Doctoral Dissertations

Keywords and Phrases

Cable Shovel; Dynamic Modeling; Fatigue Failure; Kinematic Modeling

Abstract

"Large capacity shovels are used to achieve economic bulk production in surface mining operations. The suspended payload combined with dipper weight and formation resistive forces results in severe stress loading of the shovel front-end assembly. Material flaws, high stresses and harsh excavation conditions can initiate cracks in the dipper-teeth assembly. High stresses can cause these cracks to propagate to critical lengths resulting in fatigue failure, unscheduled downtimes, costly unplanned repairs, and downstream processing circuit problems. The literature reveals that dipper-related problems significantly reduce shovel up-time. This research is a pioneering effort towards developing a solid frame work for stress profiling, and fatigue fracture failure modeling of the shovel dipper-teeth assembly.

Kinematic and dynamic models of the shovel front-end assembly have been built using the Newton-Euler iterative algorithm and incorporate the dynamic formation resistive and payload forces. A numerical simulator is designed to solve these models. A virtual P&H 4100XPC shovel prototype is built in ANSYS (R15) software for stress and fatigue failure modeling studies. It is found that maximum stress varies cubically with formation density and linearly with cutting resistance. The maximum von-Misses stress on the dipper of 282 MPa exceeds the lower limits of the yield stresses for low, medium and high carbon steels. Crack propagation simulation studies show that a 100 mm crack-length is the critical crack-length for the dipper-teeth assembly. A 75 mm bottom-plate crack can propagate to the critical length in 16 days. This new knowledge provides the basis for new shovel dipper designs for different applications in surface mining operations."--Abstract, page iii.

Advisor(s)

Frimpong, S.

Committee Member(s)

Awuah-Offei, Kwame, 1975-
Chandrashekhara, K.
Galecki, Greg
Ge, Mao Chen

Department(s)

Mining and Nuclear Engineering

Degree Name

Ph. D. in Mining Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2016

Pagination

xvi, 183 pages

Note about bibliography

Includes bibliographic references (pages 176-182).

Rights

© 2016 Muhammad Azeem Raza, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Library of Congress Subject Headings

Excavating machinery -- Dynamics
Machinery, Kinematics of
Dynamics -- Mathematical models

Thesis Number

T 10926

Electronic OCLC #

952598690

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