A COUPLING ANALYSIS MODEL OF CLAMPED MONOLITHIC BEAM IMPACTED BY FOAM PROJECTILES

The impact of foam metal projectiles may simulate the effect of explosion load. This loading technology has been applied in the impact resistance test of different protective structures. However, the actual impact load on the tested object and the interaction mechanism between the projectile and the tested object are still unclear. In this paper, the theoretical analysis and numerical simulation of the impact process of a foam projectile on a beam fixed at both ends were carried out. Based on the shock wave model of the foam and the structural dynamic response model of the clamped beam, a coupling analysis model describing the impact process was developed. The governing equations of different response stages were presented, and the numerical solution of the governing equations was obtained by using the Runge-Kutta method. The finite element model of a clamped monolithic beam impacted by a foam projectile was constructed by using the Voronoi technique and the impact process was simulated. Compared with the simulation results, it is found that the coupling analysis model can not only predict the velocity variation of projectiles and beams better than the impulsive loading model, but also obtain the actual impact pressure accurately. When the initial momentum of the foam projectile is identical, the change in the initial velocity, density, and length of the projectile can still affect the impact process due to the crushing behavior of the projectile. Finally, the effects of the density, length, and initial velocity of foam projectiles on the peak value, attenuation velocity, and duration of impact pressure were analyzed through the coupling analysis model, and the selection strategy of foam projectiles was proposed for the target simulation loads with different characteristics. The coupling analysis model provides a theoretical basis for studying the interaction mechanism between foam projectiles and the tested structure and the design guide of foam projectiles.