Advances in Thick Section Composite and Sandwich Structures (eBook)

Preface 5
Acknowledgment 11
Contents 13
Contributors 16
Dynamic Response of Composite Structures in Extreme Loading Environments 20
1 Introduction 20
2 Response of Composite and Sandwich Structures to Air-Blast Loading 22
2.1 Experimental Methods: The Shock Tube Facility 22
2.2 Theoretical Considerations 23
2.2.1 Preliminary Considerations 24
2.2.2 Model by Wang et al 24
2.2.3 Application of the Model by Wang et al. to Sandwich Composite Structures of Varying Areal Density 26
2.3 Air Blast Response of Composite Sandwich Structures 28
2.3.1 Effect of Functional Foam Core Gradation 28
2.3.1.1 Deflection 29
2.3.1.2 DIC Analysis 30
2.3.1.3 Damage Mechanisms 31
2.4 Air Blast Response of Composite Structures With Polyurea Coatings 33
2.4.1 Effect of Polyurea on Composite Plates 33
2.4.1.1 Center Point Deflection 34
2.4.1.2 Failure Mechanisms 35
2.4.2 Effect of Polyurea Location Within Composite Sandwich Structures 36
2.4.2.1 Interface Deflection 38
2.4.2.2 DIC Analysis 39
2.4.2.3 Failure Mechanisms 40
3 Response of Composite and Sandwich Structures to Extreme Underwater Loading Environments 40
3.1 Experimental Methods: Free-Field Implosion 41
3.2 Hydrostatic and Shock Initiated Implosion of Thin Cylindrical Composite Shells in Free-Field Environment 42
3.2.1 Hydrostatic Implosion of Thin Cylindrical Carbon Composite Shells 42
3.2.1.1 Deformation and Post-buckling Analysis 43
3.2.2 Hydrostatic Implosion of Thin Cylindrical Glass Fiber Composite Shells 46
3.2.2.1 Deformation and Post-buckling Analysis 47
3.2.3 Shock-Initiated Buckling of Carbon/Epoxy Composite Tubes at Sub-Critical Pressures 50
3.3 Mitigation of Pressure Pulses from Implosion of Thin Composite Shells 53
3.4 Hydrostatic and Shock-Initiated Instabilities in Double-Hull Composite Cylinders 55
3.4.1 Collapse Pressure 55
3.4.2 Implosion Under Hydrostatic Pressure: Observed Collapse Behaviors 56
3.4.2.1 Complete Collapse With Dwell 56
3.4.3 Implosion Under Hydrostatic Pressure: Impulse and Energy 57
3.4.4 Implosion Under Combined Hydrostatic and Shock Initiated Loadings: Pressure History 58
References 59
The Response of Composite Materials Subjected to Underwater Explosive Loading: Experimental and Computational Studies 62
1 Introduction 62
2 Far Field UNDEX Loading of Curved Plates 65
2.1 Conical Shock Tube Facility and Experimental Method 66
2.2 Materials and Plate Geometry 67
2.3 Computational (Finite Element) Model Overview 68
2.4 Simulation Results and Correlation to Experiments 69
2.5 Key Findings 72
3 Near Field UNDEX Flat Plates 73
3.1 Materials and Plate Configurations 73
3.2 UNDEX Facility and Experimental Method 74
3.3 Computational Model 76
3.4 Experimental and Numerical Results 77
3.5 Significant Findings 81
4 Near Field UNDEX of Cylinders 83
4.1 Cylinder Specimens 83
4.2 Experimental Method 84
4.3 Key Experimental Results and Findings 85
4.3.1 Bubble-Cylinder Interaction and Local Pressures 85
4.3.2 Transient Cylinder Response 86
4.3.3 Material Damage 87
4.4 Computational Model Overview 88
4.5 Significant Computational Results and Findings 89
4.5.1 Material Energy Comparisons 89
4.5.2 Strain Comparison 91
4.6 Results and Findings 92
5 Weathering and Ageing Effects 93
5.1 Accelerated Ageing Method 93
5.2 Material Summary 95
5.3 Underwater Blast Experiments 95
5.4 Experimental Results 96
5.5 Significant Findings 98
6 Conclusion 99
References 100
Blast Performance of Composite Sandwich Panels 103
1 Introduction 103
2 Air Blast Loading of Composite Sandwich Panels 105
2.1 Experimental Design 105
2.1.1 Effect of Core Thickness 107
2.1.2 Effect of Core Material and Core Density 107
2.1.3 Effect of Skin Configuration 108
2.1.4 Effect of Progressive Loading and Multiple Blast 109
2.2 Results 110
2.2.1 Effect of Core Thickness 110
2.2.2 Effect of Core Material and Core Density 112
2.2.3 Effect of Skin Configuration 113
2.2.4 Effect of Progressive Loading and Multiple Blast 115
2.3 Discussion 117
2.3.1 Effect of Core Thickness 117
2.3.2 Effect of Core Material and Core Density 119
2.3.3 Effect of Skin Configuration 120
2.3.4 Effect of Progressive Loading and Multiple Blast 120
3 Underwater Blast Loading of Composite Sandwich Panels 121
3.1 Experimental Design 121
3.1.1 Effect of Backing Medium 122
3.1.2 Effect of Graded Core 122
3.1.3 Effect of Skin Configuration 123
3.2 Results 124
3.2.1 Effect of Backing Medium 124
3.2.2 Effect of Graded Core 125
3.2.3 Effect of Skin Configuration 125
3.3 Discussion 126
4 Finite Element Analysis 127
4.1 Air Blast Modeling Method 127
4.1.1 The Effect of Support Conditions 128
4.1.2 The Effect of Core Thickness 129
4.1.3 The Effect of Skin Configuration 129
4.2 Air Blast Modeling Results 129
4.2.1 The Effect of Support Conditions 129
4.2.2 The Effect of Core Thickness 131
4.2.3 The Effect of Skin Configuration 131
4.3 Discussion 134
5 Conclusion 135
References 136
Explosive Blast Response of Marine Sandwich Composites 138
1 Introduction 138
2 Sandwich Composite Materials and Experimental Methodology 139
2.1 Fabrication of Sandwich Composite Materials 139
2.2 Explosive Blast Testing of Sandwich Composite Materials 140
2.3 Mechanical Property Testing of Sandwich Composite Materials 143
3 Results and Discussion 146
3.1 Blast-Induced Deformation of Sandwich Composite Materials 146
3.2 Blast-Induced Damage to Sandwich Composite Materials 151
4 Conclusion 160
References 160
Dynamic Response of Polymers Subjected to Underwater Shock Loading or Direct Impact 162
1 Introduction 162
2 Underwater Explosions and Shock Wave Focusing in Convergent Structures 163
3 Dynamic Fracture Behavior of Polymeric Materials 167
3.1 Mode-I Dynamic Fracture Behavior of Poly (Methyl Methacrylate) 168
3.2 Mode-I Dynamic Fracture Behavior of Carbon Fiber Vinyl Ester 175
3.3 Mode-II Dynamic Fracture Behavior of Carbon Fiber Epoxy 179
4 Conclusion 183
References 184
Recent Developments on Ballistic Performance of Composite Materials of Naval Relevance 185
1 Introduction 185
2 Materials 186
3 Experimental Program 188
3.1 Impact Test Set-up 188
3.2 Material Conditioning 189
4 Analytical Modelling 189
5 Experimental and Analytical Results 190
6 Numerical Simulation of Impact on MATEGLASS 192
6.1 Model Set-up 193
6.2 Materials Properties 197
6.3 Results 198
7 Discussion 199
8 Conclusions 199
References 200
Fluid-Structure Interaction of Composite Structures 202
1 Introduction 202
2 Experimental Set-Up for FSI with Impact Loading 203
3 Experimental Results of FSI with Impact Loading 205
4 Numerical Studies of FSI Under Dynamic Loading 209
5 Effect on Mode Shapes With FSI 212
6 FSI Study of Structure Containing Fluid 214
7 Structural Coupling via FSI 221
8 FSI on Moving Composite Structures 227
9 Conclusions 232
References 233
Low Velocity Impact of Marine Composites: Experiments and Theory 235
1 Introduction 235
2 Materials and Experiment 238
2.1 Materials 238
2.2 Experimental Setup 239
3 Background: Residual Strength after Impact 248
4 Results and Discussion 249
4.1 Non Destructive Damage Investigation 249
4.2 Semi-empirical Models: Influence of the Temperature 250
4.3 Residual Strength: Air-Backed Tests 254
4.4 Residual Strength: Water-Backed Impact Tests 256
4.5 Effect of the Clamping Device and Fluid-Material Interaction 257
4.6 Impact on Specimen Immersed in the Water 258
4.7 Introduction to the Theory 260
5 Conclusions 262
References 263
Inferring Impulsive Hydrodynamic Loading During Hull Slamming From Water Velocity Measurements 266
1 Introduction 266
2 A Jump in the Early 1900 to Gain Some Physical Insight 268
3 Experimental Setup at NYU 272
3.1 Apparatus 273
3.2 Data Acquisition and Analysis 274
4 PIV-Based Pressure Reconstruction 275
4.1 Pressure Reconstruction Using Navier-Stokes Equations 276
4.2 Advancements of the Approach 278
5 Validation of PIV-Based Pressure Reconstruction 280
5.1 Validation Through Experimental Measurements 280
5.2 Validation Through Synthetic Data 283
6 Exemplary Applications 285
6.1 Asymmetric and Oblique Impact of a Rigid Wedge 285
6.2 Impact of a Composite Wedge 287
7 Conclusions 289
References 291
Response of Sandwich Structures to Blast Loads 294
1 Introduction 294
2 Loads Produced by Underwater Explosions 295
2.1 Shock Wave 295
2.2 The Gas Bubble 297
2.3 Reflection of the Shock Wave from the Sea Surface and the Sea Bed 299
2.4 Cavitation 300
3 Response of Ships to an Underwater Explosion 301
3.1 Fluid Structure Interaction of Monolithic Plates 302
3.2 Fluid Structure Interaction of Composite and Sandwich Plates 306
3.3 Bubble Pulsation, Bubble Migration and Cavitation 309
4 Computational Modeling of Ships Deformations 310
4.1 Fluid Structure Interaction of Monolithic Plates 312
4.2 Fluid Structure Interaction of Composite Plates and Sandwich Panels 313
5 Summary of Batra´s Team Work 314
5.1 Homogenization of Material Properties 314
5.2 Modeling 3-D Deformations 315
5.3 Reduced-Order Models (Third-Order Shear and Normal Deformable Theory) 316
5.3.1 Effect of Curvature on Deformations of Shells 318
5.3.2 Effect of Geometric Nonlinearities on Orthotropic Plate´s Deformations 320
5.3.3 Stacking Sequence Optimization for Maximizing the Failure Initiation Load 320
5.3.4 Fluid-Structure Interaction 323
6 Conclusions 327
References 328
The Extended High Order Sandwich Panel Theory for the Static and Dynamic Analysis of Sandwich Structures 334
1 Introduction 334
2 Formulation of the Extended High Order Sandwich Panel Theory 337
3 Accuracy Study I: A Statically Loaded Simply Supported Sandwich Panel 349
4 Accuracy Study II: Wrinkling of a Sandwich Panel 353
5 Accuracy Study III: Blast Loading of a Simply Supported Sandwich Panel 354
6 Conclusion 358
References 358
Mechanics Based Modeling of Composite and Sandwich Structures in the Naval Environment: Elastic Behavior, Fracture and Damage ... 360
1 Introduction 360
2 Propagation of Plane Strain Harmonic Waves in Layered Plates 362
2.1 Multiscale Structural Model for Layered Structures with Interfacial Imperfections 363
2.2 The Influence of Interfacial Imperfections on Wave Propagation and Dispersion 366
2.3 Conclusions on Wave Propagation Analysis 368
3 Elasticity Solutions for Plates with Imperfect Thermal/Mechanical Contact of the Layers 368
3.1 Problem and Model 369
3.2 Explicit Expressions for Stresses and Displacements in Layered Plates 372
3.3 Conclusions on Elasticity Solutions through the Transverse Matrix Method 373
4 Linear Elastic Fracture Mechanics Solutions for Sandwich Beams with Face-Core Delaminations 373
4.1 Semi-Analytic Solutions for Energy Release Rate and Mode Mixity Phase Angle 374
4.2 Application to a DCB Sandwich Specimen: Influence of Shear 380
4.3 Conclusions on Interfacial Fracture Mechanics Solutions for Sandwich Beams With Face/Core Delaminations 381
5 Interaction of Multiple Damage Mechanisms in Sandwich Beams Subjected to Time-Dependent Loading 381
5.1 Models 383
5.2 Results for Quasi-Static and Dynamic Loadings 385
5.2.1 Elastic-Brittle System under Quasi-static Loading - Discussion and Conclusions 385
5.2.2 Influence of Core-plasticity on the Response under Quasi-static Loading - Discussion and Conclusions 386
5.2.3 Dynamic Loading - Discussion and Conclusions 388
6 Multiscale Structural Modeling of Delamination Fracture in Layered Beams 390
6.1 Multiscale Model 391
6.2 Single and Multiple, Mode II Dominant Delamination Fracture of Layered Beams 392
6.3 Conclusions on Multiscale Homogenized Modeling of Mode II Dominant Fracture 394
References 395
On Characterizing Multiaxial Polymer Foam Properties in Sandwich Structures 400
1 Introduction 400
2 Pressure Vessel Experiments 402
3 Transversely Isotropic Properties 403
4 Triaxial Response 404
4.1 Triaxial Compression 405
4.2 Triaxial Tension/Compression 407
4.3 Triaxial Compression and In-Plane Shear 407
5 Tsai-Wu Yield Criterion 409
6 Material Model 412
7 Concluding Remarks 418
References 418
3D Printing of Syntactic Foams for Marine Applications 419
1 Introduction 419
1.1 AM Process Chain 420
1.2 Syntactic Foams 422
1.3 Need for 3D Printing of Syntactic Foams for Marine Applications 424
2 Materials and Methods 426
2.1 Filament Material 426
2.2 Pellet Manufacturing and Filament Extrusion 427
2.3 Filament Recycling 429
2.4 CAD Modeling and 3D Printing 430
2.5 Imaging 431
2.6 Tensile Testing 431
3 Syntactic Foam Filament Manufacturing 431
3.1 Filament Quality 431
3.2 Filament Microstructure 432
3.3 Tensile Behavior 438
4 3D Printing of Syntactic Foam 442
4.1 Density 443
4.2 Microstructure of 3D Printed Syntactic Foams 443
4.3 Tensile Behavior 444
4.4 3D Printing of a Component 446
5 Conclusions 447
6 Future Perspectives 448
References 449
Damage Tolerance Assessment of Naval Sandwich Structures with Face-Core Debonds 451
1 Introduction 451
2 Fracture Mechanics of Sandwich Face/Core Interfaces 454
2.1 Griffith Criterion and Use of LEFM 454
2.2 Compliance and J-Integral Methods 457
2.3 Crack Surface Displacement Extrapolation (CSDE) Method 457
2.4 Fatigue Crack Growth 458
2.5 The Cycle Jump Technique for Fatigue Crack Growth Calculation 459
3 Experimental Fracture Characterisation Methods for Face/Core Sandwich Interfaces 460
3.1 Preliminary Remarks 460
3.2 Cracked Sandwich Beam (CSB) Test 460
3.3 Double Cantilever Beam (DCB) Test 460
3.4 Double Cantilever Beam Loaded with Uneven/Unequal Bending Moments (DCB-UBM) 462
3.4.1 Description 462
3.4.2 DCB-UBM Specimen Design and Analysis 464
3.4.3 Novel DCB-UBM Test Rig 464
3.5 Tilted Sandwich Debond (TSD) and Modified TSD Specimens 467
3.6 Mixed Mode Bending (MMB) Specimen and Test 469
3.7 G-Control 472
3.8 Shear-Torsion-Bending (STB) Test for Mixed Mode I-II-III Testing 473
3.9 Effects of Shear and Near Tip Deformations on Interface Fracture 474
3.10 Low (Arctic) Temperatures 474
4 Modelling and Testing of Sandwich Structural Components with Debonds 475
4.1 Curved Beams with Debonds 475
4.2 Debonded Sandwich Columns in Axial Compression 476
4.3 Debonded Sandwich Panels in Axial Compression 477
4.4 Debonded Sandwich Panels under Lateral Pressure Loading 480
4.5 X-Joints under Fatigue Loading: STT Test Feature 480
4.6 Improving Damage Tolerance 481
5 Damage Tolerance and Assessment Procedures for Naval Sandwich Vessels 482
5.1 Introduction 482
5.2 The SaNDI Project: Background and Aims 483
5.3 Details of the SaNDI Approach to Damage Assessment Based on Residual Strength 484
5.4 Simplified Procedure Developed for On-Board Use 488
5.5 Application to Fatigue Loading 489
5.6 Direct Estimation of Residual Fatigue Life: Integrated Fatigue Prediction System 491
6 Conclusion 491
References 492
Modeling Nonlinear and Time-Dependent Behaviors of Polymeric Sandwich Composites at Various Environmental Conditions 496
1 Introduction 496
2 Experiments 498
3 Constitutive Material Models for the Constituents 499
3.1 Nonlinear Viscoelastic Model for Foam 499
3.2 Elastic-Plastic Model for Skins 501
4 Results and Discussion 502
4.1 Uniaxial Tension Response of Skins 503
4.2 Bending Tests on Foams 505
4.3 Bending Response of Sandwich Composites 506
4.4 Time-Dependent Response of Foams and Sandwich Composites 512
5 Conclusions 516
References 516
Towards More Representative Accelerated Aging of Marine Composites 518
1 Introduction 518
2 Acceleration by Increasing Temperature 519
3 Acceleration by Applied Mechanical Loads (Stress-Diffusion Coupling) 522
4 Acceleration by Increasing Hydrostatic Pressure 523
5 Acceleration by Modifying Coupon Geometry 525
6 Influence of Aging Medium on Acceleration 528
7 Summary of Acceleration Factors 529
8 Examples of Long Duration (> 5 Year) Immersion Studies
8.1 Carbon Fiber Reinforced Composite 529
8.2 Glass Fiber Reinforced Composite 533
9 Other Factors Required to Improve Representativity of Testing 535
10 Conclusions 536
References 537
Statistical Long-Term Creep Failure Time of Unidirectional CFRP 539
1 Introduction 539
2 Statistical Prediction of Creep Failure Time of CFRP 540
3 Molding of CFRP Strands and Testing Methods 543
4 Results and Discussion 544
4.1 Creep Compliance of Matrix Resin and Static Strength of Carbon Fibers 544
4.2 Static Tensile Strengths of CFRP Strands at Various Temperatures 546
4.3 Static Tensile Strength of CFRP Strand Against Viscoelastic Compliance of Matrix Resin 550
4.4 Master Curves of Static Tensile Strength for Various CFRP Strands 551
4.5 Experimental and Predicted Statistical Creep Failure Times for Various CFRP Strands 553
4.6 Fractographs Obtained After Static and Creep Tests 555
5 Conclusion 558
References 559
Effect of Seawater on Carbon Fiber Composite Facings and Sandwich Structures With Polymeric Foam Core 560
1 Introduction 560
2 Materials 561
3 Materials Preconditioning to Simulate Marine Environment 563
4 Seawater and Temperature Effects on Constituent Materials 563
5 Effect of Seawater and Microstructure on Composite Laminates (Facings) 572
6 Fatigue Behavior of Sandwich Facing Material and Seawater Effect 576
7 CFVE Sandwich Structure Fatigue Behavior Exposed to Sea Water 578
8 Compressive Behavior and Seawater Effects 582
9 Summary 585
References 587
Failure Mechanics of Low Velocity Dynamic Impact on Woven Polymeric Composites in Arctic Conditions 588
1 Introduction 588
2 Experimental Procedures 591
2.1 Manufacturing 591
2.1.1 Material System 591
2.1.2 Laminate Fabrication 591
2.2 Impact Tests 592
2.3 Quasi-Static Tests 593
2.4 Micro Computed Tomography (micro-CT) Scanning 594
3 Results and Discussion 595
3.1 Laminate Strengthening 595
3.1.1 Compression Test Results 595
3.1.2 Tension Test Results 596
3.2 Contact Force and Deflection 597
3.2.1 Single Impact 598
3.2.2 Repeated Impact 599
3.2.3 Temperature Effect on Impact Force 602
3.2.4 Temperature Effect on Deflection 603
3.3 Absorbed Energy 604
3.3.1 Single Impact 605
3.3.2 Repeated Impact 605
3.3.3 Temperature Effect on the Degree of Damage Under Repeated Impact 606
3.4 Damage Mechanisms 607
3.4.1 Single Impact 607
3.4.2 Repeated Impact 609
4 Conclusion 610
References 611
Behavior of Composite Materials and Structures in Low Temperature Arctic Conditions 614
1 Introduction 614
1.1 Background and Motivation 614
1.2 Influence of Low Temperature on Composite Laminates 616
2 Experimental Details 617
2.1 Specimen Preparation 617
2.2 Impact Testing Setup 617
2.3 X-ray Micro-computed Tomography Analysis of Internal Damages 618
2.4 Compression After Impact Test Setup 619
2.5 Flexural After Impact Test Setup 620
3 Results and Discussion 621
3.1 Impact Damage Response 621
3.2 Impact Damage Critical Forces 621
3.3 Impact Damage Absorbed Energy 624
3.4 Impact Damage Mechanisms 625
3.5 CAI Performance 628
3.6 Flexural After Impact Performance 630
4 Conclusion 631
References 632
Mapping Interior Strain Fields in Thick Composites and Sandwich Plates With Digital Volumetric Speckle Photography Technique 634
1 Introduction 634
2 Theory of Digital Volumetric Speckle Photography (DVSP) 635
3 Strain Estimation 638
4 Experiments & Results
4.1 Experimental Setup 640
4.2 A Woven Composite Beam Under 3-Point Bending 640
4.3 A Woven Composite Beam With a Prepared Slot Under 3-Point Bending 643
4.4 A Woven Sandwich Beam Under 3-Point Bending 646
5 Discussion 649
5.1 The Effect of Subset Size 649
5.2 Influence of Artifacts in CT Images 654
6 Conclusion 655
References 656
Index 658