Control of drill-string vibrations
Dr S S Aphale
Dr A ALIAKBAR JAMSHIDI FAR
Applications accepted all year round
Self-Funded PhD Students Only
Drill-strings possess a rich nonlinear dynamic behaviour. Torsional vibrations are a main cause of concern and current area of research interest in the wider academic as well as industrial research community. Though complicated sliding-mode control-type schemes have been proposed in the past; simple, easily tunable and robust control schemes able to alleviate these unwanted vibrations are of huge practical interest. This research aims at using the well-developed linear, active vibration control techniques as motivation to find and design control schemes suitable for reducing / eliminating unwanted vibrations in drill-strings.
The candidate will start by gaining a good understanding of the drill-string system via a thorough review of existing mathematical models and preliminary simulations. A detailed critical review of existing linear and nonlinear control schemes aimed at active vibration control in general as well as drill-string vibrations specifically will be carried out to find gaps in knowledge as well as potential candidates for control design. Combined / simultaneous damping and tracking schemes, repetitive control methods, time-delayed control and fractional-order control will be focussed on. After a well-informed choice from the aforementioned control techniques, effective and robust vibration control schemes designed to specifically target and where possible, eliminate vibrations encountered in drill-strings will be designed. These designs will first undergo rigorous testing via simulations followed by experimental validation on one of the drill-string experimental rigs available at the Centre for Applied Dynamics Research, University of Aberdeen. Finally, stability analysis, investigations regarding the robustness of proposed schemes under varying parameter regimes as well as performance optimization will be carried out. This research will end with a list of lessons learned as well as possible areas of future focus.
Optical fibre sensors are widely used in many fields. In the recent past lots of research going on in optical fibre sensors related to Fibre Bragg Grating (FBG) and Photonic Crystal Fibres (PCF). This PhD research work will on modelling and simulations of optical fibre sensors. Research work will be completely theoretical.
Candidates should have (or expect to achieve) a UK honours degree at 2.1 or above (or equivalent) in Electrical, Mechatronics, Mechanical, Control Engineering or Applied Mathematics.
It is essential that the successful applicant has a background in Understanding of basic modelling and control concepts, MATLAB / SIMULINK experience essential.
A strong background in dynamics / control is a must. Preferably, the prospective candidate must have a good understanding and experience in working with at least two of the following concepts:
1. Nonlinear system dynamics
2. Linear and Nonlinear control
4. Differential Equations
MATLAB and SIMULINK, will be used extensively throughout this project and LabView will be used for experiments as and when required.
• Apply for Degree of Doctor of Philosophy in Engineering
• State name of the lead supervisor as the Name of Proposed Supervisor
• State ‘Self-funded’ as Intended Source of Funding
• State the exact project title on the application form
When applying please ensure all required documents are attached:
• All degree certificates and transcripts (Undergraduate AND Postgraduate MSc-officially translated into English where necessary)
• Detailed CV
Informal inquiries can be made to Dr S Aphale ([Email Address Removed]) with a copy of your curriculum vitae and cover letter. All general enquiries should be directed to the Postgraduate Research School ([Email Address Removed])
This project is advertised in relation to the research areas of the discipline of Electrical Engineering. The successful applicant will be expected to provide the funding for Tuition fees, living expenses and maintenance. Details of the cost of study can be found by visiting https://www.abdn.ac.uk/study/international/tuition-fees-and-living-costs-287.php. THERE IS NO FUNDING ATTACHED TO THIS PROJECT.
Thijs Vromen, ‘Control of stick-slip vibrations in drilling systems’, PhD Thesis, Eindhoven University of Technology, The Netherlands, 2015.
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