boundary conditions for sphere in rotation and translation

[Claire123]

Hi all,

I have a problem to fix the boundary conditions of my problem...My problem consists of a sphere (radius = 1cm) placed in the center of a large plate (Lx=Ly=1m). The plate is placed in the plane x-y. The sphere is in contact with the plate and it penetrates the plate in his center with an initial velocity (U3 = -10m/s, translation)AND the sphere also has an angular velocity along the z-direction (UR3 = 100 rad/s, rotation). The four edges of the plates are fixed (U1=U2=U3=UR1=UR2=UR3=0).

In BC's from Abaqus, how have I to fix the boundary conditions ? Where these boundary conditions are defined on my geometry ?

Thank you for your help

Claire

 

[portliner]

If you build the model in the CAE, you apply the BCs in Load > BC.

 

[Claire123]

Hi Portliner,

I know that I have to use load and BC' but I don't know the parameters to choose in this problem... edges of he plate to 0 ? boundary of the sphere to UR3 ?

 

[portliner]

Set the BC to zero in desired directions for the plate, do it in the "initial state" and the let the BCs propagate to the subsquemt STEPs. Choose "edge" geometry to apply BC on.

 

[Claire123]

Hi portliner,

Unfortunately, the boundaries conditions (BC) that you propose do not work. Please find in attachment the copy of my screen showing the BC used :

-BC-1 for the plate
-BC-2 for the sphere
-the final result

In this problem that I simplified, the sphere has a velocity v = 1000m/s along the z-direction (it is just a translation). The sphere and the plate are made of aluminum and the plate is like a wall fixed on the edges.

As you see, the plate is never deformed by the impact of the sphere !! but only the sphere is deformed...Why ? In this simulation I fixed at 0 the edges of the plate (U1=U2=U3=UR1=UR2=UR3=0) and I keep free U3 for the sphere. U3 = -1000 m/s is defined in Predefined fields...I fixed "deletion = YES" in the mesh menu.

Really, I don't understand !

Best

Claire

 

[portliner]

Hi,
as a understand the model consists of solid elements in the plate and the sphere as well.
Solid elements have only 3 DOFs(translations) x, y and z. NO ROTATIONS exists for solid elements! The plate should only be fixed by specifying theses DOFs to zero.
Specfying a predefined rotation of the sphere(solid elements) requires a local cylindrical c-system. This system must be oriented in such a way, the second direction pointing along the desired axis of revolution. Force the sphere to rotate by specifyng the second DOF in the cylindrical c-sys to the wanted speed.