Learning Forum

[Pranav Bhatt]

[peteroznewman]

Please reply with your question.

[Pranav Bhatt]

[Pranav Bhatt]

I was using program controlled and now since my bolts are having bending deformation I wanna know what is the significance of other two suboptions in the formulation tab of bolt pretension

[peteroznewman]

The Program Controlled option uses a small rotation assumption. In most models, the surfaces the head and nut/thread attach to do not rotate in space by large angles. When the shank of the bolt is split to apply the pretension, the direction they pull toward each other is fixed in space along the axis of the bolt.

Some models undergo large rotation of the parts in space when the load is applied. Those models need Large Deflection turned on under the Analysis settings.  Bolt Pretension loads in those models should use the Joint formulation because that will allow the pretension pull direction to rotate in space with the bolt shank which is more accurate than leaving the pull direction fixed at the initial axis of the shank.