Static structural analysis on a solid sphere?

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Discussion Overview

The discussion revolves around performing static structural analysis on a solid sphere using Ansys Workbench, specifically addressing the challenges of applying boundary conditions and constraints in the absence of contacts.

Discussion Character

  • Technical explanation, Homework-related, Debate/contested

Main Points Raised

  • One participant inquires about conducting static structural analysis on a solid sphere without specific boundary conditions or constraints.
  • Another participant explains that without constraints, the global stiffness matrix becomes singular, suggesting that constraints should be applied to the center point and neighboring nodes to achieve a non-singular matrix.
  • A subsequent post raises the idea of analyzing only the symmetrical part of the sphere to simplify the problem, questioning if this is an appropriate approach.
  • Another participant confirms that working with half of the sphere is valid as long as the load is symmetrical, emphasizing the need to apply constraints to nodes on the plane of symmetry to restrict translations.
  • A later reply indicates that the suggested approach worked for the original poster.

Areas of Agreement / Disagreement

Participants generally agree on the necessity of applying constraints to achieve a valid analysis, but there are varying opinions on the best method to apply these constraints, particularly regarding symmetry and the treatment of the sphere.

Contextual Notes

Limitations include the lack of specific boundary conditions and the dependence on the assumption of symmetry in the load distribution.

Who May Find This Useful

Individuals interested in structural analysis, particularly those using Ansys Workbench for similar problems involving symmetrical geometries.

Mitra Lanka
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Could you perform Static structural analysis on this solid sphere? No contacts to be used.
I do not have any specific boundary conditions(unable to apply constraints to a complete solid spherical body)
All i know is the pressure that needs to be applied.

You could consider a smiley ball on which pressure is applied.
I do not know how to apply constraints

I am using Ansys workbench. Please let me know how to proceed further
 
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When there are no constraints applied, the global stiffness matrix becomes singular, so no solution can be obtained.
If you know for sure that your solid sphere is in equilibrium and if you believe that the loads' distribution is such that the geometrical center point of the sphere remains unmoved, apply constraints in all three directions to the node corresponding to the center point and, possibly, to a couple of neighboring nodes. That would make the global stiffness matrix non-singular.
 
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Thanks for responding!
As the solid sphere is axi-symmetrical in x,y,z axes. Can i perform stress analysis on the symmetrical part of sphere?
This is just to view and constrain nodes near the center point.

Is this the right way of approach?.

If it is not the right approach,
then how do we constrain the center of a complete solid sphere in ansys workbench. Is there an option to do it?
 
Last edited:
Аs long as the load is symmetrical with respect to some plane passing through the center point, you can work with just a half of the sphere. In that case, the center point will be exposed. However, there is also a very important thing to do: each of the nodes that belong to that plane of symmetry must have a constraint applied such that it would completely restrict translations of those nodes in the direction perpendicular to that plane of symmetry.
 
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Thank you for the response. :) . It worked for me.
 
I am glad to hear that. Good luck !
 
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