Additively manufactured acoustic-mechanical multifunctional hybrid lattice structures

Lattice structures have demonstrated promising potential for applications in load bearing, impact protection, sound absorption and noise mitigation thanks to their lightweight and high specific mechanical properties as well as high degree of freedom in designability. However, it is difficult for a single type of lattice structure to possess better sound absorption and strong load-bearing properties at the same time. In this paper, a new acoustic-mechanical multifunctional structure of hollow tetrahedral truss-plate (HTTP) hybrid lattice is proposed, and experimental specimens are prepared using additive manufacturing techniques. The theoretical model of a multi-cascade class Helmholtz resonance cavity is established based on the transfer matrix method, and finite element numerical simulations and impedance tube experiments are carried out. Satisfactory agreement is achieved between the experimental, theoretical and numerical approaches. The results show that adjusting the inner diameters of the struts and the pore sizes of different layers can endow HTTP with a high average sound absorption coefficient and broadband half-absorption. In addition, the mechanical properties of the HTTP are investigated using the numerical homogenization methods and the quasi-static compression experiments. It is found that HTTP exhibits a high and stable plateau stress response during the plastic stage, and its specific energy absorption (SEA) and the specific modulus gradually decrease as the inner diameter of the struts increases. The HTTP multifunctional hybrid lattice structure proposed in this paper can simultaneously achieve high sound absorption and strong mechanical properties, providing a new paradigm for designing acoustic-mechanical multifunctional structures.