Rotor Crack Identification Based on Mode Shape and Derivative Order Using Combination Resonances

2019 ◽  
Author(s):  
Izabela Batista da Silva ◽  
Paulo Costa Porto de Figueiredo Barbosa ◽  
Aldemir Ap Cavalini Jr ◽  
Valder Steffen Jr ◽  
Nicolò Bachschmid
Keyword(s):  
Mode Shape ◽  
Crack Identification ◽  
Derivative Order

scholarly journals Mode shape curvature of multiple cracked beam and its use for crack identification in beam-like structures

2020 ◽  
Author(s):  
Nguyen Tien Khiem
Keyword(s):  
Finite Difference ◽  
Mode Shape ◽  
Crack Detection ◽  
Exact Expression ◽  
Finite Difference Approximation ◽  
Theoretical Development ◽  
Difference Approximation ◽  
Crack Identification ◽  
Cracked Beam ◽  
Modal Curvature

The problem of using the modal curvature for crack detection is discussed in this paper based on an exact expression of mode shape and its curvature. Using the obtained herein exact expression for the mode shape and its curvature, it is demonstrated that the mode shape curvature is really more sensitive to crack than mode shape itself. Nevertheless, crack-induced change in the approximate curvature calculated from the exact mode shape by the central finite difference technique (Laplacian) is much greater in comparison with both the mode shape and curvature. It is produced by the fact, shown in this study, that miscalculation of the approximate curvature is straightforwardly dependent upon crack magnitude and resolution step of the finite difference approximation. Therefore, it can be confidently recommended to use the approximate curvature for multiple crack detection in beam by properly choosing the approximation mesh. The theoretical development has been illustrated by numerical results.

Fatigue Crack Identification in Tensile-Shear Spot Welded Joints by Dynamic Response Characteristics

2005 ◽  
Vol 127 (3) ◽  
pp. 310-317 ◽  
Author(s):  
G. Wang ◽  
M. E. Barkey
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Mode Shape ◽  
Crack Identification ◽  
Tensile Shear ◽  
Modal Shape ◽  
Element Analysis ◽  
Response Characteristics ◽  
Crack Location ◽  
Spot Welded

A theoretical model for the estimation of fatigue crack length of tensile-shear spot welded specimen is developed which incorporates the natural frequency and mode variation. The model is based on the concept that the propagation of cracks causes a release of strain energy, which is related to the structural modal shape. The effect of the structural mode shape and crack location is also explained. The model, experimental, and finite element results indicate that the existence of cracks cause the reduction of natural frequencies and change of natural modes, and that the mode shape of the structure and crack location will affect the magnitude of the change of these dynamic variables. The predictions of the model are compared with the experimental data and finite element analysis results and agreement is found to be consistent.

scholarly journals Complexity and Chimera States in a Network of Fractional-Order Laser Systems

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 341
Author(s):  
Shaobo He ◽  
Hayder Natiq ◽  
Santo Banerjee ◽  
Kehui Sun
Keyword(s):  
Numerical Simulation ◽  
Numerical Solution ◽  
Bifurcation Diagram ◽  
Fractional Order ◽  
Dynamical Model ◽  
Chimera States ◽  
Laser Systems ◽  
Complexity Algorithm ◽  
Derivative Order

By applying the Adams-Bashforth-Moulton method (ABM), this paper explores the complexity and synchronization of a fractional-order laser dynamical model. The dynamics under the variance of derivative order q and parameters of the system have examined using the multiscale complexity algorithm and the bifurcation diagram. Numerical simulation outcomes demonstrate that the system generates chaos with the decreasing of q. Moreover, this paper designs the coupled fractional-order network of laser systems and subsequently obtains its numerical solution using ABM. These solutions have demonstrated chimera states of the proposed fractional-order laser network.

scholarly journals Mode Shape-Based Damage Detection Method (MSDI): Experimental Validation

2021 ◽  
Vol 11 (10) ◽  
pp. 4589
Author(s):  
Ivan Duvnjak ◽  
Domagoj Damjanović ◽  
Marko Bartolac ◽  
Ana Skender
Keyword(s):  
Boundary Conditions ◽  
Damage Detection ◽  
Mode Shape ◽  
Experimental Validation ◽  
Detection Method ◽  
Dynamic Properties ◽  
Damage Index ◽  
Main Principle ◽  
The Difference ◽  
Different Levels

The main principle of vibration-based damage detection in structures is to interpret the changes in dynamic properties of the structure as indicators of damage. In this study, the mode shape damage index (MSDI) method was used to identify discrete damages in plate-like structures. This damage index is based on the difference between modified modal displacements in the undamaged and damaged state of the structure. In order to assess the advantages and limitations of the proposed algorithm, we performed experimental modal analysis on a reinforced concrete (RC) plate under 10 different damage cases. The MSDI values were calculated through considering single and/or multiple damage locations, different levels of damage, and boundary conditions. The experimental results confirmed that the MSDI method can be used to detect the existence of damage, identify single and/or multiple damage locations, and estimate damage severity in the case of single discrete damage.

scholarly journals Analytical survey of the predator–prey model with fractional derivative order

AIP Advances ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 035127
Author(s):  
Souleymanou Abbagari ◽  
Alphonse Houwe ◽  
Youssoufa Saliou ◽  
\, Douvagaï ◽  
Yu-Ming Chu ◽  
...  
Keyword(s):  
Fractional Derivative ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Prey Model ◽  
Derivative Order
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