Transverse vibration of composite beams with two non-overlapping delaminations using DTM

Delamination is one of the most common types of damage in laminated fibre-reinforced composites due to their relatively weak interlaminar strengths. It causes a drastic reduction of the bending stiffness of a composite structure. Therefore, the vibrational characteristics are sensitive to the delamination. This paper introduces the differential transform method (DTM) to analyze the free vibration of a composite beam with two non-overlapping delaminations. This method has the advantage of reducing the calculations time by changing the sinusoidal solutions into polynomial ones. Moreover, the effect of delaminations length, spanwise and thicknesswise location of the delaminations and boundary conditions on the natural frequency are investigated. It is discovered that delamination reduces the natural frequencies of the beam.The more delamination length increases, the more the natural frequency decreases.The decrement is more significant as the delamination approaches the midplane of the beam. It is observed that the frequencies decrease as the delaminations move away from the center of the beam. Delamination influence on different boundary conditions is studied. More restrained boundary conditions such as clamped supports increase the rate of reduction of the natural frequency

کلیدواژه ها:

free vibration ، composite beams ، delamination ، differential transform method