Tearout Failure

[MrHiLok]

If the e/D is 2 or greater, do you have to worry about tearout failure or not? One of my team mates says that, if e/D is 2 or greater then, fatigue is not an issue, but tear out failure should be calculated. Can anyone help. Thanks

 

[SWComposites]

In what sheet material? what thickness? single shear or double shear?

Don't think you can make a blanket statement about fatigue; depends on joint config, material, fastener, loading spectrum, etc, etc.

Why not just calculate the tear out as well as bearing static margins?

 

[GBor]

Gotta' agree with SWComposites. To make a blanket statement like this doesn't make sense. Each situation is different. If you are using 0.032" sheet to try and repair a skin on a commercial aircraft...probably not going to work. Using it on an ultralight? Different story.

2D is a good "rule of thumb", but you still need to do your "due diligence".

Garland E. Borowski, PE
Engineering Manager
Star Aviation

 

[rb1957]

and what's the connection between shear-out and fatigue ?

i would always check shear-out as one of the possible modes of failure.

fatigue is an altogether different thing, sure with a reasonable edge distance the Kt is pretty much 3 (for an open hole) but not something i'd dismiss. possibly not something i'd spend a ton of time on either ... it depends on the structure involved.

 

[blakmax]

Hart-Smith recommended a 3d edge distance to prevent shear-out and a pitch of 5d to force bearing failure in preference to tension-through-hole failure.