Torson moment in padeye with shackle

[muruep00]

I am calculating a padeye with a shackle, in which the force coming from a cable is deviated a certain angle in the both represented views (vertical and horizontal deviation), due to cable misalignment.

Does the fixed surface in red have a torsion moment?. I can easily find a tension force and two bending moments, but I don't know if a torsor moment is also present.

 

[desertfox]

Hi muruep00

Is it possible that you can resolve the resultant force into the horizontal and vertical components and obtain the stresses in each of the directions and finally vectorially add them.
If the angle of miss alignment is five degrees or less I would ignore it.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[SWComposites]

in the center figure, isn't the shackle going to rotate to align with the load vector in that plane?

as stated above, its best to use superposition. resolve the force into the force in the plane of the center figure, and a side (horizontal) force in the plane of the right side figure. calc the stresses at the base for each, then combine them.

 

[BrianE22]

How are you distinguishing "moments" from "Torque"? In the first figure the shackle will rotate (as SWComposites says) until there is zero torque on the bolt axis. There will be a moment on the red base though.

 

[Ng2020]

Do a top view free body diagram. Does the applied force line of action pass through the shear centre (centroid for a rectangular section) of the red section?

 

[hydtools]

Do a free body diagram and resolve forces and moments.

Ted

 

[dvd]

Can you orient the padeye to align with the rope?

 

[muruep00]

in the center figure, isn't the shackle going to rotate to align with the load vector in that plane?

as stated above, its best to use superposition. resolve the force into the force in the plane of the center figure, and a side (horizontal) force in the plane of the right side figure. calc the stresses at the base for each, then combine them.

Yes, that is what I believe causes the torque.

How are you distinguishing "moments" from "Torque"? In the first figure the shackle will rotate (as SWComposites says) until there is zero torque on the bolt axis. There will be a moment on the red base though.

Torque is moment Mx with the black axis represented as X axis.

 

[MintJulep]

Pin joints do not transmit moments when they rotate around the pin axis.

You need to draw two free body diagrams.

1. For the clevis. This will resolve itself into a 2D diagram of you pick the right frame of reference and understand that the clevis will align with the rope.

2. For the lug.

 

[dvd]

If you can't rotate the padeye -

[URL unfurl="true"]https://www.thecrosbygroup.com/catalog/hooks-and-swivels/crosby-g-402-regular-swivels/[/url]

edit: I think this may not be a solution depending on the pull vector

 

[NRP99]

Padeyes are genarally not designed for torque, because torque will be much much lower compared to bending moments in plane and out of plane of padeye.

Torque is moment Mx with the black axis represented as X axis.

How the torque will be generated about vertical axis of padeye? Slight insignificant torque will be present after play between shackle pin and padeye hole is completed. But slings attached to shackle can't apply torque load unless you are using some means to twist padeye about vertical axis.

 

[Stress_Eng]

The pin / pad eye is going to rotate and the cable is going to slide. Determine the two angles of rotation (one being cable relative to vertical)) that result in a stationary condition of equilibrium.

 

[Ussuri]

If the shackle is not vertical, and an offlead load is present then there will be a torsion at the base of the padeye.

 

[NRP99]

If the shackle is not vertical, and an offlead load is present then there will be a torsion at the base of the padeye.

Yes but this will be still insignificant/negligible compared to bending moments in/out padeye plane due to sling angles with vertical. My question is how sling attached to shackle is able to apply "significant" torque about vertical axis? Unless you use bar passing through padeye hole for shackle pin and bar is twsting padeye vertically, amount of torque generated by sling/shackle is "insignificant".