The characterisation of carbon fiber reinforced epoxy composite materials

In this study, unidirectional carbon fiber/epoxy resin composite materials were produced. Then, the effect of change in fiber directional and number of ply on the composite structure was examined. For this objective, the specimens were fabricated from commercially available carbon/epoxy pre-impregnated tapes. The tapes were made of unidirectional carbon fibres Magnamite® AS4 pre-imregnated with Hexcel 8552 epoxy resin. Composite materials were produced by using autoclave technique. In order to determine mechanical properties of the composite materials tensile, bearing, compressive and in plane shear tests were conducted. Thermal properties of composite materials were analyzed by using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The fracture surface of the composite materials were examined by using scanning electron microscope (SEM) test method. As a result of mechanical characterization studies showed that, the directional of the fiber is very effective on the mechanical performance of the composite. The 0o orientation gave the maximum tensile strength 1713,48 MPa and tensile modulus 127,12 GPa. When the 0o orientation ply increase on multi-directional composite materials, the tensile strength of the composites samples increased. The in-plane shear strength 75,20 MPa and modulus 5,00 MPa were found with the ±45o orientations of the plies of the composite materials. When the 0o orientation ply decrease on multi-directional composite materials, the bearing strength and modulus of the composite samples increased. The maximum bearing strength 1010,46 MPa and the maximum bearing modulus 105,17 GPa was found. The decomposition temperature of the composite samples are found about 385oC from the TGA thermograms. The SEM micrographs taken from fracture surfaces were examined, the carbon fiber epoxy composites showed good wetting of fiber with resin. The fiber directions are shown clearly with the micrographs. Key Words : Carbon fiber, epoxy resin, polymer composite, mechanical properties, thermal properties