Short Edge Margin
Short Edge Margin
(OP)
Hello All,
I have short edge margin condition of 1.36D on one of the part.Actually 3 parts of aluminum are joined together by bolts and one part has short edge margin.
All the parts have sufficient bearing strength.So if I understand right bearing failure occurs before shear-tear-out-failure.So if this is right then is 1.36D okay to prevent shear-out as there is no bearing failure due to sufficient bearing strength?
Thanks
I have short edge margin condition of 1.36D on one of the part.Actually 3 parts of aluminum are joined together by bolts and one part has short edge margin.
All the parts have sufficient bearing strength.So if I understand right bearing failure occurs before shear-tear-out-failure.So if this is right then is 1.36D okay to prevent shear-out as there is no bearing failure due to sufficient bearing strength?
Thanks





RE: Short Edge Margin
If somebody is confused I just want to clear that my bearing allowable is much higher than shear tear out so I think I shouldnt be worried for shear-tear out failure even though it is 1.3 D<2D.
Am I right in this?
And is shear tear out always occur after bearing failure?
Thanks
RE: Short Edge Margin
shear out failures will occur before bearing failures when the edge distance is short enough.
at the typical 2D - 2.5D used for aluminum joint designs, bearing typically is the critical (lowest) failure mode (though there are probably a few exceptions).
at 1.3D, I would suspect that shear out failure may be critical. you need to find some short edge margin allowables for your material.
there is a section on short edge margins in Niu's, Airfame Stress Analysis and Sizing book, page 700.
RE: Short Edge Margin
the key question is how much load is directed towards the free edge ? or is the majority of the load axial ?
in any case shear tear-out is easy enough to calc so why not ?
RE: Short Edge Margin
If your loading in perpendicular to the short edge distance, then the same reduction in static bearing strength will apply, but shearout becomes less critical. However, do a hoop stress check for tearing across the short section. For this condition, fatigue issues become more of a concern. Peterson has a curve which shows the effect on Kt when the edge distance is reduced.
jetmaker