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Browsing by Author "Mousavi, Hoda"

Now showing 1 - 4 of 4
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    Experimental Characterization and Modeling of Tire-Ice Interface
    Mousavi, Hoda (Virginia Tech, 2021-03-18)
    Tire parameters play a very important role in tire performance. Depending on the driving conditions for which a given tire is designed, its parameters must be chosen appropriately (e.g., the radius of the tire, the width of the tire, material properties of different sections). Among tire characteristics, the material properties of the rubber compounds have a vital role in tire behavior. Previous studies show that the material properties of the rubber are highly dependent on temperature. Thus, a comprehensive study on the effect of the material properties of the rubber on tire performance for different temperatures as well as different road conditions is required. In this study, a theoretical model has been developed for tire-ice interaction. The temperature changes obtained from the model are used to calculate the height of the water film created by the heat generated due to the friction force. Next, the viscous friction coefficient at the contact patch is obtained. By using the thermal balance equation at the contact patch, dry friction is obtained. Knowing the friction coefficients for the dry and wet regions, the equivalent friction coefficient is calculated. The model has been validated using experimental results for three similar tires with different rubber compounds properties. For the experimental part of this study, four tires have been selected for testing. Three of them have identical tire geometry and structure but different rubber tread compounds. Several tests were conducted for the chosen tires in three modes: free-rolling, braking, and traction. The tests were performed for two different normal loads (4 kN and 5.6 kN), two different inflation pressures (21 psi (144.8 kPa) and 28 psi (193 kPa)), and three tire temperatures levels (-10°C, -5°C, and -1 °C). The Terramechanics Rig at TMVS at Virginia Tech has been used for conducting the tests. The results from this study show the sensitivity of the magnitude of the tractive force with respect to parameters such as tire temperature, normal load, etc. The results also indicate that the tire with the lowest value of the Young modulus has the highest traction among all four tires used in this study. The model developed can be used to predict the temperature changes at the contact patch, the tire friction force, the areas of wet and dry regions, the height of the water film for different ice temperatures, different normal loads, etc. The results from this study coincide with the obtained results from the experiments. According to the data available, tire B with the smallest value of Young modulus and the smallest value of the specific heat parameter was shown to have the highest friction coefficient in both simulation and experiment. After validating the results using experimentally collected data, the model was used to perform a sensitivity analysis on the tire performance with respect to six material properties of the tread rubber: thermal conductivity, rubber density, Young's modulus, specific heat, roughness parameter of the rubber, and radii of spherical asperities of the rubber. The results from this study show the sensitivity of the magnitude of the friction coefficient to the rubber material properties. The friction coefficient has a direct relationship with the density of the rubber and has an inverse relationship with Young's modulus, specific heat, and roughness parameter.
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    Investigation on static grounding analysis model of non-pneumatic tire with nonlinear spokes
    Liang, Chen; Wei, Wei; Mousavi, Hoda; Chen, Kun; Asafo-Duho, Bentil; Wang, Guolin (2021-01)
    A static grounding analysis model of non-pneumatic tire (NPT) was built and presented in this paper. The proposed NPT analysis model considers the non-linearity of the spoke stiffness and is suitable for the performance exploration of various structures of the NPT. First, the shear band, rigid rim, and spoke structure of the NPT were simplified, the main structural parameters and mechanical parameters were extracted, and an analysis model was established. The model can describe the deformation of the NPT when it is subjected to external forces. On this basis, the different stiffness of the spokes during tension and compression was considered, an iterative method was used to compensate for the difference in the deformation caused by the difference in radial stiffness of the spokes, and an analysis model of NPT with nonlinear spokes was established. Then, the contact between the tire and the road surface was introduced to iteratively compensate for the reaction force of the road surface, and the deformation of the NPT with nonlinear spokes on the road surface was obtained. Finally, the finite element software ABAQUS was used to verify the accuracy of the model. This model contains more comprehensive structural parameters and material parameters, which can more realistically simulate the structural characteristics and static grounding behavior of the NPT.
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    Tread rubber compound effect in winter tires: An experimental study
    Shenvi, Mohit Nitin; Verulkar, Adwait; Sandu, Corina; Mousavi, Hoda (Elsevier, 2022-02)
    This paper presents an indoor experimental study focused on analyzing the effect of various tread rubber compounds on the tire performance on ice. A set of sixteen tires (two per rubber compound) with identical dimensions, construction, and tread pattern, but of different tread rubber compounds, was investigated using the Terramechanics Rig which measures all forces and moments acting on a tire that is rolling (free or with slip) on ice. All operational parameters (normal load, inflation pressure, ice static coefficient of friction, ice temperature) were kept constant. Testing the tires under free rolling provided insights into the effect of the tread rubber compound on the resistive forces. The investigation led to conclusive evidence that the tread rubber compound affects drawbar pull coefficient significantly (double for best than for the worst tire). It was found that the effect of the tread rubber compound in the lower slip region is most prominent, which is also where vehicles operate most of the time. The decrease in the stiffness is generally considered a positive sign for improvement in available friction but this cannot be a generalized conclusion when analyzing the tire as a whole, which is one of the major findings of this study.
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    Tread rubber compound effect in winter tires: Benchmarking ATIIM 2.0 with classical models
    Shenvi, Mohit Nitin; Mousavi, Hoda; Sandu, Corina (Elsevier, 2022-06)
    Tire-terrain interaction is complex and affects the performance of the vehicle; more so when the terrain is ice which affects the handling of the vehicle. Analysis of the contact between the tire and ice, especially in the countries like United States, Canada, etc. is imperative but a trial-and-error approach consisting of the design and manufacture of novel tires for testing and analysis seems a foregone conclusion. Thus, it is important to have accurate methods of simulation of tire performance on ice in order to design better tires without inputting much cost in the manufacturing process. This study chose to simulate the performance of sixteen tires which were identical in all aspects of design and construction except for the tread rubber compound which varied resulting in two tires having the same tread rubber compound. These simulations were performed using the in-house developed ATIIM, ATIIM 2.0, and modified versions of three simplified classical models namely the model by Hayhoe and Shapley and two models by Peng et al. A qualitative comparison of the performance of the models was performed in order to highlight their advantages and disadvantages.