Composites are used to create parts that are stronger and lighter than metals. They are also more durable and stand up better to harsh environmental conditions.
The most popular composite materials are glass, carbon, aramid and basalt fiber-reinforced polymers. These materials are used in high-performance products such as aircraft components, boat and scull hulls and car bodies.
Fabrication
The composite fabrication process involves the use of different materials to build an end product. Unlike metals, composites can combine strength and stiffness with lightness. This makes them ideal for making products like aircraft components, boat and scull hulls, bicycle frames, and racing car bodies.
In the case of composites, the matrix is typically a thermosetting polymer (or resin) that holds the reinforcing fibres together. The type of matrix used determines the physical properties of the composite.
The dispersion and orientation of the strengthening fibres also affects panel stiffness. This is because composites are anisotropic materials that have varying strengths and weaknesses depending on the direction of forces and loads.
Curing
When meat is cured, it undergoes a chemical and physical process. The result is that the meat tastes a little different, but is preserved and safe to eat. The flavour is a composite of the original meat flavor and those introduced by the curing agents (usually salt) and by those developed by bacterial and enzymatic action.
Many modern composites have specialised functions such as being good conductors of heat or having specific magnetic properties, and these can be tailored by the raw material choice and the processing method chosen. The reinforcing and matrix materials are merged, compacted and shaped into components using methods such as wet lay up, vacuum infusion, resin transfer molding and compression moulding.
Some of the most advanced composites are used in products that need to be light and strong enough to withstand harsh environments. This includes both military and civil aircraft, where the wing and fuselage sections as well as propellers are often made of composite materials.
Finishing
In composite fabrication, the polymer matrix material — often referred to as a resin solution — is combined with one or more reinforcement materials to form a new structural material. The resulting structure is stronger, lighter and more durable than the individual component materials, yet still retains its integrity and performance when subjected to stress.
There are many fabrication methods for FRP composites, including spray-up processing (where resin is sprayed onto the reinforcement and chopped fibre is added), vacuum infusion, filament winding and continuous sheet products such as rooflights and long pipes made by pultrusion. Many of these processes are labour, resource and capital intensive.
Traditional methods are being increasingly replaced by new technologies such as composite bike 3D printing. These offer lower production costs and a more automated process. In the future, they may also be used to replace metal parts, as they are stronger and more lightweight. The amount of chopped fibre in the plastic determines part strength and quality. Shorter chopped strands boost surface finish and print accuracy, while longer strands increase strength, but reduce print quality.
Testing
Incorporating composite materials in products and components makes them lighter and more resistant than traditional metals, opening the doors to new applications. But composites are complex, and they require expert NDT inspection to make sure that they perform as expected.
This is because the physical properties of composites are often anisotropic, meaning that they are different depending on the direction of stress and force. For example, a composite’s stiffness may depend on the dispersion and orientation of the reinforcement fibres in the panel. The matrix phase may also be an important factor, including thermoset versus thermoplastic and the type of layup.
Conclusion:
It’s also crucial to ensure that the test equipment is accurately aligned with the specimen during testing, to avoid damage to the material and premature failure of the test. This is achieved using adjustable alignment fixtures that allow a check of concentricity and angularity during the test, in compliance with standards such as Nadcap AC7122/1.
