Multi-layer protective structure printed on a construction 3D printer. Physics of elastic wave passing through it

The paper presents an analysis of the dynamic properties of multilayer protective structures formed by the additive method (3D printing), with an emphasis on the mechanics of elastic waves. The evolution from quasi-static characteristics (2010s) to dynamic ones (2020s), including Koch-type fractal structures for controlling wave dispersion, is considered. Additive manufacturing provides a controlled microstructure with the integration of reinforcing elements (such as fiber), minimizing waste and implementing exclusion zones according to the Bloch-Floquet theory. The physics of elastic waves is detailed: classification; propagation velocities; their interaction with the boundaries of layers of different acoustic impedances. Energy absorption is modeled by a hysteresis loop, with sources of dissipation: hysteresis, structural and aerohydrodynamic. The coefficient of energy absorption is increased by fiber reinforcement, with the phases of destruction: pre-fracture, fractured and post-fracture. The aim is to simulate wave dynamics in 3D structures, to identify the advantages and disadvantages of enclosing structures constructed in an additive way compared to traditional monolithic products.