Laboratory of Non-Destructive Testing
Department: Department D 4 - Impact and Waves in Solids
Head: Ing. Jan Kober, Ph.D.
Mission: Research, development, and application of new methods of nondestructive testing (NDT) and evaluation (NDE) of materials and structures.
Our methods are based on elastic wave propagation in solids: Acoustic Emission, Ultrasonc Scanning and Tomography, Nonlinear Elastic Wave Spectroscopy (NEWS) including Time-Reversal Acoustics and Nonlinear Wave Modulation (NWMS).
Ing. Zdeněk Převorovský, CSc.
Ing. Jan Trnka, CSc.
Ing. Milan Chlada, Ph.D.
Ing. Josef Krofta, Ph.D.
Ing. Jan Kober, Ph.D.
Ing. Zuzana Dvořáková
Ing. Daniel Tokar
Ing. Radovan Zeman
Bc. Martin Kovanda
Ing. Milan Chlada
Nonlinear and Diffuse Ultrasonics
Nonlinear and Diffuse Ultrasonics are a wide range of ultrasonic methods for nondestructive testing and evaluation of materials and structures. These methods offer superior sensitivity to damage and changes in material and structural properties; allow damage assessment either locally or in bulk; and damage localization and imaging.
Diffuse Ultrasonics are methods based on elastic wave propagation in scattering media. The NDT Laboratory has been using Time Reversal (TR) and Coda Wave Interferometry (CWI) for various objectives. Time Reversal has been successfully applied to precise localization of burst and continuous AE sources. A new TR-based method of in-situ transducer calibration was developed and the concept of TR transfer i.e., exchange of response signals between a tested and a reference structure, was validated both experimentally and using digital twin models (FEM and Image Source Method). Coda Wave Interferometry has been used for monitoring of changes of environmental and boundary conditions, and structural shape.
Nonlinear Ultrasonics are methods based on the evaluation of material nonlinear elastic response, which is often associated with emerging damage. Various nonlinear methods have been tested and are readily available for measurements: Nonlinear Resonant Ultrasound Spectroscopy (NRUS), Nonlinear Wave Modulation Spectroscopy (NWMS), Excitation Symmetry Analysis (ESAM), Scaling Subtraction (SSM), etc. The NDT Laboratory has applied Nonlinear Ultrasonics for assessment of aerospace structures, concrete, 3D printed Ti-alloy, fatigue and corrosion damage and more.
Contact person: Jan Kober
Acoustic Emission (AE) method is widely used for nondestructive monitoring, evaluation and identification of processes in materials and structures. The research is oriented towards two problems: AE source localization and continuous AE evaluation.
In-house algorithms expand the AE source location possibilities and reliability for complex structures. The procedures involve computation of the shortest paths of elastic wave propagation between source and receiver positions. Our approach enables the data evaluation in problematic areas with respect to particular sensor placement and enables collecting representative training sets for Artificial Neural Networks (ANN) to estimate the location of emission sources. Resulting AE activity and location likelihood maps are obtainable even for discontinuous or anisotropic bodies.
Computational power of contemporary regular PC hardware and reachable prices of modern portable measuring devices as USB oscilloscopes with data streaming feature allows to perform a continuous AE monitoring with a relatively simple experimental setup. We developed Matlab-based measuring software with compact user interface allowing on-line monitoring of AE activity in more details than with conventional AE analyzers. Such measurements usually create huge datasets where advanced processing is necessary. Most recent advances in artificial intelligence enabled successful application of Convolutional ANNs for the assessment of tensile and fatigue testing, together with helicopter gearbox condition monitoring.
Contact person: Milan Chlada
Structural Health Monitoring
Structural Health Monitoring (SHM) is becoming an important emerging technology, which improves the reliability and safety of highly stressed structures by continuous assessment of their structural state. SHM involves the development and implementation of technologies and systems where monitoring, inspection, damage assessment and residual life prediction become integral parts of 'smart' structures.
The NDT Laboratory has been developing SHM systems for various application cases: parts of aerospace structures, highly loaded roof structures or nuclear power plant piping. The SHM systems build on our research in ultrasonics and acoustic emission while incorporating other NDT methods as well. These methods include visual inspection, thermography and optical fiber FBG sensors for strain, temperature and acceleration measurements.
An integral part of SHM design is a development of algorithms for data processing, structural assessment and residual life prediction. That encompasses a extended multi-disciplinary research where NDT Laboratory collaborates with other subjects. The concept of digital twin modelling of elastic wave propagation is pursued together with the Laboratory of Computational Solid Mechanics IT CAS. The assessment of structural state and residual life is done with the Laboratory of Thermomechanics of Materials IT CAS.
Contact person: Zdenek Prevorovsky
- TiePie HS6 (2x)
- Picoscope 6402C
AWG generators and Amplifiers
- Agilent 33500 series
- power amplifier Amplifier Research AR50
- power amplifier BOTEG ForesTek 40 dB
- preamplifiers BOTEG 20 dB a 40 dB (8x)
- preamplifiers PAC uDisp 20-60 dB (8x)
- modular system PXI National Instrumets
- modular system PXIe Adlink/Keysight
- TiePie HS5 (3x)
- laser vibrometer Polytec OFV-5000 (2x)
- 4D ultrasonic scanner Starmans
- thermal camera Workswell WIC 160
- mechanical testing machine Instron 100 kN
- assortment of ultrasonic and AE probes
- channel multiplexer 8Ch (2x)