DAMAGE DETECTION IN STRUCTURES: FROM MODE SHAPE TO FREQUENCY RESPONSE FUNCTION METHODS

2003 ◽  
Vol 17 (3) ◽  
pp. 489-498 ◽  
Author(s):  
N.M.M. MAIA ◽  
J.M.M. SILVA ◽  
E.A.M. ALMAS ◽  
R.P.C. SAMPAIO
Keyword(s):  
Damage Detection ◽  
Frequency Response ◽  
Response Function ◽  
Mode Shape ◽  
Frequency Response Function

Structural damage detection in plates using a deep neural network–couple sparse coding classification ensemble method

2020 ◽  
pp. 107754632092915
Author(s):  
Vahid Bokaeian ◽  
Faramarz Khoshnoudian ◽  
Milad Fallahian
Keyword(s):  
Damage Detection ◽  
Frequency Response ◽  
Response Function ◽  
Sparse Coding ◽  
Structural Damage ◽  
Frequency Response Function ◽  
Principal Component ◽  
Plate Structures ◽  
Feature Extraction Method ◽  
Damage Scenarios

The present study aims at identifying damages in plate structures by applying a pattern recognition–based damage detection technique using the frequency response function. The large number of degrees of freedom is one of the crucial obstacles in the way of accurately identifying damages in plate structures. On the other hand, frequency response functions include many details that dramatically lower the computing speed and enlarge the memory needed for storing data, hampering the application of this method. Furthermore, this study performs principal component analysis as an authoritative feature extraction method with the purpose of reducing the dimensions of the measured frequency response function data and generating distinct feature patterns. Also, because there has been no individual optimal classifier applicable to all problems, an ensemble comprising two powerful classifiers containing couple sparse coding classification and deep neural networks is used to predict the structure damage. This study evaluates the accuracy of damage detection by the proposed method in square-shaped structural plates with the lengths of 1 m and 2 m under different damage scenarios, namely, single and multiple element.

scholarly journals Identification of damage-expected members of truss structures using frequency response function

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668791 ◽  
Author(s):  
Moon-Jeong Kim ◽  
Hee-Chang Eun
Keyword(s):  
Damage Detection ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Truss Structure ◽  
Truss Structures ◽  
Modal Data ◽  
Damage Indices ◽  
Proper Orthogonal Modes ◽  
Proper Orthogonal

A damaged member in a truss structure leads to a variation in the initial responses of its adjacent members. A flexibility-based approach extracting from the modal data should be implemented as one of the structural damage detection methods. The frequency response function data as dynamic measurements provide more information on the system characteristics compared with modal data. Proper orthogonal modes from the frequency response functions extracted in the given frequency ranges and their modified forms can be utilized as damage indices to detect damages. This study considers damage detection of a truss structure using a frequency response function–based approach transformed to the proper orthogonal modes and a flexibility-based approach using the first few modal data for undamaged and damaged states. The utilization of these two methods is compared through numerical experiments on truss structures. The methods can rarely detect the damaged member accurately, but a group of damage-expected members is detected despite the existence of external noise. It is shown that the frequency response function–based approach can be utilized more explicitly than the flexibility-based approach.

DAMAGE DETECTION USING THE FREQUENCY-RESPONSE-FUNCTION CURVATURE METHOD

1999 ◽  
Vol 226 (5) ◽  
pp. 1029-1042 ◽  
Author(s):  
R.P.C. SAMPAIO ◽  
N.M.M. MAIA ◽  
J.M.M. SILVA
Keyword(s):  
Damage Detection ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function

scholarly journals Damage detection based on output-only measurements using cepstrum analysis and a baseline-free frequency response function curvature method

2022 ◽  
Vol 105 (1) ◽  
pp. 003685042110644
Author(s):  
Ayisha Nayyar ◽  
Ummul Baneen ◽  
Muhammad Ahsan ◽  
Syed A Zilqurnain Naqvi ◽  
Asif Israr
Keyword(s):  
Damage Detection ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Damage Index ◽  
Real Life ◽  
System Response ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Output Only

Low-severity multiple damage detection relies on sensing minute deviations in the vibrational or dynamical characteristics of the structure. The problem becomes complicated when the reference vibrational profile of the healthy structure and corresponding input excitation, is unavailable as frequently experienced in real-life scenarios. Detection methods that require neither undamaged vibrational profile (baseline-free) nor excitation information (output-only) constitute state-of-art in structural health monitoring. Unfortunately, their efficacy is ultimately limited by non-ideal input excitation masking crucial attributes of system response such as resonant frequency peaks beyond first (few) natural frequency(ies) which can better resolve the issue of multiple damage detection. This study presents an improved frequency response function curvature method which is both baseline-free and output-only. It employs the cepstrum technique to eliminate [Formula: see text] decay of higher resonance peaks caused by the temporal spread of real impulse excitation. Long-pass liftering screens out the bulk of low-frequency sensor noise along with the excitation. With more visible resonant peaks, the cepstrum purified frequency response functions (regenerated frequency response functions) register finer deviation from an estimated baseline frequency response function and yield an accurate damage index profile. The simulation and experimental results on the beam show that the proposed method can successfully locate multiple damages of severity as low as 5%.

scholarly journals Modal Mass and Length of Mode Shapes in Structural Dynamics

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
M. Aenlle ◽  
Martin Juul ◽  
R. Brincker
Keyword(s):  
Frequency Response ◽  
Response Function ◽  
Structural Dynamics ◽  
Mode Shape ◽  
Physical Meaning ◽  
Frequency Response Function ◽  
Degrees Of Freedom ◽  
Mode Shapes ◽  
Length Measure ◽  
Modal Mass

The literature about the mass associated with a certain mode, usually denoted as the modal mass, is sparse. Moreover, the units of the modal mass depend on the technique which is used to normalize the mode shapes, and its magnitude depends on the number of degrees of freedom (DOFs) which is used to discretize the model. This has led to a situation where the meaning of the modal mass and the length of the associated mode shape is not well understood. As a result, normally, both the modal mass and the length measure have no meaning as individual quantities but only when they are combined in the frequency response function. In this paper, the problems of defining the modal mass and mode shape length are discussed, and solutions are found to define the quantities in such a way that they have individual physical meaning and can be estimated in an objective way.

Sign in / Sign up

Export Citation Format

Share Document