Investigation On Dynamic Behaviors Of Composite Material Projectile Penetrating Targets

Theoretical analysis, experiment investigation and numerical simulation on composite material projectile penetrating concrete target are implemented. Projectile-target interaction and stress distribution of composite cylinder subjected by compression loading are analyzed. Composite material structure mechanical properties and failure modes are gained by static and dynamic experiments. And experiments and numerical simulation of composite projectile penetrating concrete target are carried out. The results can be applied in little density, high strength and high charge-weight ratio composite material projectile design. The detailed contents are as following:(1) Elastic interaction of projectile-target is analyzed by one-dimensional stress wave propagation theory. The stress is dependent on section area in quasi-static loading case. For stress wave propagation in non-uniform section body, the stress value is dependent on section radius. The Taylor momentum-impulse equilibrium equation is modified. Plastic deformation doesn't occur according to the modified expression, which revise the issue that plastic deformation isn't zero if only impact velocity is nonzero. For projectile penetrating target case, the high stress field and relative weakness of projectile is observed. And optimization problems of projectile structure and material choice are discussed.(2) Quasi-static and dynamic compression experiments of carbon fiber reinforced epoxy resin matrix composite cylinder structures are implemented by NYL-200D testing machine and drop weight equipment. In the quasi-static compression experiments, both ends of specimen are strengthened. The results show that the major failure modes of specimen without filler are fiber delamination and wrinkling on the surface of specimen. For the specimen with filler, the major failure modes are circumferential expansion delamination and fiber breakage. In the dynamic compression experiments, neither end of specimen is strengthened. The failure occurs on the relative weaker end. The fiber laminates are delaminated and crinkle inside and outside of the cylinder. The failure surface becomes petal-like and some fibers break finally. In quasi-static and dynamic compression experiments, the main failure mode is fiber delamination. Neither shear failure nor collapse is found in the experiments. So compression properties of carbon fiber reinforced composite material can be enhanced by improving interface-bonding strength between epoxy resin matrix and carbon fiber reinforcement phase.(3) Based on the material volume constancy hypothesis, circumference and radial stresses of cylinder specimen are analyzed when the cylinder is loaded along the axial direction. Circumference and radial stress distribution is radius parameter power function when specimen material constitutive relation is orthotropic. The stress distribution is radius parameter quadratic function for transverse isotropy material. Along the cylinder axial line, circumference and radial stresses are maximum and equal to each other. In the circumference boundary surface, radial stress is zero and circumference stress value is the minimum. The max tensile circumference strain failure theory is applied to calculate critical axial loading. Circumference boundary layer failure criterion of orthotropic material cylinder is described by Hill-Tsai strength theory. The obtained strength theory is not only relation to axial stress and specimen material mechanical properties, but also relation to specimen axial deformation strain rate and change rate of strain rate.(4) The experiments of projectile penetrating concrete target at several velocities are implemented. The projectiles are made of carbon fiber composite material shell and metal warhead. The angles between the perpendicular of target surface and projectile axes are 0°and 30°respectively. The compression strength of concrete target is 30MPa. And the experimental results indicate that the strength of composite material structure is strong. The composite projectile can go through the concrete target without fiber segregation and breakage. Comparing with steel projectile, the filler mass percent of composite material projectile is about twice as that of steel projectile. So little density, high strength composite material projectile can lessen weight, improve charge-weight ratio of powder and enhance specific damage powder.(5) Composite material projectile normal and oblique penetration concrete target is simulated by finite element program. For carbon fiber composite material, orthotropic constitutive is adopted. And HJC constitutive is applied to describe concrete material in finite element analysis. The process of projectile penetration target reappears in numerical results. Velocity, acceleration, Mises stress distribution and motion attitude of projectile are gained. Projectile resistance is along its axis in normal penetration cases. So projectile is approximately taken as uniformly retarded motion. For oblique penetration cases, the resistance isn't along its axis and projectile motion direction changes in penetration process.