PSI - Issue 1

Ricardo Baptista et al. / Procedia Structural Integrity 1 (2016) 074–081 Rosa Marat-Mendes/ Structural Integrity Procedia 00 (2016) 000–000

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diminution of flexural strain and flexural shear strain. The behavior of elastic modulus and strain is due to the stiffness increase with increasing graphite contents. The fracture behavior is however also increasingly more brittle. The flexural strength and shear strength overall increase with increasing graphite contents. Attained results are different for [0/90] 4s and [45/-45] 4s specimens, since under a transversal load matrix behavior and matrix load transmission behavior are more relevant than under longitudinal load. 4. Conclusions In the present study the incorporation of different amounts of graphite filler with approx. 13 μ m diameter on the mechanical properties of an epoxy resin and of carbon fiber reinforced epoxy composites were tested. Graphite-reinforced epoxy resin attained results show that 7.5, 10 and 11.5 wt%-graphite results in the best balance of mechanical (modulus, strength, strain) properties, since dispersion of graphite platelets is more homogeneous. Eliminating matrix porosity is mandatory for increased mechanical performance. The same trends result when carbon fiber is introduced as the reinforcement phase. Overall this study shows that the incorporation of graphite as matrix filler in carbon fiber reinforced epoxy results in improvement on mechanical properties, up to a limiting value. Above this limit decreased performance is expected as a result of graphite agglomeration in the matrix. The fact that graphite has low density is an advantage in prosthetic applications. This study shows that graphite/epoxy composites reinforced with carbon fiber present higher mechanical performance than conventional carbon fiber reinforced epoxy matrix composites. Acknowledgements ASTM D3039/D3039-00. 2000. Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials. ASTM International. ASTM D3518/D3518M-13. 2013. Standard Test Method for In-Plane Shear Response of Polymer Matrix Composite Materials by Tensile Test of a ± 45 ° Laminate. ASTM International. ASTM D638-14. 2014. Standard Test Method for Tensile Properties of Plastics. ASTM International. ASTM D790-02. 2002. Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials. ASTM International. Baptista, R., Marat-Mendes, R., Fortes, C., Gil, R., Queiroga, B., 2015. Comparition of mechanical behavior of basalt and carbon fiber reinforced composites applied to a prosthesis device. in: Proceedings of the “6 th Portuguese Congress on Biomechanics”. In: ESTG – Instituto Politécnico de Leiria. (Ed.). 6 th -7 th , February, Leiria, Portugal, pp. 135. Cho, J., Chen, J.Y. and Daniel, I.M., 2007. Mechanical enhancement of carbon fiber/epoxy composites by graphite nanoplatelet reinforcement. Scripta Materialia 56, 685–688. Klasson, B.L., 1995. Carbon fibre and fibre lamination in prosthetics and orthotics: some basic theory and practical advice for the practitioner. Prosthetics and Orthotics International 19, 74-91. Nolan, L., 2008. Carbon fiber prostheses and running in amputees: A review. Foot and Ankle Surgery 14, 125-129. Ozerol, E., Senkal, B., Okutan, M., 2015. Preparation and characterization of graphite composites of polyaniline. Microelectronic Engineering 146, 76-80. Scholz, M., Blanchfield, J.P., Bloom, L.D., Coburn, B., Elkington, M., Fuller, J., Gilbert, M., Muflahi, S., Pernice, M., Rae, S. I., Trevarthen, J., White, S., Weaver, P., Bond, I., 2011. The use of composite materials in modern orthopaedic medicine and prosthetic devices: A review. Composites Science and Technology 71, 1791-1803. Shokrieh, M.M., Esmkhani, M., Shahverdi, H.R., Vahedi, F., 2013. Effect of Graphene Nanosheets (GNS) and Graphite Nanoplatelets (GNP) on the Mechanical Properties of Epoxy Nanocomposites. Science of Advanced Materials 5, 1–7. Subagia, A., Kim, Y., 2013. A study on flexural properties of carbon-basalt/epoxy hybrid composites. Journal of Mechanical Science and Technology 27, 987-992. Suresha, B., Chandramohan, G., Renukappa, N.M., Siddaramaiah, 2007. Mechanical and Tribological Properties of Glass–Epoxy Composites with and Without Graphite Particulate Filler. Journal of Applied Polymer Science 103, 2472–2480. Wu, H. F., Biresaw, G., Laemmle, J. T., 1991. Effect of surfactant treatments on interfacial adhesion in single graphite/epoxy composites. Polymer Composites 12, 281–288. Yasmin, A., Daniel, I.M., 2004. Mechanical and thermal properties of graphite platelet/epoxy composites. Polymer 45, 8211–8219 . This work was supported by FCT, through IDMEC, under LAETA, project UID/EMS/50022/2013. References