Optimal Design of TPMS-Based Non-Pneumatic Tire Spoke with Adaptive Directional Stiffness

Recently, non-pneumatic tires (NPTs) featuring cellular structures have gained significant interest as a viable alternative to traditional rubber-based pneumatic tires. In this study, triply periodic minimal surface (TPMS)-based cellular structures are introduced to design NPT spokes with adaptive control of directional stiffness. While previous works have primarily focused on vertical stiffness, this study evaluated both vertical and longitudinal stiffness through finite element analyses (FEAs) for adaptive control of rolling resistance under driving and braking conditions. To achieve differentiated longitudinal stiffness between these two conditions, a spiral subdivision is proposed for asymmetric TPMS cell embedment. Various design parameters, including TPMS types and subdivision configurations, are systematically analyzed through FEAs. The optimal design is then identified by effectively connecting the design of experiments and response surface analysis. The optimized design improves longitudinal stiffness asymmetry by 47.9% compared to the reference design, while maintaining a comparable vertical stiffness. This achievement in balancing load-bearing and shock-absorbing capabilities presents a promising approach for developing high-performance NPTs with adaptive rolling resistance. With further advancements, NPTs equipped with optimized TPMS spokes could enhance mobility solutions in industrial, off-road, and military vehicle applications, offering safer, more efficient, and maintenance-free tire systems.