A Polyreference Least Square Complex Frequency domain based statistical test for damage detection

2008 ◽  
Vol 41 (2) ◽  
pp. 4511-4516 ◽  
Author(s):  
Gilles Canales ◽  
Laurent Mevel ◽  
Michle Basseville
Keyword(s):  
Damage Detection ◽  
Frequency Domain ◽  
Statistical Test ◽  
Least Square ◽  
Complex Frequency ◽  
Square Complex

Research on Identification of Narrow Bandwidth

2012 ◽  
Vol 542-543 ◽  
pp. 1238-1241
Author(s):  
Qian Qiao ◽  
Wei Tang ◽  
Bin Bao ◽  
You Xin Cheng
Keyword(s):  
Frequency Domain ◽  
Numerical Stability ◽  
Modal Identification ◽  
Least Square ◽  
Complex Frequency ◽  
Numerical Problem ◽  
Domain Identification ◽  
Narrow Bandwidth ◽  
Stabilization Diagram ◽  
Square Complex

This paper addresses numerical problem when using poly-reference least square complex frequency-domain identification (p-LSCF) in narrow bandwidth. To solve this problem, a transformation using frequency scaling and shifting is proposed, which enable us to have a well conditioned p-LSCF algorithm. Finally, the cantilever test measurements are used to validate the conclusions of the paper. The results show that the enhanced p-LSCF algorithm with great numerical stability, clearer stabilization diagram and better modal identification.

Damage Assessment of Historic Buildings Hit by Earthquake

2014 ◽  
Vol 919-921 ◽  
pp. 1020-1026
Author(s):  
Giosuè Boscato ◽  
Alessandra Dal Cin
Keyword(s):  
Dynamic Behavior ◽  
Damage Assessment ◽  
Modal Identification ◽  
Least Square ◽  
Historic Buildings ◽  
Complex Frequency ◽  
Ambient Vibrations ◽  
Output Only ◽  
Square Complex ◽  
The Church

The Church of Gesù and the tower of the Cathedral were stricken and damaged by Emilia-Romagna earthquake sequence of May 2012. This paper presents the procedure for the structural identification of the most widespread types of religious monuments. The dynamic behavior was analyzed using the ambient vibrations test to measure the dynamical properties (mode of vibration, frequencies, displacements and damping ratios) of the constructions using a modal identification of output-only systems. The operational modal analysis OMA has been carried out to identify the modal characteristics through poly-reference Least Square Complex Frequency-domain (pLSFC) estimator. The global structural health monitoring was carried out to define the real dynamic behavior of the damaged constructions that are subjected to different mechanism. These researches are useful for the structural rehabilitation and to define the possible changes in the structural behavior.

Operational Modal Analysis in Absence of a Random Distributed Load

2011 ◽  
Author(s):  
Antonio Culla ◽  
Walter D’Ambrogio ◽  
Annalisa Fregolent
Keyword(s):  
Modal Analysis ◽  
Frequency Domain ◽  
Reference Method ◽  
Operational Modal Analysis ◽  
Least Square ◽  
Complex Frequency ◽  
Test Bed ◽  
Modal Parameter ◽  
Input Force ◽  
First Case

In this paper the performance of several modal parameter estimation techniques is compared by considering a simple mechanical structure as test bed. Specifically, among Input/Output (I/O) techniques, a frequency domain poly-reference method is considered. Among Operational Modal Analysis (OMA), Frequency Domain Decomposition and poly-reference least square complex frequency-domain techniques are used. I/O technique and OMA are performed using the measurements due to a random shaker excitation. In the first case the responses and the input force are used to calculate the FRFs. On the contrary, OMA is performed by using only the set of measured responses, by supposing unknown the input force. Note that the OMA hypothesis of a random distributed force is not observed. In order to characterise the performance of the examined methods, the results obtained by the OMA are compared to the result of the I/O technique.

scholarly journals A frequency‐domain approach for damage detection in welded structures

2021 ◽  
Author(s):  
Camilla Ronchei ◽  
Sabrina Vantadori ◽  
Andrea Carpinteri ◽  
Ignacio Iturrioz ◽  
Roberto Issopo Rodrigues ◽  
...  
Keyword(s):  
Damage Detection ◽  
Frequency Domain ◽  
Welded Structures ◽  
Frequency Domain Approach

scholarly journals Use of Time- and Frequency-Domain Approaches for Damage Detection in Civil Engineering Structures

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
V. H. Nguyen ◽  
J. Mahowald ◽  
S. Maas ◽  
J.-C. Golinval
Keyword(s):  
Damage Detection ◽  
Frequency Domain ◽  
Prestressed Concrete ◽  
Civil Engineering ◽  
Damage Identification ◽  
Real Life ◽  
Hankel Matrix ◽  
Principal Component ◽  
Engineering Structures ◽  
Civil Engineering Structures

The aim of this paper is to apply both time- and frequency-domain-based approaches on real-life civil engineering structures and to assess their capability for damage detection. The methodology is based on Principal Component Analysis of the Hankel matrix built from output-only measurements and of Frequency Response Functions. Damage detection is performed using the concept of subspace angles between a current (possibly damaged state) and a reference (undamaged) state. The first structure is the Champangshiehl Bridge located in Luxembourg. Several damage levels were intentionally created by cutting a growing number of prestressed tendons and vibration data were acquired by the University of Luxembourg for each damaged state. The second example consists in reinforced and prestressed concrete panels. Successive damages were introduced in the panels by loading heavy weights and by cutting steel wires. The illustrations show different consequences in damage identification by the considered techniques.

Optical Tomography With a Least Square Finite Element Formulation of the Collimated Irradiation in Frequency Domain

2010 ◽  
Author(s):  
Olivier Balima ◽  
Joan Boulanger ◽  
Andre´ Charette ◽  
Daniel Marceau
Keyword(s):  
Finite Element ◽  
Optical Properties ◽  
Frequency Domain ◽  
Complex Geometry ◽  
Numerical Study ◽  
Optical Tomography ◽  
Least Square ◽  
Finite Element Formulation ◽  
Element Formulation ◽  
Scattering Media

This paper presents a numerical study of optical tomography in frequency domain for the reconstruction of optical properties of scattering and absorbing media with collimated irradiation light sources. The forward model is a least square finite element formulation of the collimated irradiation problem where the intensity is separated into its collimated and scattered parts. This model does not use any empirical stabilization and moreover the collimated source direction is taken into account. The inversion uses a gradient type minimization method where the gradient is computed through an adjoint formulation. Scaling is used to avoid numerical round errors, as the output readings at detectors are very low. Numerical reconstructions of optical properties of absorbing and scattering media with simulated data (noised and noise-free) are achieved in a complex geometry with satisfactory results. The results show that complex geometries are well handled with the proposed method.

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