Fig. 1. Overview of the Bambusa ventricosa-inspired biconical lattice-strut and its crystalline architectures: (a) biomimetic lattice-strut design inspired by Bambusa ventricosa; (b) functional formulation and coordinate system curves constituting the biconical strut; (c) central cross-sectional characteristics of the biconical strut within the modeled unit cell; (d) mathematically modeled crystalline architectures including L-MM structure, Q-MM structure, and C-MM structure.

Fig. 2. Geometric-structure characteristics of microlattice metamaterials as a function of median diameter: (a) volume fractions versus median diameter; (b) relative densities versus median diameters; (c) specific surface areas versus median diameters.

Fig. 3. Surface morphology and dimensional fidelity of LPBF-produced Ti-6Al-4V microlattice metamaterial specimens: (a) topographic views of 15 sets of Ti-6Al-4V microlattice metamaterials fabricated via LPBF; (b) manufacturing deviations of LPBF-fabricated microlattice metamaterials with different middle diameter parameters, D, and strut topologies.

Fig. 4. SEM morphologies of five representative LPBF-produced microlattice metamaterial specimens: (a1-e3) topographic micrographs of L0.40, Q0.40, C0.40, L0.48, and L0.56 microlattices; (a4-e4) micrographs of biconical struts in corresponding L0.40, Q0.40, C0.40, L0.48, and L0.56 microlattices.

Fig. 5. Simulated track morphology with different overhang lengths of microlattice metamaterials: (a) schematic diagram of dross phenomenon of L-MM, Q-MM, and C-MM; (b) relationship between overhang length and overhang angle at 30 µm powder thickness; (c-e) simulated track morphology under 50 µm, 100 µm and 200 µm overhang lengths, respectively; (f-h) cross-sectional track morphology under 50 µm, 100 µm and 200 µm overhang lengths, respectively; (i) and (j) the development evolution of the molten pool depth and volume throughout the process of the single melt track under various overhang lengths, respectively; (k) time snapshots showing the cross-sectional images of the molten pool evolution of the melt-track under the overhang length of 200 µm.

Fig. 6. Progressive compressive deformation, fracture mechanisms, and final failure states of microlattice metamaterials: (a) deformation behavior of L0.40, L0.48, L0.56, Q0.40, and C0.40 specimens under compressive strains of 10%, 20%, 40%, and 60%; (b1-b5) SEM fractographs after compression; (c1-c5) post-compression deformation morphologies.

Fig. 7. Mechanical properties of microlattice metamaterials with different topologies and structural parameters: (a1-a3) representative stress-strain curves, (b1-b3) energy absorption profiles, (c) elastic modulus, (d) compressive strength, and (e) yield strength.

Fig. 8. Mechanical stress distribution of microlattice metamaterials: (a1-c1) numerical simulation of stress-strain responses in L-MM, Q-MM, and C-MM structures under deformation levels of 2%, 4%, 6%, and 8%; (a2-c2) stress distribution characteristics within unit cells of corresponding L-MM, Q-MM, and C-MM architectures.

Fig. 9. Gibson-Ashby model of microlattice metamaterials: (a) mesh sensitivity analysis of stress concentration factor; Variations of (b) the relative modulus and (c) the relative yield strength versus volume fraction; (d) comparative analysis with relative modulus data reported in existing literature [40], [61], [62].

Fig. 10. Fluid dynamics in microlattice metamaterials: (a) pressure transfer diagram; (b1-b5) Numerically simulated velocity distributions on YZ cross-sectional planes of L0.40, L0.48, L0.56, Q0.40, and C0.40 microlattices; (c1-c3) flow velocity profiles along central cross-sectional lines of L-MM, Q-MM, and C-MM structural architectures.

Fig. 11. Laminar flow on XY cross-sectional planes in microlattice metamaterials: (a) schematic representation of laminar flow; (b1-b5) numerically simulated schematic representations of laminar flow on XY cross-sectional planes in L0.40, L0.48, L0.56, Q0.40, and C0.40 architectures; (c1-c3) flow velocity profiles along central cross-sectional lines of L-MM, Q-MM, and C-MM architectures.

Fig. 12. Permeability relationships with porosity and geometric factor in microlattice metamaterials: (a) computational schematic for permeability evaluation; (b) mesh sensitivity analysis of permeability; (c) pressure drop characteristics of L-MM, Q-MM, and C-MM; (d) permeability coefficients of L-MM, Q-MM, and C-MM architectures; (e) relation between the permeability k and porosity; (f) relation between the permeability k and geometric factor (1 − ρ∗)3/(S/V)2 for all microlattice metamaterials.

Fig. 13. Thermal behavior and conductivity across stent architectures in microlattice metamaterial architectures: (a) schematic diagram of three-dimensional heat conduction; (b1-b5) numerically simulated temperature distributions on YZ cross-sectional planes of L0.40, L0.48, L0.56, Q0.40, and C0.40 microlattices; (c) temperature gradient variations along Z-axis central cross-sections; (d) mesh sensitivity analysis of equivalent thermal conductivity; (e) thermal conductivity coefficients of L-MM, Q-MM, and C-MM architectures.

Fig. 14. Compares thermal conductivity (λ) and axial gradients across Ti-6Al-4V, Al, and Cu metamaterial structures: (a1-a3) heat transfer of Ti-6Al-4V, Al, and Cu-based architectures; (b) temperature gradient variations along Z-axis central cross-sections, and (c) thermal conductivity coefficients of Ti-6Al-4V-L0.40, Al-L0.40, and Cu-L0.40 architectures.

Fig. 15. Multi-physics coupling performance analysis of three bioinspired MM scaffolds (L-MM, Q-MM, and C-MM): (a1-a3) thermo-mechanical coupling performance; (b1-b3) mechano-flow coupling performance; (c1-c3) thermo-flow coupling performance.