Determination of elastic constants for 3D printed thermoplastic materials based on strain measurements using fiber-optic sensors

Additive manufacturing opens new possibilities for rapid prototyping and functional part production, necessitating a thorough understanding of utilized materials' mechanical properties. This paper presents a method for determining elastic constants - the elastic modulus and Poisson's ratio of 3D-printed materials using uniaxial tension test on rectangular crosssection samples. It is proposed to conduct longitudinal and transversal strain measurements on the surface of the samples using fiber-optic sensors based on fiber Bragg gratings, which offer comparable accuracy to standard electrical strain gages while providing advantages such as reduced size, simplified preparation, and minimal equipment requirements. The study focuses on materials manufactured by fused deposition modeling using various thermoplastic polymers: acrylonitrile butadiene styrene (ABS), ABS-based composite with 15 % carbon fiber content and Polyamide 6 (PA6) with up to 20 % volume fraction of short carbon fibers. The influence of filament deposition orientation on the Young's modulus and Poisson's ratio of these materials was analyzed. The results demonstrate a pronounced dependence of the elastic constants on the raster angle for the studied reinforced thermoplastics while insignificant variation of properties for traditional ABS material. The proposed application of fiber-optic sensors for strain measurement during experimental testing provides a reliable approach for characterizing the elastic properties of 3D-printed materials, contributing to the knowledge essential for their effective application in various industries.