| Carbon Fibre Reinforced Plastic(CFRP)/Aluminum Honeycomb Sandwich Panel has the characteristics of light weight,low density,high specific strength,high specific stiffness,impact resistance and shock absorption.Widely used in aerospace,rail transit and other fields.The mechanical properties of CFRP/aluminum honeycomb sandwich panels are mainly quasi-static and low-velocity impact,but the sandwich panels will inevitably suffer collisions with velocities ranging from several hundred meters to several kilometers per second during service.There are relatively few studies of strong shocks.In this paper,the CFRP/aluminum honeycomb sandwich panel is taken as the research object.The strong impact of the projectile is studied by means of experiments,theoretical calculations and numerical simulation.The damage region is observed and analyzed from the microscopic angle by means of scanning electron microscopy(SEM).In the medium-velocity collision research,the one-stage light gas gun was used the loading tool,and the impact test of the three different combinations of the targets and the aluminum projectile colliding with the aluminum honeycomb core and the sandwich panel was carried out.Among them,the steel projectile penetrates the CFRP front panel,the aluminum honeycomb core,the CFRP rear panel and the sandwich panel at about 300 m/s,and the duration time is about 32.5 ?s,91.7 ?s,40.3 ?s and 164.5 ?s,respectively;Through the analysis of high-velocity photography,the action time of the aluminum projectile through the aluminum honeycomb core and the CFRP/aluminum honeycomb sandwich panel is 86 ?s and 240 ?s,respectivelV.Using the formula of the three-stage model,the velocity of the steel projectile after penetrating the layers is approximated,and the error 1s small compared with the experimental measuremelt velocity.The experimental process was numerically simulated w,th ABAQUS/Explicit software.The time taken for the projectile to penetrate the composite layer was basically consistent with the experimental measurements.In the numerical simulation,the ballistic limit of the aluminum projectile colliding with the aluminum honeycomb core and the sandwich panel is about 73.21 m/s and 158.36 m/s,respectively.In high-velocity collision studies,high-velocity collision experiments were canied out on the sandwich panels by using two-stage light gas gun to load aluminum and steel pellets.The results showed that burrs,wire drawing and delamination occurred around the perforations of CFRP panels.The aluminum honeycomb core undergoes a large area of ablation that is approximately a cone.When the aluminum projectile collides with the sandwich panel,the ablation area of the aluminum honeycomb gradually decreases with the increase of the collision angle,and gradually increases with the increase of the length of the aluminum honeycomb arm,and fits the ablation area with the collision angle and aluminum.The curve of the change in the length of the honeycomb arm.When the steel projectile collides with the sandwich panel,the ablation area of the aluminum honeycomb gradually decreases with the increase of the collision angle,but the ablation area of the aluminum honeycomb back surface increases with the increase of the angle.Micro-feature analysis of carbon fiber sheet and aluminum honeycomb fractures and their surroundings was carried out by means of SEM.It was observed that the matrix fracture and fiber drawing of CFRP due to extrusion were caused by the shock wave and the cracking and delamination of the matrix and fiber.The black rod on the surface of the aluminul honeycomb is a broken carbon fiber filament embedded in an aluminum honeycomb,and the surface of the aluminum honeycomb adheres to aluminum powder,carbon powder and non-conductive resin particles.According to the EDS spectrum analysis,the main component produced by the ablation portion is Al2O3. |
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