There are many formalised repair procedures prepared by reputable organisations throughout the world, all evolved from good historical industry practice and adapted to the specific conditions of each sector.
All successful repairs carried out to any substrate rely on skilled repair technicians, good surface preparation, well designed repair procedures and the use of first rate materials. They currently also depend on stringent quality control encompassing reliable damage detection, surface cleanliness and texturing examination, drying to known limits, undertaking work within permitted temperature and humidity envelopes, and controlling resin cure to manufacturers recommendations. This should be followed by NDT inspection of the finished repair or destructive testing of sample coupons or bars.
The quality of any repair is dependent not only on the materials used and skill of the operator but also on the environment in which the repair is carried out. Temperature, humidity, and cleanliness are important factors in the creation of the optimum envelope for production of the best repair.
The more primary a structure is, and the closer it operates to its design limits, the more difficult the repair. However, even heavily-loaded primary structural FRPs have been successfully repaired for many years. Heavily loaded, oriented-fibre, advanced FRP structures require careful engineering design of major repairs; it is not simply a matter of applying a patch. In spite of this, successful repairs of complex FRP structures are being done every day. There is no “black art” to FRP repair—just training and experience. Experimentation will always prove best practice and clear-up uncertainties. Finally, quality assurance is an absolute must, requiring a thorough understanding and dedication to underlying principles and the testing required to ensure the repair will be successful long-term.
NCN report – Repair of FRP composite structures
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