Edits in strike-through and italic.
Do you know what psi means? It means pounds per squre inch. The word "per" indicates division.
Notice how it is defined in the wiki page here: [en.wikipedia.org]
Notice it is written as lbf/in². Notice there is division there not a multiplication.
How could you write it in maxima as (18000 * pound * inch * inch) instead of the correct (sans the 18000 tern) way which is (18000 * pound / inch^2)?
Instead of writing this correctly into maxima you made up a scifi theory that the term for belt cross section area needs to be somehow proportionalized instead of just used directly with its unit of inch². The expression for area should be (0.000434*inch*inch) and not your magic (1* inch * inch /(0.000434 * inch * inch)). If something in math is not working out (e.g. your final unit in 1/meter³), you do not go to introduce fudge factros willy-nilly to correct for it. You must correct the primary source of error which in your case was writing psi as pound*inch*inch instead of the correct term pound/(inch*inch).
Now this is not the end of your errors in your maxima script. How could you use "modulus" from the Gates document for a glass core? The modulus in the Gates document is for the whole belt not for the core only. If you would want to use it you cannot consider only the glass cross section but use Note 4 of the gates document. In your script, you should have used the modulus for glass fiber only which you specified in your first post:
Look how it looks when it is correct:
You are confused so much here that it is starting to be funny.Quote
A2
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The only way you can get the units to work out using the new input of cross-sectional area is to proportionalize
the area of the glass fiber bundles over 1 square inch before multiplying by the modulus of the belt, i.e. (1* inch * inch /(0.000434 * inch * inch)).
If you don't do that you get meter3, which is a bogus conclusion.
Do you know what psi means? It means pounds per squre inch. The word "per" indicates division.
Notice how it is defined in the wiki page here: [en.wikipedia.org]
Notice it is written as lbf/in². Notice there is division there not a multiplication.
How could you write it in maxima as (18000 * pound * inch * inch) instead of the correct (sans the 18000 tern) way which is (18000 * pound / inch^2)?
Instead of writing this correctly into maxima you made up a scifi theory that the term for belt cross section area needs to be somehow proportionalized instead of just used directly with its unit of inch². The expression for area should be (0.000434*inch*inch) and not your magic (1* inch * inch /(0.000434 * inch * inch)). If something in math is not working out (e.g. your final unit in 1/meter³), you do not go to introduce fudge factros willy-nilly to correct for it. You must correct the primary source of error which in your case was writing psi as pound*inch*inch instead of the correct term pound/(inch*inch).
Now this is not the end of your errors in your maxima script. How could you use "modulus" from the Gates document for a glass core? The modulus in the Gates document is for the whole belt not for the core only. If you would want to use it you cannot consider only the glass cross section but use Note 4 of the gates document. In your script, you should have used the modulus for glass fiber only which you specified in your first post:
So the final proper term for yung modulus in the maxima script should be (10000000 * pound / (inch*inch)).Quote
A2
Fiberglass
Tensile Strength 350,000 lbs/in^2
Elongation at break 2.5 – 3.5%
Modulus 10,000,000 lbs/in^2
Look how it looks when it is correct:
zsh> rmaxima Maxima 5.32.1 [maxima.sourceforge.net] using Lisp SBCL 1.1.14 Distributed under the GNU Public License. See the file COPYING. Dedicated to the memory of William Schelter. The function bug_report() provides bug reporting information. (%i1) A: (6.423*pound) * (39.37*inch); (%o1) 252.87351 inch pound (%i2) B: (Notice also that I got the result in a nice unit which is inch. It makes sense to measure elongation in inches. Notice you got the resutl in 1/inch (your inch is in denominator). How could you measure elongation (i.e. length) in (1/inch)?1510000000*pound/(inch*inch))*(0.000434*inch*inch); (%o2)6514340.0 pound (%i3) A/B; (%o3).03884385714285714.05826578571428571 inch (%i4) ^D zsh>
No, I'm not. * means multiplication in maxima. It is no special kind of placeholder. It is the sign for multiplication in maxima. So you did not show my proof of you being wrong to be incorrect.Quote
A2
You are confusing wxMaxima place holder (*) as multiplication.
Do not make things up! I did not say the Gates equation is wrong. I saied there is a contradiction in the document.Quote
A2
hercek, you continue to claim that the Gates equation is wrong, then why don't you show us the correct equation?
I said that either their formula is wrong or the unit for their special kind of modulus is wrong. Here I even posted a proof that their document contains a contradiction: [forums.reprap.org]Quote
hercek
Hell, that documents must be writen by heretics of physics. Not only the authors use "hogshead" units, but they cannot even get it right, even with them. Ok, so they define modulus as lb/in² but (based on the formula (in note 7) for ussage of their modulus values) the unit is actually only lb. Or at least I hope this is what they intended (one cannot be completely sure when they have contradictions even in such a simple document).