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Active Contributor
Posts: 32
Registered: ‎03-28-2012
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Mass + Velocity Loads & Dynamic Response

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09-23-2012 10:13 PM

Hello,

 

I was wondering whether anybody knew if Robot was capable of modelling collision type loads?  I have trawled through the help files and cannot find anythign that helps me wiht my specific problem.

 

Essentially I wish to apply a mass with a specific initial velocity to a beam/plate and get values for deflection, moment, reactions etc as various time steps similar to a time history analysis for an initial force (but effectively working backwards to discover a similar static force would be from this loading).

 

If anyone has any information on whether Robot is able to perform this type of analysis and if so how we would go about setting this up I would be very grateful.

 

Kind Regards,

 

Richard 

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tony.ridley
Posts: 637
Registered: ‎09-07-2011

Re: Mass + Velocity Loads & Dynamic Response

09-24-2012 12:18 AM in reply to: richard.whitfield

You can add masses with acceleration for the loads definition toolbar.  It's on the tab with "self weight and mass"

 

You could then potentially use this in conjunction with a time history. 

Tony

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Product Support
Posts: 461
Registered: ‎06-23-2008

Re: Mass + Velocity Loads & Dynamic Response

09-24-2012 01:24 AM in reply to: tony.ridley

Attached the simple model I made some time ago (long time ago:smileyhappy:).

 

It is modeling impact of some weight falling from specified height.

It is done using linear time history (no plactic effects etc.)

Some simplifying assumptions are made concerning constant force during the impact but they do not influence significantly the results because the response is resulting from the change of momentum corresponding to integral of force in time domain (details in attached file).

 

More advanced models of impact (separating of objects after impact, forces during impact resulting also from elastic properties of objects) can be also created using for instance compatible nodes with gaps and elastic properties.  In such case time history analysis should be used too.

 

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Regards,

 



Pawel Pulak
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