Advanced ultrasonic instrumentation for interferometric monitoring
Recent research results have shown the capabilities of new data processing techniques in detecting subtle changes (like velocity changes) in materials and structures. Among these concepts, active and passive interferometric methods such as Coda Wave Interferometry (CWI) for ultrasonic data, originating mostly from seismological research, are the most promising.
Preliminary experiments on concrete, steel or entire structures have shown the potential of these methods. A major advantage of these methods is that large areas or volumes of a structure can be monitored with a limited number of transceivers using multiply scattered waves.
The techniques are known to be very sensitive even to early stage damages. However, up to now, neither the full possibilities and limitations have been investigated, nor has the instrumentation been fully adapted for practical implementation. Besides conventional transducers, newly invented embedded ultrasonic sensors for concrete will be used for interferometric monitoring of structures (such as bridges) or certain parts hereof (such as foundations of wind energy plants).
One of the objectives is to find optimised set-ups allowing at least semi-automatic calibration, compensation of side effects and a translation of the CWI parameters (ultrasonic velocities, amplitudes, damping, dispersion) into structural engineering parameters and, if possible, wireless data transmission will be investigated. This sets the basis for new monitoring system for almost all kinds of civil infrastructures.
To solve the issue of energy supply for sensor operations, specific attention will be paid to ultrasonic systems that use ambient noise as a source. The PhD project will focus on the adaptation and further development of methods and software used for interferometric data processing to interpret ultrasonic data. This includes data integration with other types of sensors and monitoring systems in connection with the other projects in WP1.
BAM, Berlin - Germany
Fellow - ESR1
Local academic supervisor
Dr. Fabian Kirsch (GuD)
PhD Director: Dr. Ernst Niederleithinger
Start date: 1st October 2016
Duration: 36 months
Main aim is to improve ultrasonic sensor networks to monitor concrete structures under dynamic loads. This includes simulation of effect of certain damage/fatigue scenarios on ultrasonic wave propagation including sensitivity analysis, development of optimised sensors networks, test and further optimisation based on laboratory size concrete models and implementation on a real structure.
Recent publications have shown that ultrasonic data, acquired conventionally or using nonlinear techniques, processed by innovative schemes as Coda Wave Interferometry, can be used to detect subtle changes in concrete (cracks, fatigue and physical/chemical deterioration). However, up to now it is still difficult to evaluate, separate and quantify the various influence factors (as temperature, moisture, stress and deterioration) especially under field conditions. Successful applications of related imaging techniques are up to now limited to simple structures in the laboratory.
The project for ESR1 has three objectives:
- Novel algorithms have to be developed and tested to separate the influence of various effects for field data.
- Ways to quantify the interpretation of ultrasonic data e.g. in terms of degree of damage or capacity, have to be found. This objective is closely related to ESR12.
- Improve and simplify imaging techniques, extend them to arbitrary structures, to foster field applications.
Tasks and methodology
- Simulation and sensitivity analysis of effect of certain damage/fatigue scenarios on ultrasonic wave propagation.
- Development of a simplified imaging scheme for complex structures.
- Lab investigations: controlled experiments with single and multi-parameter influence (for factor separation and quantification).
- Optimisation of experimental procedure (e.g. sensor arrangement, integration with other types of sensors - secondments 1 and 2), development of guidance documents.
- Test and further optimisation based on large scale concrete models.
- Implementation on a real structure (supplied by BASt).
- Methodology for implementation, operating ultrasonic sensor networks including data processing, influence factor separation, quantification and imaging.
- Demonstration implementation at a real structure.
- Accepted peer-reviewed papers.
- Successfully defended PhD thesis.
- IFSTTAR (Nantes, France)
April, May & June 2017
Structural health monitoring focusing on innovative sensors, joint lab experiments, nonlinear ultrasonic techniques, calibration of ultrasonic results by fibre optic sensors
- NeoStrain (Krakow, Poland)
September & October 2018
Monitoring system design and assessment focusing on robust design, data acquisition, wireless data transmission, data reduction, storage, integration with other monitoring techniques
- BAST (Bergisch-Gladbach, Germany)
Demonstration implementation at a real bridge
Ultrasonics, monitoring, concrete, transmission, scattering, coda wave Interferometry
- E. Larose, A. Obermann, A. Digulescu, T. Planès, J.-F. Chaix, F. Mazerolle & G. Moreau
Locating and Characterizing a Crack in Concrete with Diffuse Ultrasound: A Four-Point Bending Test
JASA 138, Nr. 1 (Juli 2015): 232–41, doi:10.1121/1.4922330
- E. Niederleithinger, J. Wolf, F. Mielentz, H. Wiggenhauser & S. Pirskawetz
Embedded Ultrasonic Transducers for Active and Passive Concrete Monitoring
Sensors 15, Nr. 5 (27. April 2015): 9756–72, doi: 10.3390/s150509756
- E. Niederleithinger, C. Sens-Schönfelder, S. Grothe & H. Wiggenhauser
Coda wave interferometry used to localize compressional load effects on a concrete specimen
In Proceedings of 7th European Workshop on Structural Health Monitoring (EWSHM), Nantes, France, 2014
- T. Planès & E. Larose
A Review of Ultrasonic Coda Wave Interferometry in Concrete
Cement and Concrete Research 53 (November 2013): 248–55, doi:10.1016/j.cemconres.2013.07.009.