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Proceedings Paper

Guided-wave-based damage detection in a composite T-joint using 3D scanning laser Doppler vibrometer
Author(s): Ganesh Kolappan Geetha; D. Roy Mahapatra; Gopalakrishnan Srinivasan
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Paper Abstract

Composite T-joints are commonly used in modern composite airframe, pressure vessels and piping structures, mainly to increase the bending strength of the joint and prevents buckling of plates and shells, and in multi-cell thin-walled structures. Here we report a detailed study on the propagation of guided ultrasonic wave modes in a composite T-joint and their interactions with delamination in the co-cured co-bonded flange. A well designed guiding path is employed wherein the waves undergo a two step mode conversion process, one is due to the web and joint filler on the back face of the flange and the other is due to the delamination edges close to underneath the accessible surface of the flange. A 3D Laser Doppler Vibrometer is used to obtain the three components of surface displacements/velocities of the accessible face of the flange of the T-joint. The waves are launched by a piezo ceramic wafer bonded on to the back surface of the flange. What is novel in the proposed method is that the location of any change in material/geometric properties can be traced by computing a frequency domain power flow along a scan line. The scan line can be chosen over a grid either during scan or during post-processing of the scan data off-line. The proposed technique eliminates the necessity of baseline data and disassembly of structure for structural interrogation.

Paper Details

Date Published: 20 April 2012
PDF: 12 pages
Proc. SPIE 8348, Health Monitoring of Structural and Biological Systems 2012, 83481Q (20 April 2012); doi: 10.1117/12.917600
Show Author Affiliations
Ganesh Kolappan Geetha, Indian Institute of Science (India)
D. Roy Mahapatra, Indian Institute of Science (India)
Gopalakrishnan Srinivasan, Indian Institute of Science (India)


Published in SPIE Proceedings Vol. 8348:
Health Monitoring of Structural and Biological Systems 2012
Tribikram Kundu, Editor(s)

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