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8-Gravel

## Prime 7 and odesolve

I recently encountered an issue with Prime 7. The function odesolve doesn't work the way it used to in Prime 5 and I can't figure out why.

I'm updating my MathCAD sheets to Prime 7 and my current header and coding standards, and finding that there's an issue with odesolve.

Here is my solve block showing the differential equation for deflection of a beam. It's a simply supported beam, so deflection delta at 0 and at the beam's end L are both zero.

E is in units of GPa, Iy in units of mm^4, length l in units of m, and M(x) in units of kN*m. I have verified that all units are correct.

When I open this MathCAD sheet in Prime 7, I get an error "These units are not compatible", but when I open it in Prime 5, I get no error and the thing works.

What is different about Prime 7 that causes the functionality not to work anymore? MathCAD sheet attached.

Thanks!

ACCEPTED SOLUTION

Accepted Solutions
8-Gravel
(To:KevinFinity)

OK... I don't know why this is, but I solved my problem. You're not gonna believe the solution.

In the boundary condition at d(l) = 0 in, I had to delete the units from the right hand side of the equation.

I don't know why, and it definitely shouldn't work this way, but it works.

5 REPLIES 5
8-Gravel
(To:KevinFinity)

OK... I don't know why this is, but I solved my problem. You're not gonna believe the solution.

In the boundary condition at d(l) = 0 in, I had to delete the units from the right hand side of the equation.

I don't know why, and it definitely shouldn't work this way, but it works.

21-Topaz I
(To:KevinFinity)

Hi,

You could directly calculate the maximum deflections.

Cheers

Terry

Thanks, Terry.  The reason I do it using odesolve and not the direct formula is because I sometimes need to change the M(x) equation. It's easier and I make fewer mistakes to only change one thing.

23-Emerald III
(To:KevinFinity)

Some calculus. if I made no mistake, gives:

You should be able to compare that with the Odesolve result.

(I'll leave the other ODE to you...)

Success!

Luc

8-Gravel
(To:LucMeekes)

Hi Luc,