A novel honeycomb with gradient-thickness cell walls (HGTCWs) is fabricated through chemical etching to achieve progressive thickness reduction in the cell walls. This engineered honeycomb demonstrates superior energy absorption by effectively eliminating the peak load during the linear elastic stage of the load–displacement curve under impact loading, thereby preventing premature structural failure caused by excessive instantaneous loads. To systematically investigate the impact compression mechanics, energy absorption characteristics, and key influencing factors of aluminum HGTCWs, a three-factor orthogonal array of low-velocity impact experiments was designed. The design of experimental parameters for the impact test has taken into account the impact mass, impact velocity, and etching height. Comparative analysis assessed how these factors influence energy absorption performance. Results reveal that chemical etching-induced thickness gradient modification effectively suppresses peak load generation. Load–displacement curves exhibit distinct bilinear characteristics: an initial single linear phase when compression displacement is below the etching height, followed by a dual-linear phase with an inflection point at the gradient height. Time–velocity profiles during impact primarily consist of an initial nonlinear deceleration phase followed by a linear deceleration phase. Range analysis and analysis of variance identify impact velocity as the dominant factor influencing the energy absorption characteristics of HGTCWs.

The passive safety performance of trains is important. To ensure passenger safety and avoid vehicle climbing and excessive deformation in a collision, anti-climbing energy absorption devices can be installed at the end of each vehicle. In this study, two new types of anti-climbing energy absorption structures—a five-section frame filled with a PU foam core (FSF-F) and a five-section frame filled with a honeycomb aluminum core (FSF-H)—were prepared. The mechanical properties of the FSF-F and FSF-H structures were compared using a dynamic loading test and a simulation. The results showed that the energy absorption performance of the FSF-H was better than that of the FSF-F. Combined with the actual working conditions of a train, the mechanical properties of FSF-H under an offset load were further studied. The results show that it has good energy absorption performance under an offset impact and can be used as an energy absorption device at the end of the train carriage.