Page 27 - Research Report 2021 - Institut für Leichtbau und Kunststofftechnik

phased array units, if necessary. The ILK also has an ul- properties, and thirdly, it is relatively insensitive to envi-
trasound microscope for special tasks that require an ronmental influences. The fact that the method targets
inspection with very high spatial resolution. Special test deformation differences, i.e. ultimately stiffness changes
setups have already been developed at the ILK for spe- in the tested structure, means that defects that endanger
cific industrial tests, for example to measure the residual component integrity can be reliably detected. At the ILK,
wall thicknesses in coated pipes from the inside or to application-oriented methods for automated parameter
determine the stiffness tensor and its change as a result setting and defect detection have recently been devel-
of material damage. The research goals we are currently oped in particular, which are now available with a trans-
pursuing with regard to ultrasonic methods include firstly portable measuring system (laser class 1) that can be
the reliable determination of stiffness even in the case of used in the field.
strongly damping or viscoelastic materials, secondly the
improvement of defect detectability and thirdly the cou- To round off the ILK's expertise in the field of dimen-
pling with simulation results. sional, positional and shape deviations, but also surface
topology, a variety of optical measurement systems are
Thermography is another exciting method available used that cover different measurement volumes. Other
at the ILK. Lock-in and pulse-phase thermography are methods such as vibration analysis, strain measure-
particularly suitable for non-destructive testing of fibre ment with fibre sensors and acoustic emission anal-
composites. Both process variants are also suitable for ysis open up the ILK's competences in the field of NDT
inline testing and test specimens with larger dimensions. in the direction of structural health monitoring (SHM).
The methods are suitable for detecting the same defect
classes as can be detected with ultrasonic testing, al- With the equipment available, the methods and concepts
though they can scan larger areas more efficiently. The developed, the ILK has built up a wide-ranging field of ex-
ILK's research interest in the field of thermography is pertise in quality assurance for diverse lightweight struc-
firstly focused on the improvement of defect detectabil- tures and the associated manufacturing processes. So
ity and secondly the automated selection of inspection if you are asking yourself “Can this also be tested?” then
parameters based on numerical simulations and through please feel free to contact us – testing is our area of
the use of machine learning. expertise.

A less common method of NDT is shearography. In
this method, structures are illuminated by coherent la- Contact Expert group:
ser light, creating a characteristic speckle pattern on the Testing methods and material models
component surface. Excitation of the structure, for ex-
ample with ultrasound, infrared radiation, local pressure Dr.-Ing. Ilja Koch – Group leader
or mechanical stress, induces a deformation that can be +49 351 463 38394
ilja.koch@tu-dresden.de
measured and displayed by comparing the interference ✉
pattern to the reference state. The inhomogeneities that https://tud.link/srjq
become visible in the process can indicate defects. Shea- Dr.-Ing. Jörn Jaschinski
rography offers three major advantages: Firstly, it can +49 351 463 38148
achieve a high measurement resolution even for large ✉ joern.jaschinski@tu-dresden.de
components. Secondly, it is independent of material https://tud.link/yuqc

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