Wave energy trapping and localization in a plate with a delamination

• Published in: Smart materials and structures 2012-12, Vol.21 (12), p.125001-1-12
• Main Authors: Glushkov, Evgeny, Glushkova, Natalia, Golub, Mikhail V, Moll, Jochen, Fritzen, Claus-Peter
• Format: Article
• Language: English
• Subjects: Cracks; Delaminating; Delamination; Mathematical models; Oscillations; Plates (structural members); Position (location); Trapping
• ISSN: 0964-1726; 1361-665X
• DOI: 10.1088/0964-1726/21/12/125001

The research aims at an experimental approval of the trapping mode effect theoretically predicted for an elastic plate-like structure with a horizontal crack. The effect is featured by a sharp capture of incident wave energy at certain resonance frequencies with its localization between the crack and plate surfaces in the form of energy vortices yielding long-enduring standing waves. The trapping modes are eigensolutions of the related diffraction problem associated with nearly real complex points of its discrete frequency spectrum. To detect such resonance motion, a laser vibrometer based system has been employed for the acquisition and appropriate visualization of piezoelectrically actuated out-of-plane surface motion of a two-layer aluminum plate with an artificial strip-like delamination. The measurements at resonance and off-resonance frequencies have revealed a time-harmonic oscillation of good quality above the delamination in the resonance case. It lasts for a long time after the scattered waves have left that area. The measured frequency of the trapped standing-wave oscillation is in a good agreement with that predicted using the integral equation based mathematical model.