Vibration Testing

KENNETH G. McCONNELL, PE, is Professor Emeritus, Aerospace Engineering and Engineering Mechanics, Iowa State University, and has over forty-three years' experience in vibrations and experimental mechanics. He is a Fellow of the Society of Experimental Mechanics, and recipient of SEM's M.M. Frocht Award for "outstanding achievement as an experimental mechanics educator"; SEM's highest award, the William M. Murray Lecturer, for his "outstanding contribution to SEM in the fields of dynamic instrumentation, vibration testing techniques, and fluid structure interaction"; the D.J. DeMichele Award for "promoting the scientific and educational aspects of modal analysis"; and the Brewer Award, "in recognition of his contributions as an outstanding practicing experimental stress analyst." He is the author of Instrumentation for Engineering Measurements, Second Edition (coauthored with James E. Dally and William F Riley and published by Wiley) and other books in the field.PAULO S. VAROTO is professor on Dynamics and Vibrations at the Mechanical Engineering Department, School of Engineering of São Carlos, University of São Paulo. Professor Varoto earned his BSc and MSc in mechanical engineering from the University of São Paulo and holds a PhD in engineering mechanics from the Department of Aerospace Engineering and Engineering Mechanics, Iowa State University, where he worked under the supervision of Ken McConnell.

• Preface xix1. An Overview of Vibration Testing 11.1 Introduction 21.2 Preliminary Considerations 61.3 General Input-Output Relationships in the Frequency Domain 81.4 Overview of Equipment Employed 101.5 Summary 122. Dynamic Signal Analysis 132.1 Introduction 142.2 Phasor Representation of Periodic Functions 212.3 Periodic Time Histories 262.4 Transient Signal Analysis 322.5 Correlation Concepts—A Statistical Point of View 382.6 Correlation Concepts—Periodic Time Histories 402.7 Correlation Concepts—Transient Time Histories 472.8 Correlation Concepts—Random Time Histories 502.9 Summary 632.10 General References on Signal Analysis 653. Vibration Concepts 673.1 Introduction 683.2 The Single DOF Model 683.3 Single Degree of Freedom Forced Response 763.4 General Input-Output Model For Linear Systems 883.5 The Two Degrees of Freedom Vibration Model 1013.6 The Second-Order Continuous Vibration Model 1153.7 Fourth-Order Continuous Vibration System—The Beam 1303.8 Nonlinear Behavior 1433.9 Summary 1563.10 References 1614. Transducer Measurement Considerations 1644.1 Introduction 1644.2 Fixed Reference Transducers 1664.3 Mechanical Model of Seismic Transducers—The Accelerometer 1734.4 Piezoelectric Sensor Characteristics 1804.5 Combined Linear and Angular Accelerometers 1934.6 Transducer Response to Transient Inputs 1994.7 Accelerometer Cross-Axis Sensitivity 2124.8 The Force Transducer General Model 2224.9 Correcting FRF Data for Force Transducer Mass Loading 2354.10 Calibration 2464.11 Environmental Factors 2634.12 Summary 2675. The Digital Frequency Analyzer 2725.1 Introduction 2725.2 Basic Processes of a Digital Frequency Analyzer 2745.3 Digital Analyzer Operating Principles 2895.4 Factors in the Application of a Single-Channel Analyzer 2965.5 The Dual-Channel Analyzer 3145.6 The Effects of Signal Noise on FRF Measurements 3265.7 Overlapping Signal Analysis to Reduce Analysis Time 3395.8 Zoom Analysis 3485.9 Scan Analysis, Scan Averaging, and More on Spectral Smearing 3595.10 Summary 3686. Vibration Excitation Mechanisms 3746.1 Introduction 3756.2 Mechanical Vibration Exciters 3826.3 Electrohydraulic Exciters 3946.4 The Modeling of an Electro Magnetic Vibration Exciter System 4036.5 An Exciter System’s Bare Table Characteristics 4196.6 Interaction of An Exciter and a Grounded Single DOF Structure 4266.7 Interaction of an Exciter and an Ungrounded Structure Under Test 4386.8 Measuring An Exciter’s Actual Characteristics 4496.9 Summary 4607. The Application of Basic Concepts to Vibration Testing 4657.1 Introduction 4667.2 Sudden Release Or Step Relaxation Method 4687.3 Forced Response of a Simply Supported Beam Mounted on an Exciter 4857.4 Impulse Testing 4997.5 Selecting Proper Windows for Impulse Testing 5107.6 Vibration Exciter Driving a Free-Free Beam With Point Loads 5307.7 Windowing Effects on Random Test Results 5397.8 Low-Frequency Damping Measurements Reveal Subtle Data Processing Problems 5517.9 A Linear Structure Becomes Nonlinear Due To Its Test Environment 5597.10 Summary 5738. General Vibration Testing Model: From the Field to the Laboratory 5798.1 Introduction 5808.2 A Two-Point Input-Output Model of Field and Laboratory Simulation Environments 5878.3 Laboratory Simulation Schemes Based on the Elementary Model 5938.4 An Example Using a Two DOF Test Item and a Two DOF Vehicle 6038.5 The General Field Environment Model 6228.6 The General Laboratory Environment Model 6278.7 Test Scenarios for Laboratory Simulations 6308.8 Summary 634Index 641

"…is a good foundational text for engineers concerned with component vibration testing as it might relate to failure analysis, qualification testing, reliability testing, and machinery diagnostics. The book is well written and makes the presented concepts easy to understand. I recommend it both as an introduction to laboratory testing techniques for the relative novice and as a reference for experienced practitioners in the field." (Noise Control Engineering, Jan-Feb 2009)