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Page 1 of 34 A SUMMARY REVIEW OF VIBRATION-BASED DAMAGE IDENTIFICATION METHODS Scott W. Doebling, Charles R. Farrar, and Michael B. Prime Engineering Analysis Group Los Alamos National Laboratory Los Alamos, NM ABSTRACT This paper provides an overview of methods to detect, locate, and characterize damage in structural and mechanical systems by examining changes in measured vibration response. Research in vibration-based damage identification has been rapidly expanding over the last few years. The basic idea behind this technology is that modal parameters (notably frequencies, mode shapes, and modal damping) are functions of the physical properties of the structure (mass, damping, and stiffness). Therefore, changes in the physical properties will cause detectable changes in the modal properties. The motivation for the development of this technology is presented. The methods are categorized according to various criteria such as the level of damage detection provided, model-based vs. non-model-based methods and linear vs. nonlinear methods. The methods are also described in general terms including difficulties associated with their implementation and their fidelity. Past, current and future-planned applications of this technology to actual engineering systems are summarized. The paper concludes with a discussion of critical issues for future research in the area of vibration-based damage identification. INTRODUCTION The interest in the ability to monitor a structure and detect damage at the earliest possible stage is pervasive throughout the civil, mechanical, and aerospace engineering communities. For the purposes of this paper, damage is defined as changes introduced into a system, either intentional or unintentional, which adversely effect the current or future performance of that system. These systems can be either natural or man-made. As an example, an anti-aircraft missile is typically fired to intentionally introduce damage that will immediately alter the flight characteristics of the target aircraft. Biological systems can be unintentionally subject to the damaging effects of ionizing radiation. However, depending on the levels of exposure, these systems may not show the adverse effects of this damaging event for many years or even future generations. Implicit in this definition of damage is that the concept of damage is not meaningful without a comparison between two different states of the system, one of which is assumed to represent the initial, and often undamaged, state. Most currently used damage identification methods are included in one of the following categories: visual or localized experimental methods such as acoustic or ultrasonic methods, magnetic field methods, radiography, eddy-current methods or thermal field methods (Doherty, 1997). All of these experimental techniques require that the vicinity of the damage is known a
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Page 2 of 34 priori and that the portion of the structure being inspected is readily accessible. The need for
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This note was uploaded on 02/08/2010 for the course MECHANICAL 6371 taught by Professor Ha during the Winter '10 term at Concordia Canada.

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