목차

Chpater 1 Introduction 1
1.1 Background 1
1.1.1 Introduction to Vibration in Helicopters 2
1.1.2 Methodology for Vibration Reduction 5
1.1.2.1 Passive Method 6
1.1.2.2 Active Method 8
1.2 Literature Survey Relevant to the Dissertation 17
1.2.1 University of Maryland 18
1.2.1.1 Piezoelectric Bimorph Actuator 18
1.2.1.2 Piezoelectric Stack Actuator 21
1.2.2 Massachusetts Institute of Technology 22
1.2.3 McDonnell-Douglas and Boeing companies 24
1.2.4 US Army Aviation RD&E Center 27
1.2.5 University of Michigan 28
1.2.6 Advanced Technology Institute of Commuter-helicopter, Ltd. (ATIC) 29
1.2.7 Eurocopter 30
1.2.8 The Pennsylvania State University 32
1.2.9 Office National dtudes et de Recherches Arospatiales (ONERA) 34
1.2.10 Japan Aerospace Exploration Agency (JAXA) 34
1.2.11 US Army Research, Development, and Engineering Command (AMRDEC) 36
1.2.12 Korea Aerospace Research Institute (KARI) 36
1.3 Aims and Scope 37
1.4 Outline of Dissertation 40
Chpater 2 Further Improvement in the SNUF Blade Design 42
2.1 Previous SNUF Design and Experimental Results 42
2.1.1 SNUF Development History 42
2.1.2 Flap-Driving Mechanism Improvements 44
2.1.2.1 Evolution of the Flap-Driving Design 44
2.1.2.2 Previous Bench Test Results 46
2.1.3 SNUF Blade Configuration Revision 47
2.1.3.1 Blade Planform Modification 47
2.1.3.2 Detailed Root Design 48
2.2 Multidisplinary Design for Flap Driving Mechanism 51
2.2.1 Hinge Moment Estimation 51
2.2.1.1 Analytic method for hinge moment prediction 51
2.2.1.2 Computational Fluid Dynamics (CFD) estimation 54
2.2.1.3 Numerical Estimation of the Hinge Moment 57
2.2.2 Flap Driving Mechanism Design 60
2.3 Design Optimization Strategy 66
2.3.1 Blade Planform Parametric Study 67
2.3.1.1 Theoretical Background of Multibody Dynamics 67
2.3.1.2 Multibody Dynamic Modeling for SNUF blade 71
2.3.1.3 Parametric Study for the Shape of the Trailing-edge Flap 76
2.3.2 Optimization for the Blade Cross Section 77
2.3.2.1 Optimization Method by the Genetic Algorithm 78
2.3.2.2 Cross Sectional Analysis of Composite Rotor Blade 79
2.3.2.3 Framework Development for the Cross Sectional Design 82
2.4 Numerical Investigation on Design Optimization 89
2.4.1 Vibratory Loads Reduction Preliminary Analysis 89
2.4.2 Forward Flight Baseline Condition Selection 95
2.4.3 Effect of the Flap Shape Parameters 98
2.4.3.1 Case 1: Flap Center location Change 99
2.4.3.2 Case 2: Flap Length Change 102
2.4.3.3 Case 3: Flap Chord Length Change 106
2.4.4 Blade Cross Sectional Design Results 109
2.4.5 Vibratory Load Reduction Capability 116
Chpater 3 Evaluation on the Structural Integrity of the Composite Blade 126
3.1 Strain Recovery Analysis within the Cross Section 126
3.2 Two Dimensional In-plane Stress Estimation 133
3.3 Three-dimensional Static Structural Analysis 136
3.3.1 Three-dimensional Modeling of the SNUF Blade 138
3.3.2 Loading Condition for the Three-dimensional Analysis 143
3.3.3 Stress/Strain Distribution in the Composite Blade 145
Chpater 4 Static Bench and Endurance Experiments on the Present Flap-driving Components 163
4.1 Fabrication of the Flap-driving Components 164
4.1.1 Guide Component for the Stoke Conservation 164
4.1.2 Thrust Bearing for the Flap Deflection 168
4.1.3 Prototype Flap-driving Components Fabrication 170
4.2 Static Bench Experiment 172
4.2.1 Experimental Setup for Bench Test 172
4.2.1.1 Drive System 174
4.2.1.2 Measurement System 175
4.2.2 Static Bench Experiment Results 177
4.3 Endurance Experiment 178
4.3.1 Endurance Experiment Set-up including Centrifugal Loading 179
4.3.2 Flap Deflection Measurement Results 182
Chpater 5 Active Flap Closed-loop Controller for Vibration Reduction in Forward Flight 185
5.1 System Identification of the SNUF rotor system in Forward Flight 185
5.1.1 Linear time periodic system [168] 186
5.1.2 Input Data Requirements 189
5.1.3 System Identification Result of the SNUF Rotor System 194
5.2 Closed-loop Controller Design 198
5.2.1 Discrete-time HHC Algorithm 199
5.2.2 HHC Algorithm Implementation for Vibration Reduction 201
5.2.3 Continuous-time HHC algorithm 202
5.3 Implementation of the Closed-loop Controller 205
5.3.1 Stability Evaluation of the Closed-loop System 205
5.3.2 Numerical Simulation of the Closed-loop Controller 210
5.4 Flap-driving Mechanism Representation 212
Chpater 6 Conclusion 217
6.1 Summary 217
6.2 Contribution of the Present Work 219
6.3 Future Works 222
Reference 224
국문초록 251