Bearing Allowable for Graphite/Epoxy Laminate
Bearing Allowable for Graphite/Epoxy Laminate
(OP)
Anybody have general information on bearing allowables for graphite/ epoxy laminate with 60% uni-directional fibers and 40% +-45 fibers? I generally use half of the compressive strength, approximately 60 ksi, but I would like some good documentation.





RE: Bearing Allowable for Graphite/Epoxy Laminate
RE: Bearing Allowable for Graphite/Epoxy Laminate
RE: Bearing Allowable for Graphite/Epoxy Laminate
Finding an allowable outside of an actual qualification programme (which always generate confidential data) is hard. MIL-HDBK-17 has some data on AS4/997. This comes out at high 60's ksi at 180 deg F.
As eap1782 says, any real joint should have a bearing/bypass analysis. MIL-HDBK-17 can help with that as well.
MIL-HDBK-17 is currently about 22 Mb in .pdf format, though volume 2 with the allowables data in it is "only" 3.6 Mb.
RE: Bearing Allowable for Graphite/Epoxy Laminate
I heard (a few years ago) that there had been some work to increase hole bearing strength/durability dramatically. The concept is to install bushings in composite structure holes [graphite and Boron... not glass or kevlar] using something like the FTI Force-Mate process... except tailored to the explicit composite structure and CRES bushing employed. The CRES bushings are expanded in-place and "lock" into the exposed ends of the fibers. This allowed the bushing to transfer much higher bearing loads into the structure... approaching the limits of the metal.
Regards, Wil Taylor
RE: Bearing Allowable for Graphite/Epoxy Laminate