Asymptotic Homogenization Theory For Composite Material Effective Mechanics Property: CF Reinforced PTFE

Along with the development of industrial production, more and more people pay attention to the material corrosion question, especially in heat exchanger equipment of petroleum and chemical industry, the material corrosion problem is particularly acute. Taking into account the excellent corrosion resistance, the PTFE as the heat exchange equipment material is gradually attached importance by the people. However, because of the poor mechanical property, the large-scale industry application of PTFE has been limited. In order to improve the mechanical property of PTFE, considering the PTFE as polymer matrix material, adding the carbon fiber which has excellent mechanical property as the reinforcing phase, to achieve the purpose of PTFE polymer matrix composites strengthened by the carbon fiber.Based on the asymptotic homogenization, for the composite material with a periodic cellular microstructure, this article has analyzed the process of solving effective elastic modulus. Furthermore, combined with finite element method and numerical analysis, the paper has solved the microstructure displacement field, effective elastic modulus, and effective Poisson's ratio of the composite material with a periodic cellular microstructureBy using ANSYS software and MATLAB software, the author compiled the program about effective mechanical property of the composite material with a periodic cellular microstructure, and based on the classics example and variational method, the preciseness of theory and program has been verified. As a result, those programs greatly improve calculation efficiency of composite material effective mechanical property. For optimizing the composite material mechanical property, avoiding the repetitiveness experiment, it has provided the high efficiency method. For the practical problems of the carbon fiber reinforced PTFE, this article regarding the orientation of carbon fiber, has established the periodic cellular microstructure model. And along with axial direction, the 3D cellular microstructure model was simplified to 2D plane model. This article has studied the model of the carbon fiber in the different volume fraction to improvement mechanical property of PTFE polymer matrix composites. It provided the reliable numerical analysis and the appraisement method for the selection of PTFE polymer matrix composites.The results show that:Along with the increase of carbon fiber volume fraction, the composite material effective elastic modulus gradually increases, and the module basically becomes the proportion change under the 25% of carbon fiber volume fraction. The volume fraction of carbon fiber is over 25%, the slope coefficient of effective elastic modulus speeds up very quickly. This indicated the carbon fiber modified PTFE mechanics property remarkably is strengthening.With the increase of carbon fiber volume fraction, the composite material Poisson's ratio gradually decreases, and under the 25% of carbon fiber volume fraction, the composite material Poisson's ratio change slowly. When the volume fraction of carbon fiber is over 25%, the slope coefficient of Poisson's ratio decelerates very quickly, and the composite material Poisson's ratio gradually approaches the carbon fiber Poisson's ratio.