Experimental Analysis and Design of 3D-Printed Polymer Elliptical Tubes in Compression

Featured Application Slender elliptical section tubes, with potential uses in aeronautical, aerospace or other mechanical contexts, have been printed in PLA and ABS. A safe-sided design method is presented, which was originally formulated for steel tubes and is now adapted and re-calibrated for use with 3D-printed polymer materials based on material properties determined from tensile and compressive testing.Abstract Local failure modes occurring in 3D-printed polymer elliptical section tubes in compression are investigated in the present study via a series of experiments, with the results compared to existing design proposals for slender steel analogues. Polylactic acid (PLA) and acrylonitrile butadiene styrene material specimens (ABS) have been printed in three orthogonal layering orientations, and tested in tension and compression to determine orthotropic material properties including strength, elastic modulus, failure strains and Poisson's ratio. Next, twenty-four 3D-printed elliptical cross-section tubes are tested in compression, with the polymer material, cross-sectional aspect ratio and tube wall thickness varied across the set. Results including the load-deflection behaviour, longitudinal strains, failure modes and ultimate loads are discussed. A design method formulated previously for slender steel elliptical hollow sections in compression is adapted for use with the 3D-printed polymer specimens. Upon appropriate rescaling of the design parameters, safe-sided and accurate predictions are provided by the design method for the compressive resistance of the PLA and ABS elliptical specimens, thus validating its application to cross-sections in materials other than carbon steel.