Coda wave based ultrasonic methods for concrete - extending the capabilities by using 3d information combination with acoustic emission and exploitation of additional features towards the application on real structures

• Applicant: Privatdozent Dr. Ernst Niederleithinger
• Subject Area: Construction Material Sciences, Chemistry, Building Physics ; Applied Mechanics, Statics and Dynamics ; Structural Engineering, Building Informatics and Construction Operation
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 398216472

This subproject is responsible within the research group for the practical part of the ultrasonic coda measurements (including support of the other experimental projects), one of the two imaging methods for the localization of changes in the objects as well as aspects of the future practical application of the methodology on real structures. To this end, the instrumental foundations were successfully laid in phase 1 by working on the transducers and a versatile, low-cost data acquisition system. An innovative method for imaging coda waves to localize damage was developed and successfully tested but is currently limited to 2D (i.e. one plane). In addition, based on measurements on a large specimen in the open field, a methodology for eliminating environmental effects (e.g., temperature) has been developed that makes any damage events more visible. In addition, the first real structure has already been instrumented ahead of schedule and data collected on an ongoing basis.In phase 2, systematic research will now be conducted to extend and broaden the basic principles so that the method can be used on real structures in the future. Here, we will not only provide faster data acquisition for even larger sensor networks and instrument at least one more real structure for testing purposes. We will also develop sensors that separately record the three spatial components of the wave field. We will use this information in the imaging process, which has been expanded to three dimensions, to obtain better images of the changes in the object. We will combine this with results from acoustic emission analysis to further sharpen the results.In addition, with the new sensors, but also through simulations and experiments performed with the partners, we will be able to extract additional parameters from the data. These include parameters on nonlinear material behavior, but also the use of environmental effects (instead of just elimination) as an indicator of any damage to the object. We will verify our results on instrumented real structures together with our partners.

• DFG Programme: Research Units
• Subproject of: FOR 2825: Concrete Damage Assessment by Coda Waves (CoDA)