VIBRATION OF BEAMS WITH TWO NON-OVERLAPPING DELAMINATIONS UNDER AXIAL COMPRESSIVE LOADING

摘要

The free vibration of a homogeneous beam with two non-overlapping delaminations under axial compressive loading has been studied using the Euler-Bernoulli beam theory. The 'constrained mode' and the 'free mode' assumption in the study of delamination buckling and vibration were proposed. For both the 'constrained mode' and the 'free mode', the fundamental frequency decreases with the increase of the axial compressive loading. In the 'constrained mode', the fundamental frequency is the lowest when the delamination is located at the mid-plane. In both modes, beams with longer delamination length have lower fundamental frequency than beams with shorter delamination length. However, a beam in the 'constrained' mode has higher fundamental frequency than a beam in the 'free mode'. The fundamental frequency of the beam decreases as the delamination moves from the centre towards the end of the beam. The square of the primary frequency has a linear relationship with the compressive load normalized by the buckling load of the delaminated beam.