This book provides a practical application for using ground-based radar (GBR) as a remote (non-contact) sensor for structural health monitoring (SHM) in the development of sustainable and robust stationary and rotating structures, such as beam-like bridges, towers, wind turbines, and hydropower turbines. It integrates cutting-edge research into an easy-to-understand approach for non-radar and monitoring specialists, building on the methods and theory of working with radar systems, SHM frameworks, GBR signal processing, and validation techniques. All aspects of in-field monitoring and use during the design and testing of structures are covered, including data acquisition and processing, damage detection techniques, and damage prognostic techniques. The book is a hands-on reference that provides critical information on GBR for practitioners, university instructors, and students involved in structural design, optimization, and health monitoring of stationary and rotating structures.
Author(s): Francis Xavier Ochieng
Publisher: Springer
Year: 2023
Language: English
Pages: 226
City: Cham
Preface
Contents
List of Figures
List of Tables
Abbreviations and Notations
Chapter 1: Introduction to 3-Tier SHM Framework
1.1 Why the Three-Tier SHM Framework?
1.2 Condition Parameters
1.3 Organization of Book
Chapter 2: The Need for GBR and Coupling It with SHM
2.1 Challenge of Aeroelasticity and Flutter
2.2 Operational Gaps in use of Contact Sensors
2.2.1 Deficiency of Current Fatigue Damage Metrics
2.2.1.1 Fatigue Damage Metrics for Wind Turbines and Similar Structures
2.2.1.2 Main Fatigue Damage Metrics
2.2.2 Insufficient Understanding of FRPC
2.2.3 Real-Time Operating Verification of Design Results
2.3 Defining Scope for GBR Use
2.4 Broad Methodological Use of GBR
2.5 The Novelty of this Book
2.6 The Motivation for Using GBR in Three-Tier SHM
2.7 Summary
Chapter 3: Structural Damage Detection Methods
3.1 Damage Detection Using SHM
3.1.1 Unbalanced Parameters
3.1.2 The Significance of SHM in Assessing Wind Turbine Loads
3.1.3 Damage Detection Using SHM Frameworks
3.1.4 Tiered SHM Frameworks
3.2 GBR Applicative Area and Problem Characterization
3.2.1 Blade Flutter
3.2.2 Component and Type Certification
3.2.2.1 Certification Process and Forms
3.2.2.2 Role of DLCs in Type and Component Certifications
3.2.2.3 Types of Loads on a Wind Turbine
3.2.2.4 Load Assessment Based on DLCs
3.2.2.5 Partial Safety Factors in DLCs Determination
3.2.2.6 Ultimate Strength Analysis
3.2.2.7 Partial Safety Factors for Composite Materials Are Not Available
3.2.2.8 Blade Deflections
3.2.2.9 Design for Different Wind Turbine Classes
3.2.3 GRB Niche in Addressing the Research Problem
3.3 A Conceptual Framework for GBR Niche
3.4 Summary
Chapter 4: Overview of GBR
4.1 Three-Tier SHM Framework
4.2 SHM Sensors
4.2.1 Direct and Indirect Contact-Based Sensors
4.2.2 Non-contact-Based Sensors
4.2.2.1 Infrared Thermography-Based Systems
4.2.2.2 Laser-Based Systems
4.2.2.3 Radar-Based System
4.2.2.4 Photogrammetric-Based Systems
4.3 Radar SHM of WT Blades and Mast
4.3.1 Patents for WT SHM Using Radar
4.3.2 Ku Band SHM Radar Systems Affixed Partly on WT
4.3.3 L Band SHM Radar Systems
4.3.4 Vector Network Analyser Radar Systems
4.3.5 C Band SHM Radar Systems
4.4 Fully Non-contact Ku Band SHM Radar Systems
4.4.1 Evolution of GBR
4.4.2 Operating Frequencies
4.4.3 Continuous and Discontinuous GBR
4.5 Applicative GBR Case Studies
4.5.1 GBR Monitoring of a Bridge
4.5.2 GBR Deflection Monitoring of Masts
4.5.3 GBR Deflection Monitoring of Buildings
4.6 Summary
Chapter 5: GBR: Working Theory and Signal Processing
5.1 Quasi-Monostatic GBR
5.2 GBR Planar Waves and RCS
5.3 GBR Integration into a Three-Tier SHM Framework
5.4 Mathematical Model’s WT SHM Monitoring
5.4.1 Signal Decomposition Using Short-Time Fourier-Transform (STFT)
5.4.2 Limitations of STFT
5.4.3 Signal Decomposition Using Sammon Mapping and 2D Visualization
5.4.4 GBR Results in Validation Using OMA-Based Control Charts
5.5 GBR Windowing
5.5.1 Windowing Techniques on GBR Signal Processing
5.5.2 Determination of the Framework for GBR Operation at an Extremely Close Range
5.6 Load Determination of Nacelle, Blade and Mast
5.6.1 Blade Deformation
5.6.2 Mast Deformation
5.6.3 Nacelle Deformation
5.6.4 WT Blade Testing During Design (IEC 61400-23)
5.6.5 WT Tower Deformation (IEC 61400-1 and Draft IEC 61400-6)
5.7 Summary
Chapter 6: Deflection and Modal Analysis from GBR Experiments
6.1 Experimental Aims and Justifications
6.1.1 Experimental Aims
6.1.2 Justification for the Choice of Sensors
6.1.3 Justification Methodology Used and On Non-use of Modelling Techniques
6.1.4 Deformation of Structures
6.2 Experiments Undertaken
6.2.1 Static Laboratory-Based
6.2.1.1 Impact Hammer Test
6.2.1.2 GBR Set-Up
6.2.2 Dynamic Laboratory-Based
6.2.3 In Situ In-Field Experiments
6.3 Key Equipment Used
6.3.1 GBR
6.3.2 GNSS/GPS System
6.3.3 Accelerometer
6.3.4 Wind Turbine
6.4 Summary
Chapter 7: Case Study Application of GBR for Rotary and Non-rotary Cases
7.1 Test Cluster 1: Acquisition of Modal Frequencies
7.1.1 SHM Step 1: Data Acquisition and Normalization
7.1.2 SHM Step 2: Feature Extraction Using Sammon Mapping
7.1.3 SHM Step 3: Results Validation
7.1.4 Sensitivity and Error Analysis
7.1.5 Analysis of the Non-dominant/Resonant Frequency
7.1.6 Summary
7.2 Test Cluster 2: Acquisition of Deflection CPs
7.2.1 SHM Step 1: Data Acquisition and Normalization
7.2.2 SHM Step 2: Feature Extraction Using the Sammon Method
7.2.3 SHM Step 3: Results Validation
7.2.3.1 GPS Results
7.2.3.2 GBR Results
7.2.4 Sensitivity Analysis of GBR Deflection
7.2.5 Summary
7.3 Test Cluster 3: CP Acquisition for In-Field Operating WT
7.3.1 SHM 1: Data Acquisition and Normalization
7.3.2 SHM Step 2: Feature Extraction Using Sammon Mapping
7.3.3 SHM Step 3: Results Validation
7.3.3.1 Modal Frequency Validation
7.3.3.2 Deflection Validation
7.3.3.3 WT Whirling Deflections
7.3.4 Error Analysis and Applicability of Results
7.3.4.1 The Appearance of Multi-modal Dominant Frequencies
7.3.4.2 Sensitivity Analysis
7.3.4.3 Dependence on Wind Speed
7.4 Summary
Chapter 8: The Future for GBR Nexus with Three-Tier SHM
8.1 GBR’s Contribution to DLC
8.1.1 Research Significance in the Achievement of Research Objectives
8.1.2 Use of GBR as a Non-contact SHM Sensor
8.1.3 Type Certification
8.2 Main Conclusions
8.2.1 Comparing Results with Research Objectives
8.2.2 Knowledge Gaps Addressed
8.2.3 Current Limitations of GBR Applications
8.3 Recommendations for Future Research
Annexes
A.1. Chord Lengths for Large MW Wind Turbines
A.2. Very Near-, Near- and Far-Field Projections
A.3. Expository Results for I-Beam
A.3.1. Beam Experiment: SNR Results (Fig. A.3)
A.3.2. Data Acquisition and Normalization (Table A.3)
A.3.3. Feature Extraction for Range Bin 11 (Table A.4)
A.3.4. Results Validation Using 2D Visualizations and Sammon Mapping (Figs. A.4, A.5, A.6, A.7, A.8, A.9, A.10, A.11, A.12, A.13, A.14, A.15, A.16, A.17 and A.18)
A.4. Expository Results Rotating Arm
A.4.1. Rotating Experiment: SNR Results
A.4.2. Feature Extraction and Validation Using Sammon Mapping and 2D Visualization
A.5. Expository Results for WT
A.5.1. WT: Deflection and Frequency Results
A.5.2. Features Acquisition and Validation Using 2D Visualization and Sammon Mapping
A.6. WT Damage Due to Flutter and Loads (Fig. A.20)
References
Index
