Relationships among the contact patch length and width, the tire deflection and the rolling resistance of a free-running wheel in a soil bin facility

Arash Mohebbi,Parviz Tomaraee,Hamid Taghavifar,Aref Mardani

doi:10.5424/sjar/2015132-5245

Abstract

<p>Qualitative and quantitative analysis of contact patch length-rolling resistance, contact patch width-rolling resistance and tire deflection-rolling resistance at different wheel load and inflation pressure levels is presented. The experiments were planned in a randomized block design and were conducted in the controlled conditions provided by a soil bin environment utilizing a well-equipped single wheel-tester of Urmia University, Iran. The image processing technique was used for determination of the contact patch length and contact patch width. Analysis of covariance was used to evaluate the correlations. The highest values of contact length and width and tire deflection occurred at the highest wheel load and lowest tire inflation pressure. Contact patch width is a polynomial (order 2) function of wheel load while there is a linear relationship between tire contact length and wheel load as well as between tire deflection and wheel load. Correlations were developed for the evaluation of contact patch length-rolling resistance, contact patch width-rolling resistance and tire deflection-rolling resistance. It is concluded that the variables studied have a significant effect on rolling resistance.</p>

Highlights

Wheel, in off-road traversing, is subjected to different forces and the condition of soil-wheel interactions plays a fundamental role in traversing quality
The highest values of contact length and width and tire deflection occurred at the highest wheel load and lowest tire inflation pressure
We aimed to assess several experiments in this regard to shed light on the role of the above mentioned factors on rolling resistance, outlining the following hypotheses: (i) contact patch geometry determines the size of contact at soil-tire interface and contributes to soil deformation area and rolling resistance; (ii) tire deflection can potentially be assumed as an index of rolling resistance

Summary

Introduction

In off-road traversing, is subjected to different forces and the condition of soil-wheel interactions plays a fundamental role in traversing quality. As well as soil properties, are influential on steering, stability, traction, and braking of wheeled vehicles. Traction as a general term includes wheel thrust (gross traction), rolling resistance, and the subtraction of gross traction and rolling resistance (soil resistance for driving wheels) namely, net traction (drawbar pull). Free-running (free-rolling) wheel and driving wheel are separate terms. Regarding the tractive efficiency the slip level by driving wheel is considered, which indicates that the optimal soil contact surface (by 10% slip) increases with the traction requirement. It is known that rolling resistance, as an important energy loss factor, has a momentous impact on vehicle fuel efficiency. Considering the abovementioned facts, investigating the effect of tire parameters on rolling resistance is a significant issue. Many attempts have been made to explore the rolling resistance analytically, empirically and semi-empirically. The model of Shmulevich & Osetinsky (2003), which is perfectly adapted for traction and resistance forces in the field, has been successfully verified by the data reported in the literature (Osetinsky & Shmulevich, 2004; Battiato & Diserens, 2013) and by full-scale field experiments

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