Wave reflection and transmission in composite beams containing semi-infinite delamination

Wave reflection and transmission in composite beams containing a semi-infinite delamination is studied analytically based on Timoshenko beam theory. Two extreme cases of delaminated surface conditions: non-contact (open) and fully contact (closed) delaminations, are examined, respectively, for a unidirectional composite beam. Analytical solutions of reflection and transmission coefficients for time harmonic flexural waves in a semi-infinite delaminated beam are obtained. The portion of reflected and transmitted power (energy) depends strongly on the frequency of the incident flexural waves as well as the delamination position. The power reflection and transmission ratios are also calculated and verified through energy conservation. The transmitted energy among various wave modes is also investigated. The interaction of narrowband incident wave with delamination at different positions through the thickness of a composite beam is then studied by analytical analysis and verified by finite element analysis.