Pin Design
Pin Design
(OP)
Hi All,
i have designed a pin (which has got circular cross section),thats going to be in shear,i have assumed the pin to be short coloumn and considered only shear.
I did try to do some basic bending stress calculation ,but the bending stress is way above the allowable,while shear stress is below the allowable.
I am bit confused about this reponse.i thought short coloumns fail more due to shear than baending.
i appreciate your comments on this.
Thanks
Badri07.
i have designed a pin (which has got circular cross section),thats going to be in shear,i have assumed the pin to be short coloumn and considered only shear.
I did try to do some basic bending stress calculation ,but the bending stress is way above the allowable,while shear stress is below the allowable.
I am bit confused about this reponse.i thought short coloumns fail more due to shear than baending.
i appreciate your comments on this.
Thanks
Badri07.






RE: Pin Design
RE: Pin Design
yes,what you are saying is right,infact its a beam connected between adjacent plates,this has got double shear.on bending calculation i just did a basic hand calc to check the bending stress --->sigma(b)=M/Z.This calculation was performed assuming it to be a simply supported beam with point load in the center.
infact i did an FEA on the pin using beam elemnts,this is giving an bending stress of sigma(b)=133mpa.
Thanks
Badri07
RE: Pin Design
RE: Pin Design
Just post your pin size, distance between supports and load applied and we can maybe help further.
Regards
desertfox
RE: Pin Design
http://books.google.com
download "Design of Steel Bridges" by F. C. Kunz, 1915
on page 200 there is an example for the design of a truss pin.
RE: Pin Design
The thickness of the connecting plates will also be required as bearing stresses may be critical.
RE: Pin Design
Thank you all for your time,the distance between the two plates is around 150mm and the 2.22x10exp6 is applied on to the pin,the dia of the pin is 126.5mm(5").
Thanks
Badri07.
RE: Pin Design
E looks funny, units ?
what end conditions did you assume (in calculating the moment in the pin) ? ... i'd suspect that fixed would be appropriate.
where did you apply the shear forces ? mid-thickness would be conservative, closer to the mating plane is more realistic.
did you allow plastic bending ?
RE: Pin Design
RE: Pin Design
E=2.0e+005mpa,and the load applied in the pin 2.5sh tons,thats 2.22e+006N(as in my previous post),Boundary condition for Mmax is simply supported,i applied the shear force in the center of the beam,and the moment i calculated applies to elastic bending.
Thanks
Badri07
RE: Pin Design
The thickness of the end plates is 50 mm and the thickness of the middle plate is 150mm.
Thanks
Badri07.
RE: Pin Design
I would be inclined to ignore bending if the middle plate takes up the full 150mm gap between the two edge plates. If the pin tends to span and act like a beam in bending then it will deflect in the middle slightly relative to the stiff midddle plate shedding load towards the edges/ plate interpace where it is back to a pure shear situation. I would consider shear and bearing only.
RE: Pin Design
the ends of the pin are reasonably fixed in the outer plates. the shear loads can be reasonably applied close to the mating planes between the inner and outer plates (this'll reduce the moment, lots).
the applied load is 2.5 tons ? ... that's about 6,000 lbs, about 25,000 N, no? ... not 2E6N, no??
RE: Pin Design
RE: Pin Design
yes,it was by oversight i had an typo in my load,
RE: Pin Design
RE: Pin Design
A half inch bolt will almost support that in double shear.
RE: Pin Design
just that the middle plate is inducing 250sh tons,2.22e+006N,not 2.5sh tons
Thanks
Badri07
RE: Pin Design
RE: Pin Design
but consider, model the beam as 7" long (assume the reactions in the outer plates are at 1/4 thickness). assume the load is applied in two concentrated forces 0.5" from the mating plane (mirroring the outer plates reactions). now the max. moment = 125tons*1" = 280E3inlbs. (1/5 of the previous moment) now the max. stress of the hollow pin is only about 40ksi.
this isn't a complete analysis, but you can see how conservative your original assumptions are.