Blind rivet tension allowable

[dcascap]

Hi,

I came across a guideline that ask for a tension allowable reduction k=20%. So the new tensile allowable would be 20% of what the vendor (as cherrymax) specifies for that blind rivet.

Have you encounter similar guideline? I understand that blind rivets should not be designed to be used in tension, but sometimes can be almost unavoidable. This reduction factor seems too conservative, even though I could be missing something...

Is maybe this guideline if you use the material allowable? or maybe is legacy? There is no much more info than the reduction factor on the guideline itself...

Let me know what are your thoughts about it, I'm curious what you think.

Thanks!

 

[SWComposites]

Where did you see this "guideline"?

Riveted joint strength (tension and shear) is often not driven by the fastener strength, but by the sheet strength. Hence why there are "joint strength" values in MMPDS (and company allowables documents). Vendor fastener strengths are based on tests with steel sheets to force a pure shank shear failure or fastener tension failure.

 

[dcascap]

Yes, that is true but this failure only refers to the fastener itself (its a calculation method in which Ft of fastener = 0.2Ft for blind fasteners, on the other hand, for Hi lok there is no tensile reduction) other joint failures are evaluated later on.

The guideline correspond to a handbook that compiles different methods and guidelines from an OEM and other aerospace companies (I don't want to specify more due to IP).

 

[SWComposites]

maybe it means 0.2 times the material tensile strength * area? a rivet is going to develop nowhere near the base material strength.

 

[WKTaylor]

dc...

WHAT TYPE OF 'BLIND RIVET ' are you actually considering/contemplating with this question...???

Does the BR conform to a procurement spec? shear-head? tension Head? alloy? formed-tail [bulb] style?

IF you have a genuine tensile load to worry about... perhaps you should consider a high strength alloy blind rivet with a tension head and a large formed tail/bulb... or a blind bolt.