Two fiber reinforced polymer (FRP) bridge deck specimens were analyzed by means of acoustic emission (AE) monitoring during a series of loading cycles performed at various locations on the composite sandwich panels' surfaces. These panels were subjected to loads that were intended to test their structural response and characteristics without exposing them to a failure scenario. This allowed the sensors to record multiple data sets without fear of having to be placed on multiple panels that could have various characteristics that alter the signals recorded. The objective throughout the analysis ias to determine how the acoustic signals respond to loading cycles and various events can affect the acoustical data. In the process of performing this examination several steps were taken including threshold application, data collection, and sensor location analysis. The thresholds are important for lowering the size of the files containing the data, while keeping important information that could determine structurally significant information. Equally important is figuring out where and how the sensors should be placed on the panels in the first place in relation to other sensors, panel features and supporting beams. The data was subjected to analysis involving the response to applied loads, joint effects and failure analysis. Using previously developed techniques the information gathered was also analyzed in terms of what type of failure could be occurring within the structure itself. This somewhat aided in the analysis after an unplanned failure event occurred to determine what cause or causes might have lead to the occurrence. The basic analyses were separated into four sets, starting with the basic analysis to determine basic correlations to the loads applied. This was followed by joint and sensor location analyses, both of which took place using a two panel setup. The last set was created upon matrix failure of the panel and the subsequent investigation.

Two fiber reinforced polymer (FRP) bridge deck specimens were analyzed by means of acoustic emission (AE) monitoring during a series of loading cycles performed at various locations on the composite sandwich panels' surfaces. These panels were subjected to loads that were intended to test their structural response and characteristics without exposing them to a failure scenario. This allowed the sensors to record multiple data sets without fear of having to be placed on multiple panels that could have various characteristics that alter the signals recorded. The objective throughout the analysis ias to determine how the acoustic signals respond to loading cycles and various events can affect the acoustical data. In the process of performing this examination several steps were taken including threshold application, data collection, and sensor location analysis. The thresholds are important for lowering the size of the files containing the data, while keeping important information that could determine structurally significant information. Equally important is figuring out where and how the sensors should be placed on the panels in the first place in relation to other sensors, panel features and supporting beams. The data was subjected to analysis involving the response to applied loads, joint effects and failure analysis. Using previously developed techniques the information gathered was also analyzed in terms of what type of failure could be occurring within the structure itself. This somewhat aided in the analysis after an unplanned failure event occurred to determine what cause or causes might have lead to the occurrence. The basic analyses were separated into four sets, starting with the basic analysis to determine basic correlations to the loads applied. This was followed by joint and sensor location analyses, both of which took place using a two panel setup. The last set was created upon matrix failure of the panel and the subsequent investigation.

A total of 6 full-scale glass fiber-reinforced polymer (GFRP) composite bridge deck specimens were tested to study the significance of using acoustic emission (AE) for monitoring and analysis of the structural integrity of the specimens during a predetermined loading profile. The first two specimens varied in width and were loaded to failure and last four specimens were the original specimens that were repaired after failure occurred using an FRP wrap. The objective, through the use of AE monitoring and analysis, is to identify failure prediction criteria and/or a methodology that would provide a determination of the structural integrity of the in-service FRP bridge deck during field inspection. While no codes and standards exist for these types of specimens, current standards developed for FRP tanks and vessels were used as a base reference to determine if current standards could be adopted or if new or additional criteria needed to be established. Real-time monitoring was conducted for each specimen during a standard 3-point bending test. Monitoring typically covered loading up to 80% of the calculated ultimate strength. During monitoring, a selected set of features associated with each AE hit and the associated waveform were recorded in a database for post analysis. The collected data was later analyzed using comparison and intensity analysis, linear location and waveform analysis, accompanied with pattern recognition, to identify series of hits with a particular event. Each event was investigated to determine if the type of damage, such as fiber breakage, matrix cracking, and delamination, could characterize the event. These types of events were the contributing factors to the investigated criteria and the structural performance of the specimens. In post analysis, comparison analysis was performed to observe the Kaiser Effect and the calculation of a Felicity Ratio when the Kaiser Effect broke down. For the original specimens, the Felicity Ratio fell within expected values observed from previous work, while the repaired specimens, using an external FRP wrap, were generally higher than the typically accepted value of 0.85. The second type of post analysis, linear location, was performed to pinpoint the location along the axis of the specimen in which the majority of the events occurred. In the case of the original specimens, visual inspection was difficult as the majority of the damage of the specimen occurred at the inner core. While there is some associated stress redistribution that leads to delamination of the outer flutes from the top and bottom face panels, this was the only visually observable change for the original specimens. Thus, linear location becomes an important tool for the location and isolation of major damage before reaching catastrophic failure. The failure mode of the repaired specimens was restricted due to the external wrap, and provided a visual cue of damage. The third type of analysis, waveform analysis using pattern recognition, appears promising in identifying each type of damage characteristic and training a neural network to classify incoming waveforms. This damaged-based characterization could be useful for in-field service inspection. However, further investigation is needed for verification before using this form of classification.

Acoustic emission (AE) techniques have successfully been used for assuring the structural integrity of large rocket motorcases since 1963, and their uses have expanded to ever larger structures, especially as structural health monitoring (SHM) of large structures has become the most urgent task for engineering communities around the world. The needs for advanced AE monitoring methods are felt keenly by those dealing with aging infrastructures. Many publications have appeared covering various aspects of AE techniques, but documentation of actual applications of AE techniques has been mostly limited to reports of successful results without technical details that allow objective evaluation of the results. There are some exceptions in the literature. In this Special Issue of the Acoustics section of Applied Sciences, we seek contributions covering these exceptions cited here. Here, we seek contributions describing case histories of AE applications to large structures that have achieved the goals of SHM by providing adequate technical information supporting the success stories. Types of structures can include aerospace and geological structures, bridges, buildings, factories, maritime facilities, off-shore structures, etc. Experiences with AE monitoring methods designed and proven for large stru

This book provides an introduction to Acoustic Emission Testing and its applications to different materials like concrete, steel, ceramics, geotechnical materials, polymers, biological structures and wood. Acoustic Emission Techniques (AET) techniques have been studied in engineering for a long time. The techniques are applied more and more to practical investigations and are more and more standardized in codes. This is because the degradation of structures due to ageing urgently demand for maintenance and rehabilitation of structures in service. It results in the need for the development of advanced and efficient inspection techniques. In mechanical engineering and concerning the monitoring of machines and mechanical components, AE is a widely accepted observing deterioration in the frame of structural health monitoring. The advantages of AE like sensitivity, damage localization potential, non-intrusive nature as well as developments in signal analysis and data transmission allow applications that could not be considered decades ago. As such, AE techniques draw great attention to diagnostic applications and in material testing. This book covers all levels from the description of AE basics for AE beginners (level of a student) to sophisticated AE algorithms and applications to real large-scale structures as well as the observation of the cracking process in laboratory specimen to study fracture processes. This book has proved its worth over the past twelve years. Now in its second edition, it will be a resource that sets the standard and equips readers for the future. All chapters from the 1st edition have been updated and rewritten and eight extra chapters (e.g also regarding AE tomography, AE in plate-like structures and AE for investigations of hardening of fresh concrete) have been added.

Structural health monitoring (SHM) uses one or more in situ sensing systems placed in or around a structure, providing real-time evaluation of its performance and ultimately preventing structural failure. Although most commonly used in civil engineering, such as in roads, bridges, and dams, SHM is now finding applications in other engineering envir

Acoustic emission monitoring offers a simple means of studying the effects that microscopic defects have on composites, since the emissions are a direct result of material deformations. This dissertation examines the research and development applications that acoustic emission monitoring has for fiber reinforced composites. Specific emphasis is placed upon obtaining information from fundamental failure processes, but practical engineering applications are reviewed as well, including fatigue crack detection and structural integrity evaluation. Basic principles of the phenomenon are covered, including the generation of emissions, the propagation of stress waves through materials, the production of electrical signals from mechanical stress waves, and signal processing to obtain data on microscopic sample deformations. An experiment is discussed which indicates that six-ply, 0 degree, plus or minus 45 degree carbon fiber reinforced plastic can be successfully monitored for incipient failure.