Study On Strain Rate Effect And Influences Of Carbon Fiber Composites

As a new type of material,composite materials have been widely used in aerospace and other fields due to their excellent properties and changeable designability.The impact load is one of the common loads in the process of aircraft flight.When the composite is impacted,it will show a large deformation in an instant,which will lead to the strain rate effect in the mechanical properties of the material.Therefore,it is of great significance and value to study the strain rate effect of the composite to characterize its impact resistance.Firstly,the dynamic compression experiments of unidirectional carbon fiber resin matrix composite(T700/TDE85)in different directions are carried out by Hopkinson bar.The stress-strain relationship of the material under different strain rates is obtained by using two wave method.Then the dynamic strength and stiffness are obtained.Then the damage mode is observed and the one-dimensional dynamic constitutive model is established by Zhu-Wang-Tang(ZWT)constitutive model Equation.Secondly,the representative volume cell model of unidirectional composites is established from the fiber matrix scale,and the strain rate effect of the matrix is introduced.The damage evolution process was observed by using ABAQUS simulation,and the accuracy of the model was verified by comparing with the experimental results.On this basis,the dynamic tensile mechanical properties of unidirectional composites were predicted.Finally,the ballistic impact model of carbon fiber composite laminates is established on the macro scale.A continuum damage model is selected as the constitutive model of single-layer plate,and the cohesion model is used to simulate delamination.According to the strain rate effect of the single-layer plate obtained in the previous paper,the dynamic model of the single-layer plate is established by introducing the dynamic enhancement factor.Compared with the experimental results in the literature,the influence of the strain rate on the simulation results is explored,and the influence of the relevant parameters on the simulation accuracy is discussed.