using pre-tension in a grab handle

[kammieorama]

how do we model a bolt with pre-tension.
I have tried modelling one and have given it for run using abaqus. however the output shows that along with tension in bolt there the attached parts are also displaced.
I was expecting tension to be developed only in the bolt shank since i am trying to simulate pre-tension.
Is there any way that any of you know which can be used only to model pre-tension in the bolt shank.

tHANK YOU FOR YOUR RESPONSES IN ADVANCE

 

[ivymike]

maybe I'm not understanding what you're saying - but if you have tension in a bolt holding two things together, then you ought to have compression in those two things because the bolt is pushing on them.

 

[GregLocock]

The old trick was to apply a temperature load case to the bolt after assembly to give the requisite pretension. Presumably in the year 2012 'we' have come up with something more elegant.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[kammieorama]

hello Ivymike.

I am trying to medl three plates of each different component of total thickness say 5 mm.

Now these three bolts are fastened using bolts. The bolts which hold them in physical world are in tension if it is tightened very hard. This is what I want to model.

The second part of the problem is that one of the shell is pulled along the axis of bolt shank. We want to simulate this using abaqus and see how the parts behave.

thank you in advance

 

[kammieorama]

hello greg,

adding temperture load case may complicate the model in my view. I was thinking why can we aplly tension in one step say tension by giving a fixed displacement of nodes at one end. and the use it without unloading.

 

[Screwman1]

Remember that as you are tensioning that bolt you are getting elongation along the bolt axis, in conjunction with joint compression.

 

[kammieorama]

@screwman. Yes that is also there. Can you suggest a way we can model this phenomenon.

 

[Tmoose]

maybe something like this?

"Pretension is simulated by splitting the bolt body (Figure 6) and pulling each end towards the other (as an initial displacement) to obtain the
desired force (pretension). "
Section 2.1 here -

http://www.simulia.com/forms/world/pdf2008/MONTGOMERY2-AUC2008.pdf