PhD Physical Acoustics / Ultrasonic based NDT

(ref. BAP-2023-96)

Last modification : Wednesday, February 22, 2023

KU Leuven Kulak's Science & Technology group provides education in a wide range of undergraduate science programs (as well as transition options to (bio-)engineering and pharmacy), while also making the link to contemporary and cutting-edge research. Within the S&T Kulak group, the research group "Wave Propagation and Signal Processing" includes research into non- destructive techniques for material characterization and defect detection. The focus is on the development of new techniques based on ultrasound waves and the validation of innovative concepts for concrete applications in industry. The conducted research involves modelling, numerical simulations, as well as experimental measurements and verification, in strong collaboration with the Mechanics of Materials and Structures Research Group of the University Ghent.

Fiber reinforced polymers (or composites) have excellent specific stiffness/strength as well as corrosion resistance, which makes them very attractive for high-tech applications in aerospace, renewable energy… Though, composites are also known for their susceptibility to internal defects which might compromise their structural performance.

The goal of this project is to develop a low-cost and time-efficient non- destructive inspection technique by employing elastic waves. The idea is to employ the principle of elastic wave time-reversal coupled to decomposition techniques in order to selectively focus vibrational energy at defects. Doing so, defects will get selectively activated and become themselves a secondary source of nonlinear vibrations, heat and/or acoustic emission. Tracking down these secondary effects offers a unique opportunity to exclusively image defects in materials. The study will involve both experimental and numerical research in order to get a deep understanding of the various involved physical phenomena, and to optimize the technique for the wide diversity of possible defect types in composites.

More specifically, this project investigates the nonlinear interaction between guided waves (in the frequency range 25-250 kHz) and defects for NDT of composites. The project aims to implement, both experimentally and numerically, the Time-Reversal Mirror method coupled to the decomposition of the time-reversal operator (TRM-DORT) for baseline-free evaluation of defects in composites using a sparse array of acquisition sites. The focus will be on exploring the functionality of the technique based on the nonlinear responses of the defects and on exploiting the concept for various defects in composites with geometrical complexities, considering the in-plane as well as the out-of-plane nonlinear vibrational components. Apart from activating the defect as an efficient secondary nonlinear vibrational source, we will also investigate to what extent vibro-thermal and vibro-acoustical processes can be exploited for getting the defect also activated as an efficient secondary thermal and acoustic source. Including these phenomena will allow to implement a full-field, fast and cost-efficient inspection modality, which is more suitable for practical applications in industry.

The proposed project will be accomplished by targeting the following five objectives:

Objective-1: Understanding the nonlinear vibrational signature of different defect types in composites

Objective-2: Far-field detection, decomposition and classification of defects based on their nonlinear vibrational response measured by a sparse array of (arbitrarily located) transducers

Objective-3: Spatio-temporal energy localization at individual defects by means of time-reversal method

Objective-4: Localization and full characterization of defects through imaging with infrared camera

Objective-5: Localization and characterization of defects through non-contact acoustic measurements

The research tasks will be conducted by an inter-university team at the university of Leuven campus Kulak and the University of Ghent, involving several PhD students and Post-Docs. The focus can be either on numerical simulations or on combined numerical-experimental work.

In addition to the PhD work, the chosen candidate will also be employed to supervise project work (Problem Solving and Design, Experimental Physics, Mechanics and Electromagnetism Practices, etc) in the Bachelor courses at the Kulak campus in Kortrijk.

The successful candidate must hold a master's degree in physics, or a master's degree in engineering (Mechanical, Electrical, Materials Engineering) or a master's degree in industrial engineering or engineering technology (Electronics, Electromechanics, Dynamics, Automation, Mechatronics).

Further:

- You have fluent written and oral Dutch or English language skills.

- You have experience with and/or a strong interest in teaching a group of science and engineering students from Bachelor programs.

- You can work independently and collaborate well in a team.

- Knowledge of scientific software such as Python, Matlab, LabVIEW, Comsol, ABAQUS and SolidEdge is a plus.

We initially offer a full-time employment as a PhD fellow in the Science & Technology Group Kulak for 1 year. Starting date preferably before September 2023. After an evaluation at 9 months, an extension up to 4 years can be granted with a view to obtaining a joint PhD from both KU Leuven and University Ghent.

Use the online tool to submit your application.

Full CV and motivation letter are absolutely required. Also include transcripts of your Ba and Ms diploma's containing information on the education program and evaluation.

For more information please contact Prof. dr. Koen Van Den Abeele, tel.: +32 56 24 62 56, mail: [email protected]

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