discrete rigid and analytical rigid 2

[chooga4eva]

which one is best to use to model the bumper of a car.

I have read the manual but I don't understand the difference between the two

 

[bassmanjax]

- Analytical rigid surfaces are defined mathematically using lines and arcs.
- Discrete rigid surfaces are meshed using rigid elements.

Basically, if your rigid surface can be created by extruding or revolving lines and arcs then use analyticals. If not, then you have to use discrete rigid.

Rgds

Martin Stokes CEng MIMechE

 

[chooga4eva]

Thank you!!

I have just built a part (analytical rigid). I gave it a reference point but when I run a job it says it is missing a reference point? what is the problem?

 

[bassmanjax]

Have you tied the ref point and the analytical surface together as a rigid body?

Martin Stokes CEng MIMechE

 

[chooga4eva]

No i haven't. the manual didn't say.

Thank you!

anything else I should do the rigid body before i submit a job?

 

[rstupplebeen]

Make sure to constrain your reference point otherwise you will get RBM (Rigid Body Motion). I hope this helps.

Rob Stupplebeen

 

[chooga4eva]

I would like to express first of all how thankful I am for these replies.

Rob, yes I had applied a constraint to the rigid body but i am not sure actually. i went to constraint--rigid body--- analytical surface....but there were a few more options (please let me know if you would like me to specify this)

Is this what you intended I should do?

thank you.

 

[rstupplebeen]

Tie the body to the reference point. Constrain the reference point.

Rob Stupplebeen

 

[Rikuson]

Regarding the tie constraint and referrence point, you can check with the contact example in the 'interative manual'

 

[chooga4eva]

i could tie the surface with the reference point!!
i went to constraints, tie, selected the analytical surface as the master slave but then i couldn't select the reference node!!

how is this done (tying of rigid body to reference point)????

 

[chooga4eva]

sorry i meant to have said "i couldn't tie..."

Cheers

 

[bassmanjax]

I think you misunderstood what is meant by 'tie' - you don't use a 'tie' constraint between a rigid body and it's ref point.

You have to create a rigid body, which consists of the analytical rigid surface and it's reference point. You can then apply constraints to the ref point.

Might be worth looking up 'rigid body definition' in the ABAQUS Analysis Users Manual - section 2.4.1 in the v6.8 docs.

Martin Stokes CEng MIMechE

 

[chooga4eva]

Ok, thank you.
well, yes the part was created as a rigid analytical 3d part. Sorry I didn't mention it. Then I created an analytical surface by selecting the surface I wanted of the rigid part. then of course made a reference point. from the replies I understood it as tying the analytical surface to the reference point which is why I used the tie constraint. I was able to do this eventually. correct me if i am wrong.