Architected lightweight, sound-absorbing, and mechanically efficient microlattice metamaterials by digital light processing 3D printing

It is of significance, but still remains a key challenge, to attain excellent sound-absorbing and mechanical properties in a material simultaneously. To overcome this challenge, herein, novel multifunctional microlattice metamaterials based on a hollow truss-plate hybrid design are proposed and then realised by digital light processing 3D printing. Quasi-perfect sound absorption (α > 0.999) and broadband half-absorption have been measured. The sound-absorbing capacity is verified to be based on the designed cascaded Helmholtz-like resonators. Physical mechanisms behind the absorptive behaviours are fully revealed by numerical analyses. The present microlattices also display superior modulus and strength to the conventional cellular materials and modified microlattices, which is attributed to their near-membrane stress state of the plate architecture. The mechanically robust behaviour of the present microlattices in turn derives from the hollow struts. This work represents an effective approach for the design and engineering of multifunctional metamaterials through 3D printing.