Crushing Performance and Deformation Mechanics of Additively Manufactured Single-Cell Continuous Basalt Fiber/Polylactic Acid Thin-Walled Tubes

This paper investigates the quasi-static crushing behavior and progressive deformation modes of 3D-printed continuous basalt fiber-reinforced polylactic acid (CBF-PLA) single-cell thin-walled profiles. By isolating cross-sectional geometries (circular, triangular, square, pentagonal, and hexagonal) and material extrusion rates (E = 0.9, 1.0, 1.1), we demonstrate how corner-driven boundary constraints dictate stability and energy dissipation. Quasi-static axial compression tests reveal a profound geometric dependency: conventional circular tubes succumb to early global Euler buckling, resulting in sudden collapse and poor crush force efficiency (42%). In contrast, multi-sided polygonal geometries promote stable, progressive concertina folding by redistributing localized stresses to corner hinges. Hexagonal profiles exhibited the most stable progressive folding mode, achieving a 22.5% increase in total energy absorption (127.05 J) and a 36.1% improvement in specific energy absorption (5.71 J/g) over circular baselines at E = 1.0. Increasing the extrusion rate to 1.1 enhances fiber deposition density, pushing the hexagonal specific energy absorption to 7.04 J/g, but significantly spikes peak crushing forces by 48.4%. These findings establish topological design as a primary lever for customizing crashworthiness in printed sustainable composites.