Engineered repairs of composite structures

219 Pages·2019·29.726 MB·English

by  Heslehurst, Rikard Benton

Engineered Repairs of
Composite Structures

Engineered Repairs of
Composite Structures
Rikard Benton Heslehurst
CRC Press
Taylor & Francis Group
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Library of Congress Cataloging‑in‑Publication Data
Names: Heslehurst, Rikard Benton, author.
Title: Engineered repairs of composite structures / Rikard Benton Heslehurst.
Description: First edition. | Boca Raton, FL : CRC Press/Taylor & Francis
Group, 2018. | Includes bibliographical references and index.
Identifiers: LCCN 2018052810 | ISBN 9781498726269 (hardback : acid-free paper)
| ISBN 9780429198656 (ebook)
Subjects: LCSH: Concrete construction--Maintenance and repair. | Buildings,
Reinforced concrete--Maintenance and repair.
Classification: LCC TA682.446 .H47 2018 | DDC 624.1/834--dc23
LC record available at https://lccn.loc.gov/2018052810
Visit the Taylor & Francis Web site at
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I dedicate this book to the important women in my life: my wife
Fiona, my daughter Elyse, my mum Jan, my sister Leanne,
my mother-in-law Jean, and both of my grandmothers Nan
(Edna) and Mumma (Phyllis). They all are responsible for the
person I have become, and I am grateful for their influence.

Contents
Preface....................................................................................................................xiii
Acknowledgments ....................................................................................................xv
Author ....................................................................................................................xvii
Nomenclature ..........................................................................................................xix
Chapter 1 Introduction ..........................................................................................1
Definition of Composite Structure .......................................................1
Typical Composite Structures ..............................................................4
Design Requirements for Composite Structures with a Focus on
the Damaging Environment .................................................................7
Operational Requirements of Composite Repairs ................................8
What this Book Contains ...................................................................11
Chapter 2 Damage and Defect Types in Composites ..........................................13
Introduction ........................................................................................13
Summary of Damage and Defect Types ............................................13
Definitions .....................................................................................13
Defect ........................................................................................13
Failure .......................................................................................14
Defect Types ..................................................................................14
Defect Listing ................................................................................14
Classifications of Defect Types ..........................................................14
When Non-Conformities Occur in Composite Structure ..............15
Size Effect of the Non-Conformity ...............................................15
Location of the Non-Conformity...................................................15
Generalisation of Non-Conformities .............................................17
Review of Generalised Defect Types .................................................18
Transverse Matrix Cracking ..........................................................19
Delaminations ................................................................................21
Fibre Fracture ................................................................................22
Conclusions ........................................................................................24
Chapter 3 Damage Assessment ...........................................................................25
Introduction ........................................................................................25
Methods of Composite NDI ...............................................................27
Visual Inspection ...........................................................................27
Acoustic Methods ..........................................................................28
Ultrasonic Methods .......................................................................28
Thermography ...............................................................................32
Interferometry ................................................................................32
vii
viii Contents
Radiography ..................................................................................34
X-Ray Radiography ..................................................................35
Neutron Radiography ................................................................36
Microwave .....................................................................................36
Material Property Changes ...........................................................36
In Situ Methods .............................................................................36
Application of NDI Methods .........................................................37
NDI Selection Process ...................................................................37
NDI Personnel ...............................................................................38
Important Requirements ....................................................................38
Equipment and Facilities ...............................................................38
Trained Operators ..........................................................................38
Comparative Specimens ................................................................38
Chapter 4 Damage Stress Analysis .....................................................................41
Introduction ........................................................................................41
Structurally Significant Damage Types .............................................41
Matrix Cracks ................................................................................41
Delaminations ................................................................................41
Holes ..............................................................................................43
Stress State and Failure Criteria .........................................................44
Failure Criteria ..............................................................................45
Linear Elastic Fracture Mechanics (LEFM) ............................45
Point Stress Analysis ................................................................46
Out-of-Plane Stresses.....................................................................49
The Repair Process ............................................................................50
Material Properties Determination ....................................................51
Stress Analysis of Damage Types ......................................................51
Matrix Crack Analysis ..................................................................51
Delaminations ................................................................................53
Effective Laminate Stiffness ....................................................54
Sub-Laminate Buckling Instability ..........................................55
Buckling of Laminates Plates ...................................................56
Holes and Fractured Fibres ............................................................58
Hole In-Plane Stress Analysis ..................................................60
Inclusion Methodology of Stress Concentration in an
Orthotropic Material ..........................................................................65
Conclusion ..........................................................................................69
Chapter 5 Generic Repair Schemes ....................................................................71
Introduction ........................................................................................71
Overview of Generic Repair Schemes ...............................................71
Filling/Sealing Repair Scheme ..........................................................71
Surface Damage Repair .................................................................71
Contents ix
Edge Damage Repair .....................................................................71
Fastener Hole Damage Repair .......................................................72
Filling/Doubler Patch Repair Scheme................................................72
Doubler Repair Scheme – Non-Structural Filler ...........................72
Doubler Repair Scheme – Structural Filler ...................................74
Flush Bonded Patch Repair Scheme ..................................................74
Laminate Replacement ..................................................................74
Bolted External Doubler .....................................................................75
Sandwich Structure Repair.................................................................75
Surface Damage Only (Cosmetic) .................................................76
Facing (Skin) Damage (Semi-Structural or
Structural Repair) ..........................................................................76
Facing (Skin) and Core Damage (Cosmetic) .................................77
Facing (Skin) and Core Damage (Semi-Structural) ......................78
Facing (Skin) and Core Damage-Structural Repair ......................79
Chapter 6 Composite Joining Methods and Design Requirements ....................81
Introduction ........................................................................................81
Bonded vs. Bolted Joints ....................................................................82
Advantages and Disadvantages .....................................................82
Material Properties ........................................................................82
Parent Structure and Repair Patch ............................................82
Adhesive Properties ..................................................................82
Fastener Properties ...................................................................83
Composite Joint Design Hints .......................................................86
Adhesively Bonded Joints ..................................................................87
Adhesive Characteristics ...............................................................87
Adhesively Bonded Joint Failure Modes .......................................88
Adhesively Bonded Double-Lap Joint ...........................................90
Adhesively Bonded Single-Lap Joint ............................................94
Adhesively Bonded Scarf Joint......................................................96
Adhesively Bonded Stepped-Lap Joint ..........................................97
Other Adhesively Bonded Joint Considerations ..........................100
Bonded Joint Design Criteria Requirement ............................100
Mechanically Fastened Joint Design ................................................101
Mechanically Fastened Joint Failure Modes ...............................101
Single Fastener Analysis ..............................................................102
Fastener Shear Failure .................................................................102
Net-Tension Failure .................................................................103
Shear-Out Failures ..................................................................104
Bearing Failures .....................................................................105
Multiple Fastener Analysis ..........................................................105
Other Considerations for Mechanically Fastened
Joints in Composites ....................................................................107
Summary of Mechanically Fastened Joint in Composites ...............108