Local Ultrasonic Resonance Spectroscopy: A Demonstration on Plate Inspection

Rus, Janez; Große, Christian U.

doi:10.1007/s10921-020-00674-5

Cited by 16 publications

(14 citation statements)

References 28 publications

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“…CWI was already applied but the number of data was yet too little to be processed in a reliable way. Another promising approach tested elsewhere at the time being is the use of an etalon-based optical microphone for the detection of acoustic waves in a non-contact way [67].…”

Section: Resultsmentioning

confidence: 99%

Influence of fiber alignment on pseudoductility and microcracking in a cementitious carbon fiber composite material

et al. 2021

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This research examines the effect of fiber alignment on the performance of an exceptionally tough 3D-printable short carbon fiber reinforced cementitious composite material, the flexural strength of which can exceed 100 N/mm2. The material shows pseudoductility caused by strain-hardening and microcracking. An extrusion-based manufacturing process allows accurate control over the spatial alignment of the fibers’ orientation, since extrusion through a tight nozzle leads to nearly unidirectional alignment of the fibers with respect to the directional movement of the nozzle. Specimens were investigated using mechanical tests (flexural and tensile load), augmented by non-destructive methods such as X-ray 3D computed tomography and acoustic emission analysis to gain insight into the microstructure. Additionally, digital image correlation is used to visualize the microcracking process. X-ray CT confirms that about 70% of fibers show less than 10° deviation from the extrusion direction. Systematic variations of the fiber alignment with respect to the direction of tensile load show that carbon fibers enhance the flexural strength of the test specimens as long as their alignment angle does not deviate by more than 20° from the direction of the acting tensile stress. Acoustic emission analysis is capable of evaluating the spatiotemporal degradation behavior during loading and shows consistent results with the microstructural damage observed in CT scans. The strong connection of fiber alignment and flexural strength ties into a change from ductile to brittle failure caused by degradation on a microstructural level, as seen by complementary results acquired from the aforementioned methods of investigation.

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Section: Resultsmentioning

confidence: 99%

Influence of fiber alignment on pseudoductility and microcracking in a cementitious carbon fiber composite material

et al. 2021

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“…These local defect resonances have their characteristic frequencies typically in the range above several 10 kHz, but mostly below the plate thickness resonance frequency. 29,31 These effects are more pronounced, when the US is detected over a wide frequency range e.g. by optical microphones.…”

Section: Results Of the Comparison And Discussionmentioning

confidence: 99%

“…The setup was the same as used for the local ultrasonic resonance spectroscopy experiment described in Rus and Grosse. 29…”

Section: Methods Descriptionmentioning

confidence: 99%

“…The setup was the same as used for the local ultrasonic resonance spectroscopy experiment described in Rus and Grosse. 29 The increment length of the scan was 0.2 mm and the scanning speed 4 mm/s. To obtain the C-scan, the mean amplitude of the captured signal in a frequency domain between 500 kHz and 4 MHz was coded in greyscale (Figure 2(i)).…”

Section: Laser Induced Ultrasound In Combination With the Eta450 Optimentioning

confidence: 99%

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Qualitative comparison of non-destructive methods for inspection of carbon fiber-reinforced polymer laminates

Rus

Gustschin

Mooshofer

et al. 2020

Journal of Composite Materials

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In the rapidly expanding composite industry, novel inspection methods have been developed in recent years. Particularly promising for air-coupled testing are cellular polypropylene transducers which offer better impedance matching to air than piezoelectric transducers. Furthermore, broadband transmitters (laser-induced ultrasound and thermoacoustic emitters) and receivers (optical microphones) have opened a completely new chapter for advanced contact-free ultrasound inspection. X-ray dark-field radiography offers a different approach to detect porosity and microcracks, employing small angle X-ray scattering. These innovative ultrasonic and radiographic alternatives were evaluated in comparison with well-established inspection techniques. We applied thirteen different non-destructive methods to inspect the same specimen (a carbon fiber-reinforced polymer laminate with induced impact damage): air-coupled ultrasound testing (using piezoelectric transducers, broadband optical microphones, cellular polypropylene transducers, and a thermoacoustic emitter), laser-induced ultrasound testing, ultrasonic immersion testing, phased array ultrasonic testing, optically excited lock-in thermography, and X-ray radiography (projectional absorption and dark-field, tomosynthesis, and micro-computed tomography). The inspection methods were qualitatively characterized by comparing the scan results. The conclusions are advantageous for a decision on the optimal method for certain testing constraints.

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“…For local ultrasonic resonance spectroscopy, a portion of a large component (e.g., a WT blade) is excited with ultrasounds in a broadband frequency range. The vibrational response is recorded with a nearby sensor and is used to obtain the local material, geometrical, and mechanical properties, for each of the scanning-grid locations [284]. This can be seen as the ultrasound equivalent of the classic hammer and tap tests used for standard local resonance spectroscopy.…”

Section: Acoustic Emissions (Aes)mentioning

confidence: 99%

Non-Destructive Techniques for the Condition and Structural Health Monitoring of Wind Turbines: A Literature Review of the Last 20 Years

Civera

Surace

2022

Sensors

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A complete surveillance strategy for wind turbines requires both the condition monitoring (CM) of their mechanical components and the structural health monitoring (SHM) of their load-bearing structural elements (foundations, tower, and blades). Therefore, it spans both the civil and mechanical engineering fields. Several traditional and advanced non-destructive techniques (NDTs) have been proposed for both areas of application throughout the last years. These include visual inspection (VI), acoustic emissions (AEs), ultrasonic testing (UT), infrared thermography (IRT), radiographic testing (RT), electromagnetic testing (ET), oil monitoring, and many other methods. These NDTs can be performed by human personnel, robots, or unmanned aerial vehicles (UAVs); they can also be applied both for isolated wind turbines or systematically for whole onshore or offshore wind farms. These non-destructive approaches have been extensively reviewed here; more than 300 scientific articles, technical reports, and other documents are included in this review, encompassing all the main aspects of these survey strategies. Particular attention was dedicated to the latest developments in the last two decades (2000–2021). Highly influential research works, which received major attention from the scientific community, are highlighted and commented upon. Furthermore, for each strategy, a selection of relevant applications is reported by way of example, including newer and less developed strategies as well.

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Local Ultrasonic Resonance Spectroscopy: A Demonstration on Plate Inspection

Cited by 16 publications

References 28 publications

Influence of fiber alignment on pseudoductility and microcracking in a cementitious carbon fiber composite material

Influence of fiber alignment on pseudoductility and microcracking in a cementitious carbon fiber composite material

Qualitative comparison of non-destructive methods for inspection of carbon fiber-reinforced polymer laminates

Non-Destructive Techniques for the Condition and Structural Health Monitoring of Wind Turbines: A Literature Review of the Last 20 Years

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