Effect of geometric parameters on tensile properties of hybrid star re-entrant auxetic structure fabricated by fused filament fabrication

The present study investigates the effect of geometric parameters on tensile properties of hybrid star-re-entrant auxetic (SRA) structure fabricated by fused filament fabrication (FFF) technique of additive manufacturing. Geometric parameters, namely strut thickness, re-entrant angle, and star angle are considered to study their influence on specific strength, specific modulus, and specific energy absorption (SEA) of SRA structures. Stress-strain curves and deformation behaviours under tensile loading are studied. ANOVA is performed to identify significant geometric parameters, and response surface methodology (RSM) is used to maximize the responses. It is found that strut thickness is most significant geometric parameter followed by re-entrant angle and star angle for all three responses in both loading directions X and Y. Further, strength, modulus and SEA of SRA structures with same relative density is found to be higher under tensile loading in X direction than Y direction. In addition, with an increase in strut thickness, the deformation patterns shift from progressive to global deformation of the struts across the direction of the plane of applied force. The outcomes of the present study provide an insight into the tailorable mechanical strength and SEA of hybrid SRA structure.