Advances in the Bonded Composite Repair of Metallic Aircraft Structure VOLUME 1 A Edited by Alan Baker Francis Rose Rhys Jones ELSEVI ER ADVANCES IN THE BONDED COMPOSITE REPAIR OF METALLIC AIRCRAFT STRUCTURE Volume 1 Elsevier Science Internet Homepage - http://www.elsevier.com Consult the Elsevier homepage for full catalogue information on all books, journals and electronic products and services. Elsevier Titles of Related Interest VALERY V. VASILEV & EVGENY V. MOROZOV Mechanics and Analysis of Composite Materials ISBN: 0 08 042702 2 JANG-KYO KIM & YIU WING MA1 Engineered Interfaces in Fiber Reinforced Composites ISBN: 0 08 042695 6 J.G. WILLIAMS &A. PAVAN Fracture of Polymers, Composites and Adhesives ISBN: 0 08 043710 9 D.R. MOORE, A. PAVAN & J.G. 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Should you have a publishing proposal you wish to discuss, please contact, without obligation, the publisher responsible for Elsevier’s Composites and Ceramics programme: Emma Hurst Assistant Publishing Editor Elsevier Science Ltd The Boulevard, Langford Lane Phone: + 44 1865 843629 Kidlington, Oxford Fax: f44 1865 843931 OX5 IGB, UK E.mail: e.hurst@e,elsevier.com General enquiries, includingplacingorders, should bedirected to Elsevier’s Regional Sales Offices-pleaseaccess the Elsevier homepage for full contact details (homepage details at the top of this page). Book Butler logo to search for more Elsevier books, visit the Books Butler at http://www.elsevier.com/homepage/ booksbutler/ ADVANCES IN THE BONDED COMPOSITE REPAIR OF METALLIC AIRCRAFT STRUCTURE Volume 1 Editors A.A. Baker Defence Science and Technology Organisation, Air Vehicles Division, Victoria, Australia L.R.F. Rose Department of Defince, Dqfence Science and Technology Organisation, Air Vehicles Division, Victoria, Australia R. Jones Mechanical Engineering Department, Monash University, Victoria, Australia 2002 ELSEVIER Amsterdam ~ Boston ~ London - New York - Oxford ~ Paris San Diego ~ San Francisco - Singapore - Sydney - Tokyo ELSEVIER SCIENCE Ltd The Boulevard, Langford Lane Kidlington, Oxford OX5 IGB, UK Q 2002 Elsevier Science Ltd. All rights reserved. This work is protected under copyright by Elsevier Science, and the following terms and conditions apply to its use: Photocopying Single photocopies of single chapters may be made for personal use as allowed by national copyright laws. Permission of the Publisher and payment of a fee is required for all other photocopying, including multiple or systematic copying, copying for advertising or promotional purposes, resale, and all forms of document delivery. 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Because of rapid advances in the medical sciences, in particular, independent verification of diagnosis and drug dosages should be made. First Edition 2002 Library of Congress Cataloging in Publication Data A catalog of record from the Library of Congress has been applied for. British Library Cataloguing in Publication Data A catalogue record from the British Library has been applied for. ISBN: 0-08-042699-9 @ The paper used for this publication meets the requirements ofANSI/NISOZ39.4&1992 (Permanence of Paper). Printed in The Netherlands. Dr. Alan Baker Dr. Alan Baker is Research Leader Aerospace Composite Structures, in Airframes and Engines Division, Defence Science and Technology (DSTO), Aeronautical and Maritime Research Laboratory and Technical Adviser to the Cooperative Research Centre-Advanced Composite Structures, Melbourne Australia. He is a Fellow of the Australian Academy of Technological Sciences and Engineering and an Adjunct Professor in Department of Aerospace Engineering, Royal Melbourne Institute of Technology. Dr. Baker is a member of the International Editorial Boards of the Journals Composites Part A Applied Science and Manufacturing, Applied Composites and International Journal of Adhesion and Adhesives. He is recognised for pioneering research work on metal-matrix fibre composites while at the Rolls Royce Advanced Research Laboratory. More recently, he is recognised for pioneering work on bonded composite repair of metallic aircraft components for which he has received several awards, including the 1990 Ministers Award for Achievement in Defence Science. Dr. Francis Rose Dr. Francis Rose is the Research Leader for Fracture Mechanics in Airframes and Engines Division, Defence Science and Technology (DSTO), Aeronautical and Maritime Research Laboratory. He has made important research contributions in fracture mechanics, non-destructive evaluation and applied mathematics. In particular, his comprehensive design study of bonded repairs and related crack- bridging models, and his contributions to the theory of transformation toughening in partially stabilised zirconia, have received international acclaim. His analysis of laser-generated ultrasound has become a standard reference in the emerging field of laser ultrasonics, and he has made seminal contributions to the theory of eddy- current detection of cracks, and early detection of multiple cracking. He is the Regional Editor for the Znternational Journal of Fracture and a member of the editorial board of Mechanics of Materials. He was made a Fellow of the Institute of Mathematics and its Applications, UK, in 1987, and a Fellow of the Institution of Engineers, Australia, in 1994. He is currently President of the Australian Fracture Group, and has been involved in organising several local and international conferences in the areas of fracture mechanics and engineering mathematics. He currently serves on the Engineering Selection Panel of the Australian Research Council and of several other committees and advisory bodies. vi Biographies Professor Rhys Jones Professor Rhys Jones joined Monash University in early 1993 and is currently Professor of Mechanical Engineering, and Head of the Defence Science and Technology Organisation Centre of Expertise on Structural Mechanics. Professor Jones’ is best known for his in the fields of finite element analysis, composite repairs and structural integrity assessment. Professor Jones is the Founding Professor of both the BHP-Monash Railway Technology Institute and the BHP-Monash Maintenance Technology Institute. He is heavily involved with both Australian and overseas industry. In this context he ran the mechanical aspects of the Australian Governments Royal Commission into the failure at the ESSO plant in Victoria, and the Tubemakers-BHP investigation into the failure of the McArthur River gas pipe line in the Northern Territory. He is the recipient of numerous awards including the 1982 (Australian) Engineering Excellence Award, for composite repairs to Mirage 111, the Institution of Engineers Australia George Julius Medal, for contributions to failure analysis, a TTCP Award, for contributions to Australian, US, UK, Canada and NZ Defence Science in the field of composite structures, and a Rolls-Royce-Qantas Special Commendation, for his work on F-111 aircraft. Since 1999 Professor Jones has been Co-Chair of the International Conference (Series) on Composite Structures. Acknowledgement The editors are very pleased to acknowledge their appreciation of the great assistance provided by Drs Stephen Galea and Chun Wang of the Defence Science and Technology Organisation, Aeronautical and Maritime Research Laboratory, who made important contributions, in the collation and editing of this book. FOREWORD The introduction of the technology for bonded composite repairs of metallic airframe structures could not have come at a more opportune time. Today, many countries are facing the challenge of aging aircraft in their inventories. These airframes are degrading due to damage from fatigue cracking and corrosion. Repair with dependable techniques to restore their structural integrity is mandatory. The concept of using bonded composite materials as a means to maintain aging metallic aircraft was instituted in Australia approximately thirty years ago. Since that time it has been successfully applied in many situations requiring repair. These applications have not been limited to Australia. Canada, the United Kingdom, and the United States have also benefited from the use of this technology. The application for the solution of the problem of cracking in the fuel drain holes in wing of the C-141 is credited with maintaining the viability of this fleet. The concept for composite repair of metallic aircraft is simple. The bonded repair reduces stresses in the cracked region and keeps the crack from opening and therefore from growing. This is easy to demonstrate in a laboratory environment. It is another thing to do this in the operational environment where many factors exist that could adversely affect the repair reliability. The researchers at the Aeronautical and Maritime Research Laboratory in Australian realized there were many obstacles to overcome to achieve the desired reliability of the process. They also realized that failures of the repair on operational aircraft would mean loss of confidence and consequently enthusiasm for the process. They proceeded slowly. Their deliberate approach paid off in that they developed a process that could be transitioned to aircraft use by engineers and technicians. The essential ingredient for application of this technology is discipline. When the applicator of this process maintains the discipline required for the process and stays within the bounds of appropriate applications, then the repair will be successful. This book, edited by Drs A.A. Baker, L.R.F. Rose and R. Jones, includes the essential aspects of the technology for composite repairs. The editors have chosen some of the most knowledgeable researchers in the field of bonded repairs to discuss the issues with the many aspects of this technology. Included are discussions on materials and processes, design of repairs, certification, and application considerations. These discussions are sufficiently in-depth to acquaint the reader with an adequate understanding of the essential ingredients of the procedure. The application case histories are especially useful in showing the breadth of the possible uses of the technology. vii [...]... bonded repair technology, as indicated in the foreword, and, indeed, was the Chairman of an international group addressing certification issues This report is referenced in Chapter 1 It is rare to find in science and engineering, such a giant in the field who was so modest, approachable and friendly Jack was regarded both as a supportive father figure and the expert to be convinced on all airworthiness... reserved 2 Advances in ihe bonded composite repair of metallic aircrafi structure metallic patches The requirements for future research and development are then discussed, based, in part, on a recent USAF study on ageing aircraft [2] Before introducing repair issues, some brief background is provided in the next section on the key issues and terminology associated with the design and maintenance of... Testing of Generic Bonded Joints P.D Chalkley, C.H Wang and A.A Baker 103 5.1 103 103 104 104 106 108 109 1 I4 115 120 123 124 125 5.2 5.3 5.4 Introduction Damage-tolerance regions in a bonded repair 5.1.1 The generic design and certification process 5.1.2 The DOFS 5.2.1 Stress state in the DOFS 5.2.2 Experimental method 5.2.3 Experimental results The skin doubler specimen Stress state in the skin doubler... Large area repairs in a production environment Conclusions References mix 987 987 988 988 989 994 995 Chapter 4 Case History: Composite Patch Reinforcement of T-38 Lower Wing 0 Skin M.M Ratwani, J Helbling, B Heimerdinger and N.M Ratwani 997 Introduction Validation testing 40.2.1 Test specimen description 40.2.2 Composite reinforcement fabrication and bonding 40.2.3 Strain gage installation 40.2.4... published This book described the status of the technology, in the late 198Os, on bonded composite repair of conventional metallic, adhesively bonded metallic and fibre -composite airframe components Because over the last fourteen years the technology has progressed considerably and become widely exploited, a decision was made to produce this follow-up book Advances in Bonded Composite Repairs of Metallic... standardization 26.2.2 Building a database of reliable repairs - “We’re all in this together” Current approaches to training and certification Formalized trade structure 26.4.1 The purpose of a trade structure 26.4.2 A four-tiered trade structure - the ARTI model The ARTI model for training of bonded repair specialists Certification of bonded repair specialists 26.6.1 The Boeing wedge test (BWT) - an... operation of the aircraft Inspection, damage assessment, and repair requirements differ significantly between these classified structures Even within a single component, the allowable damage type and size (and consequently acceptable repair actions) may vary according to the criticality of the damaged region The component is generally zoned by the original equipment manufacturer (OEM) in the structural... comprehensive coverage of the current research and technology highlighting advances in capabilities, and case histories of recent applications It is intended to be useful both to researchers in the field and to practicing aerospace engineers Contributions to the book are largely drawn from the Defence Science and Technology Organisation, Australia, where this technology was pioneered in the early 1970s Significant... is provided on structural problems in ageing aircraft and on the requirements for repairs A case is then made for use of adhesively bonded composite (fibre-reinforced plastic or metal-laminate) reinforcements for repairs as compared to standard mechanical procedures, based on mechanically fastened 1 Baker, A.A., Rose, L.R.F and Jones, R (eds.) Advances i the Bonded Composite Repairs of Metallic Aircraft... materials and loading arrangement 10.7.2 Shape optimisation before reinforcement 10.7.3 Iterative reinforcement design 10.7.4 Discussion In- plane shaping effects 10.8.1 Geometry, loading and modelling considerations 10.8.2 Determination of Kt from FEA output 10.8.3 Uniaxial loading and patches with aspect ratios of 2:l 10.8.4 Uniaxial loading and other patch aspect ratios 10.8.5 Analogy with hole -in- a-plate . problem of cracking in the fuel drain holes in wing of the C-141 is credited with maintaining the viability of this fleet. The concept for composite repair. restore their structural integrity is mandatory. The concept of using bonded composite materials as a means to maintain aging metallic aircraft was instituted