Advanced Nondestructive And Structural Techniqu...

A complete surveillance strategy for wind turbines requires both the condition monitoring (CM) of their mechanical components and the structural health monitoring (SHM) of their load-bearing structural elements (foundations, tower, and blades). Therefore, it spans both the civil and mechanical engineering fields. Several traditional and advanced non-destructive techniques (NDTs) have been proposed for both areas of application throughout the last years. These include visual inspection (VI), acoustic emissions (AEs), ultrasonic testing (UT), infrared thermography (IRT), radiographic testing (RT), electromagnetic testing (ET), oil monitoring, and many other methods. These NDTs can be performed by human personnel, robots, or unmanned aerial vehicles (UAVs); they can also be applied both for isolated wind turbines or systematically for whole onshore or offshore wind farms. These non-destructive approaches have been extensively reviewed here; more than 300 scientific articles, technical reports, and other documents are included in this review, encompassing all the main aspects of these survey strategies. Particular attention was dedicated to the latest developments in the last two decades (2000-2021). Highly influential research works, which received major attention from the scientific community, are highlighted and commented upon. Furthermore, for each strategy, a selection of relevant applications is reported by way of example, including newer and less developed strategies as well.

Analyzing and documenting a nondestructive failure mode can also be accomplished using a high-speed camera recording continuously (movie-loop) until the failure is detected. Detecting the failure can be accomplished using a sound detector or stress gauge which produces a signal to trigger the high-speed camera. These high-speed cameras have advanced recording modes to capture some non-destructive failures.[4] After the failure the high-speed camera will stop recording. The captured images can be played back in slow motion showing precisely what happened before, during and after the nondestructive event, image by image.

Adhesively bonded sandwich structures comprising of particulate composites as core and graphite epoxy skins as stiffeners are widely used for various applications in the marine and aerospace industry. The core material and the stiffener are held together by an adhesive bond. Particulate composites are made from a mixture of a polymer resin and hollow or solid particles. Hollow particulate composites are known as syntactic foams. Particulate composites possess attractive mechanical and physical properties such as high compressive strength etc, making them attractive materials for use in structural applications. Characterization of the adhesive bondline and core material in sandwich structures is important for ensuring structural stability and reliability. Nondestructive evaluation [NDE] techniques such as ultrasound are used for better evaluation of these sandwich structured materials. The present study addresses the problems of detection of disbonds, bond surface characteristics and porosity in the adhesive panels along with characterization of particulate composites separately using NDE. The importance of the attenuation coefficient in computing the longitudinal velocities of the ultrasonic wave in particulate composite samples is also discussed. Five sets of adhesively bonded carbon epoxy composite specimens with varying bond surface preparation, twenty four different types of hollow syntactic foams and six different types of solid particulate composites, are fabricated. The adhesively bonded panels are made by including known defects in the bond layer of the samples. The particulate composites (syntactic foams and solid particulates) are fabricated by varying the volume fraction of each of the four types of microballoons and solid particle from 10% to 60%. Pulse echo UI method is selected for use in the present work. The results of this research provides a better understanding of adhesive joints and particulate composites and thus help in characterizing structures composed of these constituents. One of the major findings in this research is the discovery of a nondestructive method to determine the dynamic modulus of particulate composites. In addition, a constitutive model explaining the effect of particle size, porosity, radius ratio on the ultrasonic attenuation coefficient in particulate composites is developed.

It is highly disappointing that not many NDT methods are commonly used for structural evaluation of suspension bridges. Catastrophic failures have occurred for various reasons on a few suspension bridges. This could have been avoided had various advanced NDT methods been put to use.

Saving aging suspension bridges is important for the transportation industry. It is highly recommended to use various advanced NDT testing for structural evaluation of aging suspension bridges. Since every NDT method is unique, it is imperative to select particular methods based on the suitability for a successful inspection.

Dr. Kundu has made significant and original contributions in both basic and applied research in structural health monitoring (SHM) and nondestructive testing techniques (NDT) for material characterization by ultrasonic and electromagnetic waves. His research interests include acoustic microscopy, elastic wave propagation in multilayered solids, fracture mechanics, computational mechanics, and numerical modeling. Application areas of his research findings can be in aerospace materials, civil and structural materials, geomaterials, electronic as well as biological materials. His research on biological material characterization has also received international acclaim. He has won the Humboldt research prize (also known as the Senior Scientist Award) from Germany for his research on biological cell characterization. He has developed a new mesh-free semi-analytical/numerical technique called distributed point source method (DPSM) in collaboration with his French colleagues. This technique has been found to be superior to the finite element method (FEM) for solving many ultrasonic, electrostatic and electro-magnetic problems. He has co-authored the first book on DPSM.Dr. Kundu has collaborated with European scientists on theoretical and experimental research on engineering and biological materials. Most of his European collaborations have been funded by foreign funding agencies in Germany (Alexander von Humboldt Foundation), Belgium (NATO, North Atlantic Treaty Organization), France (French Ministry of Education), Denmark (Aarhus University Medical School), Spain, Poland, Sweden, Switzerland, Japan, South Korea, India and China. Among domestic sources, the National Science Foundation and the Air Force Office of Scientific Research have provided the lion share of his research funding. Besides Humboldt Research Prize he has won the NDE Life Time Achievement Award from SPIE and Research Award for Sustained Excellence from ASNT for his research contributions.

HF passive RFID-based monitoring networks can be formed by combining passive RFID tag with SAW (surface acoustic wave) [72]. With cost-efficient and lower power consumption, RFID-based approaches may represent a revolutionary solution for the condition and intelligent structural health monitoring of railways, in-service nuclear power plants, and aerospace applications [73]. Zhang and others [74] employed a UHF RFID antenna for structure health monitoring. Zhao and others employed a T-shape antenna UHF RFID to increase the gain of the miniaturized antenna and the sensitivity [75]. As well as cost-effective passive RFID tags with low power consumption, other sensors could easily be connected for multiple-purpose sensing. In addition, new features of RFID tags based on advanced signal processing can be used for human body temperature and other measurements.

New technologies play an increasingly important role in the analysis, monitoring, restoration, and preservation of historic structures. These technological systems continue to get more advanced and complex, for example: 3D digital construction and documentation programming, 3D imaging data (including laser scanning and photogrammetry), multispectral and thermographic imaging, geophysical data, etc. This book will present the latest nondestructive technologies used in the characterization, preservation, and structural health monitoring of historic buildings. It will include numerous case studies, as well as theoretical explanations about each of the methods and technologies used in each.

Composite materials have been used in aviation for many years. In the last decade, many new processes and materials have been introduced to improve the consistency and reliability of these composites. Yet, relatively speaking, the technologies needed to inspect composite materials have lagged. Fortunately, that's quickly changing. Several sophisticated technologies have been introduced in the last five years which are quite good. Additionally, there has been a great deal of NDT technology transfer from the knowledge used on metals. Today's nondestructive testing (NDT) of composite materials typically involves the use of more than one inspection method, including both non-instrumental and instrumental methods. Non-instrumental methods include visual inspection and tap testing. Commonly used instrumental methods include ultrasonic inspection, radiography, and advanced methods such as thermography and laser shearography.

Understanding the limitations The correct use of currently available NDT methods depends on the understanding of the capabilities and the limitations of each method. There also needs to be an understanding of the materials being tested and the defects that can occur. The metallics industry for many years has been a typical application for nondestructive test methods, but the inspection of composite materials involves using differing techniques and accessories than traditional metallics. In addition to traditional NDT methods, advanced methods of inspection can also be utilized to inspect composite materials. Following is an introduction of several of these methods, including ultrasonic, radiographic, visual inspection, and tap testing. 781b155fdc