Research On Mechanical Behavior Of Carbon Fiber Composite Structure

Due to its high specific strength,corrosion resistance and excellent designability,carbon fiber composites have been widely used in aerospace,marine pipelines,underwater vehicles,high-pressure gas storage and other fields.Due to the different meso-structure of carbon fiber composites will lead to a large gap between the macroscopic properties of materials,so the prerequisite for the application of carbon fiber composites is to accurately characterize the properties of materials.Due to the anisotropy of materials,many parameters are difficult to be measured by experiments.It is necessary to establish a model to predict the performance of composite materials.Based on this,this paper studies the mechanical properties of carbon fiber composites,and establishes a multi-scale mechanical model of composites from carbon fiber wire to macro structure,which involves multi-scale behavior.The main contents and results of this paper are as follows:1.For plain weave composite materials,considering the yarn shape boundary and fiber direction,the meso-mechanical model of plain weave composite materials is established based on the second-order two-scale method(SOTS),and the equivalent elastic parameters of plain weave composite materials are obtained by numerical calculation.The validity of the model was verified by comparing it with the Young's modulus and shear modulus measured in the experiment.2.For carbon fiber wound composites,based on the high-fidelity generalized method of cells(HFGMC),a multi-scale model from the meso-structure of carbon fiber to the macro-properties of carbon fiber wound cylinder was established,and the equivalent elastic parameters of carbon fiber wound cylinder were solved.Compared with the direct use of finite element method in the existing research work,it simplifies the modeling and calculation process,does not need to establish complex three-dimensional cell model,and greatly reduces the calculation time.The validity of the model is verified by comparing with the results of literature.On the basis of the model,the influence of different winding angles on the equivalent elastic parameters of carbon fiber winding composites is analyzed.The results show that the smaller the winding angle is,the greater the axial Young's modulus is.The model in this paper can provide theoretical foundation and basis for the optimization of the winding method of carbon fiber winding composite materials.3.Aiming at the structure of carbon fiber winding composite electromagnetic rail gun barrel,the dynamic model of carbon fiber winding composite gun barrel under electromagnetic launch condition was established,and the influence of intrinsic anisotropy of carbon fiber composite on the macroscopic vibration behavior of carbon fiber winding composite gun barrel was analyzed.The results show that the anisotropy of materials can not be ignored when studying the vibration of carbon fiber barrel.Carbon fiber barrel can achieve lightweight.Compared with traditional steel barrel,it can greatly reduce the mass of barrel and has higher modulus than steel barrel.However,the high modulus of carbon fiber composite is not enough to completely offset the impact of mass reduction on vibration.The amplitude of carbon fiber composite barrel is larger than that of traditional steel barrel.By adjusting the barrel length,barrel constraint length,barrel constraint stiffness,pulse current maximum amplitude and other parameters,the end angle and displacement of carbon fiber composite barrel are close to the end angle and displacement of steel barrel.The results of this paper provide a theoretical basis and design reference for the structural design of carbon fiber winding electromagnetic gun.In summary,this paper can predict and design the equivalent elastic parameters of carbon fiber composites by establishing the microscopic model of effective carbon fiber composites.The tedious and expensive experiments are omitted,which provides theoretical guidance and reference for the practical application of carbon fiber composites.