Date of Award

2014

Publication Type

Doctoral Thesis

Degree Name

Ph.D.

Department

Mechanical, Automotive, and Materials Engineering

Keywords

Design optimization, Fatigue life analysis, FE modelling, multi-piece wheel, OTR Tire and Wheel, safety

Supervisor

Altenhof, William

Supervisor

Andrews, Dave

Rights

info:eu-repo/semantics/openAccess

Abstract

In this research, experimental and numerical methods were used to analyse the performance of multi-piece wheel structures and two proposed innovative designs to enhance safety were validated by computer simulations. Fatality report analyses revealed that the majority (90%) of the multi-piece wheel failures were caused by use of lock rings. Experimental tire and rim base tests were conducted to understand the deflection characteristics of off-the-road tires and to validate the finite element model of a five-piece wheel/tire (sized 29.5-29) assembly. A linear relationship was found between the vertical displacement of the wheel and the maximum lateral deflection of the tire for both static and quasi static loading tests. A robust tire model was validated with an average accumulative error of 9.7% and an average validation metric of 0.96 for tire deflections, compared to the experimental tests. The rim base model was validated with an average error of 7.6% and an average validation metric of 0.93 for wheel deformations, and an average accumulative error of 12.7% and an average validation metric of 0.88 for strains, compared to experimental tests. Based on validated FE model of the five-piece wheel/tire assembly, geometry degradation (material wear out at critical regions) and material degradation (fatigue and corrosion) were studied to estimate their effects on fatigue lives. Two design innovations were proposed to enhance safety and fatigue life of the five-piece wheel. The threaded-connection design reduced the possibility of failure due to the mismatched wheel components. The BS band pull-out simulation revealed that the threaded-connection design was twice as strong as the conventional five-piece design in holding wheel components and the tire together, and the wheel may fail in a safer mode. The fatigue lives of the rim base were two orders of magnitude higher than those of the conventional five-piece wheel. The two-piece wheel design completely removed the possibility of wheel failure due to mismatched wheel components; the fatigue lives were increased by over two orders of magnitude, compared to the conventional five-piece wheel.

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