CAXTON OKOH A FRAMEWORK DEVELOPMENT TO PREDICT REMAINING USEFUL LIFE OF A GAS TURBINE MECHANICAL COMPONENT SCHOOL OF AEROSPACE, TRANSPORT AND MANUFACTURING Manufacturing Department DOCTOR OF PHILOSOPHY, PhD Academic Year: 2013 - 2017 Supervisors: Professor Rajkumar Roy, Professor JÖrn Mehnen September 2017 SCHOOL OF AEROSPACE, TRANSPORT AND MANUFACTURING Manufacturing Department DOCTOR OF PHILOSOPHY, PhD Academic Year 2013 - 2017 CAXTON OKOH A Framework Development to Predict Remaining Useful Life of a Gas Turbine Mechanical Component Supervisors: Professor Rajkumar Roy, Professor JÖrn Mehnen September 2017 This thesis is submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy © Cranfield University 2017. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright owner. ABSTRACT Power-by-the-hour is a performance based offering for delivering outstanding service to operators of civil aviation aircraft. Operators need to guarantee to minimise downtime, reduce service cost and ensure value for money which requires an innovative advanced technology for predictive maintenance. Predictability, availability and reliability of the engine offers better service for operators, and the need to estimate the expected component failure prior to failure occurrence requires a proactive approach to predict the remaining useful life of components within an assembly. This research offers a framework for component remaining useful life prediction using assembly level data. The thesis presents a critical analysis on literature identifying the Weibull method, statistical technique and data-driven methodology relating to remaining useful life prediction, which are used in this research. The AS-IS practice captures relevant information based on the investigation conducted in the aerospace industry. The analysis of maintenance cycles relates to the examination of high-level events for engine availability, whereby more communications with industry showcase a through-life performance timeline visualisation. Overhaul sequence and activities are presented to gain insights of the timeline visualisation. The thesis covers the framework development and application to gas turbine single stage assembly, repair and replacement of components in single stage assembly, and multiple stage assembly. The framework is demonstrated in aerospace engines and power generation engines. The framework developed enables and supports domain experts to quickly respond to, and prepare for maintenance and on-time delivery of spare parts. The results of the framework show the probability of failure based on a pair of error values using the corresponding Scale and Shape parameters. The probability of failure is transformed into the remaining useful life depicting a typical Weibull distribution. The resulting Weibull curves developed with three scenarios I of the case shows there are components renewals, therefore, the remaining useful life of the components are established. The framework is validated and verified through a case study with three scenarios and also through expert judgement. II ACKNOWLEDGEMENTS I appreciate God almighty for the grace and wisdom to complete this programme. I would like to appreciate Professor Rajkumar Roy and Professor Jörn Mehnen for the opportunity to undergo this PhD programme under their supervision. Their support, advice and encouragement had always given me innovative perceptions. I am grateful to the industry sponsor and supervisor, Mr. Andrew Harrison who provided me with the projects, case studies and resources for the research. Thank you for your immense support whilst undertaking these projects. And to the T900 Life Cycle, Functional System and Safety and Reliability Engineering groups for the support during this research. My gratitude goes to my colleagues at the Through-life Engineering Service (TES) centre and the Manufacturing Department at Cranfield University. Thanks to the staffs at the TES centre and the Manufacturing Department for their support. My appreciation goes to the individuals who took their time to conduct validations of the work. Appreciation to Rolls-Royce and EPSRC Research Council for sponsoring this research project conducted at the EPSRC Centre for Innovative Manufacturing in Through-Life Engineering Services at Cranfield University. My deepest gratitude goes to my wife Golden and son Joshua for their unconditional love and immense support all through this programme. III PUBLICATIONS Publications that contributed to this research i. Okoh, C., Roy, R., and Mehnen, J. (2017), Predictive Maintenance Modelling for Through-Life Engineering Services, Procedia CIRP. The 5th International Conference on Through-life Engineering Services. DOI: 10.1016/j.procir.2016.09.033 https://www.sciencedirect.com/science/article/pii/S2212827116309726 ii. Okoh, C., Roy, R., and Mehnen, J. (2017), Maintenance Informatics Dashboard Design for Through-Life Engineering Services, Procedia CIRP. The 5th International Conference on Through-life Engineering Services. DOI:10.1016/j.procir.2016.09.019 https://www.sciencedirect.com/science/article/pii/S2212827116309532 iii. Okoh, C., Roy, R., Mehnen, J. and Redding, L., and Harrison, A. (2014). Development of an Ontology for Aerospace Engine Components Degradation in Service. 6th International Conference on Knowledge Engineering and Ontology Development, Rome, Italy. DOI: 10.5220/0005090201080119 https://www.researchgate.net/publication/280300563_Development_of_an_ Ontology_for_Aerospace_Engine_Components_Degradation_in_Service iv. Okoh, C., Roy, R., Mehnen, J. and Redding, L. (2014), Overview of Remaining Useful Life Prediction Techniques in Through-life Engineering Services. Procedia CIRP, vol.16, pp. 158-163. The 6th CIRP Conference on Industrial Product-Service Systems. DOI: 10.1016/j.procir.2014.02.006 https://www.sciencedirect.com/science/article/pii/S2212827114001140 v. Roy, R., Mehnen, J., Addepalli, S., Redding, L., Tinsley, L. and Okoh, C., (2014). Service Knowledge Capture and Reuse. Procedia CIRP, 16, pp.9- 14. The 6th CIRP Conference on Industrial Product-Service Systems. DOI: 10.1016/j.procir.2014.03.001 https://www.sciencedirect.com/science/article/pii/S2212827114000869 IV TABLE OF CONTENTS ABSTRACT ......................................................................................................... i ACKNOWLEDGEMENTS................................................................................... iii PUBLICATIONS ................................................................................................. iv TABLE OF CONTENTS ..................................................................................... v LIST OF FIGURES ............................................................................................. ix LIST OF TABLES ............................................................................................. xiii LIST OF ABBREVIATIONS ............................................................................... xv LIST OF SYMBOLS ........................................................................................ xvii 1 INTRODUCTION ......................................................................................... 1 1.1 Motivation and scope ................................................................................ 3 1.2 Problem definition ..................................................................................... 6 1.3 Research questions .................................................................................. 8 1.4 Research sponsors ................................................................................... 8 1.5 Thesis structure ...................................................................................... 10 1.6 Summary ................................................................................................ 12 2 LITERATURE REVIEW ............................................................................. 13 2.1 Methodology ...................................................................................... 13 2.2 Through-life Engineering Services ..................................................... 16 2.3 Degradation Mechanisms .................................................................. 17 2.3.1 Corrosion .................................................................................... 18 2.3.2 Deformation ................................................................................ 18 2.3.3 Fracture ...................................................................................... 19 2.3.4 Wear ........................................................................................... 19 2.4 Taxonomy and Ontology .................................................................... 20 2.5 Overview of maintenance strategies .................................................. 20 2.6 Predictive maintenance ...................................................................... 22 2.6.1 Component degradation diagnostics ........................................... 23 2.6.2 Component degradation prognostics .......................................... 26 2.7 Visualisation ....................................................................................... 26 2.8 Weibull Parameter estimation ............................................................ 27 2.9 Modelling ............................................................................................ 27 2.10 Renewal theory