Author : Richard S. Gostautas
Publisher :
ISBN 13 :
Total Pages : 73 pages
Book Rating : 4.:/5 (166 download)
Book Synopsis Identification of Failure Prediction Criteria Using Acoustic Emission Monitoring and Analysis of GFRP Bridge Deck Panels by : Richard S. Gostautas
Download or read book Identification of Failure Prediction Criteria Using Acoustic Emission Monitoring and Analysis of GFRP Bridge Deck Panels written by Richard S. Gostautas and published by . This book was released on 2007 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
