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Preface |
6 |
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Contents |
8 |
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1 Introduction |
14 |
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Abstract |
14 |
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1.1 Introduction |
14 |
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1.2 Development Perspectives |
15 |
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1.2.1 Increased Damage Growth Resistance of Metal Laminates |
15 |
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1.2.2 Utilization in Context of Damage Tolerance |
16 |
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1.2.3 Increasing Strength of Composites |
17 |
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1.3 From Material Towards Structural Application |
18 |
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1.4 Contribution to the FML Knowledge |
18 |
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References |
18 |
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2 Laminate Concepts & Mechanical Properties |
20 |
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Abstract |
20 |
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2.1 Introduction |
20 |
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2.2 Aluminium with Epoxy-Based Adhesive Systems |
21 |
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2.2.1 ARALL and GLARE, Codes and Standardisation |
22 |
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2.2.2 Aramid Fibres (ARALL) |
24 |
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2.2.3 Glass Fibres (GLARE, Central) |
27 |
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2.2.4 Carbon Fibres (CARE/CARALL) |
30 |
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2.2.5 Polymer Fibres (HP-PE, Zylon) |
31 |
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2.2.6 M5 Fibres |
33 |
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2.3 Other Metal Constituents |
34 |
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2.3.1 Titanium-Based FMLs |
34 |
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2.3.2 Stainless Steel-Based FMLs |
35 |
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2.3.3 Magnesium-Based FMLs |
35 |
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2.4 Thermoplastic Adhesive Systems |
36 |
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2.5 Innovative Hybridization Concepts |
36 |
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References |
38 |
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3 Patents and Intellectual Property |
41 |
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Abstract |
41 |
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3.1 Introduction |
41 |
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3.2 Material Concept Development |
41 |
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3.2.1 Improving Fatigue and Crack Growth |
41 |
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3.2.2 Improving Impact Resistance and Tolerance |
44 |
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3.2.3 Thickness Steps |
45 |
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3.2.4 Thick Panel Concepts for Lower Wing Covers |
47 |
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3.2.5 Alternative Fuselage Skin Concepts |
49 |
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3.3 Splicing Concepts |
51 |
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3.4 Manufacturing Aspects |
53 |
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3.4.1 Post-stretching Panels After Curing |
53 |
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3.4.2 Pre-stretching Panels During Curing |
54 |
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3.4.3 Lay-up and Curing Concepts |
55 |
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3.4.4 Alternative Impregnation Processes |
57 |
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3.5 Design of Fuselage Panels |
58 |
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3.5.1 General Fuselage Panel Concepts |
58 |
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3.5.2 Interlaminar Reinforcements and Inserts |
59 |
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3.5.3 Special Design Features |
61 |
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3.6 Design of Panel Stiffening Elements |
61 |
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3.7 FML Components |
63 |
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3.8 Discussion |
64 |
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3.8.1 Flat Material Concepts |
64 |
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3.8.2 Design Aspects |
67 |
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3.9 Concluding Remarks |
67 |
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References |
68 |
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4 Stress and Strain |
71 |
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Abstract |
71 |
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4.1 Introduction |
71 |
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4.2 Stress–Strain in Orthotropic Materials Under Plane Stress |
71 |
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4.3 Classical Laminated Plate Theory |
73 |
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4.4 Residual Stresses |
73 |
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4.5 Failure of the Composite Constituent |
76 |
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4.6 Plasticity of the Metal Constituent |
77 |
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4.7 Generalized Theories of Plasticity |
78 |
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4.8 Post-stretching |
79 |
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4.9 Shear Stress and Strain |
82 |
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4.10 Out-of-Plane (Bending and Torsion) |
83 |
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4.11 Simple Methods for Design Purposes |
84 |
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4.11.1 Metal Volume Fraction |
84 |
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4.11.2 Determination of Shear Properties Using Uniaxial Material Data |
85 |
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4.12 Limit of Validity of CLT and MVF |
87 |
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References |
87 |
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5 Blunt Notch Strength |
89 |
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Abstract |
89 |
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5.1 Introduction |
89 |
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5.2 Definitions and Failure Phenomena |
91 |
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5.2.1 Definitions |
91 |
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5.2.2 Notch Sensitivity and Ductility |
92 |
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5.2.3 Biaxial Loading Using Uniaxial Data |
94 |
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5.2.4 Composite Failure Modes |
95 |
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5.2.5 Plasticity-Induced Delamination |
97 |
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5.2.6 Other Failure Phenomena |
98 |
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5.2.7 Blunt Notch Strength and Ultimate Strength |
99 |
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5.3 Theoretical Approaches |
100 |
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5.3.1 Tsai–Hill/Norris Failure Criteria |
100 |
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5.3.2 Point and Average Stress Criteria |
101 |
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5.3.3 Blunt Notch Factor to Ultimate Strength in Net Section |
103 |
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5.4 Applicability to General Loading Conditions |
104 |
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5.4.1 Uniaxial Off-Axis Loading |
104 |
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5.4.2 Shear Loading |
106 |
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5.4.3 Biaxial Loading |
107 |
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5.5 Simple Methods for Design Purposes |
108 |
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5.5.1 Metal Volume Fraction |
108 |
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5.5.2 Neuber’s Postulate |
109 |
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References |
111 |
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6 Bearing Strength |
113 |
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Abstract |
113 |
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6.1 Introduction |
113 |
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6.2 Definition of Bearing Strength |
114 |
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6.3 Failure Phenomena |
115 |
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6.3.1 Delamination Buckling |
115 |
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6.3.2 Bearing Failure |
117 |
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6.4 Diameter-to-Thickness Ratio |
119 |
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6.5 Influence of the Diameter-to-Width Ratio |
120 |
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6.6 Influence of Edge Distance |
121 |
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6.7 In-Axis Versus Off-Axis Loading |
122 |
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6.8 Analysis and Prediction Methods |
125 |
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6.8.1 Bilinear Constituent Representation with Rules of Mixtures |
125 |
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6.8.2 Simplified MVF Method |
130 |
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6.8.3 Finite Element Analyses |
131 |
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6.9 Additional Studies |
132 |
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6.9.1 Bearing/ByPass Diagrams |
132 |
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6.9.2 Environmental Exposure |
135 |
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References |
135 |
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7 Fatigue Initiation |
138 |
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Abstract |
138 |
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7.1 Introduction |
138 |
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7.2 Definition of Initiation |
138 |
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7.3 Definition of Stresses |
142 |
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7.4 Stress Concentration in a Uniaxial Stress Field |
143 |
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7.5 Peak Stresses at Locations Other Than ? = ±90° |
145 |
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7.6 Stress Concentration in a Biaxial Stress Field |
147 |
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7.7 Other Load Cases |
148 |
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7.8 Fatigue Stresses at the Notch Root |
148 |
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7.9 Fatigue Initiation Life Estimation |
150 |
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7.10 Adapting Reference Data for Sm and Kt |
150 |
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7.11 Accuracy of Predictions |
152 |
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7.12 Size Effects |
153 |
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7.13 Constant Versus Variable Amplitude Loading |
153 |
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7.14 Mechanically Fastened Joints |
155 |
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7.15 Influence of Post-stretching |
156 |
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References |
157 |
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8 Static and Fatigue Delamination |
158 |
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Abstract |
158 |
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8.1 Introduction |
158 |
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8.2 Strain Energy Release Rate |
159 |
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8.3 Interface Geometry |
161 |
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8.3.1 Resin-Rich Layers |
161 |
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8.3.2 Tapes Versus Weaves |
165 |
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8.4 Modes I, II and Mixed Mode |
166 |
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8.4.1 Mode I |
166 |
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8.4.2 Mode II |
166 |
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8.4.3 Mixed Mode |
169 |
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8.5 Constant Versus Variable Amplitude Loading |
171 |
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8.5.1 Macroscopic Observations |
171 |
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8.5.2 Microscopic Observations |
173 |
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8.6 Asymptotes in Delamination Characteristics |
176 |
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8.6.1 Static Delamination Growth |
176 |
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8.6.2 Delamination Threshold |
178 |
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8.7 Delamination Buckling |
179 |
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8.8 Effect of Post-stretching |
180 |
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References |
182 |
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9 Fatigue Crack Propagation |
185 |
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Abstract |
185 |
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9.1 Introduction |
185 |
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9.2 Crack Geometries |
186 |
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9.3 Fatigue Crack Growth Characteristics |
187 |
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9.4 Superposition of Far-Field Stresses and Fibre Bridging |
190 |
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9.5 Delamination Shapes |
194 |
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9.6 Metal Layer Crack Growth Resistance |
196 |
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9.7 Finite Width Correction Factors |
199 |
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9.8 Other Correction Factors |
200 |
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9.8.1 Open Hole and Pin-Loaded Hole |
203 |
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9.8.2 Edge Cracks Versus Central Cracks |
205 |
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9.9 Fatigue Threshold |
206 |
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9.10 Surface Cracks |
208 |
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9.11 Part-Through Cracks |
211 |
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9.12 In-Axis Versus off-Axis Loading |
213 |
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9.13 Crack Path Angles and Path Deflections |
218 |
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9.14 Constant Versus Variable Amplitude Loading |
221 |
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9.15 Post-stretching |
223 |
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9.16 Biaxial Fatigue |
224 |
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References |
227 |
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10 Residual Strength |
231 |
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Abstract |
231 |
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10.1 Introduction |
231 |
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10.2 Through-Cut Cracks |
233 |
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10.2.1 Fracture Mechanisms |
235 |
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10.2.2 KR-Curve or R-Curve Concept |
236 |
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10.2.3 Compliance Calibration for Orthotropic FML Panels |
239 |
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10.2.4 Crack Tip Opening Angle or CTOA Concept |
241 |
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10.2.5 Superposition Principles for Crack Opening |
244 |
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10.2.6 In-Axis Versus Off-Axis Loading |
246 |
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10.3 Fatigue Through Crack |
247 |
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10.3.1 Observations |
247 |
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10.3.2 Prediction Methodology |
250 |
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10.4 Part-Through Cracks |
251 |
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10.5 Surface Cracks |
254 |
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10.6 Impact Damage Tolerance |
256 |
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References |
259 |
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11 Effect of Temperature |
263 |
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Abstract |
263 |
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11.1 Introduction |
263 |
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11.2 Temperature-Induced Residual Stresses |
263 |
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11.3 Thermal Properties of FMLs |
264 |
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11.3.1 Thermal Conductivity |
264 |
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11.3.2 Specific Heat |
267 |
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11.4 Fatigue Initiation |
267 |
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11.4.1 Temperature Effect on Mechanical Properties |
268 |
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11.4.2 Temperature Effect on Fatigue Properties |
269 |
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11.5 Fatigue Damage Growth |
272 |
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11.5.1 Temperature and Fatigue Crack Growth Resistance of Metals |
272 |
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11.5.2 Temperature and Fatigue Delamination Resistance |
273 |
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11.5.3 Influence of Temperature on Damage Growth in FMLs |
276 |
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11.6 Thermal Fatigue |
277 |
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References |
278 |
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12 Effect of Environment |
281 |
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Abstract |
281 |
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12.1 Introduction |
281 |
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12.2 Moisture Absorption |
282 |
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12.2.1 Planar Diffusion of Moisture |
282 |
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12.2.2 Relevance of Exposure Type |
285 |
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12.3 Effects of Moisture Ingress |
287 |
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12.3.1 Static Strength |
287 |
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12.3.2 Blunt Notch Strength |
288 |
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12.3.3 Delamination Resistance |
291 |
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12.3.4 Fatigue Crack Growth |
293 |
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12.3.5 Residual Strength |
294 |
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12.4 Effect of Frequency |
297 |
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References |
299 |
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13 Acoustic Fatigue |
301 |
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Abstract |
301 |
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13.1 Introduction |
301 |
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13.2 Damping Characteristics |
302 |
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13.3 Acoustic Fatigue |
303 |
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13.4 High-Frequency Bending Fatigue Experiments |
303 |
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13.4.1 Specimen Configuration and Test Set-up |
303 |
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13.4.2 Test Procedure |
304 |
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13.4.3 Performed Tests |
305 |
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13.5 Results and Observations |
306 |
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13.6 Concluding Remarks |
308 |
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References |
308 |
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Index |
309 |
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