Novel Vibration-Based Methods for Detecting Delamination Damage in Composite Plate and Shell Laminates

Abstract

The paper describes an on-going research effort aimed at detecting the presence of delamination damage in composite panels based upon their higher-frequency structural response. Two alternative damage indexes are examined that facilitate the identification of the location and extent of delaminations. The damage indexes do not require vibration measurements to be performed on the undamaged structure. Use is made of the bending and twisting curvatures corresponding to the higher-frequency mode shapes that are post-processed via two different smoothing techniques. The modal data are obtained via finite element models based on Mindlin theory and including delaminations. These are introduced using a sub-laminate strategy that permits multiple damages to be modelled through the thickness. Various delamination sizes and locations are examined with a random noise superposed on the data in order to ascertain the degree of sensitivity of the damage index to the noise in the experimental data.