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Cantilever Deflection (I need help) - HP50
11-22-2020, 09:51 PM (This post was last modified: 11-22-2020 09:57 PM by CMarangon.)
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RE: Cantilever Deflection (I need help) - HP50
(11-22-2020 05:59 PM)Geoff Wrote:  I don't have a 50g, so I can only reply as a civil engineer.

For the values you selected 195 cm is the correct answer. However, the equation you show isn't what's used to arrive at 195 cm.

The first term (involving P) is only correct for x smaller than a. It should be (Pa²/6EI)(3x-a) for x greater than a. If the calculator had used the formula you show it would have reported 192 cm, so I suspect it's using the correct formula somehow.

The second term (involving M) also appears to only be for x smaller than a. A mid-span moment is unusual so I can't easily lay my hands on the correct formula for any x, but I do know the formula for the outer end. This load is only causing about 1 cm of the deflection so any formula error mid-span would be small.

The third term is correct for all x as the load is full length.

In reality a cantilever 20 m long made from such a small beam will fail, and the end deflection will be the distance to wherever it's laying on the ground. < grin >


Indeed, I have concluded that these are irreal values for a cantilever.
A cantilever of 20m long and 20cm x 30cm, should not support even its self weight.

I will also calculate its slope. I suppose that it gives a
value able to bent it 90 degrees or more.

At HP-50 AUR, 5-6 (chapter 5, page 6), it gives
a good exmple, but in ENGL units.
All I need to do is convert:-)

Thank you!

Carlos - Brazil
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RE: Cantilever Deflection (I need help) - HP50 - CMarangon - 11-22-2020 09:51 PM

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