Numerical Simulation Of Penetration Process Of Shock Waveform Generator

Under the background of the Twelfth Five-year Plan Period and the National Natural Science Foundation (No.11172139), the finite element modeling of the projectile penetration process is established to analyze the influence of buffer material types and material and structure parameters on the impact acceleration of the projectile. To obtain the half-sine wave of the projectile which meets certain pulse width and amplitude, multi-objective genetic algorithm is used to optimize the impact acceleration waveform of the projectile.Through reading lots of documents, we have known the mechanical properties and the penetration mechanism of buffer materials such as concrete, aluminum honeycomb and aluminum foam. Based on the requirement of getting a half sine shock waveform with large amplitude and wide pulse, the aluminum foam material is selected as the buffer material in the penetration process.By using the Split Hopkinson Pressure Bar test (SHPB), the dynamic compressive mechanical properties of foamed aluminum with different porosity under different strain rate conditions are analyzed. It’s found that the porosity parameter of aluminum foams has significant influences on platform stress, elastic modulus and yield strength. Aluminum foams with different porosity have different strain rate sensitivity. Aluminum foams with high porosity show no strain rate sensitivity, but the strain rate has great influence on the aluminum foams with low porosity, the yield strength of aluminum foams will be strengthen as the strain rate increases.The process of the projectile impacts the aluminum foam is studied through the theoretical analysis, experimental method and the numerical calculation respectively. A mathematical model of the conical-nosed projectiles and flat-ended projectiles impact aluminum foam material is established respectively. By deriving the resistance formulas in different penetration stages, we obtain the final penetration depth formula and penetration time formula. The acceleration signals of the projectile are measured through the air gun experiment, and the acceleration-time curve is analyzed. A finite element model of projectile penetrates foam aluminum target is established to simulate the projectile penetration process by using LS-DYNA as the solver. The reliability of the simulation model is verified by comparing the simulation results with the experimental results. The structure parameters and material parameters of the projectile and aluminum foams are researched to the influence of impulse response, especially to the influence of peak acceleration and pulse width of the projectile. The results obtained show that the shape of the projectile has significant influences on acceleration waveform. Meanwhile, the porosity and thickness of the aluminum foams, the velocity and the mass of the projectile have great effects on the peak acceleration and pulse width of the projectile.The parameter model of the projectile impacts the aluminum foam is established by using the parametric modeling method in ANSA. The ANSA software, LSDYNA software and META software are integrated in ISIGHT software, the NSGA-II algorithm is used to optimize the acceleration peak and pulse width of the projectile.The modeling method and simulation results in this paper have a certain reference value for the design of shock wave generator and the study of the mechanical properties of aluminum foams.