Numerical study on dynamic behavior and microscopic damage mechanism of 3D printed rock-like materials

The dynamic mechanical behavior and microscopic damage evolution mechanism of three-dimensional (3D) printed rock-like materials were investigated. First, the sand-powder 3D-printed samples were fabricated and a series of dynamic impact tests were carried out on the samples with five different printing bedding angles. Then, a coupled finite difference method with discrete element method was proposed to reconstruct numerical samples. The microscopic parameters for numerical simulations were obtained by calibrating the stress-stain curves. The influence of bedding spacing and thickness on the samples was analyzed in detail. Finally, the dynamic crack propagation of samples was explored from a microscopic perspective. The test results indicate that there are two classes of mechanical behaviors (i.e., Class I and Class II) in dynamic responses. Dynamic compressive strength positively correlates with strain rate and generally shows a V-shape variation trend with the increase of inclined angle. Numerical simulations found that the dynamic compressive strength and elastic modulus increase with the increase of bedding vertical spacing, but decrease with the increase of bedding thickness. As the strain rises, the number of cracks exhibits an S-shape growth mode, increasing rapidly in the pre-peak stage and slowing down in the post-peak stage.