New Free Volume and Weight Calculator

Before I get all excited, is this a Win32 application ? The screenshot doesn't look like you used MFC or any other Microcrap-only tools ... If you don't intend to someday turn it into a commercial program, source would allow Linux and other Unix users to compile for their own platform ... Or if you did it in Java - yeah, ugh, but then it would be cross-platform ...

That's about right.

Strength depends on the alloys being considered. There are aluminum alloys up to about 75Ksi tensile and steels up to about 250Ksi but whether they are practical in a given situation ...

However if you can come up with a strong enough design, the deflection would be about the same. Steel has 3 times the weight and 3 times the elastic modulus.

Ted

Huh? Volume of a sphere is (4/3) pi r^3. Hollow sphere is (4/3) pi (R^3 - r^3).

How can it be faster?

Ted

Thanks Ted.

It appears to be. It downloads as a ".zip", and "unzip -l" (on unix) shows that it contains a ".exe" file which could be either Windows or MS-DOS. Size of the executable is 206k, which suggests that it is tailored for Windows. I'm not going to bother unzipping it and looking with strings to see what usage messages it may have (like I do with new virii. Something that claims to be a sound file, but contains strings like "This program cannot be run in DOS mode!" is a pretty good clue that it truly is a virus. (Unlikely in this case, of course.)

Yes -- source would be a nice thing -- then I could have a crack at making it run on my unix boxen.

Enjoy, DoN.

[ ... ]

I think that what he wanted to do is enter the OD and the desired weight, and have it come up with an ID for his hollow sphere to get the right weight.

Enjoy, DoN.

If that's the case, would it be a capability that a lot of folks would benefit from?

Mike

Nicely done, Mike. The abilities to work in mixed units and fractions is very welcome.

Gary

Seems likely it would be useful to casters. Might be useful to others too, if they were trying to build something that would float.

I like your program as is, but it could be somewhat more generally useful if you allowed any fields to be inputs and any fields to be outputs, depending on where the user plugged in numbers. In other words, if it could solve for any missing numbers once enough numbers had been input to give a unique solution.

That's a pretty ambitious requirement, though. Some of the equation engines (Mathcad, TKsolver, etc) can do it, but it isn't a simple programming task since the engine has to be able to determine when it has enough information to arrive at a unique solution for a given shape.

Gary

.exe's are also used/run in OS/2. Of course the OS calls are different.

Things like GLURP.JPG.EXE are used to spoof windows users since the default browser setup only shows the first extension. Why am I not surprised? Of course, DoN knows this but others might not.

Ted

Probably. Seems doing a bit of elementary math is something many (most?) are allergic to.

Ted

Worse, even when you tell Explorer NOT to hide file extensions, it still hides some of them. For example, a .lnk file is used as a sort of symbolic link (alias) to a program, and Explorer won't show the .lnk suffix.

Dave

I thought about it some after Jerry's sphere question popped up. Aside from the unquestioned value of being able to "force" one dimension so as to arrive at a given weight, would you ever actually reduce the total number of entries? It seems to me that the last dimension would always have to await the evaluation of the second to last. And not having to input the last would be cancelled by having to manually input the weight.

I'm not a mathematician, just a hobbyist programmer. It would be great to hear some other thoughts on this.

Mike

On Sun, 6 Jul 2003 22:54:03 +0100, "sniffer" wrote something ......and in reply I say!:

Ted. I did not get your message direct, bu7t can read it here. SO.

I am not sure if you were among those that guided me through this maze, but the Elastic modulus is not the whole story, from my extensive blundering about on this subject. High tensile steel is "stronger" than mild steel mainly because it can withstand more distortion before Elastic Modulus (Young's) is overcome and the metal reaches its permanent deformation point. Young's then no longer applies.

My favourite examples are spring steel and mild steel. The spring is actually no "stiffer" than the mild steel, but continues to resist permanent deformation for a long time, while also applying Young's modulus to a greater and greater strain. Both will have a YM around

210 MPa.

So the "tested stress maximum" is often more important than the Elastic modulus.

How does this apply to aluminium vs say, mild steel? From the Beam.exe programme it appears about the same using a 100mm tube, with a 6 mm wall of alum and a 2mm wall of steel. Both reached approixmately the same proportion of their failure strain under a given load.

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Actually I would say that or consider you to be an Mathematician Michael. How many people do you think in the world to the world population can do what you do. Rocket science, hell its all science. You know sometimes, I think if you or I didnt know what we know now, wouldnt it be wonderful to be a younger guy then, doing what you do now At 37 I can't go back, but he will sure give one hell of a fight on the way out

Exactly so.

Often there are two criteria for a satisfactory design: It must be strong enough so that it will not fail. It must be stiff enough so that it doesn't deflect more than an acceptable ammount.

For example, most building codes state that floor joists must be strong enough that the floor can withstand so many lbs/sq. ft. They also state that the deflection must not exceede 1 unit/so_many_units of length. Frequently this requires far "stronger" joists than would be necessary for resistance to failure.

Considering your tube (I recall the raw data for an inch system so I'm adjusting the diameter and wall): BeamOut ''(10E6,I_tube 100 6÷25.4)Beam 0 120 (60 1000) {Aluminum} pos'n pt. shear bend. slope def'l force stress stress 0 -500 -363.1 0 0.01906 0 60 1000 363.1 -12510 0 0.7626 120 -500 0 0 -0.01906 0 BeamOut ''(30E6,I_tube 100 2÷25.4)Beam 0 120 (60 1000) {steel} pos'n pt. shear bend. slope def'l force stress stress 0 -500 -1047 0 0.01689 0 60 1000 1047 -33240 0 0.6754 120 -500 0 0 -0.01689 0

The deflection are close but not identical. This is because the tube wall is not *VERY* much less than the OD. The thinner the wall, the closer the deflections would be. The stress is roughly 1/3 in the aluminum tube. An aluminum alloy with a yield strength of (say) 36Ksi would be stressed to only 1/3 of its yield. A 36Ksi yield mild steel (water pipe grade) would be stressed to about 90% of its yield but a

100Ksi steel alloy would be stressed to the same fraction of its yield.

Simply put, you must design for both sufficient strength and sufficient stiffness.

Hope this helps.

Ted