Sensors and Instrumentation, Aircraft/Aerospace, Energy Harvesting & Dynamic Environments Testing, Volume 7: Proceedings of the 39th IMAC, A ... Society for Experimental Mechanics Series)

Sensors and Instrumentation, Aircraft/Aerospace and Energy Harvesting, Volume 7: Proceedings of the 39th IMAC, A Conference and Exposition on Structural Dynamics, 2021, the seventh volume of nine from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Shock & Vibration, Aircraft/Aerospace, Energy Harvesting & Dynamic Environments Testing including papers on: Alternative Sensing & Acquisition Active Controls Instrumentation Aircraft/Aerospace & Aerospace Testing Techniques Energy Harvesting Preface 6 Contents 7 1 Exploring Iterative Optimization Methods to Develop a MIMO Control Input 9 1.1 Introduction 9 1.2 Definition of MIMO Control Problem for Iterative Optimization 10 1.2.1 Design Variable Choice to Account for Input and Output CPSD Constraints 10 1.2.2 Optimization Workflow 10 1.2.3 Example Problem Definition 12 1.3 Exploration of Objective Functions with Sampling 12 1.4 Applying Iterative Optimization to MIMO Control Problem 14 1.4.1 Impact of Optimization Algorithm on Output CPSD 14 1.4.2 Impact of Iterations and Other Optimization Parameters 17 1.5 Comparing Iterative Optimization to Other Methods for MIMO Control Input Development 19 1.6 Accounting for Experimental Limitations in Optimization Application 21 1.6.1 Directly Constraining MIMO Control Input 21 1.6.2 Accounting for Shaker Limitations with Electromechanical Model 21 1.7 Conclusions and Future Work 25 References 25 2 All-Electric X-Plane, X-57 Mod II Ground Vibration Test 26 Nomenclature 26 2.1 Introduction 27 2.2 Test Objectives 29 2.3 Test Description 29 2.3.1 Test Article 30 2.3.2 Finite Element Model 32 2.3.3 Ground Vibration Test Setup 34 Airplane on Soft Supports 34 Aircraft On-Tires 35 2.3.4 Ground Vibration Test Instrumentation 36 2.3.5 Ground Vibration Test Accelerometer Layout 36 2.3.6 Test Configurations 37 2.4 Results 38 2.4.1 Test Display Model 38 2.4.2 Airplane Results 39 2.4.3 Motor Assembly Results 41 2.4.4 Airplane Rigid-Body Results 44 2.5 Summary 45 References 46 3 Mechanical Environment Test Specifications Derived from Equivalent Energy in Fixed Base Modes, with Frequency Shifts from Unit-to-Unit Variability 47 3.1 Motivation 47 3.2 MATV Hardware, Instrumentation, and Test 48 3.3 Modal Test of the Removable Component on the Rigid Fixture 48 3.4 Analysis 50 3.4.1 Introducing Unit-to-Unit Variability 50 3.4.2 Treating Each Test Unit Independently 53 3.5 Conclusion 54 A.1 Appendix A 56 A.1.1 Review of Modal Theory for Base-Mounted Component on Fixture 56 A.1.2 Extracting the Nominal Fixed Base Modal Cross-Spectra from System-Level Test 59 B.1 Appendix B 62 C.1 Appendix C 66 References 69 4 Investigation of Transmission Simulator-Based Response Reconstruction Accuracy 70 4.1 Introduction 70 4.2 Transmission Simulator-Based Response Reconstruction 71 4.3 Stool on Plate Assembly and Environment Definitions 72 4.4 MIMO Simulations 73 4.4.1 Shaker Location Algorithm 74 4.5 Methodology 75 4.5.1 Experimental MIMO Tests 75 4.5.2 Experimental Industry Test 76 4.6 MIMO Reconstruction Tests 76 4.7 Impedance Match Case Study 78 4.8 MIMO Simulation Analysis 79 4.9 Conclusion 80 References 80 5 A Proposed Standard Random Vibration Environment for BARC and the Boundary Condition Challenge 82 5.1 Introduction 82 5.2 Field and Laboratory Configurations 83 5.3 Input and Output Degrees of Freedom 84 5.4 Modes and FRFs of the BARC Model 86 5.5 Random Vibration Environment 86 5.6 Example Usage: Simulated Multi-shaker Lab Vibration Test 86 5.7 Data Format 87 5.8 Conclusions 89 References 89 6 Assessment of Metrics Between Acceleration Power Spectral Density Metrics and Failure Criteria 90 6.1 Introduction 90 6.2 Cross Power Spectral Density Comparison Metrics 91 6.3 Analytical Metric Comparisons of a Beam Model 91 6.3.1 Simple Model Description and Alterations 91 6.3.2 Statistical Methods of Assessment 92 6.3.3 dB Error Metric 93 6.3.4 Frequency Assurance Function and Band Averaged Metrics 97 6.3.5 Global Error (MIL-STD-810) Metric 97 6.3.6 Visualization of Metric Correlations 98 6.4 Acceleration Metric Correlation to Stress and Fatigue 99 6.4.1 Representative System Model 101 6.4.2 Model Variation Details 101 6.4.3 Comparisons of Metrics 102 6.5 Conclusions 105 References 106 7 Using Parameterized Optimization to Model a Slip Table 108 7.1 Introduction 108 7.2 Test Configuration and Finite Element Model 109 7.3 Optimization of Spring Boundary Constraints 111 7.4 Conclusion 114 References 114 8 Using Modal Projection Error to Evaluate 115 8.1 Introduction 115 8.2 Background Theory 116 8.3 Test Item and Setup 117 8.4 Field Data Analysis 117 8.4.1 Expanding with Fixed Based Shapes 119 8.4.2 Expanding with Free Based Shapes 119 8.4.3 Selecting the Most Important Modes 122 8.5 Conclusion 124 Appendix: Bobblehead FEM Mode Shapes 125 References 142 9 WaveHit: The First Smart Impulse Hammer for Fully Automatic Impact Testing 143 9.1 Introduction 143 9.2 Background 144 9.3 Analysis 146 9.4 Conclusion 149 References 149 10 Aeroelastic Analysis Using Ground Vibration Test Modes 150 10.1 Introduction 150 10.2 Model Used for Investigation 150 10.3 Analytical Test Simulation 152 10.4 Aeroelastic Analysis 154 10.5 Summary 161 Reference 162 11 Localizing Perturbed Objects in a Room with Reflective Boundaries Using Dispersed Acoustic Measurements 163 11.1 Introduction 163 11.2 Theory 164 11.3 Experimental Setup 164 11.4 Results and Discussion 166 11.5 Conclusion 168 References 168 12 Application of Smartphones in Pavement Deterioration Identification Using Artificial Neural Network 169 12.1 Introduction 169 12.2 Data and Test Setup Description 170 12.3 Methodology 170 12.3.1 Preprocessing 170 12.3.2 Algorithms 171 12.3.3 Model Evaluation 172 12.4 Results 172 12.5 Conclusion and Future Study 175 References 176 13 Impacts of Test Fixture Connections of the BARC Structure on Its Dynamical Responses 177 13.1 Introduction 177 13.2 Experimental Measurements and Comparison to Computational Simulations 178 13.3 Conclusions 179 References 179 14 Experimental and Computational Investigations on Fixture Interference for BARC Systems 180 14.1 Introduction 180 14.2 System's Description and Experimental Testing Setup 181 14.3 Impacts of Fixture Interference on the Natural Frequencies of the System 181 14.4 Conclusions 182 References 182 15 Aeroelastic Test of the Nixus FBW Sailplane 183 Nomenclature 183 15.1 Introduction 183 15.2 Why Fly-by-Wire 184 15.3 Design Philosopy 185 15.3.1 Aerodynamic Design 185 15.3.2 Structural Design 185 15.3.3 Fly-by-Wire Design 186 15.3.4 Fly-by-Wire Operation 186 15.3.5 Fly-by-Wire Hardware 186 15.4 Testing 187 15.4.1 Structural Ground Test 187 15.4.2 Ground Vibration Test 187 15.4.3 Flutter Flight Test 193 15.5 The Educational Aspect of Nixus 194 15.6 Final Considerations and Conclusions 196 References 197 16 Operational Modal Analysis of the Space Launch System Mobile Launcher on the Crawler Transporter ISVV-010 Rollout 198 16.1 Background 199 16.2 Space Shuttle Mobile Launch Platform and Partial Stack Rollout 202 16.3 ISVV-010 Rollout Data and Environment 204 16.4 ISVV-010 OMA Analysis Procedure 206 16.5 Conclusions 217 References 220 17 Structural Damage Detection in Civil Engineering with Machine Learning: Current State of the Art 222 17.1 Introduction 222 17.2 Parametric Damage Detection Methods Based on Machine Learning 223 17.3 Nonparametric Damage Detection Methods Based on Machine Learning 225 17.4 Discussion and Conclusions 226 References 226 18 Nonlinear Analysis and Characterization of Piezoaeroelastic Energy Harvesters with Discontinuous Nonlinearities 229 18.1 Introduction 229 18.2 Nonlinear Piezoaeroelastic Formulation 230 18.3 Impact of Discontinuous Nonlinearities on the Energy Harvester's Response 231 18.4 Conclusions 232 References 232 19 Basic Vibration Analysis in a Laboratory Classroom Using Virtual Instruments 233 19.1 Introduction 233 19.2 Lecture Materials 234 19.3 Virtual Instruments 237 19.4 Experimental Laboratory Exercise 238 19.5 Experimental Results 240 19.6 Conclusions 241 References 241 20 Model Class Selection and Model Parameter Identification on Piezoelectric Energy Harvesters 243 20.1 Introduction 243 20.2 Bayesian Inference 244 20.2.1 Model Parameter Updating 245 20.2.2 Model Class Selection 245 20.2.3 Likelihood Function for PEHs 245 20.3 PEH Nonlinear Model 246 20.4 Model Class Selection in Nonlinear PEHs 246 20.5 Conclusions 249 References 250