含有工程结构缺陷的复合材料层合板力学行为研究
发布时间：2021-09-25 02:41
Defects,such as voids and fiber wrinkles,are known to have detrimental effects on the structural integrity of fiber reinforced composite materials.Such defects may originate from sources such as raw materials,manufacturing processes and in-service conditions and very often are impossible to be completely eliminated.With the understanding of their formation mechanisms and their effects on composite mechanical performance,on the one hand,appropriate combinations of processing parameters could be d...
【文章来源】：浙江大学浙江省 211工程院校 985工程院校 教育部直属院校
【文章页数】：184 页
【学位级别】：博士
【文章目录】：
ABSTRACT
ACKNOWLEDGEMENT
LIST OF ACRONYMS
1 INTRODUCTION
1.1 Motivation
1.2 Technical challenge
1.3 Objectives
1.4 Scope and significance
1.5 Novelty of work
1.6 Structure of thesis
2 LITERATURE REVIEW
2.1 Consolidation of fiber and matrix
2.2 Voids and Characterization techniques for void detection
2.2.1 Void forming mechanism
2.2.2 Characterization of voids
2.2.3 Effect of voids on mechanical properties
2.3 Interlaminar fracture properties of composite laminates
2.3.1 Mode Ⅰ fracture toughness of composites
2.3.2 Mode Ⅱ fracture toughness of composites
2.4 Interlaminar shear strength of composite laminates
2.5 Fiber wrinkles in composite laminates
2.5.1 Origin and mechanism of wrinkle formation
2.5.2 Characterization of wrinkles
2.5.3 Effect of wrinkles on the mechanical performance of composites
2.5.4 Numerical and Analytical modeling of wrinkles
2.6 Composite bi-stable laminates with residual stresses
2.6.1 Mechanism and sources of shape change
2.6.2 Effect of external stimuli
2.6.3 State-of-the-art
2.7 Summary
3 MATERIALS AND METHODS
3.1 Materials
3.2 Manufacturing of composite laminate panels
3.3 Characterization techniques
3.3.1 C-Scan
3.3.2 X-ray computed tomography
3.3.3 Light microscopy
3.3.4 Scanning electron microscopy
3.4 Test methods and standards for mechanical testing
3.4.1 Acid digestion technique
3.4.2 Tensile testing of laminates
3.4.3 Compression testing of laminates
3.4.4 Mode Ⅰ fracture toughness
3.4.5 Mode Ⅱ fracture toughness
3.4.6 Interlaminar shear strength
4 COMPOSITE LAMINATES MANUFACTURED UNDER VARYING PRESSURE
4.1 Compaction and void model theory during consolidation in the autoclave
4.2 Processing parameters and environmental effect on laminate quality
4.2.1 Effect of vacuum pre-compaction and load application
4.2.2 Microstructural evolution with pressure
4.2.3 Effect of pressure on thickness
4.2.4 Void characterization and analysis
4.3 Mechanical testing of quasi isotropic laminates cured at different pressures
4.3.1 Tensile and compression strength relation with pressure
4.3.2 Tensile and compression failure mode of QI laminates
4.4 Summary
5 DEPENDENCE OF INTERLAMINAR FRACTURE PROPERTIES OF CFRPLAMINATES ON CURING PRESSURE
5.1 Mode Ⅰ fracture toughness of composite laminates
5.1.1 Load displacement curves
5.1.2 Mode Ⅰ fracture toughness initiation dependence on curing pressure
5.1.3 Correlation between crack propagation resistance and curing pressure (R-curve)
5.1.4 Effect of curing pressure on Fiber bridging
5.2 Mode Ⅱ Fracture toughness of composite laminates under varying cure pressure
5.2.1 Load displacement of quasi isotropic laminates under mode Ⅱ loading conditions
5.2.2 Mode Ⅱ fracture initiation dependence on pressure
5.3 Dependence of mode Ⅱ fracture toughness on crack interface
5.3.1 Mode Ⅱ load-displacement curves at different crack interface
5.3.2 Mode Ⅱ fracture initiation of laminates with different crack interface
5.3.4 Phenomenon of crack propagation under Mode Ⅱ loading conditions in QI laminates
5.3.5 Crack jump in QI laminates under mode Ⅱ conditions
5.4 Interlaminar shear Strength (ILSS) of quasi isotropic laminates
5.4.1 Fracture mechanic theory of interlaminar shear stress resolution
5.4.2 Load displacement curves for ILSS in QI laminates
5.4.3 ILSS evolution with curing pressure
5.4.4 Effect of voids on ILSS
5.4.5 Fracture analysis of studied QI laminates after short beam test
5.5 Comparison between ILSS of UD and QI laminates under varying curing pressure
5.6 Summary
6 COMPOSITE LAMINATES WITH ARTIFICIALLY INDUCED WRINKLES
6.1 Manufacture of laminates with induced wrinkles
6.2 Characterization of induced wrinkle
6.2.1 Wrinkle morphology
6.2.2 Wrinkle angle and severity
6.3 Mechanical testing of composite laminates with engineered wrinkles
6.3.1 Load displacement response of laminates with induced wrinkles under tensile loading
6.3.2 Tensile performance of laminates with induced wrinkles
6.3.3 Performance of wrinkle-containing laminates under compression loading
6.3.4 Relation between wrinkle angle and mechanical properties
6.3.5 Effect of double wrinkle on the tensile performance
6.4 Discussion on the effect of defect parameters on the mechanical performance of laminateswith induced wrinkle
6.4.1 Effect of varying defective layers on the mechanical performance of laminates containing wrinkles
6.4.2 Effect of varying gap width on the mechanical response of wrinkle-containing laminates
6.5 Failure mode of wrinkle-containing laminates
6.5.1 Tensile failure of wrinkle-containing laminates
6.5.2 Compressive failure of wrinkle-containing laminates
6.6 Development of analytical model for wrinkle generation
6.7 Numerical Simulation of the effect of coupling gaps and overlaps in composite laminates
6.8 Numerical simulation of the effect of wrinkles generated via the coupling of gaps andoverlaps
6.8.1 Description of pre-processing tool and model for wrinkle generation and failure modeprediction
6.8.2 Numerically predicted wrinkle details
6.8.3 Tensile performance and failure mode identification
6.9 Summary
7 BI-STABLE COMPOSITE LAMINATES WITH LOCKED-IN RESIDUALSTRESSES
7.1 Theory of thermally induced bi-stable structure
7.2 Void characterization in cross ply laminates
7.3 Effect of curing pressure on bi-stable properties
7.3.1 Dependence of bi-stable curvature on pressure
7.3.2 Correlation between residual stresses,curing pressure and bi-stable curvature
7.3.3 Dependence of snapthrough and snapback on curing pressure
7.3.4 Effect of voids on bi-stable curvature
7.4 Effect of tailored defects on bi-stable properties of cross ply laminates
7.4.1 Bi-stable laminates with induced gaps and overlaps
7.4.2 Numerical simulation of bi-stable composite laminates with tailored defect
7.5 Multi-stable laminates with enhanced geometric compatibility
7.5.1 Geometric incompatibility in multi-stable laminates
7.5.2 Design and preparation of multi-stable structures
7.5.3 Cured multi-stable laminates with several deformation states
7.6 Summary
8 CONCLUSION
8.1 Main contribution
8.2 Future work
9 REFERENCES
APPENDIX
PUBLICATIONS
Vitae
本文编号：3408924
【文章来源】：浙江大学浙江省 211工程院校 985工程院校 教育部直属院校
【文章页数】：184 页
【学位级别】：博士
【文章目录】：
ABSTRACT
ACKNOWLEDGEMENT
LIST OF ACRONYMS
1 INTRODUCTION
1.1 Motivation
1.2 Technical challenge
1.3 Objectives
1.4 Scope and significance
1.5 Novelty of work
1.6 Structure of thesis
2 LITERATURE REVIEW
2.1 Consolidation of fiber and matrix
2.2 Voids and Characterization techniques for void detection
2.2.1 Void forming mechanism
2.2.2 Characterization of voids
2.2.3 Effect of voids on mechanical properties
2.3 Interlaminar fracture properties of composite laminates
2.3.1 Mode Ⅰ fracture toughness of composites
2.3.2 Mode Ⅱ fracture toughness of composites
2.4 Interlaminar shear strength of composite laminates
2.5 Fiber wrinkles in composite laminates
2.5.1 Origin and mechanism of wrinkle formation
2.5.2 Characterization of wrinkles
2.5.3 Effect of wrinkles on the mechanical performance of composites
2.5.4 Numerical and Analytical modeling of wrinkles
2.6 Composite bi-stable laminates with residual stresses
2.6.1 Mechanism and sources of shape change
2.6.2 Effect of external stimuli
2.6.3 State-of-the-art
2.7 Summary
3 MATERIALS AND METHODS
3.1 Materials
3.2 Manufacturing of composite laminate panels
3.3 Characterization techniques
3.3.1 C-Scan
3.3.2 X-ray computed tomography
3.3.3 Light microscopy
3.3.4 Scanning electron microscopy
3.4 Test methods and standards for mechanical testing
3.4.1 Acid digestion technique
3.4.2 Tensile testing of laminates
3.4.3 Compression testing of laminates
3.4.4 Mode Ⅰ fracture toughness
3.4.5 Mode Ⅱ fracture toughness
3.4.6 Interlaminar shear strength
4 COMPOSITE LAMINATES MANUFACTURED UNDER VARYING PRESSURE
4.1 Compaction and void model theory during consolidation in the autoclave
4.2 Processing parameters and environmental effect on laminate quality
4.2.1 Effect of vacuum pre-compaction and load application
4.2.2 Microstructural evolution with pressure
4.2.3 Effect of pressure on thickness
4.2.4 Void characterization and analysis
4.3 Mechanical testing of quasi isotropic laminates cured at different pressures
4.3.1 Tensile and compression strength relation with pressure
4.3.2 Tensile and compression failure mode of QI laminates
4.4 Summary
5 DEPENDENCE OF INTERLAMINAR FRACTURE PROPERTIES OF CFRPLAMINATES ON CURING PRESSURE
5.1 Mode Ⅰ fracture toughness of composite laminates
5.1.1 Load displacement curves
5.1.2 Mode Ⅰ fracture toughness initiation dependence on curing pressure
5.1.3 Correlation between crack propagation resistance and curing pressure (R-curve)
5.1.4 Effect of curing pressure on Fiber bridging
5.2 Mode Ⅱ Fracture toughness of composite laminates under varying cure pressure
5.2.1 Load displacement of quasi isotropic laminates under mode Ⅱ loading conditions
5.2.2 Mode Ⅱ fracture initiation dependence on pressure
5.3 Dependence of mode Ⅱ fracture toughness on crack interface
5.3.1 Mode Ⅱ load-displacement curves at different crack interface
5.3.2 Mode Ⅱ fracture initiation of laminates with different crack interface
5.3.4 Phenomenon of crack propagation under Mode Ⅱ loading conditions in QI laminates
5.3.5 Crack jump in QI laminates under mode Ⅱ conditions
5.4 Interlaminar shear Strength (ILSS) of quasi isotropic laminates
5.4.1 Fracture mechanic theory of interlaminar shear stress resolution
5.4.2 Load displacement curves for ILSS in QI laminates
5.4.3 ILSS evolution with curing pressure
5.4.4 Effect of voids on ILSS
5.4.5 Fracture analysis of studied QI laminates after short beam test
5.5 Comparison between ILSS of UD and QI laminates under varying curing pressure
5.6 Summary
6 COMPOSITE LAMINATES WITH ARTIFICIALLY INDUCED WRINKLES
6.1 Manufacture of laminates with induced wrinkles
6.2 Characterization of induced wrinkle
6.2.1 Wrinkle morphology
6.2.2 Wrinkle angle and severity
6.3 Mechanical testing of composite laminates with engineered wrinkles
6.3.1 Load displacement response of laminates with induced wrinkles under tensile loading
6.3.2 Tensile performance of laminates with induced wrinkles
6.3.3 Performance of wrinkle-containing laminates under compression loading
6.3.4 Relation between wrinkle angle and mechanical properties
6.3.5 Effect of double wrinkle on the tensile performance
6.4 Discussion on the effect of defect parameters on the mechanical performance of laminateswith induced wrinkle
6.4.1 Effect of varying defective layers on the mechanical performance of laminates containing wrinkles
6.4.2 Effect of varying gap width on the mechanical response of wrinkle-containing laminates
6.5 Failure mode of wrinkle-containing laminates
6.5.1 Tensile failure of wrinkle-containing laminates
6.5.2 Compressive failure of wrinkle-containing laminates
6.6 Development of analytical model for wrinkle generation
6.7 Numerical Simulation of the effect of coupling gaps and overlaps in composite laminates
6.8 Numerical simulation of the effect of wrinkles generated via the coupling of gaps andoverlaps
6.8.1 Description of pre-processing tool and model for wrinkle generation and failure modeprediction
6.8.2 Numerically predicted wrinkle details
6.8.3 Tensile performance and failure mode identification
6.9 Summary
7 BI-STABLE COMPOSITE LAMINATES WITH LOCKED-IN RESIDUALSTRESSES
7.1 Theory of thermally induced bi-stable structure
7.2 Void characterization in cross ply laminates
7.3 Effect of curing pressure on bi-stable properties
7.3.1 Dependence of bi-stable curvature on pressure
7.3.2 Correlation between residual stresses,curing pressure and bi-stable curvature
7.3.3 Dependence of snapthrough and snapback on curing pressure
7.3.4 Effect of voids on bi-stable curvature
7.4 Effect of tailored defects on bi-stable properties of cross ply laminates
7.4.1 Bi-stable laminates with induced gaps and overlaps
7.4.2 Numerical simulation of bi-stable composite laminates with tailored defect
7.5 Multi-stable laminates with enhanced geometric compatibility
7.5.1 Geometric incompatibility in multi-stable laminates
7.5.2 Design and preparation of multi-stable structures
7.5.3 Cured multi-stable laminates with several deformation states
7.6 Summary
8 CONCLUSION
8.1 Main contribution
8.2 Future work
9 REFERENCES
APPENDIX
PUBLICATIONS
Vitae
本文编号：3408924
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