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Hi everybody


 


I would like to create a rigid mesh on the surface of a body, because i need a rigid


 


body, for which are not calculated stresses neither strains.


 


Could i mesh this surface using "rigid body mesh" panel in automesh panel?


 


if it is the way, the mesh created will be used just to compute other things like interfaces 


 


reactions or others, and the mesh created will be completely rigid ... i'm i wrong?


 


thanks


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Hi Damir,


 


As far as i know,it is only an option for meshing.It is useful for meshing parts which will be used as rigid mesh,but if you define any different kind of property and material it won't behave like rigid.


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HI Damir,


 


One way I could think about is having rigid elements on the mesh and constrainting in all DOFs.


 


For example, imagine you have a plate with elements. Connect all the nodes of the mesh with rigid and constraint the rigid.


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Thanks NSKRTLUS and Prakash


 


I have a body that i mesh 2D with shell elements; for that body i define i rigid with a master


node in the centre and the mesh nodes as slave nodes. In the master i apply a initial velocity.


 


But if i mesh it with "rigid body mesh" in Automesh panel, the software will not calculate straind and stresses?


 


Why should not behave like rigid mesh if i define i propery and material?


 


Foe example in any ditching problems i wolud like to treat the ditching object like rigid, but i need a mesh


 


to define interfaces between the object and the fluid.


 


Supposing that the body will float, if i do not define a thikness and density for that rigid ditching body, how can


 


software compute the Arichimedes  Principle?


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Hi Damir,


 


RIGID mesh doesn't have any FE details other than elements which represent topology.


 


But when you have RBODY, you should not see any stress- strain. If you are seeing any stress strain data, let us know.


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Hi Prakash


 


no, i do not see any stress strain data...


 


to be explicit i'm on the sphere ditching in SPH (water);


 


but my doubt is this: if rigid mesh defines elements just for a topological reppresentation,


 


how can i use these elements as master surfaces in type 7 interface, if don't define a young modulus for sphere material


 


(supposing type7 interface vith ISTF=0 and STFAC= %of young modulus if the material of master surface)


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Damir,


 


Rigid mesh may not be the right idea for your case. Maybe you have to go for a normal mesh with coarser elements and define contacts for the same.


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ok...and this is an idea...


 


what if i use rigid mesh in automesh panel and instead of ISTF=0 i use ISTF=1 so defining a precise STFAC in Pascal?


 


in conclusion i need a sphere (shell elemnts) that behaves as rigid body, so no stresses and strains calculated and output, but 


 


with the need to define a type7 contact with a interface stifness...


 


whitch could be the easiest way to do this?


 


thanks


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Damir,


 


Penalty values will have its effect on time step in explicit analysis. 


 


In your case, yes and no. I ran a simple plate with different STFACs and literally there is no change in time step or vey very minimal.


 


But my problem here is simple. When you have more a complicate models and non-linearity this may not be true.


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hello sir, 

i want to create rigid mesh on the surface and i want to assign mass to that rigid ,please tell me how i will do this.

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Hi Monu,

 

What is the solver you are using and what is the objective?

 

You can create a node away from surface mesh and create rigid elements such that the node created will be independent and surface mesh nodes are dependent nodes.

 

At the end, create mass element on the independent node.

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