Effect Of Hygrothermal Cycling Environment On The Penetration Resistance Of Carbon Fiber Reinforced Resin Matrix Composites

Carbon fiber reinforced resin matrix composite(CFRP)has been widely used in naval architecture and ocean engineering for its excellent mechanical properties,vibration and noise absorption,designability and corrosion resistance.During the service period,Marine structures not only suffer from the hygrothermal environment for a long time,but also are inevitably invaded by torpedo and missile fragments.Hence,it is of necessity to study the CFRP penetration resistance under the hygrothermal environment in an attempt to master the damage characteristics and the energy absorption mechanism of CFRP under different impact loads.Furthermore,the influence laws of the hygrothermal,the impact velocity of the projectile and the angle of laminated laminate layer on the energy absorption traits,the penetration failure mechanism and the failure mode of CFRP were revealed.In this dissertation,experimental and finite element methods are used to study the penetration resistance of CFRP laminated plates in the hygrothermal cycling environment.Firstly,the hygroscopic dynamic curves of CFRP laminated plates were obtained by manufacturing[0/90]_6s,[0/30/90/-60]_3s and[0/45/90/-45]_3s CFRP laminated plates and conducting the hygrothermal cycle experiment.The Fick diffusion model was used to analyze the hygroscopic traits of CFRP laminated plates.The results showed that the hygroscopic speed of the laminated plates increased first,then decreased and finally became flat.The experimental results were consistent with the Fick diffusion model.The finite element method was used to obtain the law of water diffusion in laminates.The results showed that the water diffused from the surface of laminates to the interior;the water content in laminates increased with the augment of the diffusion time;the diffusion process of water in the three laminates was roughly the same.Environmental scanning electron microscope(ESEM)was utilized to observe the influence of the hygrothermal environment on the interface of carbon fiber,the resin matrix and the fiber matrix in CFRP.Then,the ballistic experiment was carried out on CFRP laminated plates with different degrees of hygrothermal treatment,and the high-speed camera was applied to recording the process.Through these pictures,the residual velocity,the deformation and failure characteristics of the laminated plates were obtained.According to the results,when the laminate type is identical,the ballistic limit of laminate decreases with the increase of the hygrothermal time.When the processing time of hygrothermal time is the same,the ballistic limit of the three laminated plates is:[0/90]_6s>[0/45/90/-45]_3s>[0/30/90/-60]_3s.When the lamination type and the impact velocity is the same,the energy absorption rate of the laminate diminishes with the increase of the hygrothermal time.When the hygrothermal time and the lamination type is the same,the energy absorption of the laminated plate increases first and then decreases.Then,it tends to the constant as the impact velocity of the projectile body climbs.When the impact velocity and hygrothermal time is the same,the energy absorption rate of laminated plate is:[0/90]_6s>[0/45/90/-45]_3s>[0/30/90/-60]_3s.The failure modes of the laminate under projectile penetration include bending deformation,fiber pulling out and fracture,matrix breaking,lamination and shear punching.The bending deformation degree of[0/90]_6s laminated plate is the largest if the impact velocity of the projectile body is the same.When the lamination type is the same,the degree of bending deformation increases first and then decreases as the impact velocity of the projectile body rises.Supposing that the impact velocity of the projectile body is much higher than the ballistic limit of the laminated plate,the shear plug failure occurs and the part of kinetic energy of the projectile body is converted into the kinetic energy of the plug.Finally,the constitutive model of CFRP is given based on the following assumptions:the fiber is linear elastomer and the matrix is a viscoelastomer composed of two Maxwell bodies;the modulus and strength degradation model of CFRP in the hygrothermal environment is applicable;the Hashin failure criterion and the exponential degradation law of material stiffness can be used to simulate the occurrence and the evolution process of material failure.The constitutive model was defined by VUMAT subroutine,and the numerical simulation model of CFRP laminated plate was built on ABAQUS software.Numerical simulation results display that the model of CFRP laminated plate presented in this dissertation is effective.The error of the ballistic limit of the three laminated plates calculated by the simulation model is within 10%.For[0/45/90/-45]_3s and[0/30/90/-60]_3s laminates,the residual velocity,failure characteristics and back deformation of the laminates calculated by the model are in a small margin of error than[0/90]_6s laminate.For the[0/90]_6s laminated plate,when the impact velocity of the projectile body is far greater than its ballistic limit,the residual velocity of the projectile body,failure characteristics of the laminated plate and back deformation calculated by the model are in a small margin of error.However,the error of the calculated residual velocity increases gradually with the decline of the impact velocity of the projectile.