 75 x 200 mm sandwich construction with various core thicknesses. The purpose of this test is to obtain the compressive strength and from that compressive strength, calculate shear strength. We will use the results from this simulation to compare with our in-person results to see if they conform to our standards.
Stackup:
The test specimen I used was a sandwich of a top layer using 3 layers of 0.15 mm prepreg, a 1 inch, 1/2 inch, or 1/4 inch nomex Nomex and a bottom layer again using 3 layers of 0.15mm prepreg.
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Figure 1: Picture of the test specimen with fibre directions
The loading condition:
For this test will be a displacement of -18mm on the middle of the top face of the test specimen.
Figure 1: Picture of the test specimen
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Figure 2: Fixed supports attempting to emulate the test setup from the ASTM standard (pictured below)
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Figure 3: Displacement of -18mm attempting to emulate the test setup for the ASTM standard
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simulation, I used a nodal force of 1000 N downwards on the top face. There are also fixed supports on both ends of the specimen, on the bottom face.
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Figure 2: Loading and Boundary Conditions
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Figure 3: Deformation of sandwich construction (1/2 4 inch core)
Results:
Specimen | Maximum Deformation (mm) |
|---|---|
1/4 Inch Nomex | 181.3222 |
1/2 Inch Nomex | 180.19458726 |
1 Inch Nomex | 180.10727903 |
1/4 Inch Nomex
Sandwich Layer | Minimum Stress (MPa) | Maximum Stress (MPa) | Notes |
|---|---|---|---|
Top Layer | -146979.9727 | 73967.8187 | Averaged value |
Honeycomb | -0.0285680015432 | 0.0143240014185 | |
Bottom Layer | -70764.8794 | 140676.5318 | Averaged value |
1/2 Inch Nomex
Sandwich Layer | Minimum Stress (MPa) | Maximum Stress (MPa) | Notes |
|---|---|---|---|
Top Layer | -158040.6422 | 78434.03893 | Averaged value |
Honeycomb | -0.03210300082218 | 0.0158300076126 | |
Bottom Layer | -76634.35106 | 154539.0351 | Averaged value |
I Inch Nomex
Sandwich Layer | Minimum Stress (MPa) | Maximum Stress (MPa) | Notes |
|---|---|---|---|
Top Layer | -165020.13348 | 81217.06697 | Averaged value |
Honeycomb | -0.034290004234 | 0.01675300039471 | |
Bottom Layer | -80217.7492 | 163120.13113 | Averaged value |
Below are the three pictures of each layer, going from top to bottom. I haven’t included all three thicknesses of Nomex as all of them look pretty much the same so I didn’t feel the need to include them all, these pictures will give an example of where the max/minimum stresses occur.
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Figure 5: Top Layer
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Figure 6: Middle Layer
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is a table of where the stresses occurred in the 1/4 inch Nomex
Layer | Stress |
|---|---|
Top |  Comment: Max stress of 64.94 MPa on red area. |
Middle |  Comment: Max stress of 0.0014185 on red area. |
Bottom |  Comment: max stress of 72.423 MPa on red area. |