Guided elastic waves and their impact interaction in CFRP structures characterized by 3D laser scanning vibrometry

Abstract

The paper presents guided elastic waves and their identification and damage interaction in a CFRP plate. After the excitation of a fiber transducer, different elastic waves emerge in a plate. By using specially developed 3D laser scanning software it was possible to specify the different wave modes. These wave modes have been described concerning their propagating velocities and different motion components. The interaction of different wave modes with introduced impact damage (7J) is shown. In some expts., it was proven that impact locations can be derived from the detected Lamb waves. This work is continued to develop structural health monitoring systems (SHM) for selected aircraft components (e. g. stringer elements, panels)

Guided wave excitation by a CLoVER transducer for structural health monitoring: theory and experiments

“…This set is characterized by the fact that both edges of the transducer, inner and outer, send waves propagating in the positive radial direction (henceforth referred to as outward direction). The form of the solution, i.e., the combination of equations (18) and (31), suggests that the integral definition of the Bessel function of kth order be used:…”

Measurement of the Rayleigh wave polarization using 1D Laser vibrometry

“…As an alternative, the resolution of the displacement components can also be achieved through 1D-SLDVs by repeating the experiments at various angles of incidence, provided knowledge of such angles and of the location of the specimen with respect to the Laser head. This approach, which has been demonstrated and presented in [11,12], is very attractive since it avoids the large equipment costs associated with 3D-SLDVs and their hardware. Specifically in [12], the three velocity components of Lamb and Shear Horizontal waves are evaluated through three 1D-SLDV measurements, and subsequently post-processed to investigate the interaction of Lamb waves with damage in composite plates.…”

“…This approach, which has been demonstrated and presented in [11,12], is very attractive since it avoids the large equipment costs associated with 3D-SLDVs and their hardware. Specifically in [12], the three velocity components of Lamb and Shear Horizontal waves are evaluated through three 1D-SLDV measurements, and subsequently post-processed to investigate the interaction of Lamb waves with damage in composite plates.…”

“…The current paper applies a similar approach as in [12] to demonstrate the feasibility of 1D-SLDV for wave polarization measurements. The study focuses on the Rayleigh wave, for which measured polarizations are compared with analytical ones as presented in classical reference books [5].…”

A baseline‐free and non‐contact method for detection and imaging of structural damage using 3D laser vibrometry

“…In a number of recent studies, SLV systems were applied to detect and visualise damage in both metallic and composite components . In particular, the SLV systems were employed to create wavefield images around structural defects with a high spatial resolution , as well as to experimentally investigate the mode conversion effects as a result of wave scattering from various types of defects . In addition, advanced signal and post‐processing techniques have been developed over the past 5 years to improve the accuracy and resolution of structural defect imaging systems based on 1D and 3D SLV .…”