Title Page
ABSTRACT
Contents
NOMENCLATURES 18
CHAPTER 1. INTRODUCTION 22
1.1. General background 22
1.1.1. Catamaran 22
1.1.2. Slamming phenomenon 23
1.1.3. Effect of slamming pressure 24
1.1.4. Base frames of a catamaran 26
1.1.5. Sound transmission loss of insulation materials 27
1.2. Literature Review 27
1.3. Research objectives and Approaches 33
1.4. Outline of the thesis 34
CHAPTER 2. THEORY OF SLAMMING AND FINITE ELEMENT METHOD 36
2.1. Yon Karman theory 36
2.2. Wagner theory 40
2.3. Formulation of slamming forces 49
2.4. Finite Element Method 51
2.4.1. Matrix Structural Analysis 53
2.4.2. Stress and Strain 55
2.4.3. Finite Element Modeling 56
2.4.4. ANSYS software 57
CHAPTER 3. STRUCTURAL ANALYSIS OF CATAMARAN'S HULL DUE TO SLAMMING PRESSURE 59
3.1. Specific Catamaran 59
3.2. Determine Slamming Pressure 61
3.2.1. Bottom Slamming pressure 61
3.3.2. Side Slamming pressure 64
3.3. Model design 65
3.4. Structural Analysis 69
3.4.1. Meshing and Boundary condition 69
3.4.2. Basic parameters of structural analysis 71
3.4.3. Results of analysis 73
3.5. Analysis wetdeck structure of a catamaran 78
3.5.1. Formula of wetdeck slamming pressure 79
3.5.2. Model design 81
3.5.3. Results of analysis 85
CHAPTER 4. TOPOLOGY OPTIMIZATION AND ANALYSIS OF BASE FRAMES FOR A CATAMARAN. 89
4.1. Introduction 89
4.2. Theory of Topology Optimization 90
4.2.1. Introduction of topology optimization 90
4.2.2. Structural Optimization 91
4.2.3. Solid Isotropic Material with Penalization (SIMP) 95
4.3. Topology Optimization Solvers in ANSYS 97
4.4. Design of base frames 99
4.5. Analysis and Topology Optimization of the Base Frame 105
4.5.1. Process of the ANSYS topology optimization 105
4.5.2. Boundary Conditions and Loads 107
4.5.3. Static Structural Analysis 112
4.5.4. Topology optimization results and analysis 116
4.5.5. Static structural analysis of the base frame after optimization 119
4.5.6. Modal analysis 121
4.5.7. Harmonic analysis 126
CHAPTER 5. EXPERIMENT ON THE COMPOSITION OF MATERIALS TO IMPROVE THE SOUND INSULATION PERFORMANCE OF ENGINE ROOM WALLS 128
5.1. Basics of sound 128
5.1.1. Generation of sound 128
5.1.2. Equations of plane wave's motion 131
5.1.3. Velocity of plane waves 135
5.1.4. Specific acoustic impedance 137
5.1.5. Sound intensity 139
5.1.6. Levels 140
5.1.7. The Decibel 142
5.2. Absorption and transmission loss 143
5.2.1. Absorption 143
5.2.2. Sound transmission loss 145
5.3. Experiment of insulation material for the engine room of the catamaran 150
5.3.1. Introduction 150
5.3.2. Experiment setup 152
5.3.3. Test panels description 155
5.3.4. Results and discussion 157
CHAPTER 6. CONCLUSIONS 165
REFERENCE 167
Table 3.1. Basic parameters of catamaran 60
Table 3.2. Material properties of aluminium plate 68
Table 3.3. Designed Models 68
Table 3.4. Principal particulars 70
Table 4.1. Main engine specifications 102
Table 4.2. Properties of Aluminum 103
Table 4.3. Results of Static structural analysis of the base frame before... 115
Table 4.4. Results of optimization 118
Table 4.5. Comparison between existing and optimized base frame 121
Table 4.6. Natural frequencies of the optimized base frame(내용없음) 13
Table 5.1. Composition of specimens 153
Figure 1.1. Typical catamaran cross section 22
Figure 1.2. Structure damage due to slamming pressure on HSS Stena... 26
Figure 2.1. Wedge entry geometry 37
Figure 2.2. Water entry of a wedge with constant velocity 41
Figure 2.3. Model of Wagner's theory 42
Figure 2.4. Slamming pressure parameters during water entry of 2D rigid... 46
Figure 3.1. Catamaran profile 59
Figure 3.2. The 3D Model of Catamaran 60
Figure 3.3. Design area factor 63
Figure 3.4. Vertical acceleration distribution factor 63
Figure 3.5. Deadrise angle 64
Figure 3.6. Area of the side slamming pressure 64
Figure 3.7. Vertical acceleration distribution factor 65
Figure 3.8. Forward shell area of catamaran hull 66
Figure 3.9. 3D model of forward shell 67
Figure 3.10. Mesh of the studied model 69
Figure 3.11. Loads and boundary condition 71
Figure 3.12. Total deformation of model 1 73
Figure 3.13. Equivalent stress of model 1 74
Figure 3.14. Total deformation of model 6 74
Figure 3.15. Equivalent stress of model 6 75
Figure 3.16. Total deformation of model 11 75
Figure 3.17. Equivalent stress of model 11 76
Figure 3.18. Comparison of maximum stress for eleven models 77
Figure 3.19. Maximum equivalent stress of two bottom shells(A₁ and A₂) 78
Figure 3.20. Wetdeck pressure distribution factor 81
Figure 3.21. Font part model of catamaran 82
Figure 3.22. Loads and Boundary condition in case one 83
Figure 3.23. Loads and boundary condition in case two 83
Figure 3.24. Loads and boundary condition in case three 84
Figure 3.25. Von-Mises stress in case one 86
Figure 3.26. Total deformation in case one 86
Figure 3.27. Total deformation in case two 87
Figure 3.28. Von-Mises stress in case two 87
Figure 3.29. Total deformation in case three 88
Figure 3.30. Von-Mises stress in case three 88
Figure 4.1. Types of structural optimization 91
Figure 4.2. The generalized shape design problem of finding the optimal... 92
Figure 4.3. Main engine installation 100
Figure 4.4. Basic dimensions of a base frame 103
Figure 4.5. 3D geometry of base frame 104
Figure 4.6. Engine room model of catamaran 105
Figure 4.7. ANSYS Flow chart for Topology optimization 107
Figure 4.8. Boundary conditions and loads applied for optimization 108
Figure 4.9. The flowchart of topology optimization methodology in ANSYS 110
Figure 4.10. Equivalent stress of the base frame before optimization 113
Figure 4.11. Total deformation of the base frame before optimization 113
Figure 4.12. Shear stress (XY) plane in the base frame 114
Figure 4.13. Normal stresses (X-Axis) in the base frame 114
Figure 4.14. Equivalent elastic strain in the base frame 115
Figure 4.15. Material removals from the base frame 117
Figure 4.16. Objective and mass response convergence 117
Figure 4.17. Model of the base frame after optimization 119
Figure 4.18. Loads and boundary condition of optimized frame 119
Figure 4.19. Total deformation of the optimized base frame 120
Figure 4.20. Equivalent stress of the optimized base frame 120
Figure 4.21. Performance curve of main engine 123
Figure 4.22. Natural frequencies of the optimized base frame 124
Figure 4.23. The mode shapes (1-10) of optimized base frame 125
Figure 4.24. Analysis position 127
Figure 4.25. Frequency response of assembled position 127
Figure 5.1. The generation of sound waves 129
Figure 5.2. a) Relation between pressure, period, and frequencies; b)... 131
Figure 5.3. Strain of a layer 137
Figure 5.4. Measure of STL 146
Figure 5.5. Insulation of the engine room 152
Figure 5.6. Design of source tube 153
Figure 5.7. Experiment setup 154
Figure 5.8. Noise meter 154
Figure 5.9. Test specimens 155
Figure 5.10. Composition material: a) MFF, b) SI, c) Rubber, d) S 156
Figure 5.11. Sound level of specimen 1 158
Figure 5.12. Sound level of specimen 2 159
Figure 5.13. Sound level of specimen 3 159
Figure 5.14. Sound level of specimen 4 160
Figure 5.15. Sound level of specimen 5 160
Figure 5.16. Comparison of total noise level 161
Figure 5.17. Total STL of five specimens 161
Figure 5.18. STL for low frequency band (12.5㎐-63㎐) 162
Figure 5.19. STL for low and medium frequency band (80㎐-400㎐) 162
Figure 5.20. STL for medium and high frequency band (500㎐-2.5㎑) 163
Figure 5.21. STL for high frequency band (3.15㎐-20㎑) 163