Staff members at Los Alamos National Laboratory (LANL) produced a summary of the structural health monitoring literature in 1995. This presentation will summarize the outcome of an updated review covering the years 1996 2001. The updated review follows the LANL statistical pattern recognition paradigm for SHM, which addresses four topics: 1. Operational Evaluation; 2. Data Acquisition and Cleansing; 3. Feature Extraction; and 4. Statistical Modeling for Feature Discrimination. The literature has been reviewed based on how a particular study addresses these four topics. A significant observation from this review is that although there are many more SHM studies being reported, the investigators, in general, have not yet fully embraced the well-developed tools from statistical pattern recognition. As such, the discrimination procedures employed are often lacking the appropriate rigor necessary for this technology to evolve beyond demonstration problems carried out in laboratory setting.

A review of structural health monitoring literature 1996-2001

Welding Metallurgy of

Fluid dynamic turbulence is one of the most challenging computational physics problems because of the extremely wide range of time and space scales involved, the strong nonlinearity of the governing equations, and the many practical and important applications. While most linear fluid instabilities are well understood, the nonlinear interactions among them makes even the relatively simple limit of homogeneous isotropic turbulence difficult to treat physically, mathematically, and computationally. Turbulence is modeled computationally by a two-stage bootstrap process. The first stage, direct numerical simulation, attempts to resolve the relevant physical time and space scales but its application is limited to diffusive flows with a relatively small Reynolds number (Re). Using direct numerical simulation to provide a database, in turn, allows calibration of phenomenological turbulence models for engineering applications. Large eddy simulation incorporates a form of turbulence modeling applicable when the large-scale flows of interest are intrinsically time dependent, thus throwing common statistical models into question. A promising approach to large eddy simulation involves the use of high-resolution monotone computational fluid dynamics algorithms such as flux-corrected transport or the piecewise parabolic method which have intrinsic subgrid turbulence models coupled naturally to the resolved scales in the computed flow. The physical considerations underlying and evidence supporting this monotone integrated large eddy simulation approach are discussed.

New insights into large eddy simulation

This book equips the reader to understand every important aspect of the dynamics of rotating machines. Will the vibration be large? What influences machine stability? How can the vibration be reduced? Which sorts of rotor vibration are the worst? The book develops this understanding initially using extremely simple models for each phenomenon, in which (at most) four equations capture the behavior. More detailed models are then developed based on finite element analysis, to enable the accurate simulation of the relevant phenomena for real machines. Analysis software (in MATLAB) is associated with this book, and novices to rotordynamics can expect to make good predictions of critical speeds and rotating mode shapes within days. The book is structured more as a learning guide than as a reference tome and provides readers with more than 100 worked examples and more than 100 problems and solutions.

/pdf/dynamics-of-rotating-machines-499re2kizd.pdf

Dynamics of rotating machines

Mobility of mechanisms: a critical review

Single Blade Vibrations Discrete Analysis of Blades Small Aspect Ratio Blades Blade Group Frequencies and Mode Shapes Excitation Damping Forced Vibrations Transient Vibrations Coupled Blade-Disc Vibrations Some Thoughts on Fatigue Life Estimation Some Reflections Appendices: Heat Transfer and Thermal Stress of Turbine Blades SI Units Nomenclature Index.

Turbomachine blade vibration

Foreword Preface Acknowledgements 1 Beginnings of the Wheel References 2 Science before the Medieval Period References 3 Water Wheels References 4 Wind Mills References 5 Renaissance and Scientific Revolution References 6 Renaissance Engineers References 7 Industrial Revolution References 8 Turbomachines References 9 Fundamentals of Elasticity References 10 Energy Methods 10.1 Euler-Lagrange Equations 10.2 Lagrange Method 10.3 Rayleigh's Energy Approach 10.4 Ritz Method 10.5 Lagrange Method for Vibration Problems 10.6 Galerkin Method 10.7 Hamilton's Principle 10.8 Complementary Virtual Work 10.9 Hellinger-Reissner Variational Principle 10.10 Hu-Washizu Principle 10.11Different Theories of Torsion of Rods 10.11.1 Coulomb (1784) Elementary Theory , see Timoshenko and Goodier [42] for Circular Rods 10.11.2St. Venant (1853) Theory, see Todhunter [43] and Timoshenko and Goodier [42] for Circular Rods 10.11.3 Love's (1944) Theory 10.11.4 Timoshenko (1945) - Gere's (1954) Theory 10.11.5 Reissner (1952) and Lo-Goulard's (1955) Theory 10.11.6 Barr's (1962) Theory 10.11.7 Refined Theory by Rao (1974) References 11 20th Century Graphical and Numerical Methods 11.1 Stodola-Viannello (Rayleigh's Maximum Energy) Method in Graphical Form 11.2 Stodola-Viannello Iterative Method in Tabular Form 11.3 Dunkerley's Method 11.4 Proof of the Dunkerley Formula by Blaess [1] 11.5 Hahn's Proof Using Matrix Algebra [3] 11.6 Holzer Method for Torsional Vibration 11.7 The Myklestad Method [7,8] 11.8 Prohl's Method [9] References 12 Matrix Methods 12.1 Torsional Vibration Systems 12.2 Far-Coupled Systems 12.3 Graffe's Method of Successive Approximations 12.4 Matrix Iteration Method 12.5 Method of Priebs [10] 12.6 The Holzer Method (Close Coupled Systems) in Transfer Matrix Form 12.7 Myklestad-Thomson (1949, 1953) - Prohl Methods in Transfer Matrix Form for Far-Coupled Systems 12.8 A Brief Note on Computers and Evolution References 13 Finite Element Methods 13.1 Beam Finite Element 13.2 Tocher Triangular Plate Element (1962) 13.3 Shell Element 13.4 Interface Damping through Finite Element Analysis 13.5 Illustration of Turbomachine Blade Analysis using Commercial Codes References 14 Rotor Dynamics Methods 14.1 De Laval Model 14.2 Jeffcott Rotor Analysis 14.3 Fluid Film Bearings 14.4 Oil Film Instabilities 14.5 Quality Factor 14.6 Gyroscopic Effects 14.7 Internal Friction, Hysteresis 14.8 Shafts with Gravity and Variable Elasticity 14.9 Misalignment 14.10 Bowed Rotors 14.11 Variable Inertia 14.12 Seals and Instabilities 14.13 Steam Whirl 14.14 Cracked Shafts References 15 Transfer Matrix Methods 15.1 Torsional Vibration due to Short Circuit of Generators 15.2 Transfer Matrix Method for Lateral Vibrations of Rotors 15.3 Twin Spool Rotor Analysis References 16 Finite Element Methods for Rotor Dynamics 16.1 Nelson's Beam Element 16.2 Geared Rotors and Chaos 16.3 Solid Rotors 16.4 Two Spool Aircraft Engine [21] 16.5 Cryogenic Pump Rotor Dynamic Analysis References 17 Bladed Disks 17.1 Armstrong's Analysis for Tuned Systems 17.2 Ewins' Analysis 17.3 Mistuning Arrangement 17.4 Damping 17.5 Micro-Slip Damping (Fretting Fatigue) References 18 Lifing 18.1 High Cycle Fatigue (HCF) Life Estimation 18.2 Low Cycle Fatigue (Strain Based Life Estimation) 18.3 Linear Elastic Fracture Mechanics References 19 Optimization 19.1 Shape Optimization 19.2 Weight Optimization References 20 Concluding Remarks Index.

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History of Rotating Machinery Dynamics

Vibratory Condition Monitoring of Machines

Advanced theory of vibration

Preface / Introduction / Variational Principles / Rectangular Plates/ Circular plates / Finite element methods for thin plates / Plates with combined Lateral and in-plates forces / Finite element methods for initially stressed thin plates / Anisotropic plates / Pre-twisted Plates/ Finite Element Method for shells / Reference / Inex

J. S. Rao

Papers

Turbomachine blade vibration

History of Rotating Machinery Dynamics

Vibratory Condition Monitoring of Machines

Advanced theory of vibration

Dynamics of Plates