Infusion-Test Panel and Fuselage
Ran across an interesting Youtube video demonstrating an epoxy resin infusion process on some test panels and fuselage. It is interesting how everybody has their own terminology and technique for resin infusion. There is definitely more than one way to get the job done.
They use an interesting layup, including lots of the Soric material. I have used this before, and it is a good material to infuse with. Made by a company called Lantor, it is a non-woven polyester material that acts as a core material. It appears that the folks in the video are using the SF grade Soric, which comes in several thicknesses.
An advantage of using Soric as a core is that it flows resin very well for infusion. It is easy to cut and handles well.
Disadvantages also abound. One of them is the possibility of print-thru on the surface of the laminate. Another is the negative effect on the structural properties of the laminate. This non-woven material does not have much crush resistance such as a balsa or foam material. A serious issue that I have found is the higher risk of delamination. Like any core, this material works by separating the two skin layers to create a sort of “I beam” effect. The problem is that this material is not inherently strong within itself. Though it does become saturated with resin during a proper infusion, it is not nearly as strong as glass or carbon fiber reinforcement.
As the video demonstrates, a proper resin infusion can look easy. With proper materials, practice, and knowledge it can be.
Boeing’s 787
Boeing’s 787 will be the first composites-intensive commercial airliner. Traditionally made from aluminum, carbon fiber composites will work to create a plane that is stronger and lighter with fewer manufactured parts. Carbon Fiber reinforcement with Epoxy resin will be the main construction of these composites, which will make use of an autoclave during processing to control the molding conditions and ensure the quality and durability of the laminate.
Composites will reduce the number of parts for the airplane, and Boeing predicts that the front section alone would normally require using 1,500 sheets of aluminum, which also means drilling between 40,000 and 50,000 holes for the nuts and bolts to attach these sheets together and to the underlying framework. Carbon Fiber composites will allow for the skin and underlying supports to be molded as one large piece. Boeing predicts that assembly line time will be reduced from about three weeks to attach all of this aluminum together to about 3 days to attach the large composites sections together for the entire plane fuselage.
Switching materials has its’ own set of problems to overcome. The customers’ mechanics will need to be trained to repair damage on these composite planes. Damage detection will be important as well. Some will be visible to the naked eye, and other damage will not. Several forms of Non Destructive Testing will be employed to test for damage and wear on the composites body to ensure a safe aircraft.
Composites have been used in aircraft before, but not as extensively in commercial airplane bodies. Existing commercial airplanes have made use of composites in other areas to help make the planes stronger and lighter. Military jets have used carbon fiber composites for many years in their technologies for strength and weight advantages. Private business jets have utilized fiberglass composites for many years in their construction. Homemade kit planes have also made extensive use of fiberglass to make inexpensive craft in personal shops.
The profile of carbon fiber composites will definitely be elevated if Boeing’s 787 becomes as successful as promised.
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