碳纤维增强环氧树脂复合板材的制备及其各向异性传热和弹性变形行为

Preparation,anisotropic heat transfer and elastic deformation of CF EP composite plates

采用模压成型技术制备了太阳能电池阵用碳纤维增强环氧树脂(CF EP)复合板材,并通过光学显微镜、SEM及XRD对其宏观、微观结构进行表征。基于多物理场耦合计算软件Comsol建立了CF EP复合板的固体传热数值模型,借助曲线坐标系转换算法揭示了热量于复合板碳纤维中优先沿纤维轴向传导,进而解释了碳纤维对CF EP复合板导热性能提升的作用机制。并基于有限元计算软件Abaqus,建立了CF EP的轴向应力-应变模型。研究发现在CF EP的弹性变形过程中,沿平行于应力方向排列的碳纤维承担了绝大部分应力,且当应变率升至1%时,轴向碳纤维的内部应力最高可达54.1 MPa。

In this paper,carbon fiber reinforced epoxy(CF EP)composite plates for solar arrays were prepared by molding technology,and the macrostructure and microstructure were characterized by optical and scanning electron microscopy.Based on the above characterization results,a three-dimensional geometric model of CF EP composite plates was constructed and substituted into the subsequent heat transfer and mechanical numerical model for solution.Firstly,based on the multi-physics field coupling calculation software Comsol,the solid heat transfer numerical model of CF EP composite plates was established to reveal the mechanism of the influence of carbon fibers′anisotropy on the heat transfer behavior of the composite plates.Through the curve coordinate system conversion algorithm,the relevant geometric model was converted from the three-dimensional Cartesian coordinate system to a curve coordinate system which is more suitable to describe the axial longitudinal properties of carbon fibers,and can simplify the calculation.The actual heat transfer behavior of CF EP was simulated with the boundary conditions such as surficial heat source region and surface air convection area.A constant temperature area and a thermal insulation area were set to reduce the difficulty of the solution.The above mathematical models were further solved based on the finite element method.Based on the calculated temperature field diagram and the heat vector in CF EP composite plates,it is found that heat was transmitted preferentially along the axial direction of carbon fibers during heating.However,the thermal conductivity of the fiber in the radial direction was low.The mechanism of carbon fibers in improving the thermal conductivity of CF EP composite plates was thus revealed.Further,the CF EP three-dimensional geometric modelwas substituted into the mechanical numerical model,and the axial stress-strain model of CF EP was established based on the finite element calculation software Abaqus.The research shows that,in the uniaxial tensile test along the fiber axis,the stress concentration occurs preferentially at the bonding interface between the carbon fiber and the resin matrix.The stress-strain relationship of CF EP composite plates is calculated.It is found that during the initial elastic deformation of CF EP,the carbon fibers arranged along the direction parallel to the stress bear most of the stress.When the strain rate rises to 1%,the internal stress of the axial carbon fibers can reach 54.1 MPa at most.It can be seen that the strengthening effect of carbon fiber reinforcement on the mechanical properties also presents obvious anisotropy.In conclusion,based on the three-dimensional geometric model of the actual CF EP composite plate,the anisotropic heat transfer and elastic deformation behavior model of CF EP was constructed by combining the physical properties of carbon fibers and epoxy resins.The finite element method was used to solve the above models.The strengthening mechanism of carbon fibers on the heat transfer and mechanical properties of the epoxy resin matrix was revealed.This work can serve as a positive theoretical significance for the subsequent production,preparation and performance optimization of high-performance CF EP composites and other carbon fiber-reinforced composites.