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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
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.
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.
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