![]() Molding conditions of CF/Nylon 6 laminates and CF/Epoxy laminates were 280˚C for 3.5 mins under a compression pressure of 4 kg/cm 2 and 130☌ for 50 minutes under a compression pressure of 25 kg/cm 2, respectively. CFRP laminates with a thickness of 2 mm were prepared by laminating 20 plies of thin prepreg sheets (single ply laminate ≈ 0.1 mm) with stacking sequences of 20 for both 0-degree and 90-degree 3-point bending tests. Table 1 shows the mechanical properties of the raw materials. Two types of UD prepreg sheets were fabricated from carbon fiber films with Nylon 6 (MXD-PA, Mitsubishi Gas Chemical, Tokyo, Japan) film, and carbon fibers (T700SC 12K, Toray) with epoxy (MCP939, Maruhachi Corporation, Fukui, Japan) film, respectively. Two kinds of UD CFRP laminates were manufactured by using same carbon fiber (T700SC 12K, Toray, Tokyo, Japan) but two different types of matrix systems. Manufacturing of Unidirectional Composites Step-by-step 3 point bending test, microscope observation and scanning electron microscope observation were carried out to investigate the failure behavior and fracture mechanism.Ģ.1.1. The effects of fiber volume fraction, void content, fiber distribution and their hybrid effects on mechanical properties were investigated. The fracture toughness of laminates was measured by compact tension tests. The transversal tensile strength was evaluated by tensile tests of 90 degree unidirectional laminates. The interfacial properties were evaluated by push-out test. Fiber distribution, fiber volume fraction, and void content were measured by the optical observation method. In this study, typical thermoplastic resin Nylon 6 and thermosetting epoxy resin were used as matrices to manufacture 0 and 90 degree UD CF/Nylon 6 (same to CF/PA6) and CF/Epoxy laminates for investigating their flexural properties and failure behavior through a great quantity of experimental tests. Voids were found to have a negative effect on the flexural modulus and strength, which both decreased by about 1.5% for each 1% of voids but a clear positive effect on the beam stiffness. Hagstrand PO studied the void content on the flexural properties of beams manufactured by compression moulding multiple unidirectional commingled glass/polypropylene fiber tows. Results indicate that specimens with fibers positioned on the compression side (≈250 MPa) showed higher flexural strength than specimens with fibers positioned on the tension side (500 - 600 MPa). Lassila J and Vallittu P investigated the influence of the position of fiber rich on the flexural properties of FRPs construction. Except the above mentioned factors, the presence of local inhomogeneities and defects, which are often difficult to characterize and model, also influence the flexural properties and failure in flexure. The flexure response of FRPs has been the subject of continued investigation. Ĭonventional laminate composites are sensitive to out-of-plane loading, as they are weaker in the through-the-thickness direction than in the plane of lamination. ![]() Longitudinal tensile failure of UD CFRPs having low interfacial bonding strength displays a splitting/broom fracture behavior, while those having a high interfacial bond display a step-like/brittle fracture behavior. Modification of the interface could affect fracture modes of unidirectional (UD) CFRPs, resulting in disparate mechanical properties. One of the most efficient methods to ameliorate the capability of composites is to select a reasonable combination of reinforcement and matrix. Good interfacial adhesion allows more effective stress transfer from the matrix to the reinforcement, enhancing the ultimate strength. The sensitivity of the mechanical behavior of composites materials to the fiber/matrix interfacial bond strength has long been realized. Lots of methods to improve the mechanical properties of CFRPs such as reasonable structure optimization (hybrid reinforcements, layup and so on), fiber treatment, post-treatment, and micro- or nano-scale filler doping have been carried out. The properties of CFRPs are related to lots of factors such as properties of raw materials, fiber orientation, manufacturing processes and compatibility between fiber and resin. Lots of present traditional materials, metal for instance, were gradually substituted by some new replacements such as carbon fiber reinforced plastics (CFRPs). Till now, fiber reinforced plastics (FRPs) have given rise to a wide range of engineering applications of types of materials to various application fields including aerospace and aircraft structure, yachts as well as wind generator blades and other products on the account of their outstanding mechanical properties, lightweight and longer service life. ![]()
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