Research On Dynamic And Penetration Properties Of The Three-dimendional Orthogonal Woven Glass Fiber Composites

Three-dimensional orthogonal woven composites is a kind of an advanced composite materials with better performances, such as better tear resistance to penetration, higher resistance to high temperature, higher energy absorption, and so on. So are widely used in the aerospace, protective engineering, automotive manufacturing fields. In this paper, dynamic mechanical properties and penetration properties of the three-dimensional orthogonal woven E glass fiber/epoxy composite are systematically studied by the method of a combination of experiments, engineering analysis methods, numerical simulation and dimensional analysis method.Dynamic and static mechanical properties of the three-dimensional orthogonal woven glass fiber/epoxy composites are investigated using the MTS and SHPB equipments, and the stress-strain curves in different directions are obtained at different strain rates, acquired the mathematical expressions of the failure stress with the strain rate and the failure strain with strain rate, the mathematical expressions and experimental results show that the material has a significant strain rate effect, at the same time, the material also showed strong anisotropic characteristics, the strength of the thickness direction is higher than that in-plane. Putting forward a damage weakening factor which depends on strain and strain rate into a nonlinear viscoelastic model in Macro, a one-dimensional stress dynamic viscoelastic constitutive relation with damage weakening effect is obtained, which is related to strain rate. In Micro, the pressure-shear coupled damage mechanism in the process of deformation is analysed. Based on new idea of "a nuclear grown up" and the concept of "equivalent micro-void system", defined the damage variable of statistical microscopic and given the damage coupled pressure-shear evolution, damage evolution of internal defects of the three dimensional orthogonal woven glass fiber/epoxy composite in the process of high-speed impact deformation is introduced into Maxwell model which represented the viscoelastic of the material. The damage evolution equations under different strain rates and constitutive relation are obtained by fitting at least squares method.The ballistic impact experiments of the three-dimensional orthogonal woven glass fiber/epoxy composites are performed using the ballistic impact equipments, and the law of effect of different factors on the anti-penetration properties and the failure mode of the material is gained. Based on conservation of energy of bullet and the high velocity penetration experimental results, the definition of "critical consumption energy" is proposed, which is assumed to be a function of the kinetic energy of bullet, the calculation of V50is acquire by Taylor series expansion and successfully predict the value of V50. The process of the round and cylindrical projectile penetrating this composite target is simulated by ls-dyna software, and the time history cures of the speed and acceleration of the projectile in this process is given, the relationship between the resistance to penetration and the energy absorption of the target is discussed, the simulation results are in good agreement with the anti-penetration experimental results.In terms of engineering analysis method, based on the improved transversely isotropic material constitutive model, considering the anisotropy correction and the strain rate effect of the material itself, an engineering analysis method of computing the penetration of a bullet into fiber-reinforced composite targets is present with the ball cavity model and the column cavity model combined. The problems of bullet penetration into the three-dimensional orthogonal woven glass fiber/epoxy composites is computed and analyzed by the computed cod, the simulation results about the relation between the projectile residual velocity and penetration depth are in good agreement with the experiments results. In the end, in contrast with the ls-dyna simulation results, good agreement shows that this engineering analysis method is effective.In the end, the method of dimensional analysis method is adopted to build a universal model for the throughout problem, which is applied to the three-dimensional orthogonal woven glass fiber/epoxy composite, and a model law is obtained for the problem of anti-throughout. Furthermore, a similar law of two types of questions is discussed, which is the relation between the maximum penetration depth and the projectile size on the conditions of the same projectile striking speed, and the relation between the dimensionless residual velocity of the projectile and the dimensionless target thickness. The analyzed results are in good agreement with experiment results.