Vibration Analysis and Damping Characteristics of Delaminated Composite Laminates

Abstract

Fiber reinforced composite laminates are rapidly replacing metallic components in various structures.However sometimes due to manufacturing defect or loading conditions debonding occurs between layers leading to delaminations. This may cause significant reduction in the strength and stiffness of composite laminates as out of plane displacements can easily occur in such conditions. Vibration analysis is an important part of structural analysis of composite structures. In present scenario, where vibration of machinery or structural components is unavoidable determination of the components’ damping characteristics is also important. The current works is based on study the effects of geometry, boundary conditions, fiber properties, orientations,delamination size, distance between multiple delaminations on the non-dimensional frequencies and damping characteristics of laminates. The eight noded isoparametric shell element based on first order shear deformation theory is adopted for the finite element modelling to analyze the composite laminates. The damping properties of the laminates are quantized by the means of Specific Damping Capacity model

Numerical results for variation of first mode non-dimensional frequency and specific damping with various geometric and material properties of laminates, boundary conditions and delamination sizes, numbers and locations have been discussed here. As obvious, the first mode frequency decreases with increase in delaminations. Conversely, the specific damping capacity increases with increase in delamination. This may be due to easy dissipation of energy from the failure points.