Blast-loading simulators: Multiscale design of graded cellular projectiles considering projectile–beam coupling effect

Graded cellular materials with a proper design may simulate blast loading and can be applied to test the anti-blast performance of protective structures. A multiscale design strategy is proposed to obtain the density distribution and mesostructure of graded cellular projectiles when taking a clamped beam as a protective structure and an exponential attenuation load as the simulation target. A projectile–target coupling model is developed for determining the projectile density distribution, and the dimensionless governing equations containing two kinds of dimensionless parameters, namely target-independent parameters and coupling parameters, are obtained. The closed-cell mesostructure of a graded cellular projectile is generated through the Voronoi technique, and the cell configuration parameters are optimized to achieve the designed density distribution while ensuring manufacturability. The graded cellular projectiles are prepared by using 3D printing technology, and their load simulation effects are verified through numerical simulations and impact tests. Case studies demonstrate the necessity of considering the projectile–target coupling effect in the density design. The applicable test condition and selection method of initial parameters of graded cellular projectiles are analyzed with dimensionless parameters. It is found that the initial momentum of the projectile mainly governs its effective simulation duration. With the increase of the initial momentum, the effective simulation duration increases, and the initial momentum should be less than the total impulse of the simulated blast load. The impact technique of well-designed graded cellular projectiles shows great potential in simulating various blast loadings and testing novel protective structures in a laboratory environment.