Topology optimization of multi-morphology composite lattice structure with anisotropy properties.

[Display omitted] • A novel design method of composite lattice structure is proposed based on triply periodic minimal surface lattice cells. • The tunable anisotropy of elastic modulus is achieved by adjusting the design parameters of composite lattice structure. • The unique optimization method can significantly improve the global stiffness of composite lattice infill structure. • The multiple deformations of bending and compression are observed in composite lattice infill structures. Compared with the single-morphology lattice structures, multi-morphology composite lattice structure shows the potential to achieve a broad spectrum of customizable mechanical properties by modify the architectural feature of substructures. Inspired by Sigmoid mathematical function, a new parametrical design method for composite lattice structure was presented by combining the two cell lattice structs with complementary spatial distribution of elastic modulus based on previous studies. The results indicate that the unique anisotropy control strategy of elastic modulus is achieved by changing the design variables. Moreover, instead of altering the volume fraction of single-morphology lattice structure, the elastic constants of new composite lattice structure can be modified under a constant volume fraction by adjusting the design parameters. To further enhance the structural stiffness of composite lattice infilling structures, we propose a novel stiffness optimization approach based on the principal stress direction. This anisotropy control strategy enables the optimal distribution of design variables in the lattice-infill structures. Finally, the numerical results show that the proposed approach improves global stiffness compared to traditional approaches. [ABSTRACT FROM AUTHOR]