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IgorBraz1-Visitor
1-Visitor
January 29, 2020
Question

Differential equation

  • January 29, 2020
  • 2 replies
  • 4529 views

Hi, 

 

I'm trying to solve the Differential equation of motion using the comand rkfixed, however I'm not getting.

 

The correct form to write the equation is in the captura in the attachment, but the Mathcad not solves it, just solve if the mass divide all terms (stiffiness and damper)

 

Can anyone help me please?

 

2 replies

F
Fred_Kohlhepp23-Emerald I
23-Emerald I
January 29, 2020

I believe your mathcad sheet is correct and your png is wrong, from the equation for forced harmonic motion:

Capture.JPG

But that does not explain why the png form doesn't work.  Since I have only Express I can't do more, sorry!

I
IgorBraz1-VisitorAuthor
1-Visitor
January 29, 2020

Hi  FredKohlhepp, thanks for your answer

 

In fact you're right. thanks very much for your help

F
Fred_Kohlhepp23-Emerald I
23-Emerald I
January 29, 2020

Note that Prime can use units in differential equations (I don't think that Rkfixed can, but a solve block using Odesolve can.)  Units, and the proper conversion of them, was/is one of the primary benefits of this software.  So you can use:

Capture1.JPG

W
Werner_E25-Diamond I
25-Diamond I
January 29, 2020

You may consider using a solve block with odesolve

B1.PNGB2.PNG

    I
    IgorBraz1-VisitorAuthor
    1-Visitor
    January 29, 2020

    Werner_E, Thanks for your answer

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