Author: AKeson

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. order viagra 50mg 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...

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NASA Composite Crew Module

NASA, the space agency for the U.S. government, has investigated the use of advanced composites for use in future vehicle programs.  The Composite Crew Module (CCM) has been designed and built as a travel vehicle for astronauts in future space programs to travel.  Drawing parallels to the Apollo program, this module will be launched on a rocket and break away as a module. This technology and material are undergoing testing and evaluation before it is officially accepted for the Orion program.  As a partnership between government agencies and public companies, this technology aims to reduce weight and improve performance of the manned vehicles. From NASA’s website “Led by the NESC, the project team is a partnership between NASA and industry, including design, manufacturing, and tooling expertise. Partners are civil servants from nine NASA Centers – ARC, DFRC, GRC, GSFC, JSC, JPL, KSC, LaRC, and MSFC; the Air Force Research Laboratories; and contractors from Alcore, Alliant Techsystems, Bally Ribbon Mills, Collier Corporation, Genesis Engineering, Janicki Industries, Lockheed Martin, and Northrop Grumman. The CCM team operates in a virtual environment, electronically connecting participants across the country.” This full-scale structure has strain gauges attached to monitor loads on the structure.  It was announced on January 25 that it has passed a battery of stress tests to prove viability. The structure appears to be made with carbon fiber materials, maybe with some graphite...

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Panel Stiffness

Composites structures have requirements for stiffness to provide support and stability. Tests can be completed to identify the stiffness of a given area on a composites structure, i.e. how much it will bend for a given force. The required stiffness of a section of a composites part depends upon the overall design and service expectations. Several factors, including the life expectancy of the object, the load rating of the composites surface, the inter-laminar bond strength, will help determine the threshold requirements. Testing is very important to determine the life expectancy of the part and whether it meets the requirements of its’ job. Panel stiffness can be modified to meet these requirements using two basic methods. One way to increase the stiffness of an unsupported composites panel is to reduce the size of the panel through additional support structures. The other way is to increase the panel thickness across the same area. Choosing which method to use depends upon the engineering of the part and determining which method is acceptable with the surrounding part layout. If there is room to add supports, this is likely a quick and easy option. If there is room to increase the thickness, adding new or additional coring materials may be a simple solution. Building a strong and stiff composites structure can be accomplished with the extremes of building a robust “skeleton” with small open...

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Making Holes

If you are working with fiberglass parts, you may need to attach other parts, pieces, and features mechanically with fasteners.  Bolts and rivets are the most common mechanical fasteners used to accomplish this. Composites with a nice, decorative gelcoat finish such as boats and RV”s require special care to make holes in them for placing bolts and rivets.  Disturbing the area around your hole in a gelcoated surface can lead to very expensive repairs by a fiberglass expert. You can make holes yourself, but it requires extra care and attention.  I found a great Youtube video that demonstrates this from user CenturionCrew.   The biggest mistake that can be made is improper pokies online placement of the hole. Following the instructions in the video and drilling a nice slow speed hole is the best way to be successful.  He also mentions the caution that must be noted to stop the drill chuck from contacting the gelcoated surface.  One tip that I have is to place a small piece of rubber hose over the drill bit to contact the gelcoat before the drill chuck. One other note with holes (all shapes and sizes) in cored composites fiberglass pieces.  If there is a layer of balsa or foam core in the cross section, extra precautions should be exercised.  One is to coat the inside surface of the hole with gelcoat, resin,...

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Vacuum Bagging Video

Vacuum bagging is a process that requires unique materials and processes, but can be simple to operation in an ongoing basis. There are many advantages to vacuum bag molding, a few of which include: Improved resin/glass ratio More consistency across the laminate and part -to -part as compared to open layup Containment of air emissions from the resins As compared to hand layup and chop layup, there are a few disadvantages, including Higher consumable material cost Higher capital equipment cost Difficulty with superior surface finish Some parts are more suitable for vacuum bag molding than others. It also depends upon which process it is being compared with. Vacuum bag molding requires an extremely tight seal between the mold and the bag. Molds with multiple pieces or holes for inserts can be difficult to complete a seal. Parts that are overly large and complex can present challenges with placing resin and reinforcement before the cure cycle starts. The bag must be completely sealed and under full vacuum before the curing cycle of the resin begins. The basic premise of vacuum bag molding is that the air is removed from the bag, allowing the atmosphere (air on the outside of the bag) to push the bag onto the part on the mold, compressing the layers of resin and reinforcement. Many misinterpret the process as “sucking the extra resin out.” We are...

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