Experimental Investigation on Crashworthiness Behaviors of <scp>3D</scp> ‐Printed Cellular Composite Sandwich Structures

ABSTRACT This study presents an experimental investigation into the quasi‐static crashworthiness of carbon fiber‐reinforced polymer (CFRP) sandwich structures incorporating 3D‐printed cores with four distinct geometries: honeycomb, re‐entrant, double‐arrowhead, and missing rib‐cut. The core structures were fabricated by fused deposition modeling (FDM) using polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) and subsequently bonded to CFRP face sheets to assemble the sandwich panels. The specimens were tested under quasi‐static axial compression to evaluate key crash indicators, including energy absorption (EA), specific energy absorption (SEA), peak crush force (PCF), mean crush force (MCF), and crush force efficiency (CFE). The highest EA was obtained from missing rib‐cut core specimens, reaching 85.25 (PLA) and 52.85 J (ABS), with corresponding SEA values of 1.74 and 1.27 J/g, respectively. The lowest SEA values were recorded in re‐entrant core specimens with 0.68 (PLA) and 0.51 J/g (ABS). Honeycomb cores exhibited the highest CFE values of 0.670 (ABS) and 0.519 (PLA), indicating more efficient force distribution. Force‐displacement responses showed that honeycomb and double‐arrowhead cores maintained consistent peak force patterns, while re‐entrant cores displayed a nearly constant force in the plateau region after an initial peak. Missing rib‐cut cores exhibited irregular peak forces until densification. Across all geometries, PLA cores showed higher SEA and EA values than ABS. The results indicate that both core geometry and material selection significantly affect the crash performance and energy absorption characteristics of sandwich structures under quasi‐static loading conditions.