Doctoral Dissertations

Abstract

"The deployment of large machinery for low cost, bulk surface mine production operations has resulted in high-impact shovel loading operations (HISLO). In extreme cases, shovels load large dump trucks with 100-ton (or more) passes generating high-impact forces under gravity. HISLO generates high-frequency shockwaves that cause severe truck vibrations exposing operators to whole body vibrations (WBV). This WBV levels may exceed the recommended International Standards Organization (ISO) limits resulting in longterm lower-back disorders and other health problems. There is a need for fundamental and applied research to determine HISLO vibration levels for heavy mining machinery, their comparisons to ISO 2631 limits and the safety of operators under these conditions.

Previous studies have dealt with vibration problems by designing ergonomic seats with no emphasis on the source of machine vibrations. In this study, the mechanics of truck vibrations under HISLO conditions is developed using Lagrangian formulation for a 9-DOF system. The Fehlberg fourth-fifth order Runge-Kutta numerical method is used to solve the corresponding equations of motion. Furthermore, a 3D virtual truck prototype model with 38-DOF is built and simulated in MSC.ADAMS. Simulation experiments are carried out to determine the dynamic characteristics of the truck under the HISLO conditions and to investigate the potential sources of vibration and their propagation. The simulation results show that the vertical RMS accelerations are equal to 3.56 m/s², 1.12 m/s² and 0.90 m/s² for the operator's seat, lower-back and cervical regions, respectively. These values agree with the experimental results by Kumar (1999) in the oil sands operations. The vibration levels also fall within the extremely uncomfortable zone compared to the ISO 2631 limits, which pose severe health threats to truck operators over long-term exposure.

This pioneering research initiative has developed comprehensive truck vibration theory, dynamic models and virtual prototype simulation for determining accelerations on critical body parts of a dump truck operator. It advances the heavy mining machinery vibrations frontier and contributes immensely to its body of knowledge. It also provides a foundation and a platform for comparing operator WBV exposures to ISO Limits toward creating a safe working environment that guarantees long-term operator health"--Abstract, page iii.

Advisor(s)

Frimpong, Samuel

Committee Member(s)

Awuah-Offei, Kwame, 1975-
Baird, Jason, 1955-
Cawlfield, Jeffrey D.
Stutts, Daniel S.
Tien, Jerry C.

Department(s)

Mining Engineering

Degree Name

Ph. D. in Mining Engineering

Publisher

Missouri University of Science and Technology

Publication Date

2008

Pagination

xvi, 188 pages

Note about bibliography

Includes bibliographical references (pages 173-187).

Rights

© 2008 Nassib Aouad, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Loaders (Machines) -- Vibration -- MeasurementMining machinery -- Vibration -- MeasurementDamping (Mechanics)Vibration -- Prevention

Thesis Number

T 10159

Print OCLC #

861227036

Electronic OCLC #

905545735

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