Learning Forum

[Rameez_ul_Haq]

So I have a sample model, as shown below.

[Surya Prakash]

Weak Springs are automatically-created springs with just enough stiffness to constrain the rigid body motion.The Weak springs feature will create an imaginary ÔÇÿbounding boxÔÇÖ for each part, where springs at each of the 8 ÔÇÿcornersÔÇÖ are added for each part. So, if we imagine a ÔÇÿboxÔÇÖ covering each part, each node nearest to these 8 corners gets weak springs acting in the 3 orthogonal directions X, Y, and Z. The free ends of all the springs are constrained to ground. The spring stiffness is automatically calculated and defined by Mechanical to be a very low value.
This should not be used in place of actual boundary conditions, but rather a support feature that helps to prevent the rigid body motion present due to any imbalance in the loads and boundary conditions given. We should also make sure that they should not affect the analysis results by checking the reaction forces developed in the weak springs by using a probe>force reaction and scoping it to the weak springs in the solution tab. The resultant force reactions should be close to zero to get accurate results.
In addition to this, for the model that you have shared- you can use a symmetry model.
Thanks Surya
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[Rameez_ul_Haq]

,well thanks for the info.
What do you think, should the stress results change in the local regions within my model where ANSYS adds the Weak Spring?

[Rameez_ul_Haq]

,would be really glad if you could give your views on the question I asked in my above comment.

[Surya Prakash]

If you are properly constraining the model, then the stress results should not change irrespective of whether you are using weak springs or not. In case if the stress results are changing, then the model is not properly constrained and the weak springs do produce some reaction forces, which is undesirable. Hope this clarifies

Thanks Surya