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how to apply a force on a sphere

  • Thread starter Thread starter ignazio8
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ignazio8

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Hello, I have to do buckling analysis on a spherical shell. I should apply an axial compression force on a spherical shell but I can't select on the geometry where I want to apply it (i.e. the upper part of the ball ), it only takes the entire surface. I would also need to apply the enclosure but in the lower part.
 
I am no longer ansys user for a while, so sorry if I am not accurate, but in the integrated cad there is the possibility to partition geometry.
If you divide your ball into four ears, automatically in the mechanical environment you will have the option to select the top and bottom line intersection point.
 
eh... before ansys had the design modeller as module cad.. I know that the latest releases have integrated spaceclaim. or maybe he has both
 
here you can see how a two-half cylinder is partitioned to select them separately.

It is usually used to go to define areas on which to apply finer or higher order mesh, but it is also a good trick to bring out edges and lines on which to apply forces and constraints
 
quoti @stan9411 , you have to cut the surface of the ball in 3 parts, on 2 supplies respectively constraints and load, the 3 of course would be the rest of the ball.
You could also cut the ball to the level usually but then it would force you to use "bonded" constraints.

the cut of the surface can be done with any cad or with spaceclaim that is used specifically to clean/seat cad files and make them suitable for fem.
 
I managed to cut it but maybe I should join it again because it doesn't make me do the solution
 
After splitting and applying load and bond to the point that I was interested in how do I gather everything?
 
because you split the solid volume of the ball instead of just the outer surface, so now in the mechanical environment you should define the contacts.
there is also a split option of only external surfaces, which will keep the ball as a unique body, but with various areas on which to apply loads and constraints.

Please...
 
thank you for your availability, unfortunately I messed up and now I returned to the starting point or I created a ball to the entire space claim what should I do now?
Is there a function that allows me to divide in 4 slices the ball?
 
I don't know spaceclaim.
I modified my models with the modeller design before opening them in mechanical.
and also there, I no longer remember where the key is to partition. But there is.
"spaceclaim surface partition..."
 
I don't know maybe I didn't explain well.
After creating geometry on spaceclaim I go mechanically to apply a compression force and I would like to apply it on the y axis on the axial surface.
when I go to select the point it does not make me select it because obviously there is no summit being the surface one. How could I do it?
 
I don't know what you mean by "axial surface", I imagine you want to apply force on an exact point of the sphere (a sort of "northern pole" pass me the concept...).

imposing force in a precise point (vertice) would lead you to have singularity in the simulation, each load must be applied on surfaces (as small as you want) as it happens in reality (point contact is only theoretical).

the same principle just mentioned for loads also applies to constraints.

the direction of the load instead defines it inside the mechanical environment.
 
ok but if I take the entire surface where I apply the force then when I go to apply the bond on the same surface because it makes me take only the entire surface taking it doesn't do anything to me because ovviamnete I have stuck the whole surface
 
ignazio8 said:
when I go to select the point it does not make me select it because obviously there is no vertex being the surface still one
Click to expand...
but did you do it blessed partition? otherwise it is normal that there are no vertices.. .
 
I tried to do it with the split function and I got out of the top.
then going on mechanical inserting force and bond on opposite vertices gives me error in the solution perhaps because I no longer reunited the surface because I couldn't make it
 
on mechanical you can not gather surfaces, most likely you had the selection of active "surfaces" and not of "spigolo or vertex".

all these info however are classic things that are explained during the course of analysis to the finite elements. . .
 
So what function do I want to share? I did split body in geometry and divided the ball into 4 spikes then I should switch in mechanical to put strength and bond in the point I need sure there is some mechanical function that allows me to combine the surfaces
 

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