2DOF spring-mass free vibrations

[peppiniello]

hi to all

i am looking for a simple program that makes linear dynamic analysis of spring-mass systems with 2DOF or more, under free vibrations


any suggestion?

 

[Qshake]

Most texts on structural dynamics have developed the differential equation for such a model and condiditions. Thus I recommend that you grab a text on the subject and with a little work in MathCad, Matlab, Excel, etc you can use linear piece-wise interpolation integration to determine the velocity and displacement responses.

Some texts that are useful are

Structural Dynamics by Clough and Penzien
Structural Dynamics by Craig
Dynamics of Structures by Chopra


Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[GregLocock]

http://www.brunel.ac.uk/~mepgffk/Modal testing(Theory).htm#_Toc65555145

has all the relevant equations, as Qshake says, chuck them at a piece of mathematical software and you'll get the answers.

http://www.explorelearning.com/index.cfm?method=cResource.dspView&ResourceID=21

may or may not help

Cheers

Greg Locock

 

[peppiniello]

thanks qshake,
that's what i am doing actually, i am using a worksheet (mathcad) for calculating free vibrations of a 2dof system, and since i don't like my results i would check something else

greg thanks for the link

http://www.explorelearning.com/index.cfm?method=cResource.dspView&ResourceID=21

but it's for external actions only and allows only K1=K3, i'd need something even easier, just initial displacement conditions

 

[GregLocock]

Well, why not post your working? or if you don't want to do that, results for the obvious test cases.

Are the errors in the predicted resonant frequencies (for which formualae are easily available) or in the amplitude of response?





Cheers

Greg Locock