Does anyone know of work toward thermal fatigue of composite bonded joints? Here 's some background to my question. ... I've done my literature search and this subject is a void. It's standard practice to subject space flight hardware to a mere 10 to 20 thermal cycles during component qualification tests. It is not uncommon that these tests reveal partial bond failure, particularly where a metal fitting is bonded to composite, with failure in the composite. It would be costly to require all such qualification tests to include the thousands of cycles representative of end-of-life conditions. We also do not analyze to end-of-life conditions because: 1) parts are typically not flight critical, and 2) analysis method does not exist. As its stands, if a part experiences disbond during the few cycles tested, then the part is either redesigned to pass that test, or if the disbond is partial and not catastrophic, then the component can be subject to a full end-of-life number of cycles in hope of showing that it does not worsen. All that analysis can do is help to guide the design toward passing a single thermal-cycle.
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Concordia University, Montreal, Canada.
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Development of a Solar Array substrate for the Europa environment".5. I do believe FWT is your best test method for an issue between facesheet and core.6. Toughness of your film adhesive can make a major difference.7. Consider your surface preparation and depth of abrasion. We found less resin to be better than more resin (we abraded until some "black" was present, from the carbon fiber).8. Recall that composites are not homogeneous and are composites of two different materials, each with unique allowables. A debond would typically be film-adhesive or matrix-driven. You should work with failure criteria which can handle matrix-driven failures (We adapted SIFT, or Onset Theory, to our application and I am very much a believer in this criteria for this kind of situation). This will inform you about the temperature limits of your system and will show you just how much your design window shrinks if you are working at extreme temperature limits.
An aromatic or aliphatic zirconate is an excellent adhesion promotor for graphite – see link: http://4kenrich.com/wp-content/uploads/2017/10/pci1017p48-Kenrich-FT-PCI-Oct-2017-Issue-PCI-Approved-for-Publication.pdf .
Salvatore J. Monte
P.E., B.C.E., M.S.-Polymeric Materials, Fellow (SPE)
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