While the carbon fibers themselves are not affected by the moisture diffusing into the material, the moisture plasticizes the polymer matrix. While CFRPs demonstrate excellent corrosion resistance, the effect of moisture at wide ranges of temperatures can lead to degradation of the mechanical properties of CFRPs, particularly at the matrix-fiber interface. As a result, when using CFRPs for critical cyclic-loading applications, engineers may need to design in considerable strength safety margins to provide suitable component reliability over its service life.Įnvironmental effects such as temperature and humidity can have profound effects on the polymer-based composites, including most CFRPs. While steel and many other structural metals and alloys do have estimable fatigue or endurance limits, the complex failure modes of composites mean that the fatigue failure properties of CFRPs are difficult to predict and design against.

This means, theoretically, that stress cycle failure cannot be ruled out. ĭespite their high initial strength-to-weight ratios, a design limitation of CFRPs are their lack of a definable fatigue limit. However, PEEK is much more difficult to process and more expensive. One such material with high promise is PEEK, which exhibits an order of magnitude greater toughness with similar elastic modulus and tensile strength. As such, recent efforts to toughen CFRPs include modifying the existing epoxy material and finding alternative polymer matrix. Although CFRPs with epoxy have high strength and elastic modulus, the brittle fracture mechanics present unique challenges to engineers in failure detection since failure occurs catastrophically. Typical epoxy-based CFRPs exhibit virtually no plasticity, with less than 0.5% strain to failure. The fracture toughness of carbon fiber reinforced plastics is governed by the following mechanisms: 1) debonding between the carbon fiber and polymer matrix, 2) fiber pull-out, and 3) delamination between the CFRP sheets. The following equation,Į c = V m E m + V f E f The two different equations governing the net elastic modulus of composite materials using the properties of the carbon fibers and the polymer matrix can also be applied to carbon fiber reinforced plastics. The properties of a CFRP depend on the layouts of the carbon fiber and the proportion of the carbon fibers relative to the polymer. Unlike isotropic materials like steel and aluminum, CFRPs have directional strength properties. Reinforcement gives CFRPs their strength and rigidity, measured by stress and elastic modulus respectively. Because CFRPs consist of two distinct elements, the material properties depend on these two elements. The matrix is usually a thermosetting plastic, such as polyester resin, to bind the reinforcements together. In CFRP the reinforcement is carbon fiber, which provides its strength. In this case the composite consists of two parts: a matrix and a reinforcement. The most common additive is silica, but other additives such as rubber and carbon nanotubes can be used.Ĭarbon fiber is sometimes referred to as graphite-reinforced polymer or graphite fiber-reinforced polymer ( GFRP is less common, as it clashes with glass-(fiber)-reinforced polymer).ĬFRP are composite materials. The properties of the final CFRP product can be affected by the type of additives introduced to the binding matrix (resin). The binding polymer is often a thermoset resin such as epoxy, but other thermoset or thermoplastic polymers, such as polyester, vinyl ester, or nylon, are sometimes used. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and stiffness (rigidity) are required, such as aerospace, superstructures of ships, automotive, civil engineering, sports equipment, and an increasing number of consumer and technical applications. Tail of a radio-controlled helicopter, made of CFRPĬarbon fiber-reinforced polymers ( American English), carbon-fibre-reinforced polymers ( Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic ( CFRP, CRP, CFRTP), also known as carbon fiber, carbon composite, or just carbon, are extremely strong and light fiber-reinforced plastics that contain carbon fibers.

Carbon fiber kit