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Dec 2014, AutoPIPE V8i 09.06.01.10
How to model a Hyspan Barco Ball Joint?
See the following AutoPIPE help section for modeling technique:
Help > Contents> Contents Tab> Modeling Approaches> Modeling Approaches> Flexible Joints> Ball and Socket Joint example in AutoPIPE's online help.
Actual ball and socket joints are limited in their range of angular rotation (shown below). AutoPIPE will not limit this range. Therefore, they should be placed in the piping system so that these limits are not exceeded.
Question: In AutoPIPE a ball and socket is modeled as a Flexible Joint, what Flexible Joint stiffness values on the dialog represent the angular motion shown in the image above? Axial, Shear, Torsional, or Bending?
Answer: Correct... Bending Stiffness values correctly represent this type of movement, see wiki here to understand Flexible joint dialog.
Generally, the vendor provides a set of break-away torques for the ball joint assembly. For this, I would recommend modeling the ball joint with a breakaway stiffness that will be constant throughout the travel. This will be conservative. There is a limit load reached before the joint goes to 'zero' stiffness. You can check the Forces and Moments report at the joint to see if this load is reached. If the load has not been reached, increase the corresponding stiffness and recheck. If load has been exceeded, decrease stiffness accordingly and recheck until breakaway forces have been approximated.
This issue has been logged as a requested program enhancement with tracking number CAE-TR-4779.
See items below for comparative approach.
How to best model the bending stiffness and torsional stiffness of the ball joints.
How to model a Ball joint in AutoPIPE?
Bentley AutoPIPE