published_or_final_version / Civil Engineering / Master / Master of Philosophy

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 445-453) Also available in print.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (p. 113-118). Also available in print.

Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 81-82).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 240-244).

Thesis (M. Sc.)--University of Hong Kong, 2005.

In order to optimise the Resonance Enhanced Drilling (RED) performance in different rock formations, it is important to understand both the influence of the system parameters on the drilling dynamics, and other measures that are involved in the drilling operation. This work studies the dynamic behaviour of the drilling system. It also investigates the influence of various system parameters on the drilling module dynamics in order to identify in real-time the formation being drilled from the dynamical responses of the drilling assembly. It also aims to optimise the selection of the operating parameters for a drilled formation, resulting in an improvement in the Rate Of Penetration (ROP). A nonlinear time series analysis approach has been used to infer the changes in the system parameters from subtle changes in the system dynamics. Using the acceleration time-series as a measurement of simulated and experimental impact oscillators representing a model for drilling conditions with intermittent impacts, the systems attractors were reconstructed and characterised. It is shown that the stiffness correlates well with the topology of the reconstructed attractor. Nonimpacting trajectories formed an approximate plane within the three dimensional reconstructed phase-space. Contact with the constraint caused a systematic deviation from the linear subspace, the inclination of which, measured by statistics of the tangent vector, can be used to infer the stiffness. Based on the developed framework it is now possible to classify stiffness of the impacted material from a single variable in a simple way and in real-time. An experimental impact drilling rig was designed, built and used to study the influence of the system parameters on the high-frequency impact drilling. The newly designed rig is a smaller and simpler apparatus. It is designed to mimic the actual RED apparatus in terms of providing controlled axial vibration into a conventional rotary drilling whilst avoiding complications that might arise from including all RED rig elements. An instrumentation and sensing system was also developed to measure motions and forces resulting from the dynamic interactions between the drill-bit and the rock formations.

Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Civil Engineering. / Bibliography: leaves 175-179. / M.S.