Experimental characterization of the compression-compression fatigue performance in 3D printed flexible honeycombs

Abstract Cellular materials are gaining popularity as constituent materials in end-use products due to their tunable stiffness and energy absorption capabilities. Additive manufacturing technologies have allowed the fabrication of these porous materials with engineered topologies. Previous works have characterized the mechanical response of cellular materials mainly under static loading scenarios; their fatigue behavior is a complex phenomenon, not yet thoroughly studied. In this work, we exploited the benefits of fused filament fabrication to build thermoplastic polyurethane cellular materials and experimentally characterize their properties under static and dynamic loadings. Three different topologies (hexagonal, re-entrant, and square) with same volume fraction were studied. A geometrical assessment was conducted on specimens to evaluate the accuracy of the selected fabrication process. Compression-compression fatigue tests (2 Hz, R = 0.1) resulted in the construction of stiffness degradation and energy absorption ability plots. Samples exhibited a loss of 30% of their original rigidity and 50% of their normalized energy absorbed after 100,000 loading cycles. Our findings comparatively illustrated the advantages between different cellular materials and the selection of thermoplastic polyurethane as constituting material in terms of fatigue life performance.