Characterization of delamination-type damages in composite laminates using guided wave visualization and air-coupled ultrasound

Abstract

This article reports on the characterization of delamination damages in composite laminates using wave visualization method. A combination of plate-guided ultrasound and air-coupled ultrasonics is used to locate and visualize delaminations. The study focuses on the physics of Lamb wave propagation and interaction with delaminations at various through-thickness locations and positions. Three-dimensional finite element simulations are used to study, in detail, the changes in wave features such as mode velocity, wavelength and wave refraction in the delamination region. These wave features provide information on the location, position and orientation of the delamination. These studies are validated by experimental measurements. The influence of position of source and delamination on wave refraction in the delamination region is examined. This method also correlates the results obtained from experiments and finite element simulations to theoretical dispersion curves in order to distinctly determine the delamination location.

In-situprocess- and online structural health-monitoring of composites using embedded acoustic waveguide sensors

“…Confinement similar to the effect of a sleeve was achieved by imposing Dirichlet (rigid boundary) conditions at the top and bottom edges of the strip, with continuity conditions at the 'sleeve opening' connecting the 'strip' to the epoxy substrate. The average element size in epoxy region was λ/14, whereas in waveguide it was λ/200 (where λ=wavelength of the wave in the waveguide) [10,11,26]. In-plane excitation consisting of a Hanning-windowed toneburst centered at 100 kHz was provided at one end of the strip, generating S 0 -type guided waves.…”

“…Typically, guided wave based structural health monitoring approaches for composites use surface bonded piezoelectric or magnetostrictive transducers [7][8][9][10][11][12][13][14][15][16]. Surface-bonded transducers generate cylindrical (twodimensional) waves, which decay away from the source, limiting the field of view, especially in inaccessible/ hidden regions of complex structures.…”

“…Here we seek to develop a novel embedded waveguide sensor concept for detecting and monitoring the condition of composites, during curing and service. Guided wave based NDE and SHM approaches have been proposed for composites, but these are typically based on surface-bonded transducers (see [7][8][9][10][11][12][13][14][15][16] referred above). Embedded fiber-based optical waveguide approaches have also been reported [17,18].…”

Air-Coupled Excitation of a Slow A0 Mode Wave in Thin Plastic Films by an Ultrasonic PMN-32%PT Array

“…There are cases when guided ultrasonic waves may be excited only by contactless, e.g., air-coupled, techniques: hygroscopic materials like paper, thin flexible materials like plastic films, or specimens moving with a high velocity [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. For non-destructive testing purposes, the antisymmetric A 0 Lamb wave mode is widely used because it is sensitive to various types of defects, which are met especially in composite materials [ 10 ].…”

Non-contact damage detection on a rotating blade by Lamb wave analysis

“…By means of LU, defects, such as cavities [18], cracks [2] [24], and holes [25] have been detected, sized, and imaged in plates. Imaging of delamination defects on wind turbine blades has been achieved by B.Park et.al [9].Ultrasonic methods such as contacting, air coupled, and immersion, transducers have also been used to determine the size of cracks [26], holes [13], bonding flaws [27] [18] and delaminations [28] in plates and even to study stress accumulation in automobile break pads [29].…”