Volume 8, Issue 1, 1999

Application Of The Rapid Frequency Sweep Technique For Delamination Detection In Composite Laminates

S.H. Diaz Valdes and C. Soutis¹

Department of Aeronautics Imperial College of Science Technology and Medicine, Prince Consort Road, SW7 2BY, London, U.K.

¹author to whom correspondence should be addressed

ABSTRACT

As a first step in developing a health monitoring system, the effect of delamination on the natural frequencies of laminated composite beams has been investigated. A piezoceramic patch driven with a linear rapid frequency sweep was used to induce vibrations on the structure and its response registered via piezoelectric film sensors. Modal frequencies were obtained through a method defined here as the maximum amplitude at resonance (MAR), which has proved to be a simple and effective procedure. Changes of the modal frequencies after delamination initiation, compared to those of an uncracked (non-delaminated) specimen, gave a good indication of the degree of damage, especially at high modal frequencies (9-12 kHz).