Yiping Zhao

Lattice structures hold great promise for body protective gear and prosthetic joint buffers, benefiting from their excellent surface area-to-density and strength-to-weight ratios. Homogeneous and functionally graded triply periodic minimal surface (TPMS) structures (Schwarz P, Gyroid, Diamond) were fabricated using thermoplastic polyurethane (TPU)/polylactic acid (PLA) composites via 3D printing. The internal architectures were characterized via computed tomography (CT). Macroscopic mechanical responses were systematically investigated through tensile and three-point bending tests, coupled with finite element analysis (FEA). Results revealed that TPMS architecture significantly influences stress transfer and load-bearing capacities. Under uniaxial tension, Diamond structures exhibited superior peak force and ductility compared to the Schwarz P. FEA demonstrated the P structure undergoes stretch-dominated deformation with severe localized stress concentrations and rapid yielding, whereas Diamond and Gyroid utilize bending- and shear-dominated mechanisms to continuously dissipate stress. Flexural assessments indicated graded Diamond and Gyroid possess significantly enhanced bending stiffness and deflection resistance over homogeneous counterparts, whereas the graded P structure exhibited inferior responses. Corresponding simulations confirmed that the graded Diamond architecture effectively dissipates compressive loads outward. Consequently, this work demonstrates that Diamond-based graded TPMS structures offer a highly optimized balance of mechanical resilience and energy absorption, representing excellent candidates for advanced 3D-printed buffer components.

The aim of this study is to fabricate biodegradable PLA-based composite filaments for 3D printing to manufacture bear-loading lattice structures. First, CaCO₃ and TCP as inorganic fillers were incorporated into a PLA matrix to fabricate a series of composite filaments. The material compositions, mechanical properties, and rheology behavior of the PLA/CaCO₃ and PLA/TCP filaments were evaluated. Then, two lattice structures, cubic and Triply Periodic Minimal Surfaces-Diamond (TPMS-D), were geometrically designed and 3D-printed into fine samples. The axial compression results indicated that the addition of CaCO₃ and TCP effectively enhances the compressive modulus and strength of lattice structures. In particular, the TPMS-D structure showed superior load-carrying capacity and specific energy absorption compared to those of its cubic counterparts. Furthermore, the deformation behavior of these two lattice structures was examined by image recording during compression and computed tomography (CT) scanning of samples after compression. It was observed that pore structure could be well held in TPMS-D, while that in cubic structure was destroyed due to the fracture of vertical struts. Therefore, this paper highlights promising 3D-printed biodegradable lattice structures with excellent energy-absorption capacity and high structural stability.

Biodegradable polymers have been rapidly developed for alleviating excessive consumption of non-degradable plastics. Additive manufacturing is also a green energy-efficiency and environment-protection technique to fabricate complicated structures. Herein, biodegradable polyesters, polyglycolic acid (PGA) and poly (butyleneadipate-co-terephthalate) (PBAT) were blended and developed into feedstock for 3D printing. Under a set of formulations, PGA/PBAT blends exhibited a tailored stiffness-toughness mechanical performance. Then, PGA/PBAT (85/15 in weight ratio) with good thermal stability and mechanical property were extruded into filaments with a uniform wire diameter. Mechanical testing clearly indicated that FDM 3D-printed exhibited comparable tensile, flexural and impact properties with injection-molded samples of PGA/PBAT (85/15). Furthermore, uniform and graded Diamond-Triply Periodic Minimal Surfaces (D-TPMS) structures were designed and successfully manufactured via the fused deposition modeling (FDM) technique. Computer tomography (CT) was employed to confirm the internal three-dimensional structures. The compressive test results showed that PGA/PBAT (85/15) D-surface structures bear better load-carrying capacity than that of neat PGA, giving an advantage of energy absorption. Additionally, typical industrial parts were manufactured with excellent dimension-stability, no-wrapping and fine quality. Collectively, biodegradable PGA/PBAT material with good printability has great potentials in application requiring stiffer structures.