hub on shaft stress conctration factors
hub on shaft stress conctration factors
(OP)
i'm having a tuff time locating stress concentration factors when a hub subjects a shaft to a bending load.
Any good sources?
Thanks,
Dan T
Any good sources?
Thanks,
Dan T





RE: hub on shaft stress conctration factors
RE: hub on shaft stress conctration factors
I'm not sure if you want shrink fit studies or simply the bending moment induced by some hub loaded at the rim on the shaft. Such a case could be handled as an eccentric load in the transverse case.
I'm not sure if this helps. Good luck none-the-less.
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: hub on shaft stress conctration factors
Good site link, but on my first run thru I only found shafts with differing diameters and shoulders with radius or fillet entry required, not separate hubs.
our hub (hollow shaft gear reducer) is a clearance fit, to boot.
RE: hub on shaft stress conctration factors
presumably there's a dowel pin connecting the hub to the shaft ? but then this is a dafferent matter ...
RE: hub on shaft stress conctration factors
http://ww
http://www.cleanspeedeng.com/Bent1.JPG
RE: hub on shaft stress conctration factors
the pictures clearly show some bike forks being bent by a normal load introduced by the front wheel (like they hit something). isn't this a simple bending problem ? and if you've got a fatigue load, this geometry is simply a shaft in bending, no?
RE: hub on shaft stress conctration factors
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: hub on shaft stress conctration factors
This is actually a heavy hollow shaft gear reducer cantilevered on a smallish vertical shaft. Our stress group applied factors for the keyway and local shaft diameter changes, but did not apply a stress concentration factor for the fact the bending is applied via the reducer's hollow shaft, which I described as a hub.
RE: hub on shaft stress conctration factors
if they've accounted for the key-way (whatever is supplying the shear connection to the shaft) and presumably they've accounted for the bending stresses ... not clear on what you think is the "stress concentration factor for the fact the bending is applied" ...
RE: hub on shaft stress conctration factors
My dilemma is finding published stress concentration factors for solid shafts in this arrangement (hub / shaft)
RE: hub on shaft stress conctration factors
your picture helps, you've got an eccentric column load on the shaft (i had pictured the shaft as being horizontal).
clearly the load is putting some bending into the shaft, no doubt the flange mount takes this into account.
how is the shaft supported (laterally) ? a lateral couple could react the off-set moment.
but let's assume that the shaft is fixed at it's base. the then moment is introduced at the top, yes ? and reacted at the base, simple enough. so the shaft is reacting the column load and moment, again simple enough; don't see where "stress concentration" comes into it ... there may well be some local plasticity, and maybe you want Zero plasticity at ultimate load ... very conservative design; maybe it's a fatigue problem, but then that hasn't been mentioned.
IMHO, i think you have a situation where the flange mount is applying shear loads into the shaft, and these shear loads apply the column load and off-set moment onto the shaft.
RE: hub on shaft stress conctration factors
Sorry for the confusion. The flange in the too-simple drawing has loose fitting pins to react the gearbox torque. (unfortunately) The gearbox flange contributes nothing to supporting the gearbox/motor assembly. The 50,000 lb-in moment is resisted entirely by the shaft. The proportions of the hollow shaft in the gearbox (which is the only useful connection to the vertical solid shaft) would create a pair of several 1000 lb reactions a foot or so apart. This is further enforced by the relief or oversized diameter in the middle third or so of the hollow shaft. If the geometry of the hollow shaft makes it stiff, in the limit each reaction would be applied to the 3.25 inch shaft thru a knife edge.
It runs 24/7 and accumulates 1,000,000 fully reversing cycles every week, so I think I'm justified in being >>very<< concerned about fatigue.
RE: hub on shaft stress conctration factors
Petersen fig164 has a hole in a tube under bending, not too different from a hole in tension ... but if you've got shear loads I think the method from Michael Niu's book (pp232) is most appropriate.
RE: hub on shaft stress conctration factors
htt
The fixing bolt should be "tightened lightly snug"
RE: hub on shaft stress conctration factors
back to the stress concentration question, i don't think this arrangement has a stress concentration factor. there is an effect due to the contact (between the shaft and the gear), but that's more a contact/wear/fretting question.
RE: hub on shaft stress conctration factors
RE: hub on shaft stress conctration factors