Creo3 fasteners & 'carries shear'

[346gnu]

Hi,

Can we switch off a fastener's ability to carry shear?

I want to work out what happens when a dowelled cover slides and I want the worst case - fasteners carry no shear.

Thanks

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[sdensberger]

In the fastener dialog box there is a pull-down called, "Stiffness" where the default is, "Using diameter and material" that can be changed to, "Use spring stiffness property". Selecting this option will allow you to use the properties of an advanced spring, of which you can set Kyy and Kzz to 0 (these are the stiffness components that are orthogonal to the direction of the fastener direction; see the image below). You will, of course, have to determine what stiffness values to use (which are tied to the size and material associated with your bolt). Also make sure that you have "Frictionless Interface" checked if you don't want the faying surfaces to carry any shear.

Where:

1. Kxx—extensional stiffness along the axis of the fastener.
2. Kyy—shearing stiffness
3. Kzz—shearing stiffness
4. Txx—torsional stiffness of fastener
5. Tyy—bending stiffness
6. Tzz—bending stiffnes

[346gnu]

Thanks Shaun,

I saw this and got my calculator out .... I was looking for the lazy way out similar to a WF4 check box.

Also, this is a spring and not the new beam fastener released with Creo.

In either case (beam or spring) would a nice to have be 'estimate stiffness matrix from model' and present an editable table?

[sdensberger]

I saw this and got my calculator out .... I was looking for the lazy way out similar to a WF4 check box.

If I recall correctly, getting a spring element to behave exactly like a beam element isn't simple.

Also, this is a spring and not the new beam fastener released with Creo.

Did they change over from spring elements to beam elements in 3.0 for the fastener tool?

[346gnu]

Agreed, springs aren't the same.

Mind you, everything is an approximation and in my case, carrying shear is not good.

I thought the change over was with the intro of Creo1.0

[sdensberger]

Agreed, springs aren't the same.

Mind you, everything is an approximation and in my case, carrying shear is not good.

Exactly; so while a spring might not behave exactly like a beam element, you can adjust it to give a good enough approximation. On the same note, if these differences are cause for concern, then maybe you need to consider not using idealizations.

I thought the change over was with the intro of Creo1.0

My understanding was that the fastener tool was re-worked, but that a change from spring to beam elements was not made due to legacy reasons.