Browsing by Author "Worajinda N."

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    Design and Analysis of a Composite SACH Foot: Experimental Validation and Finite Element Modeling
    (2025-01-01) Worajinda N.; Phromjan J.; Rugsaj R.; Phakdee S.; Suvanjumrat C.; Worajinda N.; Mahidol University
    One of the critical components in the rehabilitation of lower limb amputees is the prosthetic foot. The solid ankle cushion heel (SACH) foot is commonly prescribed to patients due to its ability to reduce impact loading at heel strike, as well as its durability and cost-effectiveness. This research focuses on developing a composite SACH foot using two different polymers. The keel was constructed from Nylon fiber, while the shell, designed to resemble an amputee's foot, was made from Polyurethane (PU) foam. The keel functions as a surrogate for the amputee's bone and is therefore specifically designed and embedded within the shell. The developed SACH foot underwent static testing according to the ISO 10328:2016 standard at various angles. Additionally, it was modeled and analyzed using the finite element method (FEM). Material tests were conducted on both the keel and shell to establish their material models for FEM. The finite element analysis (FEA) demonstrated an average error of less than 15.22%. Moreover, the FEA provided insights into the deformation and stress experienced by both the keel and the shell. This detailed investigation into the structural behavior of both SACH components offers valuable guidance for the future design and development of composite SACH feet.
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    DEVELOPMENT OF CONTACT AREA MODEL FOR MOTORCYCLE TIRE HYDROPLANING THROUGH EXPERIMENTAL INVESTIGATION
    (2024-01-01) Chaiworapuek W.; Suvanjumrat C.; Worajinda N.; Rugsaj R.; Chaiworapuek W.; Mahidol University
    Hydroplaning, a phenomenon prevalent in high-speed vehicle movement on wet surfaces, poses a significant risk by compromising tire traction and inducing slippage. This risk is particularly pronounced in motorcycles due to their reduced surface area and heightened susceptibility to rollovers. The hydroplaning force acting on motorcycle tires is intricately tied to tire-ground interaction and tire contact characteristics. This study endeavors to formulate a mathematical model to predict the contact area and contact pressure of motorcycle tires, with a specific focus on the impact of tread and groove geometries. A set of 2.5-17 inch motorcycle tires commonly used in Thailand was selected for comprehensive investigation. Eight commercially available tires, each featuring distinct tread and groove profiles, underwent testing utilizing a vertical tire testing machine. Standardized conditions, encompassing a vertical load of 850 N and an inflation pressure of 29 psi, were consistently applied. Testing was conducted at five positions along the tire circumference to minimize position-related variability, and results were averaged for accuracy. Pressure measurement film captured footprints at each load and inflation pressure, with a conversion algorithm employed for interpretation. The resultant mathematical model seeks to elucidate the dynamic alterations in the tire-ground contact area and predict both the contact area and contact pressure. This model’s applicability extends to forecasting hydroplaning forces for motorcycle tires with diverse tread and groove profiles, thereby contributing valuable insights to the broader understanding of tire characteristics and enhancing safety considerations for motorcycles.