Learning Forum

[oumaimalahmar.ol]

hello

I have a question concerning the springs, I apply springs on all the surface with a stiffness of 7N/mm is it necessary to divide the stiffness by the number of nodes where I apply them or even if I have for example 60 springs each spring contains a stiffness of 7N/mm.

thank you 

[peteroznewman]

A spring element applied to a selection of faces will have a single spring with the 7 N/mm stiffness. A set of either rigid or deformable Constraint Elements will spider out from a pilot node at the centroid of the selected faces to all the nodes of those faces. The other end of the spring might be applied to a different selection of faces or be connected to ground. In either case, there is a single pilot node for the other end of the spring.

[oumaimalahmar.ol]

Apparently I explained it wrong, in fact I wanted to link two surfaces by springs while each surface contains 20 nodes is it necessary to divide the stiffness by the number of nodes. 
For example I take a 7N/mm spring so I need 20 springs so each spring has 7N/mm or each spring has 7/2

[peteroznewman]

So you mean you are creating a spring element by selecting a node on one surface for the Reference on the first spring and a node on the second surface for the Mobile on the first spring. Then you repeat that 19 more times?

In that case, yes, you would divide the total spring rate you want between the surfaces by the number of springs and assign that value to each spring.

[peteroznewman]

Why are you creating springs at each node between two surfaces?  Are you trying to model a gasket?  There is a Gasket Material you can assign to a solid body that goes between two surfaces. The Gasket body material model has the pressure-displacement curve for the gasket material. You just mesh a single layer of elements through the thickness of the gasket and apply the gasket material model and you have a model similar to what you are doing, but with a lot less work.

A benefit of the Gasket model over using 20 spring elements is that the Pressure-Displacement curve in the gasket model can be nonlinear. Typically the pressure goes up exponentially as the displacement increases.