Special Topics in Structural Dynamics & Experimental Techniques, Volume 5

Preface	6
Contents	7
1 A Comparative Study of Joint Modeling Methods and Analysis of Fasteners	8
Nomenclature	8
1.1 Introduction	8
1.2 Modeling Methods for Fastener Joints	9
1.2.1 Tied Surfaces at Joint: Tied Contact Method	9
1.2.2 Spring Model of Fastener: Spring Method	9
1.2.3 Beam Model of Fastener: Beam Method	10
1.2.4 Solid Model of Fastener: Plug Method	11
1.2.5 Cylinder of Solid Elements: Ring Method	11
1.2.6 Including Preload and Fastener Properties: Ring-Beam Method	11
1.2.7 Frustrum Calculation	12
1.3 Example Problem	13
1.4 Results	14
1.4.1 Modal Comparisons	14
1.4.2 Random Vibration Comparisons	15
1.5 Conclusion	16
References	20
2 Historical Perspective of the Development of Digital Twins	21
2.1 Background	21
2.2 Pre-delivery Usage	22
2.2.1 Design Usage	22
2.2.2 Manufacturing Usage	22
2.3 Asset Management Usage	22
2.3.1 Life-Cycle Determination	23
2.3.2 VVUQ	23
2.4 Digital Twin Hierarchy	23
2.5 Conclusions	24
References	25
3 Distributed Home Labs at the Time of the Covid	27
3.1 Introduction	27
3.2 Experimental Laboratories as a Tool for Practitioner Engineering	28
3.3 The New Revolution Offered by Microelectronics	29
3.4 The Smartphone: A Complete Measurement Lab	29
3.5 Some Preliminary Attempts with Small Groups on Research Projects	31
3.6 Some of the Most Interesting Projects	31
3.7 Final Remarks and Conclusions	33
References	34
4 Closed-Form Solutions for the Equations of Motion of the Heavy Symmetrical Top with One Point Fixed	35
4.1 Background	35
4.2 Derivation of the EOM	36
4.3 The Cubic Polynomial f(u)	37
4.4 General Closed-Form Solution of the EOM	38
4.5 Closed-Form Solution for h == 1	40
4.6 Closed-Form Solution for h == 2	41
4.7 Conclusion	43
References	44
5 Equations of Motion for the Vertical Rigid-Body Rotor: Linear and Nonlinear Cases	45
5.1 Definition of the Equations of Motion	45
5.2 Kinetic Energy of a Rigid-Body Rotor	46
5.3 Nonlinear Generalized Forces	48
5.4 Linear Form of the EOM	48
5.5 Results from the Linear Example	49
5.6 Procedure for Solving of the Nonlinear EOM	50
5.7 Results for the Nonlinear Example	53
5.8 Example That Exhibits Chaotic Behavior	55
5.9 Duffing Equation	56
5.10 Conclusions	58
A.1 Appendix A	59
References	60
6 Vibration Control in Meta-Structures Using Reinforcement Learning	61
6.1 Introduction	61
6.2 Q-Learning Algorithm Framework	62
6.3 Conclusion	63
References	64
7 Using Steady-State Ultrasonic Direct-Part Measurements for Defect Detection in Additively Manufactured Metal Parts	65
7.1 Introduction	65
7.1.1 Defects in Additively Manufactured Parts	66
7.1.2 Quality Control and Non-destructive Evaluation	67
7.1.3 Acoustic Wavenumber Spectroscopy	67
7.2 Background	68
7.2.1 Materials	68
7.2.2 In Situ Data Acquisition Process	69
7.3 Analysis	70
7.3.1 Post-build Data Processing	70
7.3.2 Defect-Indicative Features	71
7.3.3 X-Ray Computed Tomography Labeling	73
7.3.4 Results	74
7.3.5 Future Work	75
7.4 Conclusion	76
A.1 Appendix A: Montage of Figures	76
References	78
8 Toward Developing Arrays of Active Artificial Hair Cells	80
8.1 Introduction	80
8.2 Array of Self-Sensing Artificial Hair Cells	81
8.3 AHC Array Simulation Results	82
8.4 AHC Array Simulation Results	82
8.5 Conclusion	84
References	85
9 Challenges Associated with In Situ Calibration of Load Cells in Force-Limited Vibration Testing	86
9.1 Introduction	86
9.2 Test Setup	88
9.3 Apparent Mass Calculation	88
9.4 Load Cell Summing Implications on In Situ Calibration	90
9.5 Conclusion	92
References	93

RkJQdWJsaXNoZXIy MTMzNzEzMQ==