Characterization of 3D Printed Auxetic Sinusoidal Patterns/Nylon Composite Fabrics

This study intended for the assessment of the stiffness, tensile and bursting properties of 3D printed auxetic sinusoidal patterns of different density and thickness deposited on the nylon fabric by means of fused deposition modeling (FDM) with the use of thermoplastic polyurethane (TPU) filament. Morphology, weight variation, flex stiffness, tensile property, Poisson’s ratio and bursting strength were analyzed for the characteristic evaluation of produced composite. The prototypes of two auxetic pattern repeat of 47 mm×43 mm and 20 mm×20 mm were developed named as low density (LD) and high density (HD) respectively. Both patterns were repeatedly combined to produce bigger size patterns and 3D printed with various thicknesses. Weight variation is found proportional to the density and thickness of 3D printed auxetic sinusoidal. Maximum up to 552 % weight increase was recorded for LD pattern and for HD 857 %. Flex stiffness increased with the rise of density and thickness of 3d printed auxetic sinusoidal pattern. Maximum flex stiffness for HD was 7.21 cm-g and for LD 4.73 cm-g. Warp direction is stiffest comparing with diagonal and weft in all cases. In case of tensile strength, a great extent of elongation was noticed due to the presence of auxetic sinusoidal 3D pattern and TPU filament. Maximum, more than 500 % elongation was showed by HD diagonal direction. HD patters exhibited more strength and toughness than LD patterns. In addition, warp direction is strongest and diagonal direction is weakest whereas the weft stays in between. Both LD-1.0 and HD-1.0 3D printed pattern showed negative Poisson’s ratio and the value was between -1.0 to 0. The enhanced bursting strength is found in HD patterns up to 1514 kPa comparing up to 1449 for LD. Thus, this study confirmed the excellent stiffness, tensile and bursting properties of HD 3D printed auxetic sinusoidal pattern/nylon composite over LD.