
Re: Derivative of two functions
FredKohlhepp Jan 3, 2012 5:58 AM (in response to Marcin)Try renaming your derivative function; the apostrophy isn't working the way you think it should.


Re: Derivative of two functions
FredKohlhepp Jan 3, 2012 8:39 AM (in response to Marcin)Your original function t(x,q)' was the first derivative of t(q) with respect to q as a finite difference. Using the derivative functions in mathcad will not give you the correct form of that equation, especially the derivative with respect to x, which you don't want.
just rename t(x,q)' to something else dT(x,q) := (t(x+q)  t(xq))/(2q) and get the evaluation that way.

Re: Derivative of two functions
FredKohlhepp Jan 3, 2012 1:00 PM (in response to Marcin)I don't have Prime available right now, so the attached file is xmcd (regular Mathcad.) I've added a pdf for the mathcad impaired.
I'm worried about your equation for stress areastep changes in area are rare in real life. I've plotted area (assuming I wrote it right) and a simplified area (only the first term. Both blow up at pi/2beta.
Given area is right, you can then compute tau, shear stress. And I've given you two ways to get the derivativea numeric computation and a symbolic deerivative of the "simple" stress (available in mathcad and Prime 2.0, not in Prime 1.0.)
Helps?

shear stress lug.xmcd.zip 68.5 K




Re: Derivative of two functions
VladimirN. Jan 13, 2012 12:01 AM (in response to Marcin)You work in Pro/ENGINEER?



Re: Derivative of two functions
VladimirN. Jan 13, 2012 12:37 AM (in response to Marcin)Why not use in this case, Pro/MECHANICA (for strength calculations by using FEM)?


Re: Derivative of two functions
Marcin Jan 13, 2012 2:03 AM (in response to Marcin)I have done FEA using Pro/mechanica
Somebody have done similar calculation previously where dog stop was calculated manually and I would like to use this example for my design to confirm that FEA is correct