Numerical Study On Thermal Conductivity Of Carbon Fiber And Its Binary Mixture Filler Reinforced Composite

With the rapid development of science and technology,the thermal conductivity of composite materials has been widely used,especially the filling composites have become the research focus of scholars.In this paper,a representative volume element model of carbon fiber packing and two element mixed filling rubber composite material has been obtained by DIGIMAT software,and the thermal conductivity of the composite model is numerically simulated by the finite element analysis software ANSYS.In this paper,the effect of the amount of carbon fiber,the number of filling,the ratio of length to diameter and the degree of curvature on the thermal conductivity of composites are discussed.The influence of filling order,filling ratio and one of the content changes of two element mixed filler on thermal conductivity of composite was studied.The results show that when the composites are added with different fillers,the spatial distribution of the fillers has obvious influence on the thermal conductivity of the composites due to the obvious anisotropy of the carbon fibers.When the number of carbon fiber filled root changes,the thermal conductivity of the composite changes little.The thermal conductivity of composite increases with the increase of carbon fiber filling fraction,and the numerical simulation results are in agreement with the theoretical results and the changing trend of experimental results.When the content of carbon fiber is constant,the thermal conductivity of the composite can be improved by increasing the aspect ratio of the carbon fiber.For straight carbon fibers,the thermal conductivity of the composites is the largest at a certain angle.When the tortuous carbon fiber is added into the composites,the thermal conductivity of the composites increases firstly and then decreases.Changing the aspect ratio of the bent carbon fiber,the fitting relationship between the thermal conductivity of the composites and the aspect ratio at different sections was obtained.The thermal conductivity of composite materials with different aspect ratio can be better predicted by using the fitting formula.As for the composite with binary mixed fillers,the sequence of two fillers has certain influence on the thermal conductivity of composites.The thermal conductivity is higher when filling the carbon filler firstly.Under the different ratios of two kinds of fillers,carbon fibers play an important role in the thermal conductivity of composites,and the thermal conductivity of the composites increases along with the increase of the carbon fiber filling ratio.When the content of one kind of filler is constant,the thermal conductivity of the composites increases with another filler contents enlarging.In addition to discussing carbon fibers,the thermal conductivity of the carbon nanotube composite was also investigated,and the multi walled carbon nanotubes were equivalent to the cylinder.The thermal conductivity of the composites decreased with the increase of the carbon nanotube tortuosity.Increasing the filling capacity by increasing the diameter of the nanotube,the thermal conductivity of composite shows a linear increasing trend.