New highly-sensitive and non-contact methods for acoustic recognition and imaging of defects in composites

• Applicant: Professor Dr. Marc Daniel Leonhard von Kreutzbruck
• Subject Area: Measurement Systems ; Acoustics ; Plastics Engineering ; Mechanics
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 389769996

• Final Report Year: 2022

Final Report Abstract

The project validates LDR concept and applies it to development of new approaches to boost efficiency of ultrasound-activated NDT techniques by having implemented the following: The LDR concept has been extended to a more rigorous analytics for various shapes of planar defects to recognize the impact of these factors on LDR frequency. In nonlinear NDT, the LDR concept has solved a bottleneck problem of low efficiency conversion to nonlinear frequency components. The way to enhance the efficiency of the higher harmonic generation by orders of magnitude has been found by mode matching. A new approach to highly-efficient nonlinear frequency mixing based on LDR is proposed, analysed and tested. In ultrasonic thermography, the progress in LDR studies has enhanced dramatically the efficiency of ultrasonic vibration conversion to heat that removes a long-term obstacle to practical applications of thermosonic NDT. The defect activation of low-energy vibrothermography has been further improved by sweeping the ultrasonic excitation frequency and Fourier-transforming the temperature data. In the framework of the project, a prototype of a mobile and compact testing system potentially applicable in aerospace, train, automotive and wind energy industries has been developed. A manifold (20-30 dB) increase of the damage vibration amplitude provided by LDR opens up wide opportunities for efficient non-contact NDT. A new technique for non-contact NDT provided by commercial sonic equipment uses two-step resonant experimental approach: first, overall acoustic matching between air and the specimen is implemented in the resonant slanted mode, followed by frequency-selective matching via LDR. The other options for non-contact NDT developed are concerned with Resonant Air-Coupled Emission (RACE) detected either by a scanning robotic arm or an immediate full-field defect imaging by using an acoustic camera.

Publications

• Validation of resonant frequency sweep thermography by means of POD analysis, Materials Testing, (2018), 60, 5, 483-488
  M. Rahammer, M. Kreutzbruck
  (See online at https://doi.org/10.3139/120.111179)
• Analytical evaluation of resonance frequencies for planar defects: Effect of a defect shape, NDT & E International, (2019), 102, March 2019, 274-280
  I. Solodov, M. Rahammer, M. Kreutzbruck
  (See online at https://doi.org/10.1016/j.ndteint.2018.12.008)
• Mode matching to enhance nonlinear response of local defect resonance, Journal of Sound and Vibration, (2019), 461, 114916
  I. Solodov, M. Kreutzbruck
  (See online at https://doi.org/10.1016/j.jsv.2019.114916)
• Nonlinear acoustic response of damage applied for diagnostic Imaging, In: Nonlinear ultrasonic and vibroacoustical techniques for non-destructive evaluation, Ed. T. Kundu, (2019), Chapter 8, Springer, Switzerland
  I. Solodov
  (See online at https://doi.org/10.1007/978-3-319-94476-0_8)
• Single-sided access remote imaging via resonant airborne activation of damage, NDT & E International, (2019), 107, 102146
  I. Solodov, M. Kreutzbruck
  (See online at https://doi.org/10.1016/j.ndteint.2019.102146)
• A mobile nondestructive testing (NDT) system for fast detection of impact damage in fiber-reinforced plastics (FRP), J. Sens. Sens. Syst., 9, 43–50, 2020
  J. Rittmann, M. Rahammer, N. Holtmann, M. Kreutzbruck
  (See online at https://doi.org/10.5194/jsss-9-43-2020)
• Listening for airborne sound of damage: a new mode of diagnostic imaging, Front. Built Environ., 28 May 2020
  Y. Bernhardt, D. Solodov, D. Müller, M. Kreutzbruck
  (See online at https://doi.org/10.3389/fbuil.2020.00066)
• Nonlinear acoustic measurements for NDE applications: Waves versus vibrations, In: Measurement of Nonlinear Ultrasonic Characteristics, Ed. K.-Y. Jhang et al., (2020), Chapter 4, Springer Nature Singapore Pte Ltd.
  I. Solodov
  (See online at https://doi.org/10.1007/978-981-15-1461-6_4)
• Ultrasonic frequency mixing via local defect resonance for defect imaging in composites, Ultrasonics, (2020) 108, 106221
  I. Solodov, M. Kreutzbruck
  (See online at https://doi.org/10.1016/j.ultras.2020.106221)