Degradation of Aircraft Structures

Meyendorf, Norbert; Eylon, D.; Frankel, G. S.; Hoffmann, J.; Khobaib, M.; Rösner, H.; Sathish, Shamachary; Shell, Eric B.

doi:10.1007/978-3-662-08988-0_1

Cited by 4 publications

(2 citation statements)

References 19 publications

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“…But conventional NDT can only detect macroscopic cracks, after about 90% of the fatigue life has been consumed. 1) Therefore, early detection of fatigue damage has been required in respect to their maintenance and safety management. In order to detect fatigue damage at an early stage, it is necessary to detect changes in the dislocation structure, microcracks, and closed cracks associated with fatigue damage, which is however very difficult with general UT using linear ultrasonic waves.…”

Section: Introductionmentioning

confidence: 99%

Measurement of nonlinear three-wave interaction using shear-vertical-wave point-focusing electromagnetic acoustic transducers

Takishita,

Takamatsu,

Ogi

2024

Jpn. J. Appl. Phys.

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We developed a method of nonlinear three-wave interaction using shear-vertical-wave point-focusing electromagnetic acoustic transducers (SV-wave PF-EMATs). EMATs can excite and detect ultrasonic waves without couplants through interaction between electromagnetic fields and solid mechanics and are generally unsuitable for the nonlinear ultrasound measurement due to their low signal conversion efficiency. However, our originally developed PF-EMAT can focus SV waves at a focal point in phase, achieving a large local displacement. Here, two PF-EMATs with different driving frequencies are placed facing each other so as to match their focal points, where the focused SV waves intersect to induce the third waves with the frequencies of the sum and difference of the incident frequencies through the nonlinear three-wave interaction. We demonstrate that the local nonlinearity can be measured by this method with EMATs and demonstrate its applicability to evaluation of fatigue damage in a fatigue crack initiation phase with aluminum alloy specimens.

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Section: Introductionmentioning

confidence: 99%

Measurement of nonlinear three-wave interaction using shear-vertical-wave point-focusing electromagnetic acoustic transducers

Takishita,

Takamatsu,

Ogi

2024

Jpn. J. Appl. Phys.

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“…Numerous NDT techniques were used for the assessment of impact damage in composite laminates. 10 Impact-induced delamination in such materials was imaged by digital shearography, 11 which demands sensitive and expensive instruments as well as highly skilled inspectors for the use of this technique. In addition, the lack of clarity of defects deep beneath the surface also limits the application.…”

Section: Introductionmentioning

confidence: 99%

Assessment of low-velocity impact damage in composites by the measure of second-harmonic guided waves with the phase-reversal approach

Jiang

Qing

et al. 2019

Science Progress

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Structural strength and integrity of composites can be considerably affected by the low-velocity impact damage due to the unique characteristics of composites, such as layering bonded by adhesive and the weakness to impact. For such damage, there is an urgent need to develop advanced nondestructive testing approaches. Despite the fact that the second harmonics could provide information sensitive to the structural health condition, the diminutive amplitude of the measured second-order harmonic guided wave still limits the applications of the second-harmonic generation–based nonlinear guided wave approach. Herein, laminated composites suffered from low-velocity impact are characterized by use of nonlinear guided waves. An enhancement in the signal-to-noise ratio for the measure of second harmonics is achieved by a phase-reversal method. Results obtained indicate a monotonic correlation between the impact-induced damage in composites and the relative acoustic nonlinear indicator of guided waves. The experimental finding in this study shows that the measure of second-order harmonic guided waves with a phase-reversal method can be a promising indicator to impact damage rendering in an improved and reliable manner.

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Influence of intergranular metallic nanoparticles on the fretting wear mechanisms of Fe–Cr–Al2O3 nanocomposites rubbing on Ti–6Al–4V

Stempflé

Pollet

Carpentier

2008

Tribology International

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Degradation of Aircraft Structures

Cited by 4 publications

References 19 publications

Measurement of nonlinear three-wave interaction using shear-vertical-wave point-focusing electromagnetic acoustic transducers

Measurement of nonlinear three-wave interaction using shear-vertical-wave point-focusing electromagnetic acoustic transducers

Assessment of low-velocity impact damage in composites by the measure of second-harmonic guided waves with the phase-reversal approach

Influence of intergranular metallic nanoparticles on the fretting wear mechanisms of Fe–Cr–Al2O3 nanocomposites rubbing on Ti–6Al–4V

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