Damage detection in elastic structures using vibratory residual forces and weighted sensitivity

Abstract

A methodology is presented for detecting structural damage in elastic structures by nondestructive means. Measured modal test data along with a correlated analytical structural model are used to locate potentially damaged regions using residual modal force vectors and to conduct a weighted sensitivity analysis to assess the extent of mass and/or stiffness variations, where damage is characterized as a stiffness reduction. The current approach is unique among other approaches in that it accounts for 1) variations in system mass, system stiffness, and mass center locations, 2) perturbations of both the natural frequencies and modal vectors, and 3) statistical confidence factors for the structural parameters and potential experimental instrumentation error. Moreover, this procedure can be used with either full or reduced models. A wide variety of numerical examples are presented that show that the current method provides a precise indication of both the location and the extent of structural damage.

Structural Health Monitoring Studies of the Alamosa Canyon and I-40 Bridges

“…The Hemez/Alvin algorithm [Hemez and Farhat (1995), Alvin (1996)] computes the sensitivities at the elemental level, then assembles them to produce the global sensitivity matrices. The Ricles/Kosmatka algorithm [Ricles and Kosmatka (1992)] computes a "hybrid" sensitivity matrix using both analytical and experimental sensitivities. …”

Detection of Spring Support Locations in Elastic Structures Using a Gradient-Based Finite Element Model Updating Technique

“…Based on a concept similar to Ricles and Kosmatka [34] in their study on crack identi"cation in structures, a modi"ed estimate of the system sti!ness derivative has been constructed as given below…”

“…Using these methods, many research studies on the crack identi"cation are also reported using residual modal force as an updating parameter. A few examples are the research studies by Chen et al [32], Haug et al [33], Ricles et al [34], Farhat et al [35] and Hemez et al [36].…”

Damage identification of structures with uncertain frequency and mode shape data

“…This method is based on the fact that structural damages usually cause decrease in the structural sti ness, which produces changes in the vibration characteristics (notably frequencies, mode shapes and damping) of the structure. The vibration data used for damage detection are such types as frequency response function [2], natural frequency [3][4][5], mode shape [6][7][8], mode shape curvature [9], modal exibility [10; 11], and modal strain energy [12], etc. Early damage detection methods use natural frequency changes as damage indicator.…”