School of Engineering, University of Guelph, Albert A. Thornbrough Building, 80 South Ring Road East, Guelph, ON N1G 2W1, Canada; Bioproducts Discovery and Development Centre, CRSC, 117 Reynolds Walk, Guelph, ON N1G 1Y, Canada.
School of Engineering, University of Guelph, Albert A. Thornbrough Building, 80 South Ring Road East, Guelph, ON N1G 2W1, Canada.
J Biomech Eng. 2022 Nov 1;144(11). doi: 10.1115/1.4054776.
When runners impact the ground, they experience a sudden peak ground reaction force (GRF), which may be up to 4× greater than their bodyweight. Increased GRF impact peak magnitude has been associated with lower limb injuries in runners. Yet, shoe midsoles are capable of cushioning the impact between the runner and the ground to reduce GRF. It has been proposed that midsoles should be tunable with subject mass to minimize GRF and reduce risk of injury. Auxetic metamaterials, structures designed to achieve negative Poisson's ratios, demonstrate superior impact properties and are highly tunable. Recently, auxetic structures have been introduced in footwear, but their effects on GRF are not documented in literature. This work investigates the viability of a three-dimensional auxetic impact structure with a tunable force plateau as a midsole through mass-spring-damper simulation. An mass-spring-damper model was used to perform 315 simulations considering combinations of seven subject masses (45-90 kg), 15 auxetic plateau forces (72-1080 N), and three auxetic damping conditions (450, 725, and 1000 Ns/m) and regression analysis was used to determine their influence on GRF impact peak, energy, instantaneous, and average loading rate. Simulations showed that tuning auxetic plateau force and damping based on subject mass may reduce GRF impact and loading rate versus simulated conventional midsoles. Auxetic plateau force and damping conditions of 450 Ns/m and ∼1 bodyweight (BW), respectively, minimized peak impact GRF. This work demonstrates the need for tunable auxetic midsoles and may inform future work involving midsole testing.
当跑步者撞击地面时，他们会经历一个突然的地面反作用力峰值（GRF），这个峰值可能高达体重的 4 倍。增加 GRF 冲击峰值幅度与跑步者下肢受伤有关。然而，中底可以缓冲跑步者与地面之间的冲击，从而降低 GRF。有人提出，中底应该能够根据受试者的体重进行调节，以最大限度地降低 GRF 并降低受伤风险。超弹性（auxetic）超材料是为了实现负泊松比而设计的结构，具有卓越的冲击性能，并且高度可调。最近，超弹性结构已被引入到鞋类中，但它们对 GRF 的影响在文献中尚未记载。本研究通过质量-弹簧-阻尼器模拟，研究了一种具有可调力平台的三维超弹性冲击结构作为中底的可行性。使用质量-弹簧-阻尼器模型，考虑到七种受试者体重（45-90 公斤）、十五种超弹性平台力（72-1080 牛）和三种超弹性阻尼条件（450、725 和 1000 牛/米）的组合进行了 315 次模拟，并使用回归分析来确定它们对 GRF 冲击峰值、能量、瞬时和平均加载率的影响。模拟结果表明，根据受试者体重调节超弹性平台力和阻尼可能会降低 GRF 冲击和加载率，与模拟传统中底相比。超弹性平台力和阻尼条件分别为 450 牛/米和约 1 个体重（BW）时，可将峰值冲击 GRF 最小化。本研究证明了可调超弹性中底的必要性，并可能为未来涉及中底测试的工作提供信息。
