ABSTRACT
Advanced fiber-reinforced layered composites are increasingly used in various weight-sensitive industries due to their promising material characteristics such as high specific strength and stiffness, durability, fatigue resistance, etc. that can be tailored for specific applications. The layered composites are always subjected to a defect called delamination (detachment/separation of different consecutive laminas), which is an unavoidable and major cause of failure of these structures. The delamination originates in both manufacturing and service life stages. The introduction of foreign particles, improper curing, geometrical and material discontinuity, unfavorable environmental conditions, eccentric loading, dynamic loading, among other factors, causes the introduction of delamination during manufacturing and service life. The presence of delamination decreases the composite’s integrity and overall stiffness, which may lead to a reduction in natural frequency and resonance conditions. In view of the above, the free vibration responses of the laminated/delaminated composite plate structure have been investigated. First, a finite element model of the delaminated composite flat panel has been developed using a FEM-based modeling and analysis software package ABAQUS. Different shapes (square, circular, elliptical, and rectangular) and size of delamination are modeled using the sublaminate approach. The natural frequency of the modeled plates is obtained using an appropriate solver. Second, the validity of the developed model has been checked by comparing the frequency responses of the laminated and delaminated composite plate with that of the already published results. The effect of different shapes and sizes of delamination including the input parameters such as thickness ratio on natural frequency characteristics of the plate structure has been investigated and discussed in detail.
