Thermal and Mechanical Properties of Hybrid Composite Strengthened by Carbon Fibers/Aramid Fibers

This work deals with the thermal, mechanical and dynamic properties of hybrid composites reinforced with carbon fibers and aramid fibers, whose matrix is ​​epoxy resin. In this study a series of hybrid fiber composite are prepared with carbon and aramid fibers as reinforcement.  Thermal properties are obtained by thermal gravimetric analysis (TGA), Thermo-mechanical analysis (TMA) and hot plate analysis. Also mechanical properties are obtained by tensile and modal analysis tests. The experimental results are compared with the similar theoretical ones. Besides the effect of stacking sequence and hybrid ratio (adding the number of layers of carbon fibers), on the thermal and mechanical properties are investigated. The results show that by increasing the hybrid ratio although the weight of the sample is more, the thermal conductivity of the carbon fibers used is higher than that of the aramid fibers and this increase in thermal conductivity causes the heat to be transferred to the sample much faster and the temperature of the glass increases with the increase of the hybrid ratio. Due to the high stiffness of carbon fibers, adding it to the composite causes, the tensile modulus of the samples increases. By combining carbon fibers with aramid fibers, the toughness of carbon fibers can be increased and at the same time the brittle property of carbon fibers is removed due to the malleability of aramid fibers. It is concluded that aramid fiber has an effective role in improving failure strain due to its high toughness and malleability, while carbon fiber is very fragile. The lowest tensile strength occurs at the hybrid ratio of ۲۹% with a value of ۶۷۷.۶۶ MPa. which is very close to the theoretical critical hybrid ratio. The results also show when the carbon fibers and aramid fibers are on the outer and the middle layers of the beam respectively, the frequency has a larger value because the aramid fibers have a very high impact resistance.

کلیدواژه ها:

Laminate hybrid composite ، aramid fibers ، carbon fibers ، Mixture law ، Thermal properties ، Mechanical Properties ، Modal Analysis