Impact load wave transmission in elastic metamaterials

Structures that consist of resonating endo-structures within a load bearing exo-structure possess the ability to mitigate dynamic load within a fixed frequency range. Their dynamic behavior can be characterized by the enactment of negative effective mass density. This research work presents the design, fabrication and dynamic load characterization of a locally resonant elastic metamaterial. Mass-spring system with negative effective mass is experimentally investigated and numerically analyzed, with the aim to reveal stress wave transmission property in low-frequency range under impact loading. Local resonance frequencies of the basic unit cells are designed and generated using springs with different spring constants. Results evidently show that impact load mitigation occurs in the presence of internal resonators. Parametric studies reveal that wave attenuation performance is improved by using a variety of resonance frequencies in the local resonators design. In addition, alternating the arrangement of different local resonators have negligible influence on wave attenuation. A good agreement between numerical simulation and experimental testing is achieved. The significance of this work lies in the experimental and numerical evaluation of wave attenuation efficiency in elastic metamaterials, thus providing a strong foundation and design basis in the future potential of elastic metamaterials for impact protection applications.