Split lock ring bearing calculation
Split lock ring bearing calculation
(OP)
Hi,
Looking for a bit of advice on a design (I've attached a couple of pictures to explain)
This is a subsea tubing hanger actuation sleeve.

A tubing hanger retrieval tool c/w split lock ring is run into this sleeve at which point the split lock ring is energized and forced outwards into the locking ring profile. Upwards pull on the tool then pulls up this actuation sleeve.

I've worked out all of the bearing & shear stresses that will arise, however the one failure mode I'm struggling with is the top of the actuation sleeve 'opening out' due to the horizontal component of the upwards force and the retrieval tool forcing its way out of the actuation ring. Something like this:
I'm not sure how to work out whether the upwards force experienced during operation would cause this type of deformation. I'm also not sure if this is a bending problem or hoop stress. If the lock ring groove was further down the actuation ring body then I would say it is a hoop stress problem but with it being so close to the free end I am not so sure so any advice is welcome.
Thanks,
RH
Looking for a bit of advice on a design (I've attached a couple of pictures to explain)
This is a subsea tubing hanger actuation sleeve.

A tubing hanger retrieval tool c/w split lock ring is run into this sleeve at which point the split lock ring is energized and forced outwards into the locking ring profile. Upwards pull on the tool then pulls up this actuation sleeve.

I've worked out all of the bearing & shear stresses that will arise, however the one failure mode I'm struggling with is the top of the actuation sleeve 'opening out' due to the horizontal component of the upwards force and the retrieval tool forcing its way out of the actuation ring. Something like this:

I'm not sure how to work out whether the upwards force experienced during operation would cause this type of deformation. I'm also not sure if this is a bending problem or hoop stress. If the lock ring groove was further down the actuation ring body then I would say it is a hoop stress problem but with it being so close to the free end I am not so sure so any advice is welcome.
Thanks,
RH





RE: Split lock ring bearing calculation
" I'm also not sure if this is a bending problem or hoop stress."
It's both due to the 45 degree angle creating a wedging action, plus some shear stresses and bearing stresses at/near the contact face. Even a snap ring under the pull force "F" tends to bend/roll and create the wedging action you are working with if the force gets large enough.
RE: Split lock ring bearing calculation
RE: Split lock ring bearing calculation
regardless what type of forces is acting there, i believe there are combination of them.
R.Efendy
RE: Split lock ring bearing calculation
Then, for analysis, this will be imo a combination of local bearing stress which due to the inclined / oblique surface result in
hoop stress from the radial component
bending stress from the axial component
If applicable, pls. also check for fatigue strength.
Pls. check the attachment, unf. i can't upload images into the text.
Regards
Roland Heilmann
Lpz FRG
RE: Split lock ring bearing calculation
I should just clarify that the picture of the FEA is exaggerated, I just did that to clearly show the type of failure I'm concerned about, but the FEA result in that picture is not an actual representation. So what I am doing now is trying to work out with an applied force of 250,000 lbf, will the end of the tube deform or not.
My design calcs have to be done using hand calcs so I won't be using FEA for this. I have found something to allow me to work out hoop and radial stresses in the actuating sleeve. This is a procedure for working out stresses for a hanger sitting on a tapered load shoulder (similar to my case):
I'd be quite happy using this on its own if the lock ring groove was lower down and not so close to the end of the pipe as bending would not really be an issue. But since it is, I think I need to do an additional bending calc to work out the bending stresses and deflection at the end of the pipe. So my question is, does anyone know how to perform such a calculation by hand? A textbook reference would be great. I had thought of simplifying this and effectively 'unrolling' the pipe into a beam and working out bending that way but that doesn't seem like a very accurate way of doing it.
btrueblood, you mentioned you have to work with this kind of design regularly.
"Usually I end up adding reinforcement to that open end (locally thickening the o.d.) to reduce the deflection to something tolerable" - how do you work out this deflection, as this might be exactly what I am trying to do...
Thanks,
RH
RE: Split lock ring bearing calculation
Thought I would update as I think I have found the solution.
Roark's has a case similar to mine where a radial load is applied to a cylinder at a distance 'a' from the end. This works out deformation and angle of deflection. I think I can use this by simply using a negative value for the force as mine is acting radially outward
RH
RE: Split lock ring bearing calculation
https://www.rotorclip.com/formulas.php
and
https://www.rotorclip.com/images/wysiwyg_images/li...
RE: Split lock ring bearing calculation