Analysis of elastic nonlinearity for impact damage detection in composite laminates

Abstract

This paper concerns the experimental analysis of nonlinear response features of a
\ncomposite laminate plate for impact damage detection. The measurement procedure is based on
\nthe Scaling Subtraction Method (SSM) and consists in exciting the damaged specimen with two
\nsinusoidal signals at different amplitude. The linearly rescaled response signal at low amplitude
\nexcitation is subtracted from the response at large amplitude excitation to extract the nonlinear
\nsignatures. The latter are analysed in the time domain to infer the presence of damage. Results
\nare compared with frequency domain analyses using the nonlinear vibro-acoustic modulation
\ntechnique (NWMS). Changes in amplitude and phase as well as modulation effects of the
\nacquired responses are also monitored. Surface-bonded, low profile piezoceramic transducers
\nare used for excitation and sensing. Both measurements techniques are applied to detect barely
\nvisible impact damage in laminate composite plate. Non-destructive penetrant-enhanced X-ray
\ninspections are carried out to characterize the extent of internal damage. The behavior of the
\nnonlinear features and the sensitivity of each technique are also investigated in the paper.