Doctoral Dissertations


Wedam Nyaaba


The cost benefits associated with the use of heavy mining machinery in the surface mining industry has led to a surge in the production of ultra-large radial tires with rim diameters in excess of 35 in. These tires experience fatigue failures in operation. The use of reinforcing fillers and processing aids in tire compounds results in the formation of microstructural inhomogeneity in the compounds and may serve as sources of crack initiation in the tire. Abrasive material cutting is another source of cracks in tires used in mining applications. It suffices, then, to assume that every material plane in the tire consists of a crack precursor of some known size likely to nucleate under the tire's duty cycle loads. This assumption eliminates the need for prior knowledge of the location and geometry of crack features to be explicitly included in a tire finite element model, overcoming the key limitations of previous approaches.

In this study, a rainflow counting algorithm is used to consistently count strain reversals present in the complex multiaxial variable amplitude duty-cycle loads of the tire to assess fatigue damage on its material planes. A critical plane analysis method is then used to account for the non-proportional loading on the tire material planes in order to identify the plane with the highest fatigue damage. The size of the investigated tire is 56/80R63, and it is typically fitted to ultra-class trucks with payload capacities in excess of 325 tonne (360 short ton). Experimental data obtained from extracted specimens of the tire were used to characterize the stress-strain and fatigue behavior of the tire finite element model in ABAQUS. A sequentially coupled thermomechanical rolling analysis of the tire provided stress, strains, and temperature data for the computation of the tire's component fatigue performance in the rubber fatigue solver ENDURICA CL. The belt endings (tire shoulder), lower sidewall, and tread lug corners are susceptible to crack initiation and subsequent failure due to high stresses.

This pioneering research effort contributes to the body of knowledge in tire durability issues in relation to mining applications. In addition, it provides a basis for off-road tire compounders and developers to design durable tires to minimize tire operating costs in the mining industry"--Abstract, page iii.


Frimpong, Samuel

Committee Member(s)

Galecki, Greg
Aouad, Nassib
He, Xiaoming
Chandrashekhera, K.


Mining Engineering

Degree Name

Ph. D. in Mining Engineering


Saudi Mining Polytechnic Program
Endurica LLC


Missouri University of Science and Technology

Publication Date

Summer 2017


xxi, 203 pages

Note about bibliography

Includes bibliographic references (pages 192-202).


© 2017 Wedam Nyaaba, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 11181

Electronic OCLC #