Bearing Bypass Stress

[TDI]

Can someone explain to me the concept of "bearing bypass stress". It seems to be related to bolted joints in composite materials but does it also apply to metals?
Thanks

 

[rb1957]

maybe, ... to me, by-pass stress applies to a loaded fastener. by-pass stress means the remainder of the total stress that is not reacted by the laod transferred by the fastener, ie total stress (upstream of the fastener) = the stress transferred by the fastnere + the by-pass stress (that by-passes the fastener). load (that'd be the stress expressed over one fastener pitch) might be a better way to express it ... total load = fastener (shear) load + by-pass load.

 

[SWComposites]

There is no thing as "bearing-bypass stress". There is however, a bearing-bypass strength interaction, which uses bypass stress (or strain on the y-axis and bearing stress on the x-axis to define a failure envelope. With metals, the envelope it typically a rectangular box; i.e., no interactin. With composite laminates the envelope has on the tension side a downward sloping line from pure bypass to a lower bypass value at maximum bearing, a veritical line at maximum bearing, and on the compression side an elliptical interaction between bearing and bypass (there are other compression brg-byp interactions in use; the data is less clear on the compression side of the envelope). There are several definitions of "bypass" in use in the industry (some including the load reacted by bearing and some not), and the determination of "bypass" load/stress/strain in a complex joint can be tricky.