Huirong Le

Ultra-high molecular weight polyethylene (UHMWPE) is the preferred bearing material for total knee arthroplasty, yet its limited service life (15–20 years) remains a clinical challenge. This study investigates graphene oxide (GO) nanoplatelets as reinforcing fillers to enhance the mechanical and tribological performance of UHMWPE for longer-lasting implants. GO/UHMWPE composites with 0–1 wt% GO were fabricated via solution blending and hot compression molding. Direct SEM imaging combined with oxygen elemental mapping confirmed uniform GO dispersion up to 0.5 wt%, whereas higher loadings induced agglomeration. Dynamic mechanical analysis showed that the storage modulus at 37 °C increased with GO content, peaking at 0.5 wt% (improved by ~28% over neat UHMWPE), then decreased due to aggregation. Tribological tests under dry reciprocating sliding revealed that GO progressively reduced the wear rate (up to ~45% at 1.0 wt%), but also raised the steady-state friction coefficient from 0.13 to 0.19, attributed to molecular chain anchoring. The optimal balance of enhanced stiffness and wear resistance, with only a marginal friction increase, was achieved at 0.5 wt% GO. The reinforcement mechanism involves efficient stress transfer to rigid GO sheets and reduced surface peeling. This work provides a robust processing route and direct dispersion evidence, offering practical guidance for designing high-performance UHMWPE composites for orthopedic applications.

The widespread deployment of service robots in domestic and professional environments demands structural solutions that simultaneously achieve high stiffness, low mass, and intrinsic safety. Traditional metallic structural designs face a fundamental physical conflict: achieving high stiffness typically results in excessive mass, which compromises operational safety and battery life. To solve this, this paper presents a critical review of an integrated lightweighting strategy combining material selection, structural design, and additive manufacturing for Carbon-Fiber-Reinforced Polymer (CFRP) service robot structures. Three critical findings are presented. First, specific stiffness is established as the governing criterion for material selection, providing a unified basis to resolve the stiffness–mass conflict. Second, among current 3D printing techniques, Fused Deposition Modeling (FDM) with continuous-fiber reinforcement overcomes the geometric constraints of traditional molding, enabling the fabrication of complex, customized structures. Third, to realize the full potential of 3D-printed CFRP, we highlight the importance of integrating material properties (anisotropy), structural design (topology optimization), and manufacturing processes (path planning) into a concurrent framework. This integrated approach is validated through a collaborative robotic-arm case study, achieving a 30% reduction in structural mass.