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系統識別號 U0026-2507201816232200
論文名稱(中文) 纖維加勁複材裂縫預測之數值方法
論文名稱(英文) A Numerical Approach for Crack Detection in Fiber Reinforced Composites
校院名稱 成功大學
系所名稱(中) 航空太空工程學系
系所名稱(英) Department of Aeronautics & Astronautics
學年度 106
學期 2
出版年 107
研究生(中文) 文森特
研究生(英文) Vincent Frament
學號 P46067093
學位類別 碩士
語文別 英文
論文頁數 169頁
口試委員 指導教授-胡潛濱
口試委員-屈子正
口試委員-楊文彬
中文關鍵字 none 
英文關鍵字 Numerical model  Lamina Composite Plate  Crack Detection  Fibers Influence  Impulse loads  Ultrasonic  Non-Destructive Testing  Finite Elements  ANSYS 
學科別分類
中文摘要 none
英文摘要 The main objective of this Master’s Thesis was to develop a 2D numerical Non-Destructive testing (NDT) method for crack detection in unidirectional fiber-reinforced laminas, thanks to the finite element code ANSYS. In that respect, a numerical approach based on the traveling time of reflected elastic waves on interfaces has been formulated, thanks to the identification of specific peaks in strain response signals. The impulse loads used are characteristic of an ultrasonic testing approach at a frequency of 0.5 MHz. The approach was proven to be effective and accurate for the detection of through thickness cracks, and the retrieval of their positions, lengths and orientations, for several composite properties and multiple fibers orientations. The chosen inspection configuration and the model boundary conditions were typical of those encountered in real inspections situations, such as the inspection of a composite wing in the vicinity of its root. Finally, an assessment of the material properties effect on the wave propagation has been done, which led to further suggestions regarding detection accuracy.
論文目次 ABSTRACT I
ACKNOWLEDGMENTS II
TABLE OF CONTENTS III
LIST OF TABLES VI
LIST OF FIGURES VIII
SYMBOLS XIV

CHAPTER I INTRODUCTION 1
1.1 General Introduction and Motivations 1
1.2 References Review 3
1.3 Thesis structure 3

CHAPTER II MODEL VALIDATION 4
2.1 Plane Stress approach and Elements used 4
2.2 Material properties and fiber orientation control 5
2.2.1 Material Models 5
2.2.2 Fiber Orientation considerations and matrices 6
2.2.2.A Orthotropic materials and matrices 7
2.2.2.B Fibers rotation 10
2.2.3 Material properties input check 14
2.2.3.A Results comparison to uniform loading theoretical results 16
2.2.3.B Results comparison between ANSYS and BEM-AEPH 18
2.3 Mesh considerations in regards to the loading 22
2.3.1 Load and signal choice 22
2.3.1.A Impulse load choice 22
2.3.1.B Signal choice and impulse characteristics 23
2.3.1.C Impulse load frequency and study time increment 29
2.3.2 Mesh size and Convergence study 31
2.4 Cracked Models Geometry 34
2.4.1 Model & Crack creation 34
2.4.2 Regular and Concentration Point-based meshes 38
2.5 Boundary Conditions and Mesh considerations in regards to the cracks 41
2.5.1 Stresses verification in regards to long time responses 41
2.5.2 Mesh type in regards to the cracks 45
2.5.2.A Theoretical Stress Intensity Factor 45
2.5.2.B Concentration Point-based mesh 47
2.5.2.C Uniform straight mesh 53
2.5.2.D Results summary and mesh discussion 60
2.5.2.E Convergent Concentration Point-based mesh and mesh choice 62

CHAPTER III RESULTS 67
3.1 Approach and Process 67
3.1.1 General Principles of the approach 67
3.1.2 Simulation Process 69
3.2 Crack Detection results 71
3.2.1 Fully centered flat crack 71
3.2.1.A Fully centered crack with regular 12.5 mm mesh 72
3.2.1.B Fully centered crack with concentrated 12.5 mm mesh 76
3.2.1.C Fully centered crack with concentrated 3.125 mm mesh 78
3.2.2 Decentered flat cracks 81
3.2.2.A Decentered left crack 81
3.2.2.B Decentered right crack 84
3.2.3 Tilted cracks 87
3.2.3.A Centered 10° tilted crack 87
3.2.3.B Decentered left -15° tilted crack 90
3.3.4 Multiform cracks 93
3.3.4.A Multiform crack with a 10° tilted part 93
3.3.4.B Multiform crack with a -15° tilted part 96
3.2.5 Multiple cracks 99
3.2.5.A Decentered Flat and -15° Multiform cracks 99
3.2.5.B Multiform crack with a 10° tilted part and fully decentered flat crack 103
3.2.6 Crack Detection summary 107
3.3 Effect of the material properties on wave speed 110
3.3.1 Analysis Process 110
3.3.2 Material Influence Results 112
3.3.2.A Fibers influence on wave propagation for Kevlar/Epoxy 113
3.3.2.B Fibers influence on wave propagation for Carbon/Epoxy 117
3.3.2.C Fibers influence on wave propagation for Glass/Epoxy 120
3.3.2.D Material Influence summary 123

CHAPTER IV CONCLUSION 124
4.1 General Conclusion 124
4.2 Approach Pros and Cons 129
4.3 Suggestions 129

REFERENCES 130
APPENDIX TABLE 131
參考文獻 [1] JEAN-F. BEGUE, Composite & Metallic materials course, DGA, IPSA (2017)


[2] ROBERT M. JONES, MECHANICS OF COMPOSITE MATERIALS, 2nd Edition, Taylor & Francis, Philadelphia, PP. 56, 58, 63, 64, 70, 71, 73, 75, 79 (1999)

[3] ANSYS 14.5 Mechanical APDL Reference

[4] C. HWU, Anisotropic Elastic Plates, Springer, New York, PP. 18, 20, 21, 22, 87,89, 90, 100, 205 (2010)



[5] AEPH Finite Element Code, C. HWU Research Group, NCKU Taiwan

[6] KARL F. GRAFF, Wave Motion in Elastic Solids, Dover, New York, P77 (1975)

[7] HENXIN C. , CHANLI K. , YUNFEI S. , Simulation of Ultrasonic Testing Technique by Finite Element Method, Prognostics & System Health Management Conference (Beijing), IEEE (2012)



[8] D. PERCY ROOKE, D. JOHN CARTWRIGHT, Compendium of Stress Intensity Factors, The Stationery Office, London, PP. 9, 10 (1976)



[9] DON E. BRAY, RODERIC K. STANLEY, NONDESTRUCTIVE EVALUATION-A Tool in Design Manufacturing and Service, McGraw-Hill, New York, PP. 70, 113 (1993)
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