Carbon Fibre Composite

Carbon Fibre CompositeStrength of Laminated Fibrous Composites science labSummaryThis report compares the results of theoretical calculations undertaken to predict the tensile military capability of carbon fibre reinforced composites against experimental results. Two main methods for the calculation of tensile strength are utilize the rule of mixtures and the ten percent rule. These standard theories appear to be valid for the majority of cases although inconsistencies are observed for the 90, transversely loaded, isostress condition.AimsTo survive familiar with composite materials, their structure and qualityTo understand how carbon fibre reinforced polymer, CFRP, materials are tensile testedObjectivesTo examine samples of composites and their precursorsExamine typical microstructuretractile test different samples of CFRP compositesIntroductionThis work looks at the tensile strength of different structural make-ups of carbon fibre reinforced polymers. Carbon fibres have greatest strength when they are loaded in the isostrain (0) condition as illustrated in Figure 4.1. In the isostrain condition, the majority of the applied load is transferred to the long fibre strands whereas in the isostress condition, the load is acting perpendicular to the fibre length and yields a far lower maximum strength. When there are multiple layers of fibres in the composite, orientated in different directions, otherwise known as a mixed ply lay-up, the maximum tensile strength varies with respect to the fibre angle.Figure 4.1 Composite lodeFour different composite lay-up structures are looked at in this report. Each lay-up consists of a total of 16 layers which are symmetrical to the highest degree the neutral axis. The layups of the composites areWhere subscripts2, 4, 8 = multiple of layers noted in the bracketsS= refers to symmetry about the neutral axisA 0 8SB 90 8SC +45,-45 4S D 0/+45/-45/902SThe test specimens consist of a section of CFRP with metal plates attach ed with epoxy resin at any end as shown later on in Figure 5.1. These metal plates are purely for clamping of the CFFP section into the in the tensile testing rig as shown in Figure 5.2.Experimental MethodThe dimensions of the test specimens are noted for each piece prior to any testing and will be used for fair comparison in the theoretical calculation methods. Dimensions for each specimen, A-D are shown below where x and y relate to the dimensions shown in Figure 5.1.