Attached is a simple sketch for a fall arrest anchorage post. I need to know what is the best way to define constraint for this model which replicates the real function of the post under the load.
Thanks for your reply. That's what I exactly did, but I got this error message "No equilibrium achieved" and I can only see the result up to the point that post touches the concrete. Do I have to take friction into account to balance the forces?
Not sure if friction would help, but you can turn on the soft spring option to give it just enough stability to solve and then possibly identify the problem. Make sure you turn the option off when solving with "fix."
I have already tried "soft spring option", the very same warning comes up (No equilibrium achieved). Do we have to add a force or constraint to stop axial displacement of the post? I guess, there will a normal reaction force between the disc and the ground.
I have also sent my model to our reseller to investigate this problem, I haven't heard anything form them so far.
I think that friction is needed in the no penetration contact set. Without it, I imagine that the post would slide out of the hole (assuming it is perfectly level) due to the location of the force applied.
It might help to remove the concrete temporarily, then restrain just the underside annulus of the 20mm thick ring. Run, and then, find the reaction forces at those locations. This might give a good idea of the reactions that the concreate would need to impart on the pipe to hold it there (you could resolve the net reaction force on the underside of the ring into force and equivalent moment vectors that the concrete would need to excert on the pole - since you've already identified the contact areas from concrete to the end of the pole). Just a thought to help isolate where and what value of reactions are required of the concrete).
Try out the attached to see if that makes sense to you. In SWS 2009 SP4.1, implemented symmetry BC's, friction coeff of 0.5 on the contact between metal and concrete, and meshing controls.
This is a good example of where I made use of Draft quality elements to test out settings to make sure they work before committing it to a more lengthy yet more accurate High quality (2nd-order) element.
Thanks for your model. I ran the study with "large displacement" flag on (program asked me to turn the option on). The same warning came up (Equilibrium satisfaction not achieved). I am wondering if you had the same warning too. I have SW2009 SP4.1 on 64bit Vista.
Joe
Thanks for your reply. That's what I exactly did, but I got this error message "No equilibrium achieved" and I can only see the result up to the point that post touches the concrete. Do I have to take friction into account to balance the forces?
Regards,
I have already tried "soft spring option", the very same warning comes up (No equilibrium achieved). Do we have to add a force or constraint to stop axial displacement of the post? I guess, there will a normal reaction force between the disc and the ground.
I have also sent my model to our reseller to investigate this problem, I haven't heard anything form them so far.
I think that friction is needed in the no penetration contact set. Without it, I imagine that the post would slide out of the hole (assuming it is perfectly level) due to the location of the force applied.
--Bryson
Try out the attached to see if that makes sense to you. In SWS 2009 SP4.1, implemented symmetry BC's, friction coeff of 0.5 on the contact between metal and concrete, and meshing controls.
This is a good example of where I made use of Draft quality elements to test out settings to make sure they work before committing it to a more lengthy yet more accurate High quality (2nd-order) element.
Attachments
Hi Joe
Thanks for your model. I ran the study with "large displacement" flag on (program asked me to turn the option on). The same warning came up (Equilibrium satisfaction not achieved). I am wondering if you had the same warning too. I have SW2009 SP4.1 on 64bit Vista.
This simple model is giving me headache!
Regards,