This short and focused book provides a description of the fundamentals of adhesive bonding within the field of aerospace applications, aimed at engineering master degree students and all those who wish to learn more about this technology. It highlights the foundations behind the use of adhesive bonding, always within the context of aeronautical cases of use. The book is written to be easily accessible to those with limited knowledge in the field and includes many illustrations to facilitate the comprehension of the concepts exposed. The work is divided into nine chapters, including theory of adhesion, surface preparation, adhesive formulations, joint manufacturing processes, quality control, repair and durability.
PREFACE
1. INTRODUCTION
1.1. Basic adhesive bonding concepts
1.2. A brief history of bonding in the aeronautical industry
1.3. Main advantages of adhesive bonding in aerospace applications
1.3.1. Key advantages
1.3.2. Limitations
1.4. Examples adhesive bonding in aerospace applications
1.4.1. Aircraft and rotorcraft
1.4.2. Space applications
2. THEORY OF ADHESION
2.1. Adhesion forces
2.2. Surface wetting
2.3. Theories of adhesion
2.3.1. Mechanical theory
2.3.2. Chemical and physical adsorption theories
3. SURFACE PREPARATION
3.1. Surface treatment selection
3.1.1. Metals
3.1.2. Polymers
3.1.3. Composites
3.2. Surface treatment techniques
3.2.1. Passive processes
3.2.1.1. Cleaning and degreasing
3.2.1.2. Abrasive processes
3.2.2. Active processes
3.2.2.1. Active surface treatment of metals
3.2.2.2. Active surface treatment for polymers and polymer matrix composites
4. ADHESIVES USED IN AEROSPACE APPLICATIONS
4.1. Structural adhesives
4.1.1. Epoxy adhesives
4.1.2. Phenolic adhesives
4.1.3. Aromatic adhesives
4.1.4. Comparison between the performance of different structural adhesives used in aeronautical construction
4.2. Non-structural adhesives and sealants
4.2.1. Elastomeric adhesives
4.2.2. Inorganic adhesives
4.3. Mechanical characterization of adhesives
4.3.1.1. Bulk tensile and compression testing
4.3.1.2. Shear testing
4.3.1.3. Fracture toughness testing
4.4. Effect of temperature on adhesive properties
4.5. Effect of moisture on adhesive properties
4.6. Effect of strain rate on adhesive properties
5. JOINT MANUFACTURING 69
5.1. Manufacture process
5.2. Adhesive storage
5.3. Surface preparation
5.4. Adhesive metering, mixing, and application
5.4.1. Paste and liquid adhesives
5.4.2. Film adhesives
5.5. Joint assembly
5.6. Adhesive hardening
6. QUALITY CONTROL OF THE ADHESIVE BONDING PROCESS
6.1. Quality control of the incoming materials
6.1.1. Glass transition temperature
6.1.2. Surface state
6.2. Quality control of the manufacturing process
6.3. Quality control of finished bonded structures
6.3.1. Types of defects present in bonded joints
6.3.2. Destructive tests
6.3.2.1. Proof tests
6.3.2.2. Fractography analysis
6.3.3. Non-destructive testing (NDT)
6.3.3.1. Visual inspection
6.3.3.2. Tap test
6.3.3.3. Ultrasonic test
6.3.3.4. Radiography test
6.3.3.5. Thermal infrared method
6.3.3.6. Acoustic emission test
6.3.3.7. Lamb wave method
6.3.3.8. Electromechanical impedance spectroscopy
6.3.3.9. Laser-based NDT7. SAFETY AND REPAIR
7.1. General precautions associated to adhesive usage
7.1.1. Use of personal protective equipment
7.2. Dangers associated to adhesives used in aerospace applications
7.2.1. Epoxy adhesives
7.2.2. Phenolic adhesives
7.2.3. Aromatic adhesives
7.2.4. Silicones and sealants
7.2.5. Other materials associated to bonding processes
7.3. Repair
7.3.1. Performance of bonded repairs
7.3.2. Repair procedures
8. JOINT DESIGN
8.1. Main geometrical configurations of bonded joints
8.2. Analytical methods
8.2.1. Simple analysis
8.2.2. Volkersen
8.2.3. Goland and Reissner
8.2.4. Hart-Smith
8.3. Failure criteria for bonded joints
8.3.1. Cohesive failure in the adhesive
8.3.1.1. Generalized yielding of the adhesive
8.3.2. Failure in the adherend
8.3.2.1. Adherend yielding
8.3.2.2. Interlaminar failure of composite adherends
8.4. Failure load prediction using numerical methods
8.5. Parameters affecting joint performance
8.5.1. Effect of the adhesive layer thickness
8.5.2. Effect of overlap length
8.5.2.1. Overlap length and adhesive type
8.5.2.2. Overlap length and adherend strength
8.5.2.3. Overlap length and composite adherends
8.5.3. Presence of disbonds in the overlap
8.5.4. Effect of service temperature and thermal stresses
8.6. Optimization of the behaviour of bonded joints
8.6.1. Use of adhesive fillets and adherend modifications
8.6.2. Mixed adhesive joints
8.6.3. Functionally graded joints
8.6.4. Techniques for delamination avoidance in composites
8.6.5. Hybrid bonded joints
9. DURABILITY
9.1. Environmental effects
9.1.1. Hygrothermal ageing
9.1.2. Temperature
9.1.3. Radiation damage
9.2. Loading conditions
9.2.1. Fatigue
9.2.1.1. Total fatigue life (S-N) approach
9.2.1.2. Fatigue crack growth approach
9.2.2. Creep
RECOMMENDED BIBLIOGRAPHY
FIGURES INDEX
TABLES INDEX
Eduardo A. S. Marques
Marques is a postdoctoral researcher at the Institute of Mechanical Engineering and Industrial Management (INEGI) and guest lecturer at the Department of Mechanical Engineering of the Faculty of Engineering of the University of Porto (FEUP).
He obtained his PhD in the area of structural adhesive bonding for aerospace applications at FEUP in 2016 and now studies the effect of high strain rates, extreme temperature and high relative humidity on the behaviour of various materials and bonded structures.
Ricardo J. C. Carbas
Carbas is currently a postdoctoral researcher at the Advanced Joining Processes unit, part of the Institute of Mechanical Engineering and Industrial Management (INEGI). He obtained his PhD in functionally graded bonded joints from the Faculty of Engineering of the University of Porto (FEUP) in 2013 and regularly carries out consultancy work for national and international companies.
Alireza Akhavan-Safar
Akhavan-Safar is a postdoctoral researcher at the Institute of Mechanical Engineeringand Industrial Management (INEGI). He earned his PhD in 2017 in the field of adhesive joints. His postdoctoral research focuses primarily on the durability (hygrothermal ageing and fatigue) of bonded joints both numerically and experimentally. The investigation of the mechanical response of adhesive joints from the fracture mechanics point of view is also part of his research.
A. Francisco G. Tenreiro
Tenreiro is a mechanical engineering PhD candidate working on the field of non-destructive testing of adhesive joints. He has obtained his Master thesis in the design and development of a novel Split Hopkinson pressure bar tester for the characterization of bonded joint under very large strain rates. He is the author of several research articles in this field.
Lucas F. M. da Silva
Silva is Full Professor in the Department of Mechanical Engineering at the Faculty of Engineering of the University of Porto (FEUP) and editor-in-chief of The Journal of Adhesion. He leads the Advanced Joining Processes Unit (AJPU) of the Institute of Mechanical Engineering and Industrial Management (INEGI).