Numerical and experimental investigation of free vibration of multilayer delaminated composite beams and plates

The use of vibration-monitoring techniques as non-destructive methods for d etection of delaminations in layered composite beam and plate structures is a current field of interest for many researchers. However, an extensive se arch of published literature shows that information on numerical and especi ally experimental investigations into the dynamic behaviour of delaminated layered composite beams and plates is limited. For this reason the present authors have developed theoretical models and carried out an extensive expe rimental investigation to establish changes in the first three bending natu ral frequencies due to delaminations. The subsequent results of these numer ical calculations are consistent with the results of the corresponding expe rimental investigations. As the result of this work models of a finite delaminated beam element and delaminated plate element have been developed. The method of modelling dela minations presented in this work enables its easy modification according to specific cases of damage (i.e. multiple delaminations).