PZFlex Time Reversal FEM Modelling in Thin aluminium plates for defects detection
Abstract. A novel Non Destructive Testing technique for the detection and
characterization of defects in thin plate-like structures is presented. When having
large structures to be scanned, the use of guided waves is a useful tool to avoid the
monitoring of the sample with conventional and very time-consuming techniques.
These waves, Lamb modes, interact with the existing defects when travelling along
the structure. However, the dispersive nature of these waves makes difficult defect
identification because of the complex signals to be analysed. These signals are
composed of the multiple modes propagating through the structure. Even in the case
of having the possibility of exciting only one mode over the structure, Lamb wave
conversion can occur if the wave travelling finds a discontinuity in the material, ie
flaws, boundaries, thickness changes. A Time Reversal -TRM- process can help in
the signal analysis. In this work, the first steps of the study and development of
ultrasonic techniques to detect the relative variation of the integrity of a structure are
described. Finite Element models using PZFlex have been developed to study the
distortion of the TRM signature when appearing cracks in thin aluminium plates. An
experimental set-up was used to validate the models.