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Level 10

## Fasteners references edges definition error

Hallo,

I have a problem with defining fasteners idealization in Simulate (Creo 2.0 M110).

I have to define a fastener between two components, when I select the two corresponding edges, this error message appears:

I suppose this errror is due to the fact that those are planar (in the sense that lie on a plane) but the visible one is not on a surface, but it's the end edge of the bolt hole:

the question is, can I define in some way an idealized bolt for this case without having to add material (otherwise it would be convenient to directly add the bolt itself)?

thanks

bye

10 REPLIES 10

## Re: Fasteners references edges definition error

Tommaso,

Try adding a surface region or volume region where the fastener bounderies are.  This will give you a valid flat edge / line on the cylinder surface to select.

Hope this helps
Don Anderson

## Re: Fasteners references edges definition error

When I encounter problems like this I model the bolt using a beam element that I attach using  weighted or rigid links at the beam endpoints. Create a surface region for the bolt head/nut mating surface, as the independent side of the link. The pre-load i create using a zero coefficient of thermal expansion for "the rest" of the model. The bolt/screws are modeled with a large coefficient of thermal expansion. Then I prescribe a "-1 degree" global temp load. The bolts then contract. I can tune, either the coefficient of thermal expansion or the temp load to get the pre-load that I wan

Unfortunately beams can't be used in large deformation analysis, even though the beam itself does not undergo large deformations, other than "rigid" body motion.

## Re: Fasteners references edges definition error

Hi Don,

I tried with a surface region in simulate but it can be created only on already-existing surfaces. In paametric instead, if I create a surface just inside the edge, in simulate it is not recognized and the error message still appears. With a volume region how can I do then to define the bolt?

thanks

bye

## Re: Fasteners references edges definition error

Tommaso,

I was incorrect, you can use my approach for the end of the screw but not for the head.
You will need to use Mats suggestion or model the fastener as a solid and use the preload feature.

Don

Thanks,
Don Anderson
No time Like the Present!

Hi Donald,

bye

## Re: Fasteners references edges definition error

Hi Mats,

thanks for the tips,how you define a beam? with a curve between the two points in parametric and then you define them as beams in simulate? or this can be done directly in simulate selecting the two points?

bye

## Re: Fasteners references edges definition error

I typically create a point-point beam, from hole center to hole center. And yes, you can create the datum points in creo simulate, either on the top level, or on part level. If you create datum points on part level, in the creo simulate environment, the points end up as "Simulate features" in the model tree for that part, and are only visible in the simulate environment.

This technique is useful when the prerequisites for the "fastener" are not fulfilled, for example non-circular hole, or the surface might not be planar or parallel.

/Mats L/

## Re: Fasteners references edges definition error

ok thanks, yes in fact the beam I think is maybe the best way to work around the problem, as it it the same as the fastener (or even better maybe, I don't know if the software considers also the bending with the function fastener, while with a beam it does...)

bye

## Re: Fasteners references edges definition error

This is why I like using beams, you have full control, and you can access/control what d.o.f.'s that you want to activate/deactivate through beam releases, etc. Fasteners act a bit like a "black box" and you don't know what's going on...