Damage Characterisation in FRP Sandwich Beams using a Wavelet based Multifractal Approach

Dawood, Tariq
Shenoi, Ajit R.
Veres, S. M.
Gunning, M. J.
Fibre reinforced plastic (FRP) sandwich composite materials are widely used in the construction of aerospace and marine structures. A cause for concern however in the use of these materials is the fact that internal defects can occur between layers which, if not identified early on, can lead to rapid structural degradation. This paper describes an approach, based on measuring structural vibration characteristics, to identify these internal defects. The idea being that an occurrence of a defect of this nature, within the structure, would alter the singularity properties of the structure’s vibration signal. Using the wavelet transform modulus maxima method to perform multifractal analysis, a spectrum of the distribution of the singularities present in the structure’s vibration signal can be obtained in the form of a Lipschitz exponent distribution, which is a measure of singularity strength. To demonstrate the validity of this approach, a defect in the form of a debond between the core-skin interface is investigated experimentally for a number of FRP sandwich beams containing embedded fibre optic Bragg grating (FBG) strain sensors. Unique features in the Lipschitz exponent distribution which are sensitive to defect characteristics such as severity and location are highlighted which provide a basis for comprehensive assessment of damage in FRP sandwich beams.
Citation Formats
T. Dawood, A. R. Shenoi, S. M. Veres, and M. J. Gunning, “Damage Characterisation in FRP Sandwich Beams using a Wavelet based Multifractal Approach,” 00, 2004, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/80513.