scholarly journals Fatigue damage identification by means of modal parameters

2011 ◽  
Vol 10 ◽  
pp. 1697-1702 ◽  
Author(s):  
F. Curà ◽  
A.E. Gallinatti
Keyword(s):  
Fatigue Damage ◽  
Damage Identification ◽  
Modal Parameters

Free Vibration of Damaged Beam Structure with a Notch Defect

2012 ◽  
Vol 226-228 ◽  
pp. 44-47 ◽  
Author(s):  
Jiang Yi Chen ◽  
Li Ge Fan ◽  
Dong Chen Qin
Keyword(s):  
Damage Identification ◽  
Delta Function ◽  
Theoretical Background ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Beam Structure ◽  
Arbitrary Boundary ◽  
Numerical Examples ◽  
Elastically Supported ◽  
Universal Expression

In this paper, we derive the universal expression of the modal parameters for a damaged beam under arbitrary boundary conditions. The delta function is first employed to describe a notch damage in the beam and consequently to derive the governing equation for the damaged beam. Second, by virtue of the perturbation method, the eigenvalues and the corresponding mode shapes are obtained for the damaged beam. Finally, numerical examples are given for an elastically supported beam. It is believed that the proposed approach could provide the necessary theoretical background for damage identification in beam structures.

Fatigue damage in bending of reinforced concrete frames using non-destructive tests for dynamic strength of the cylinder

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Dragan D. Milašinović ◽  
Aleksandar Landović ◽  
Danica Goleš
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Damage ◽  
Cross Section ◽  
Modal Parameters ◽  
The Finite Element Method ◽  
Concrete Frames ◽  
Content Type ◽  
Non Destructive

PurposeThe purpose of this paper is to contribute to the solution of the fatigue damage problem of reinforced concrete frames in bending.Design/methodology/approachThe problem of fatigue damage is formulated based on the rheological–dynamical analogy, including a scalar damage variable to address the reduction of stiffness in strain softening. The modal analysis is used by the finite element method for the determination of modal parameters and resonance stability of the selected frame cross-section. The objectivity of the presented method is verified by numerical examples, predicting the ductility in bending of the frame whose basic mechanical properties were obtained by non-destructive testing systems.FindingsThe modal analysis in the frame of the finite element method is suitable for the determination of modal parameters and resonance stability of the selected frame cross-section. It is recommended that the modulus of elasticity be determined by non-destructive methods, e.g. from the acoustic response.Originality/valueThe paper presents a novel method of solving the ductility in bending taking into account both the creep coefficient and the aging coefficient. The rheological-dynamical analogy (RDA) method uses the resonant method to find material properties. The characterization of the structural damping via the damping ratio is original and effective.

A particle filter-based model selection algorithm for fatigue damage identification on aeronautical structures

2017 ◽  
Vol 24 (11) ◽  
pp. e2002 ◽  
Author(s):  
Francesco Cadini ◽  
Claudio Sbarufatti ◽  
Matteo Corbetta ◽  
Marco Giglio
Keyword(s):  
Model Selection ◽  
Particle Filter ◽  
Fatigue Damage ◽  
Damage Identification ◽  
Selection Algorithm

Research on Modal Analysis of Aero-Engine Key Parts Structure Damage

2016 ◽  
Vol 693 ◽  
pp. 187-193
Author(s):  
Yan Xiao Huang ◽  
Shu Ming Li ◽  
Ying Zhang
Keyword(s):  
High Speed ◽  
Damage Identification ◽  
Modal Parameters ◽  
Element Analysis ◽  
Structure Damage ◽  
Modal Theory ◽  
The Finite Element Analysis ◽  
Aero Engine ◽  
Inherent Frequency ◽  
Damage Extent

As the premise, exploring aero-engine structure parts damage accurately can guarantee safety of the aero-engine structure parts, which are restricted by the working condition under the high temperature, high pressure and high speed. Analyzed the structure parts modal parameters by the modal theory, and researched the facts how to influence the modal parameters based on the different damage extent of the structure parts. Then construct the different damage extent structure models on the structure junctions with the finite element analysis method. At last, constructed and verified seven models with the example of aero-engine turbine structure damage in the constant temperature. The results were shown that the characteristic parameters with the inherent frequency and the inherent frequency deviation square can explore the structure damage accurately, but have no significant influence on the structural damages. So it will be important for us to ensure reliable operation and structure damage identification timely by the proposing the structure damage parameters.

scholarly journals Statistical Identification of Parameters for Damaged FGM Structures with Material Uncertainties in Thermal Environment

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-21
Author(s):  
Yalan Xu ◽  
Yu Qian ◽  
Kongming Guo
Keyword(s):  
Stochastic Model ◽  
Material Properties ◽  
Damage Identification ◽  
Model Updating ◽  
Thermal Environment ◽  
Iteration Process ◽  
Functionally Graded ◽  
Computational Method ◽  
Modal Parameters ◽  
Material Uncertainties

Considering that the statistic numerical characteristics are often required in the probability-based damage identification and safety assessment of functionally graded material (FGM) structures, an stochastic model updating-based inverse computational method to identify the second-order statistics (means and variances) of material properties as well as distribution of constituents for damaged FGM structures with material uncertainties is presented by using measurable modal parameters of structures. The region truncation-based optimization method is employed to simplify the computational process in stochastic model updating. In order to implement the forward propagation of uncertainties required in the stochastic model updating and avoid large error resulting in the nonconvergence of the iteration process, an algorithm is proposed to compute the covariance between the modal parameters and the identified parameters for damaged FGM structures. The proposed method is illustrated by a numerically simulated damaged FGM beam with continuous spatial variation of material properties and verified by comparing with the Monte-Carlo simulation (MCS) method. The influences of the levels and sources of measured data uncertainties as well as the boundary conditions on the identification results are investigated. The numerical simulation results show the efficiency and effectiveness of the presented method for the identification of material parameter variability by using the measurable modal parameters of damaged FGM structures.

scholarly journals Operational modal analysis using lifted continuously scanning laser Doppler vibrometer measurements and its application to baseline-free structural damage identification

2019 ◽  
Vol 25 (7) ◽  
pp. 1341-1364 ◽  
Author(s):  
Y.F. Xu ◽  
Da-Ming Chen ◽  
W.D. Zhu
Keyword(s):  
Structural Damage ◽  
Damage Identification ◽  
Laser Doppler Vibrometer ◽  
Laser Doppler ◽  
Scanning Laser ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Experimental Investigations ◽  
Scanning Laser Doppler Vibrometer ◽  
White Noise Excitation

A continuously scanning laser Doppler vibrometer (CSLDV) system is capable of efficient and spatially dense vibration measurements by sweeping its laser spot along a scan path assigned on a structure. This paper proposes a new operational modal analysis (OMA) method based on a data processing method for CSLDV measurements of a structure, called the lifting method, under white-noise excitation and applies a baseline-free method to identify structural damage using estimated mode shapes from the OMA method. The lifting method enables transformation of raw CSLDV measurements into measurements at individual virtual measurement points, as if the latter were made by use of an ordinary scanning laser Doppler vibrometer in a step-wise manner. It is shown that a correlation function with nonnegative time delays between lifted CSLDV measurements at two virtual measurement points on a structure under white-noise excitation and its power spectrum contain modal parameters of the structure, that is, natural frequencies, modal damping ratios, and mode shapes. The modal parameters can be estimated by using a standard OMA algorithm. A major advantage of the proposed OMA method is that curvature mode shapes associated with mode shapes estimated by the method can reflect local anomaly caused by small-sized structural damage, while those estimated by other existing OMA methods that use CSLDV measurements cannot. Numerical and experimental investigations are conducted to study the OMA method and baseline-free structural damage identification method. In the experimental investigation, effects of the scan frequency of a CSLDV system on the two methods were studied. It is shown in both the numerical and experimental investigations that modal parameters can be accurately estimated by the OMA method and structural damage can be successfully identified in neighborhoods with consistently high values of curvature damage indices.

scholarly journals Damage Identification for Prestressed Adjacent Box-Beam Bridges

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Kenneth K. Walsh ◽  
Brendan T. Kelly ◽  
Eric P. Steinberg
Keyword(s):  
Damage Identification ◽  
Longitudinal Direction ◽  
Longitudinal Axis ◽  
Element Model ◽  
Modal Parameters ◽  
Civil Infrastructure ◽  
Response Data ◽  
Acceleration Data ◽  
Bridge Damage ◽  
Damage Types

Structural health monitoring (SHM) has gained considerable attention as a tool for monitoring the health of civil infrastructure. For bridge infrastructure, previous methods have focused on the detection of localized damage through modal parameters extracted from the longitudinal direction of the structure. This paper investigates a new damage detection method based on the change in the first vertical mode extracted from the transverse direction of the bridge. The mode is determined through application of modal curve fitting to frequency response functions (FRFs) that are formed using vertical response data obtained in the direction perpendicular to the bridge’s longitudinal axis. Using this method, both local damage and global damage in the bridge reveal themselves as having a localized effect on the bridge response. Furthermore, damage is revealed in such a way that it enables differentiation of the damage types. To demonstrate the effectiveness of the method, modal parameters were extracted from acceleration data obtained from a finite element model of a full bridge. Analysis of the modal parameters showed that the proposed approach could not only detect both local and global bridge damage, but could also differentiate between damage types using only one mode shape. The proposed method was compared to a previously developed SHM method.

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