Damage Detection in Composite Beam Using Numerical Modal Analysis

Abstract

There is a pressing need to develop effective techniques for structural health monitoring (SHM), so that the safety and integrity of the structures can be improved. The main objective of this study is to evaluate the damage detection techniques for the composite beam. Cost-effective and reliable damage detection is critical for the utilization of composite materials. The study is carried out both analytical and experimental methods for the detection of damage in composite materials and the results are presented in this paper. A crack in a structure will affect the modal parameters both locally as well as globally. The present work discusses the studies carried out using those parameters that get changed locally and globally as well as a procedure to identify the crack location. Structural damage detection has gained increasing attention from the scientific community since unpredicted major hazards, most with human losses, have been reported. Aircraft crashes and the catastrophic bridge failures are some examples. Since damage alters the dynamic characteristics of a structure, namely its eigen properties (natural frequencies, modal damping and modes of vibration), several techniques based on experimental modal analysis have been developed in recent years. A cantilever composite beam was considered and modeled. The crack was introduced and analyzes the propagation of the crack. The crack is a through-thickness one, growing along the breadth of the beam starting from one edge. The location of the crack is also moved from the fixed end to the free end along its length. The changes in natural frequencies are observed from analytical study, due to the presence of the crack at different locations and depths and 2-Dfinite element models were created the percentage change in frequency values are calculated. These results are confirmed by the experiments. The numerical finite element (FE) analysis is performed to complement the damage detection by using different algorithms. Due to refined analysis of FE approach, all the algorithms are viable of detecting the damage using the FE data. The add-on advantage of the damage detection algorithms (Gapped Smoothing Method and Strain Energy Method) is that the data from the healthy beam are not required as the reference, thus simplifying the detection process.