Dale E. Chimenti

Bio: Dale E. Chimenti is an academic researcher from Iowa State University. The author has contributed to research in topics: Reflection (physics) & Lamb waves. The author has an hindex of 22, co-authored 91 publications receiving 3486 citations. Previous affiliations of Dale E. Chimenti include Johns Hopkins University.

Review of Progress in Quantitative Nondestructive Evaluation

Abstract: The Review of Progress in Quantitative NDE is the world's leading conference in reporting annually new research and development results in quantitative NDE. The conference reports on both fundamental and applied advances in NDE and promotes communication between the research and engineering communities and emphasize current reporting of work in progress. Attendees include representatives of academia (including students), industry, and government with approximately one-half coming from the United States and the other half from overseas. This volume represents the best report of ongoing work that is available anywhere. Connections and overlap with the medical diagnostic community are highlighted.

Leaky Lamb waves in fibrous composite laminates

Abstract: Results of experimental measurements and theoretical calculations on ultrasonic leaky Lamb‐wave propagation in fiber‐reinforced, unidirectional composite laminates are presented. With the Lamb wave vector oriented parallel to the fiber direction, dispersion curves of phase velocity versus frequency and plate thickness have been constructed from measurements of ultrasonic reflection from fluid‐loaded composite plates. The experimental results are supported by a theoretical model of Lamb‐wave propagation in the composite plate. The model begins with an approximate calculation of the effective, homogeneous, transversely isotropic elastic behavior of a unidirectional composite laminate in the long‐wavelength limit, using a two‐step procedure based on alternating layered media. This intermediate continuum result is then incorporated into a calculation of the ultrasonic reflection coefficient of a fluid‐loaded anisotropic plate, which is assumed to approximate the fibrous composite laminate. Good quantitative agreement with the model is found if the fiber volume fraction is taken to be an adjustable parameter. However, not all portions of the dispersion curves predicted by the model can be observed in the data. It is conjectured that relative differences in mode coupling account for this discrepancy.

Air-coupled acoustic imaging with zero-group-velocity Lamb modes

Abstract: A Lamb wave resonance has been found that allows unusually efficient transmission of airborne sound waves through plates. This occurs at the zero-group-velocity point at the frequency minimum of the first-order symmetric (S1) Lamb mode. At this frequency, plane waves with a range of incident angles can couple between the air and the Lamb mode in the solid plate, dominating the spectrum of transmitted focused sound beams by 10 dB or more. We use this frequency for C-scan imaging, and demonstrate the detection of both a 3.2-mm-diameter buried flaw and a subwavelength thickness changes of .005λ (1%).

Propagation of guided waves in fluid-coupled plates of fiber-reinforced composite

Abstract: Guided wave propagation in fluid‐coupled plates of fiber‐reinforced composites has been investigated by studying ultrasonic reflection in these structures. From measurements of ultrasonic reflection on unidirectional graphite‐epoxy plates over a range of incident angles, experimental dispersion curves using a total‐transmission criterion for leaky plate waves have been constructed. Theoretical calculations with no adjustable parameters demonstrate excellent agreement with the experimental data. Unusual behavior observed in the fundamental total‐transmission curve led to a reexamination of the mode identification criteria. Both the total‐transmission curves and the normal modes of the fluid‐coupled plate differ significantly from the result expected on the basis of the widely used Cremer coincidence condition to identify propagating plate waves. It is found that these differences are particularly pronounced in cases where the ratio of fluid to solid densities is high, as for composite materials. The existence of such behavior is also demonstrated numerically in a fluid‐coupled aluminum plate by arbitrarily increasing the density of the fluid.

Kelvin probe force microscopy

Abstract: Measurements of the contact potential difference between different materials have been performed for the first time using scanning force microscopy. The instrument has a high resolution for both the contact potential difference (better than 0.1 mV) and the lateral dimension (<50 nm) and allows the simultaneous imaging of topography and contact potential difference. Images of gold, platinum, and palladium surfaces, taken in air, show a large contrast in the contact potential difference and demonstrate the basic concept.

Atomic-scale friction of a tungsten tip on a graphite surface.

Abstract: Using an atomic force microscope, we have observed atomic-scale features on the frictional force acting on a tungsten wire tip sliding on the basal plane of a graphite surface at low loads, < 10-4 N. The atomic features have the periodicity of the graphite surface and are discussed in terms of a phenomenological model for the tip motion described by the sum of a periodic tip-surface force and the spring force exerted by the wire.

Intelligent Fault Diagnosis and Prognosis for Engineering Systems

Abstract: PREFACE. ACKNOWLEDGMENTS. PROLOGUE. 1 INTRODUCTION. 1.1 Historical Perspective. 1.2 Diagnostic and Prognostic System Requirements. 1.3 Designing in Fault Diagnostic and Prognostic Systems. 1.4 Diagnostic and Prognostic Functional Layers. 1.5 Preface to Book Chapters. 1.6 References. 2 SYSTEMS APPROACH TO CBM/PHM. 2.1 Introduction. 2.2 Trade Studies. 2.3 Failure Modes and Effects Criticality Analysis (FMECA). 2.4 System CBM Test-Plan Design. 2.5 Performance Assessment. 2.6 CBM/PHM Impact on Maintenance and Operations: Case Studies. 2.7 CBM/PHM in Control and Contingency Management. 2.8 References. 3 SENSORS AND SENSING STRATEGIES. 3.1 Introduction. 3.2 Sensors. 3.3 Sensor Placement. 3.4 Wireless Sensor Networks. 3.5 Smart Sensors. 3.6 References. 4 SIGNAL PROCESSING AND DATABASE MANAGEMENT SYSTEMS. 4.1 Introduction. 4.2 Signal Processing in CBM/PHM. 4.3 Signal Preprocessing. 4.4 Signal Processing. 4.5 Vibration Monitoring and Data Analysis. 4.6 Real-Time Image Feature Extraction and Defect/Fault Classification. 4.7 The Virtual Sensor. 4.8 Fusion or Integration Technologies. 4.9 Usage-Pattern Tracking. 4.10 Database Management Methods. 4.11 References. 5 FAULT DIAGNOSIS. 5.1 Introduction. 5.2 The Diagnostic Framework. 5.3 Historical Data Diagnostic Methods. 5.4 Data-Driven Fault Classification and Decision Making. 5.5 Dynamic Systems Modeling. 5.6 Physical Model-Based Methods. 5.7 Model-Based Reasoning. 5.8 Case-Based Reasoning (CBR). 5.9 Other Methods for Fault Diagnosis. 5.10 A Diagnostic Framework for Electrical/Electronic Systems. 5.11 Case Study: Vibration-Based Fault Detection and Diagnosis for Engine Bearings. 5.12 References. 6 FAULT PROGNOSIS. 6.1 Introduction. 6.2 Model-Based Prognosis Techniques. 6.3 Probability-Based Prognosis Techniques. 6.4 Data-Driven Prediction Techniques. 6.5 Case Studies. 6.6 References. 7 FAULT DIAGNOSIS AND PROGNOSIS PERFORMANCE METRICS. 7.1 Introduction. 7.2 CBM/PHM Requirements Definition. 7.3 Feature-Evaluation Metrics. 7.4 Fault Diagnosis Performance Metrics. 7.5 Prognosis Performance Metrics. 7.6 Diagnosis and Prognosis Effectiveness Metrics. 7.7 Complexity/Cost-Benefit Analysis of CBM/PHM Systems. 7.8 References. 8 LOGISTICS: SUPPORT OF THE SYSTEM IN OPERATION. 8.1 Introduction. 8.2 Product-Support Architecture, Knowledge Base, and Methods for CBM. 8.3 Product Support without CBM. 8.4 Product Support with CBM. 8.5 Maintenance Scheduling Strategies. 8.6 A Simple Example. 8.7 References. APPENDIX. INDEX.