Compress & External Pressure Charts/Tables
Compress & External Pressure Charts/Tables
(OP)
I am having trouble correlating a value for 'A' given by Compress and one looked up (and even interpolated) manually when calculating a shell and ellipsoidal head for external pressure.
I was wondering if anyone knows how Compress finds this value? I would assume that the method used for finding a value from Figure or Table G would be the same method for finding value B from the appropriate chart.
I was wondering if anyone knows how Compress finds this value? I would assume that the method used for finding a value from Figure or Table G would be the same method for finding value B from the appropriate chart.
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RE: Compress & External Pressure Charts/Tables
I believe Compress uses double logarithmic interpolation of Table G.
I have developed a spreadsheet for doing logarithmic interpolation. Tell me the values of L/Do and Do/t, and I will give you the value for 'A'. See if it matches the one calculated by Compress.
RE: Compress & External Pressure Charts/Tables
L/Do = 1.7037
Do/t = 247.8448
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RE: Compress & External Pressure Charts/Tables
RE: Compress & External Pressure Charts/Tables
Interesting...UG-28(c)(1) Step 3 states: '...interpolation may be made for intermediate values of Do/t...'
I used linear interpolation using the tables...probably not the best method. Looks like I'll be developing your spreadsheet for myself, doc.
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RE: Compress & External Pressure Charts/Tables
Your double logarithmic interpolation should like this...
y = 10^[log(y1) + (log(x) - log(x1)) * (log(y2) - log(y1)) / (log(x2) - log(x1))]
I've attached my "rough" spreadsheet for your reference.
RE: Compress & External Pressure Charts/Tables
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