Nondestructive Testing (NDT)

The aim of this book is to collect the newest contributions by eminent authors in the field of NDT-SHM, both at the material and structure scale. It therefore provides novel insight at experimental and numerical levels on the application of NDT to a wide variety of materials (concrete, steel, masonry, composites, etc.) in the field of Civil Engineering and Architecture

Nondestructive Testing in Composite Materials

In this era of technological progress and given the need for welfare and safety, everything that is manufactured and maintained must comply with such needs. We would all like to live in a safe house that will not collapse on us. We would all like to walk on a safe road and never see a chasm open in front of us. We would all like to cross a bridge and reach the other side safely. We all would like to feel safe and secure when taking a plane, ship, train, or using any equipment. All this may be possible with the adoption of adequate manufacturing processes, with non-destructive inspection of final parts and monitoring during the in-service life of components. Above all, maintenance should be imperative. This requires effective non-destructive testing techniques and procedures. This Special Issue is a collection of some of the latest research in these areas, aiming to highlight new ideas and ways to deal with challenging issues worldwide. Different types of materials and structures are considered, different non-destructive testing techniques are employed with new approaches for data treatment proposed as well as numerical simulations. This can serve as food for thought for the community involved in the inspection of materials and structures as well as condition monitoring

Quality Assessment of Composite Materials using Ultrasonic Non-Destructive Testing Methods

Non-destructive ultrasonic evaluation (NDE) is commonly used for assessment of civil infrastructure and characterization of construction materials. It is an efficient technique that could save millions of dollars with respect to traditional intrusive tests. However, limitations regarding the use of NDE techniques are still present. The conventional non-destructive testing (NDT) methods (impact echo, ultrasonic pulse velocity [UPV]) are focused on velocity; therefore, neither the frequency content of the response nor the frequency characteristics of the transmitter signal to a tested material is usually utilized. However, it has been shown that this can lead to misinterpretation of ultrasonic data. Even for the fairly simple method like UPV (where the method is based on the concept of measuring the time of flight for the first arriving ultrasonic wave from one side of the specimen to another), it has been shown that the UPV results may be affected by many factors, such as water-cement ratio, aggregate size, or distribution of moisture. Additionally, traditional wave velocity-based methods are not sufficient for early damage detection (which is an active research field in the non-destructive testing of civil infrastructure) as they use only one data point of information, neglecting the frequency content of ultrasonic signals. Finally, the long-term durability of glass-FRP (GFRP) in concrete remains an unresolved issue. The necessity of reliable NDE techniques for GFRP bars is even more important for in-situ testing of concrete members with GFRP reinforcement because the bars embedded in concrete show no visual deterioration and cannot be cut out of a structure to test in a traditional way. The main objective of this research is to enhance the understanding of the frequency effects on ultrasonic measurements and establish a comprehensive methodology for early damage detection of composite materials (based on wave velocity, attenuation, and dispersion). This research consists of four studies. First, a characterization procedure is developed, using a state-of-the-art laser Doppler vibrometer, to understand the frequency content transmitted by ultrasonic transducers typically used in civil engineering applications. Second, a group of concrete specimens of different diameter and length is tested with a traditional ultrasonic pulse velocity method (using ultrasonic transducers with different resonant frequencies and the laser vibrometer) to evaluate how the frequency content of the recorded ultrasonic measurements changes with different resonant frequency transducers and how it depends on specimen dimensions.vi Third, a new methodology, based on wavelet synchrosqueezed transform (WSST) and both velocity and attenuation approaches, is developed to address an issue of early damage detection in cementitious materials (i.e. concrete elements and cemented sand specimen). The proposed framework is verified with synthetic signals and two real, lab-scale applications. Finally, the functionality of the newly developed ultrasonic procedure (i.e. based on characterized ultrasonic transducers, the WSST, and velocity and attenuation approach) is investigated on progressive damage of glass fibre reinforced polymer specimens. The ultrasonic evaluation is verified with the traditional destructive test (i.e. shear test) and numerical simulations. The characterization procedure, developed for ultrasonic transducers typically used in civil engineering applications, reveals that frequency content, transmitted by the transducers to the tested medium, consists of more than just transducer resonant frequency. The importance of using well-characterized ultrasonic transducers (i.e. including the full frequency content in the NDT evaluation) is demonstrated on the ultrasonic evaluation of concrete elements, cemented sand specimen, and GFRP reinforcing bars. The study of frequency effects is continued with concrete cylinders of different dimensions. Therefore, practical recommendations regarding the minimum specimen length, effects of increasing length and diameter, and limitations regarding the use of high frequencies in the ultrasonic evaluation of concrete elements are given. Next, a framework based on wave velocity and attenuation (including a demonstration of the advantages of applying the wavelet synchrosqueezed transform [WSST]) is proposed for the evaluation of distributed damage (i.e. early damage induced by freeze and thaw cycles in concrete elements) and localized damage (i.e. cemented sand specimen with a subsurface void). The results indicate that the WSST technique has the potential to improve both the detection of distributed damage by up to 52% and localized damage detection by up to 36%. Finally, a progressive deterioration of GFRP reinforcing bars is studied using the developed ultrasonic procedure. The comparison of ultrasonic evaluation based on wave amplitude, destructive shear test, and numerical simulations shows that ultrasonic techniques can successfully predict the degradation of shear strength (and ultimately tensile strength) of GFRP bars (with the maximum error of 7%). The findings presented in this thesis provide practical recommendations and frameworks that can successfully increase the reliability of non-destructive ultrasonic evaluation of composite materials used in civil engineering ap

Advanced Techniques for Ground Penetrating Radar Imaging

Ground penetrating radar (GPR) has become one of the key technologies in subsurface sensing and, in general, in non-destructive testing (NDT), since it is able to detect both metallic and nonmetallic targets. GPR for NDT has been successfully introduced in a wide range of sectors, such as mining and geology, glaciology, civil engineering and civil works, archaeology, and security and defense. In recent decades, improvements in georeferencing and positioning systems have enabled the introduction of synthetic aperture radar (SAR) techniques in GPR systems, yielding GPR–SAR systems capable of providing high-resolution microwave images. In parallel, the radiofrequency front-end of GPR systems has been optimized in terms of compactness (e.g., smaller Tx/Rx antennas) and cost. These advances, combined with improvements in autonomous platforms, such as unmanned terrestrial and aerial vehicles, have fostered new fields of application for GPR, where fast and reliable detection capabilities are demanded. In addition, processing techniques have been improved, taking advantage of the research conducted in related fields like inverse scattering and imaging. As a result, novel and robust algorithms have been developed for clutter reduction, automatic target recognition, and efficient processing of large sets of measurements to enable real-time imaging, among others. This Special Issue provides an overview of the state of the art in GPR imaging, focusing on the latest advances from both hardware and software perspectives

Innovative Methods and Materials in Structural Health Monitoring of Civil Infrastructures

In the past, when elements in sructures were composed of perishable materials, such as wood, the maintenance of houses, bridges, etc., was considered of vital importance for their safe use and to preserve their efficiency. With the advent of materials such as reinforced concrete and steel, given their relatively long useful life, periodic and constant maintenance has often been considered a secondary concern. When it was realized that even for structures fabricated with these materials that the useful life has an end and that it was being approached, planning maintenance became an important and non-negligible aspect. Thus, the concept of structural health monitoring (SHM) was introduced, designed, and implemented as a multidisciplinary method. Computational mechanics, static and dynamic analysis of structures, electronics, sensors, and, recently, the Internet of Things (IoT) and artificial intelligence (AI) are required, but it is also important to consider new materials, especially those with intrinsic self-diagnosis characteristics, and to use measurement and survey methods typical of modern geomatics, such as satellite surveys and highly sophisticated laser tools

Radioactive Waste

The safe management of nuclear and radioactive wastes is a subject that has recently received considerable recognition due to the huge volume of accumulative wastes and the increased public awareness of the hazards of these wastes. This book aims to cover the practice and research efforts that are currently conducted to deal with the technical difficulties in different radioactive waste management activities and to introduce to the non-technical factors that can affect the management practice. The collective contribution of esteem international experts has covered the science and technology of different management activities. The authors have introduced to the management system, illustrate how old management practices and radioactive accident can affect the environment and summarize the knowledge gained from current management practice and results of research efforts for using some innovative technologies in both pre-disposal and disposal activities

Nondestructive Testing Methods and New Applications

Nondestructive testing enables scientists and engineers to evaluate the integrity of their structures and the properties of their materials or components non-intrusively, and in some instances in real-time fashion. Applying the Nondestructive techniques and modalities offers valuable savings and guarantees the quality of engineered systems and products. This technology can be employed through different modalities that include contact methods such as ultrasonic, eddy current, magnetic particles, and liquid penetrant, in addition to contact-less methods such as in thermography, radiography, and shearography. This book seeks to introduce some of the Nondestructive testing methods from its theoretical fundamentals to its specific applications. Additionally, the text contains several novel implementations of such techniques in different fields, including the assessment of civil structures (concrete) to its application in medicine

AIMETA 2005. Atti del XVII Congresso dell'Associazione italiana di meccanica teorica e applicata. Firenze, 11-15 settembre 2005

The volume collects the contributions presented at the XVII national congress of AIMETA. The contributions are grouped according to the various sectors of theoretical and applied mechanics and are offered by a vast scientific community. In addition to the classical sectors, themes of interdisciplinary significance and of considerable interest and highly innovative content were added, for the analysis of which small exchange symposia were proposed. Organised according to 52 sessions (plenary and parallel), the volume contains 290 scientific works that are mainly the result of international cooperation. Therefore, the work represents a significant picture of the current situation and future prospects for mechanics

EG-ICE 2021 Workshop on Intelligent Computing in Engineering

The 28th EG-ICE International Workshop 2021 brings together international experts working at the interface between advanced computing and modern engineering challenges. Many engineering tasks require open-world resolutions to support multi-actor collaboration, coping with approximate models, providing effective engineer-computer interaction, search in multi-dimensional solution spaces, accommodating uncertainty, including specialist domain knowledge, performing sensor-data interpretation and dealing with incomplete knowledge. While results from computer science provide much initial support for resolution, adaptation is unavoidable and most importantly, feedback from addressing engineering challenges drives fundamental computer-science research. Competence and knowledge transfer goes both ways