I Need Some guides to Write a code or model a single and double pendulum problem in FEM 1

[frztrb]

Hi All

I was interested to solve some dynamic and modal analysis of pendulum , in FEM , need some guides to know after knowing the equations of motion , where to start and how to transpose them into FEM , any useful link or resource is also welcomed

thanks All again

 

[IRstuff]

Having trouble picturing why you'd use FEM, unless that's just a misnomer. The equations can be discretized, but the problem is a rigid body motion problem. You can start with:

http://ctms.engin.umich.edu/CTMS/index.php?example=InvertedPendulum&section=SystemModeling

but I would guess there are dozens of sites with similar information

TTFN
faq731-376

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[frztrb]

I would like to solve both with FEM and MATLAB so I can compare the M and K matrices that are extracted , to know if they are equal , and under which conditions there might be differences , I need to learn all the possible ways to solve it , through modal analysis let's say.. maybe I am not yet clear , cause am new to this case , but I am reading your link , thanks still for the next steps and guides in advance

 

[IRstuff]

That site contains a multitude of Matlab approaches to the problem, including discretized. Nevertheless, I think there is a communications issue when you say "both FEM and Matlab." Since Matlab is simply a calculation program, there is not precluding Matlab from performing FEM calculations. Likewise, Matlab includes a plethora of continuous time functions.

Additionally, I suggest you peruse the Matlab user file exchange:

http://www.mathworks.com/matlabcentral/fileexchange/index?utf8=✓&term=inverted+pendulum

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

Of course I can. I can do anything. I can do absolutely anything. I'm an expert!

 

[frztrb]

Sure thank you , I was thinking writing a FEM code in MATLAB or using a commercial FEM but the first one looks more interesting to do , I mean after you have the equations , how you discretize them in the FE ? I mean for this example , not only how to solve the whole problem by any method

 

[frztrb]

Any ?

 

[IRstuff]

have you looked at any of the code?

TTFN
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Need help writing a question or understanding a reply? forum1529

Of course I can. I can do anything. I can do absolutely anything. I'm an expert!

 

[frztrb]

Yes , but they only have modelled and solved the system without FEM , right ?

 

[frztrb]

The Robert Cook has discussed the dynamic FE Analysis very general , the direct method and mode analysis , but has no example about how to formulate , the Bathe has no discussion about it , where can I get a good discussion on this topic ?

 

[btrueblood]

FE methods are useful for solving continuum mechanics problems, whereas a pendulum is usually modelled by idealized discrete elements. Not sure that the usual/typical FEA code can/should be used here, their dynamics solvers are usually not that robust (just simple time-marching algorithms, no Runge-Kutta or other methods available).