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Barry1492 (Mechanical) (OP)
4 May 06 11:12
Can someone help me out or point me to a good web resource?

I need to calculate bearing stress and, frankly, I don't think this was covered in school.

Simply, imagine a piece of U-Channel with the open end facing down.  Drill a hole through one side and out the other.  Put a bolt through it and hang something heavy from the bolt.  

I know how to claculate stress if I was simply pulling on a flat plate with a hole in the middle (P/A with some stress concentration factor for the hole), but what about deformation of the hole if the load is ON the hole (as stated above).

Any help will be greatly appreciated.

Barry1492 (Mechanical) (OP)
4 May 06 11:42
OK....I think I found something.  Feel free to comment on applications.

A(bearing) = Diamter x Thickness
Sigma (bearing) = F/A
N(bearing) = Sy/Sigma

A(tearout) = length x thickness
tau = F/A
N(tearout) = 0.577xSy/tau
diamondjim (Mechanical)
4 May 06 12:34
Your bearing stress area would be
the area of the washer od
minus the area of the hole diameter.
This is a surface stress.
Helpful Member!(3)  CoryPad (Materials)
4 May 06 12:34
Your calculations for bearing stress are accepted as an initial starting point.  The tearout area should be multiplied by two because you are creating two surfaces.  You can find the analysis technique in section 12.2 of Handbook of Bolts and Bolted Joints edited by Bickford and Nassar.  You also can find information on this subject in Guide to Design Criteria for Bolted and Riveted Joints by Kulak, Fisher, and Struik available for free here:



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CoryPad (Materials)
4 May 06 12:37
diamondjim's answer is for bearing stress (more appropriately called surface pressure) due to the fastener's preload.  It is unrelated to your question.



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Barry1492 (Mechanical) (OP)
4 May 06 14:25
Thanks.  DiamondJim, my load would be perpendicular to the axis of the bolt.  

CoryPad, I don't really understand the reasoning behind tearout area.  Why do I multiply it by 2?  .........wait, I'm looking at the example in the book now.  They multiply by 4 for a situation such as this.  In other words, thickness is the thickness of the material that each of the 2 holes is in and there are 4 surfaces total that these 2 holes are on.

I get it.  Thanks for checking my work!
CoryPad (Materials)
4 May 06 14:52
you are welcome



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