Effect of 3D-printing and compression molding on anisotropy of ABS micro specimen: A comparative study based on DIC

This paper aims to calculate and compare normal anisotropy coefficients in 3D-printed and hot-compression molded micro ABS specimens. To achieve this goal, micro specimens of additively-printed and compression-molded ABS were fabricated and tested using a micro-tensile testing apparatus integrated with an optical microscope while the deformation of the specimens was recorded by a camera. Frames from this video were selected and strain distribution on a micron-sized area of interest was obtained using digital image correlation (DIC) analysis. It was shown that there exists a close agreement between DIC results and in situ optical observations. The plastic anisotropy coefficients (R-values) were then calculated from the surface strains as a function of applied strain. For this purpose, through-thickness strain component was obtained assuming plastic incompressibility condition. Results showed that both micro samples revealed an anisotropic response during plastic deformation. At low plastic strains, the printed micro specimen exhibits a more anisotropic behavior than the monolithic micro specimen. As the deformation proceeds, the normal anisotropy coefficient increases for the additively-manufactured micro specimen and decreases for the hot-pressed micro specimen.