A little guidance in regards to the strength of this assembly.
A little guidance in regards to the strength of this assembly.
(OP)
Well this is a structural question, but as I scanned through the structural forum, I noticed mainly building related questions and answers. I figured I would give the mechanical forum a shot!
My question is in regards to the picture attached to my post. The bolt that secures the shaft to the plate is made of a much stronger material then the shaft itself. Shear load is applied to the radius area of the shaft. Is it safe to assume the shaft is as strong with the bolt fastened into it as the plate and shaft made as one solid piece?
If the bolt is stronger then the material it is replacing, I don't see it being a weaker design...
I don't have a degree in engineering so please excuse my ignorance and confusion.
Thanks, Andrew
My question is in regards to the picture attached to my post. The bolt that secures the shaft to the plate is made of a much stronger material then the shaft itself. Shear load is applied to the radius area of the shaft. Is it safe to assume the shaft is as strong with the bolt fastened into it as the plate and shaft made as one solid piece?
If the bolt is stronger then the material it is replacing, I don't see it being a weaker design...
I don't have a degree in engineering so please excuse my ignorance and confusion.
Thanks, Andrew





RE: A little guidance in regards to the strength of this assembly.
if the loading is cyclic in nature:
- to avoid fatigue the clamping force needs to be greater than prying force resulting from applied load.
http://session.masteringphysics.com/problemAsset/1...
- the clamping force needs to be great enough to prevent motion of the interface
RE: A little guidance in regards to the strength of this assembly.
I also have configured 4 smaller bolts into a circular pattern around the larger bolt in the center. I didn't show them in the picture because I didn't think they would be relevant.
Thanks, Andrew
RE: A little guidance in regards to the strength of this assembly.
the shaft has to carry the loads to the reactions (the bolts). the bolts have to carry these loads into the plate (supporting everything). if there's a single bolt, you'd expect the off-set moment to come out as a couple between the edge of the shaft flange and the bolt (in tension). if there's a pattern of bolts, then the base for the couple will be bigger (and the loads smaller). so the critical bolt is carrying tension and shear. i'd make sure the the holes in the shaft (for the bolts) weren't tapped at the interface ... so you really want to have a shear spigot on the CL (close tolerance hole) to carry the shear and tapped (clearance) holes to the bolts reacting tension.
clear as mud ?
does the shaft sit in a recess on the plate ?
Quando Omni Flunkus Moritati
RE: A little guidance in regards to the strength of this assembly.
RE: A little guidance in regards to the strength of this assembly.
A bearing slides on the shaft up to the point of the radius, that is why I assume the raduis area would be the point of shear.
The other 4 bolts are 1/4 20's. They thread into the shaft 3/8 of an inch via a 90 degree 1.125 inch diameter degree bolt pattern.
The shaft presses into the plate around .2 to .25 of an inch.
To give you guys a scale, the large bolt in the center is 1/2 inches in diameter...
Thanks for the answers guys! I'm trying to be as clear as possible, but sometimes it's a bit hard to type it out! lol
RE: A little guidance in regards to the strength of this assembly.
prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes and launchers for fun rides
http://www.levitans.com : Air bearing pads
RE: A little guidance in regards to the strength of this assembly.
If the plate and shaft was one piece then you be able to model it easier and add some more re-inforcement on the shoulder / taper it in. I can't see any fundamental flaws in this design, but where it would fail is not clear until you run some numbers and do checks on buckling and shear in all the components. If vibration or shock loading are involved then it gets much more complex...
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: A little guidance in regards to the strength of this assembly.
does the shaft sit in a recess ?
Quando Omni Flunkus Moritati
RE: A little guidance in regards to the strength of this assembly.
RE: A little guidance in regards to the strength of this assembly.
Another consideration though, is that the bolt, in tension, will see combined shear and tension loading. The shaft will see combined shear and compression loading. You should look at the magnitudes of the stresses from each of those loads (applied shear and bolt preload) and evaluate the combined stresses for both the bolt and the shaft.