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.
Please help!
Thanks!
Solved! Go to Solution.
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.
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.
Hi,
Glad you found the problem.
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.
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
Hi Luc,
Your answer is really close to the formula published at
Digital Edition - 14th Edition Steel Construction Manual (usc.edu)
Well done with your calculus!