Stresses on a hinge pin
Stresses on a hinge pin
(OP)
Can anyone help on this problem?
A hinge pin is loaded such that the the entire length of the pin is bearing against the hinge padeyes. There is an upper padeye and a lower padeye on one side of the hinge and only one middle padeye on the other side of the hinge. Double shear of the pin will be considered. Would bending of the pin need to be considered and combined with the shear stress as a combined loading?
If bending is considered, what is the typical loading pattern used in this analysis?
Thanks in advance,
A hinge pin is loaded such that the the entire length of the pin is bearing against the hinge padeyes. There is an upper padeye and a lower padeye on one side of the hinge and only one middle padeye on the other side of the hinge. Double shear of the pin will be considered. Would bending of the pin need to be considered and combined with the shear stress as a combined loading?
If bending is considered, what is the typical loading pattern used in this analysis?
Thanks in advance,





RE: Stresses on a hinge pin
However, this is only true when the hinge is new, in time with wear and deformations the bearing holes become larger and then the reactions move to the farmost sides of the bearing padeye. Unless the pin is wery thick (more friction moments loses in the hinge) the pin deflects. Therefore, as the distance between the reaction forces is now larger than the original distance (when the hinge was new), the bending forces become very dominant.
Therefore, a good design should make the hinge as narrow as possible, meaning, shorter pin and as a result less bending moments. The designer should assume that the reactions may move to the edges of the pin and calculate the bending stresses in order to be on the safe side.
Few years ago I had a chance to invesigate and solve such a problem after many occasion of pin break before time. The hinge width was ~20mm wide and the pin was 8mm diameter. My calculations showed that taking into consideration that the reaction moved to the end of the pin, the pin should be brake at the middle, and this was the case.
The new design was 8 mm wide hinge with 5 mm dia pin and this never break.
RE: Stresses on a hinge pin
RE: Stresses on a hinge pin
Excuse my ignorance if this is trivial but if I need to combine these 2 stresses how would I do this?
RE: Stresses on a hinge pin
in my field (lifting appliances) codes define the equivalent stress as:sigma=sqrt(sigmax^2+sigmay^2-sigmax*sigmay+3*tau^2).this should be <=sigma allowable.
hope this answers your question
Zvi
RE: Stresses on a hinge pin
RE: Stresses on a hinge pin
When you design the joint it has to withstand both the shear and the bending stresses simultaniously because at the fixed side the bean fills the shear stress as the result of the load at the end and the tensile stress from the bending caused by the load a the end.
RE: Stresses on a hinge pin
So if I'm understanding correctly following on from zvivik we get
sigmax=(My)/I where M=1/2 Pin Length * 1/2 Load
tau=F/A where F=1/2 Load
Then use failure criterian (Is this Von Mises??) as presented by zvivik.
Have I understood you correctly??
RE: Stresses on a hinge pin
L is the maximum length between the "simple" supports
P is the maximum load in the center.
You can calculate your section modulus as Z=d^3/6. (All units in inches of course.)
Your bending stress (using AISC terms) is fb=M/Z. Y
our allowable stress for this case is Fb=.75*Fy.
For the shear, fv = P/A and the allowable Fv=.4Fy
One way I have done it is via the unity check where Fv/fv + Fb/fb =< 1.0
At least that is what us old farts have always done.....Chili
RE: Stresses on a hinge pin
RE: Stresses on a hinge pin
Yes, you are correct.