Theoritical and experimental investigation of crack identification in fiber reinforced composite beams using vibration analysis

Abstract

The issue of crack/damage detection and diagnosis has gained wide spread newlineindustrial interest. It also affects the industrial economic growth. Generally damage/crack in a structural element may occur due to normal operations, accidents, deterioration or severe natural events such as earth quake or storms. The presence of cracks changes the physical characteristics of a structure which in turn alter its dynamic response newlinecharacteristics. Therefore, there is a need to understand the dynamics of cracked newlinestructures. Identification of crack depths and their location from reference point are the standard methods in performance monitoring of the structures. Currently available Non Destructive Testing (NDT) methods, such as acoustic, ultrasonic and magnetic field methods are time consuming. Vibration analysis based technique has been proved quick and inexpensive for crack identification. The vibration analysis of a physical system consists of four major steps namely mathematical modeling of a physical system, formulation of governing equations, mathematical solution of the governing equation, and physical interpretation of the results. In the present work, an attempt has been made to develop a mathematical model newlineof cracked composite beams based on elasto-plastic fracture mechanics techniques in newlineorder to consider the crack tip plasticity in the analysis. Irwin s plastic zone correction newlinefactor is considered for crack model. A finite element model has been developed to newlineformulate the stiffness matrices for single edge cracked structural elements using transfer matrix theory. These matrices take into account, the effects of axial, flexural and shear newlinedeformations due to crack presence. The composite beam with edge crack and transverse newlineloading is considered. The bending stiffness matrix of composite beam is developed. newlineEigen values of laminated composite beams at different crack depth and location are newlinecalculated.