Dynamic Study of Composite Cracked Beam by Changing the Angle of Bidirectional Fibres

Composite beam type structures fail in the presence of cracks. While in use the crack depth gradually increases, the structural stiffness decreases and as a result the beam becomes weaker than its earlier conditions. At the end, the beam may collapse because of an initial or developed small crack. Hence, identification of the crack and its severity is a challenge for researchers. In the present work, vibration signatures were used to detect the crack position as well as crack depth in a cracked FRP composite beam. Seven types of epoxy-glass fibres bidirectional (woven) composite beams made of 13 layers oriented along 0°, 7.5°, 15°, 22.5°, 30°, 37.5° and 45° with clamp-free end condition were studied. Fibre orientation effects on the FRP composite beam with varying crack location and crack depth were evaluated using analytical, finite element methods and Sugeno-fuzzy approach. The results were obtained and verified by experiments. The outcomes of all the methods were in good agreement. It was concluded that the natural frequency and mode shape in free vibration were largely affected by orientation of fibre and crack location and its depth.