Abstract—The composite materials are well known by their excellent combination of high structural stiffness and low weight. Their inherent anisotropy allows the designer to tailor the material in order to achieve the desired performance requirements. However the delamination which is one of the serious defects often develops and propagates in composite structure. The presence of delamination warrants the design life of the structure and the safety. Hence the presence of such defect has to be detected in time to plan the remedial action well in advance. The present study involves extensive experimental works to investigate the free vibration of woven fiber Glass/ Epoxy composite laminate plates in simply supported boundary conditions based on the comparison between natural frequencies of the healthy and delaminated composite laminate plates. The square specimens of woven glass fiber and epoxy matrix composite were manufactured by the handlayup technique with different areas of artificial delamination. Elastic parameters of the plate were also determined experimentally by tensile testing. The present free vibration experiments were used to validate the results obtained from the FEM numerical analysis. A three-dimensional finite element modelling was employed to simulate the dynamic response of composite laminated plates with and without delamination to extract their natural frequencies. The effect of increasing delamination area on natural frequencies was studied experimentally and numerically. The natural frequencies extracted from the current numerical simulations were compared with experimental results. Numerical results showed a good agreement with available experimental data.

Index Terms—Laminated composite material, Finite element method, Free vibration test, Delamination

Cite: R Sultan, S Guirguis, M Younes, and E El-Soaly, "Delamination Identification on Composite Material by Free Vibration Test," International Journal of Mechanical Engineering and Robotics Research, Vol.1, No.3, pp. 227-236, October 2012.