Study on penetration protection properties of continuous fiber-reinforced high-porosity composites

It is of great scientific significance and application value to study the penetration protection performance of continuous fiber-reinforced high-porosity composites. First, the ballistic penetration experiments of 20 mm thick continuous fiber-reinforced high-porosity composites were carried out by using two-stage light gas gun firing Q235 steel projectiles with a diameter of 4.5mm. Based on the analysis of the initial and final velocity of bullet penetration, the ballistic limit of the material is obtained. By observing the damage patterns of the target plate, these patterns were divided into three types from low to high according to the initial velocity of the projectiles: back-crack type, back-burst type and penetrated type. The penetration protection performance of this composite material was compared with other materials by specific energy absorption, showing that the protection performance of the composite against low-speed penetration of 600m/s or below is better than that of steel, aluminum, Kevlar and glass fiber composite. Then, an orthogonal anisotropic continuum damage constitutive model was proposed for the continuous fiber-reinforced high-porosity composites. The constitutive model was written as a subroutine and embedded in the finite element software by secondary development. On this basis, the finite element simulations of ballistic penetrations of continuous fiber reinforced high-porosity composites were carried out. The validity of the constitutive and finite element models is verified by comparing the final velocity, ballistic limit and damage range of the back surface obtained from experiment and simulation. Furthermore, the damage mechanism of the penetration process was analyzed by observing the shape of the bullet hole, stress distribution and damage distribution of the finite element simulation. The results showed that the formation of the bullet hole during the penetration process of spherical projectile is caused by shear damage, the debonding of fiber and matrix was caused by the combined action of compression and shear, the delamination damage of the target plate is caused by the tension wave formed by the reflection of compression wave, and the fiber breakage belongs to tension damage. Besides that, the kinetic energy, internal energy and their proportion to the kinetic energy change of the bullet were compared with the initial velocities. It is pointed out that the kinetic energy of the projectile will be more transformed into the kinetic energy of the fragment of target plates and the plastic deformation energy of the projectile. The research results provide a reference for the multifunctional integration of these composite materials in heat protection, penetration protection and load bearing.