Nonlinear ultrasonic modulation based failure warning for aluminum plates subject to fatigue loading

Kim, Yongtak; Lim, Hyung Jin; Sohn, Hoon

doi:10.1016/j.ijfatigue.2018.05.014

Cited by 40 publications

(17 citation statements)

References 45 publications

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“…The nonlinear parameter

is inversely proportional to the excitation amplitudes and wavenumbers of two incident waves as shown in Equations ( 1 ) and ( 2 ):

and

where

and

are modulated material nonlinear parameters;

and

are wavenumbers of two incident waves; and

and

are amplitudes of two incident waves, respectively [ 39 , 40 ]. The nonlinear parameters

and

are constants corresponding to sideband frequencies (HF-LF) and (HF+LF), respectively.…”

Section: Quantitative Analysis Of Wave Modulation With Seam Crackmentioning

confidence: 99%

Detection of Micro-Cracks in Metals Using Modulation of PZT-Induced Lamb Waves

Lee

Hong

2020

Materials

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The ultrasonic modulation technique, developed by inspecting the nonlinearity from the interactions of crack surfaces, has been considered very effective in detecting fatigue cracks in the early stage of the crack development due to its high sensitivity. The wave modulation is the frequency shift of a wave passing through a crack and does not occur in intact specimens. Various parameters affect the modulation of the wave, but quantitative analysis for each variable has not been comprehensively conducted due to the complicated interaction of irregular crack surfaces. In this study, specimens with a constant crack width are manufactured, and the effects of various excitation parameters on modulated wave generation are analyzed. Based on the analysis, an effective crack detection algorithm is proposed and verified by applying the algorithm to fatigue cracks. For the quantitative analysis, tests are repeatedly conducted by varying parameters. As a result, the excitation intensity shows a strong linear relationship with the amount of modulated waves, and the increase of modulated wave is expected as crack length increases. However, the change in the dynamic characteristics of the specimen with the crack length is more dominant in the results. The excitation frequency is the most dominant variable to generate the modulated waves, but a direct correlation is not observed as it is difficult to measure the interaction of crack surfaces. A numerical analysis technique is developed to accurately simulate the movement and interaction of the crack surface. The crack detection algorithm, improved by using the observations from the quantitative analyses, can distinguish the occurrence of modulated waves from the ambient noises, and the state of the specimens is determined by using two nonlinear indexes.

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“…The nonlinear parameter

is inversely proportional to the excitation amplitudes and wavenumbers of two incident waves as shown in Equations ( 1 ) and ( 2 ):

and

where

and

are modulated material nonlinear parameters;

and

are wavenumbers of two incident waves; and

and

are amplitudes of two incident waves, respectively [ 39 , 40 ]. The nonlinear parameters

and

are constants corresponding to sideband frequencies (HF-LF) and (HF+LF), respectively.…”

Section: Quantitative Analysis Of Wave Modulation With Seam Crackmentioning

confidence: 99%

Detection of Micro-Cracks in Metals Using Modulation of PZT-Induced Lamb Waves

Lee

Hong

2020

Materials

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“…In this study, the first modulation components (A + M and A À M ) are used for prognosis because (1) the modulation components are less affected by other sources of nonlinearities induced by transducers or data acquisition (DAQ) systems, and (2) selecting the frequencies and modes of input ultrasonic signals is more flexible compared with the use of a harmonic technique. 26,27 In general, the nonlinearity produced by a fatigue crack is represented using the nonlinear parameter (b parameter) obtained by normalizing the amplitudes of modulation components with respect to the amplitudes of input signals as follows [19][20]24 b =…”

Section: Nonlinear Parameter For Fatigue Crack Assessmentmentioning

confidence: 99%

“…Similar trends are also observed in experiments on additional aluminum plate specimens with different thicknesses. 19 The growth of a fatigue crack can be described using the Paris-Erdogan equation, and it is written as…”

Section: Nonlinear Parameter For Fatigue Crack Assessmentmentioning

confidence: 99%

Online fatigue crack prognosis using nonlinear ultrasonic modulation

Lim

Sohn

2019

Structural Health Monitoring

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This article presents an online remaining fatigue life estimation (prognosis) technique using nonlinear ultrasonic modulation. When two ultrasonic inputs at two distinct frequencies are introduced to a structure with a fatigue crack, modulation components at the sum and difference of input frequencies are generated owing to crack opening and closing. First, a fatigue index is defined for prognosis and extracted from nonlinear ultrasonic modulation measurement. Subsequently, it is shown that the fatigue index is expressed as a simple power function of loading cycles applied to a target structure based on the Nazarov–Sutin and Paris–Erdogan theories. Then, the real-time remaining fatigue life estimation method is proposed by fitting the power function to online data obtained from the target structure. The performance of the proposed prognosis technique is evaluated using either notched or welded aluminum (6061-T6) plate specimens.

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“…SHM is a revolutionary innovation technology to determine the structural integrity and a key technology to improve the operation safety of advanced equipment, and moreover can improve the present design concept of damage tolerance [ 4 ]. There are some SHM technologies which have been used for the damage monitoring of bolted joints, such as ultrasonic guided wave [ 5 , 6 , 7 ], electromechanical impedance [ 8 , 9 ], comparative vacuum monitoring sensor [ 10 ], vibration [ 11 ], acoustic emission [ 12 ] and so on. However, these technologies have the following problems: (1) It is difficult to identify the cracks in the non-surface layer of a multi-layer jointed structure; (2) It is difficult to accurately quantify the angle of hole edge cracks, and then identify the failure mode.…”

Section: Introductionmentioning

confidence: 99%

Quantifying Hole-Edge Crack of Bolt Joints by Using an Embedding Triangle Eddy Current Sensing Film

Fan

Sun

et al. 2021

Sensors

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Hole-edge crack quantification of bolt joints is critical for monitoring and estimating structural integrity of aircraft. The paper proposes a new triangle eddy current sensor array for the purpose of increasing the level of quantifying hole-edge crack parameters, especially, the crack angle. The new senor array consists of triangular coils instead of planar rectangular coils. The configuration of the novel sensor array, including the excitation current directions and the excitation winding shape, is optimized by simulation. The ability of the proposed sensing film to identify the crack parameters has been verified by finite element simulations and experiments. Results shows that triangular coils with same current directions in circumferentially adjacent coils and opposite current directions in axially adjacent coils achieve better performance in sensor linearity and resolution compared to rectangular coils. In addition, it has also been proved that the sensing film has a good potential to identify the crack depth and length.

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Nonlinear ultrasonic modulation based failure warning for aluminum plates subject to fatigue loading

Cited by 40 publications

References 45 publications

Detection of Micro-Cracks in Metals Using Modulation of PZT-Induced Lamb Waves

Detection of Micro-Cracks in Metals Using Modulation of PZT-Induced Lamb Waves

Online fatigue crack prognosis using nonlinear ultrasonic modulation

Quantifying Hole-Edge Crack of Bolt Joints by Using an Embedding Triangle Eddy Current Sensing Film

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