Mechanical behavior of micro‐fiber‐reinforced foam‐filled carbon fiber composite tubes under axial compression loading

Abstract This study examines the axial crushing behavior of Carbon Fiber Reinforced Polymer (CFRP) tubes, both hollow and filled with polyurethane (PU) foam enhanced by varying amounts and sizes of milled glass fibers. The micro‐glass fibers were incorporated into the foam during fabrication to improve its crushing properties. Weight percentages (5% and 20%) and fiber sizes (1/16 inch and 1/32 inch) were added to the foam, and their performance was analyzed. Axial crushing tests were performed on the fully cured composite tubes to evaluate load‐bearing capacity, energy absorption, crushing efficiency, and specific energy absorption. Results revealed that foam‐filled tubes with finer 1/32‐inch fibers exhibited the highest load‐bearing capacity (~18.05–18.12 kN) and energy absorption (~0.47–0.49 kJ), with the 5% fiber configuration showing the best performance (~0.49 kJ). Conversely, hollow CFRP tubes demonstrated the highest specific energy absorption (~35 J/g), highlighting their efficiency relative to weight. Microscopic analysis indicated that finer and lower quantities of fibers (1/32 with 5%) had minimal impact on foam cell size compared to larger fibers or higher quantities (1/16 and 1/32 with 20%). Highlights Crashworthiness of carbon tube structures is investigated comprehensively. PU foam/microfibers filling enhanced load bearing properties significantly. Carbon tubes with PU foam showed improved energy absorption capacity. Best performance achieved with carbon tubes and microfiber reinforcement.