امير شهمراد

Mechanical metamaterials are a class of engineered materials that exhibit properties beyond those of conventional natural materials due to their tailored structural geometry. The design of such structures can be achieved through various approaches. In the present study, two distinct design strategies—unit cell combination an‎d topology optimization—were employed, resulting in the development of four an‎d three different lattice structures, respectively; in total, seven lattice architectures were designed an‎d investigated. All specimens were fabricated using fused deposition modeling (FDM) additive manufacturing under identical printing conditions. Polylactic acid (PLA) was selec‎ted as the base material for experimental sample preparation. The mechanical behavior of the structures was experimentally eva‎luated under static (compression test) an‎d dynamic (impact test) loading conditions. The experimental results were further compared with numerical simulations. In addition, a sensitivity analysis was conducted to assess the influence of key parameters on energy absorption performance. The results demonstrated that both design approaches possess significant potential for developing auxetic structures with high energy absorption capability. In the unit cell combination method, all four designed structures exhibited higher specific energy absorption compared to the solid reference sample in compression tests, with negative Poisson’s ratios ranging from −1.0 to −1.7. Among them, the structure composed of honeycomb an‎d tetrachiral unit cells showed the highest energy absorption under compressive loading. Under impact loading, the hybrid structure combining honeycomb, tetrachiral, an‎d cubic unit cells achieved the highest specific energy absorption. Sensitivity analysis under dynamic conditions revealed that impact height, Poisson’s ratio, an‎d structural geometry were the most influential parameters affecting energy absorption performance. For the topology-optimized structures, similar trends were observed, where structure TV exhibited the highest energy absorption under compression, while structure TH demonstrated superior performance under impact loading. Analysis of deformation an‎d energy absorption mechanisms indicated that the dominant mechanisms differ between the two design strategies. Furthermore, topology optimization enables the development of lighter structures with enhanced energy absorption efficiency an‎d tunable performance for targeted engineering applications.

=فرامواد مكانيكي= , ساختارهاي شبكه اي , جذب انرژي , ساختارهاي اگزتيك , بهينه سازي توپولوژي

Mechanical metamaterials , Lattice structures , Energy absorption , Auxetic structures , Topology optimization

Amir Shahmorad

Ramin Hashemi-Majid Rajabi