Characterization and modeling of thermo-mechanical behavior of solid tires with graphite as a heat transfer enhancer

Abstract

The solid resilient tire construction consists of three layers namely tread, cushion and base. The cushion or the middle layer provides a comfortable ride but also needs to reduce the heat buildup when the tire is subjected to heavy loads. Repeated loading on the cushion compound causes heat generation due to hysteresis and combined with the heat due to friction from tread needs to be relived promptly to reduce the risk of tire damage. The aim of the study is to enhance the thermal properties of the cushion compound of the solid tire using Sri Lankan vein graphite powder as a filler. This study reports mechanical, chemical and thermal properties of vein graphite powder sourced from Bogala mines, Sri Lanka. Five varieties of graphite powder samples were chosen to investigate their potential for application and each were characterized through Thermal Constant Analyzer, Differential Scanning Calorimetry, and Ultrasonic pulse-echo method. The ultrasonic method was adopted to obtain measurements of the Poisson's ratio (ϑ), Young's modulus (E), and Shear modulus (G) of the graphite powder samples. Highest value of thermal conductivity, volumetric heat capacity, and thermal diffusivity was reported from the grade of graphite powder possessing larger particle size. The study also focused on the improvement of the mechanical, curing, and thermal properties of vein graphite filled cushion compounds. The results showed a decrease in tensile strength with the graphite powder content. Maximum torque and the cure time were not significantly changed with the graphite particle content. Furthermore, results revealed a 66% of increase in thermal conductivity at the 10% of graphite particle addition to the compound relative to the unfilled cushion compound. It was observed that tensile strength decreased (with increased hardness) due to low interfacial adhesion and air gaps present between graphite particles and the compound. Furthermore, Dynamic mechanical analysis was performed on the vein graphite filled solid tire compounds to investigate the interaction between graphite and the polymer matrix. Next, an empirical equation, derived from the relationship between theoretical and experimental thermal conductivity values, was established to model the for graphite-iii filled solid tire compound. This equation is a valuable tool for estimating thermal conductivity within the 0-10% graphite filler loading range. Then, a comprehensive tensile test and thermal conductivity test simulations were carried out using Abaqus software and compared the obtained results with experimental data, which was observed to have reasonable correlation.