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| For t=0.0020 and dia=0.250, I ran 10 cycles up to 200 psi to see if it would fatigue and fail early. On the 11th time, I took it to failure at 250 psi. Note that the actual Ftu doesn't seem to match the trend of the other samples. I wonder if the multiple cycles contributed to some strain hardening. |
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| For t=0.0050 and dia=0.375, I ran two samples. One failed at 480 and the other at 470 psi. |
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| Discussion: |
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| My crude analysis assumes the failure mode is hoop tension in the dome of the disk prior to bursting. The failure mode probably isn't just hoop tension - there probably is some shear but I don't have the shear stress allowables for 1145-0 aluminum. Also, I don't know the tolerances on the aluminum sheet thicknesses or on the material properties. |
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| Material |
Brass sheet (C360?, unknown material condition) |
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| FTU |
??? |
psi |
(from data sheet) |
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| Units are inches and psi |
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fTU = Pd/4t |
(hoop stress) |
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Hole dia. |
0.375 |
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Burst pressure (psi) |
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| Thickness (inches) |
Actual |
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| 0.0020 |
400 |
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| For the tests with brass, I ran 5 samples and they burst anywhere from 390 to 410 psi. |
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| Discussion: |
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| The brass evidently has a much higher ultimate strength than the 1145-0 aluminum sheet, around 18750 psi based on my calculations. |