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Differential equation

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Participant

Differential equation

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?

 

6 REPLIES 6
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Re: Differential equation

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!

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Re: Differential equation

Hi  FredKohlhepp, thanks for your answer

 

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

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Re: Differential equation

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

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Re: Differential equation

Fredkohlhepp, I used to solve using odesolve comand, however I stoped to use it when a try to input a second fredom degree (TMD). The Odesolve comand didn't work well, the response was different from analytical solution.

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Re: Differential equation

You may consider using a solve block with odesolve

B1.PNGB2.PNG

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Re: Differential equation

Werner_E, Thanks for your answer

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