The role of flexible polymer composite materials properties in energy absorption of three-dimensional auxetic lattice structures

In this work, the ability of lattice structures with 3D periodic auxetic structure to absorb energy have been investigated. The lattice structures were printed using the FDM method from five types of filaments characterized by different strength, plasticity, and viscoelasticity ratios. The mechanical properties of the filaments were determined by tensile, hardness and impact tests. Quasi-static cyclic tests were used to investigate the visco-elastic behavior. The energy absorption ability of lattice structures was determined by compression tests. It has been established that TPU and nylon fibers are inferior to PLA filaments in terms of strength and hardness, but significantly surpass them in terms of the ability to withstand shock loads and damping properties. Significant differences in the mechanisms of strain energy absorption depending on the properties of the initial filaments have been demonstrated. PLA stuctures exhibit high energy values (0.06 - 0.12 J/cm3), but they are brittle and unable to recover their shape. TPU filaments provide the ability to restore shape, but absorb significantly less energy (0.011 J/cm3). Nylon fibers are less durable than PLA, but have a higher absorption energy (0.136 J/cm3) and are more prone to shape recovery. In further optimization of the structure and properties of 3D structures, it is advisable to use combined lattices consisting of materials with different plasticity and damping ability, which is proposed to be combined by mechanical behavior.