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Abstract:A three-dimensional finite element (FE) model of a four-ply fiber-reinforced
composite plate, with and without delamination, is developed using ABAQUS
software to investigate its vibration characteristics. Initially, modal analysis is
conducted on the undamaged (healthy) composite plate to examine the influence of
stacking sequence, boundary conditions (BCs), and fiber orientation angle on the
fundamental natural frequency. Four different stacking sequences are analyzed,
comprising two symmetric layups—[ϴ/ϴ/ϴ/ϴ] and [ϴ/-ϴ/-ϴ/ϴ]—and two antisymmetric layups—[ϴ/-ϴ/ϴ/-ϴ] and [ϴ/ϴ/-ϴ/-ϴ]. The boundary conditions
considered include Clamped-Free (CF), Clamped-Clamped (CC), Clamped-Simply
Supported (CS), and Simply Supported-Simply Supported (SS). The fiber
orientation angle (ϴ) is varied from 0° to 90° in 15° increments. The simulation
outcomes are validated by comparing them with existing numerical and
experimental results from the literature.
Subsequently, the developed plate model is employed to investigate the effect of
mid-plane circular delamination on the modal natural frequencies of the composite
structure. Delaminations of varying diameters—2 cm, 4 cm, and 8 cm—are
introduced at the mid-plane to assess their influence under different stacking
sequences and fiber orientation angles, consistent with the configurations used in
the healthy beam model. However, in this phase, the boundary condition is limited
to a single case: one edge clamped and the remaining edges free. The results reveal
that delamination size has a pronounced impact on the fundamental frequency, with
larger delaminations causing greater reductions. These findings highlight that
changes in modal parameters, particularly natural frequency, can serve as effective
indicators for detecting delamination in composite plates. |