Crack Characterisation in Turbine Disks

Bond, Leonard J.; Saffari, Nader

doi:10.1007/978-1-4684-1194-2_23

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…Lamb and plate waves are produced in relatively thin isotropic material plates and anisotropic laminates [5][6][7]. The injection of a longitudinal wave onto the specimen's surface results to leaky surface waves [8,9]. Although Lamb waves can be considered dispersive in nature [10,11], mostly due to out-of-plane/anti-symmetric modes; however, under low-frequency approximations (200 kHz-1 MHz), Lamb waves can exhibit nondispersive symmetric modes and a dispersive anti-symmetric modes [12,13], and the Lamb wave propagation behaviour can possibly be described by the use of dispersion curves [14], that are plots of phase velocities against the product of frequency and thickness created by computing the plate wave expressions.…”

Section: Introductionmentioning

confidence: 99%

Determination of acousto-ultrasonic wave propagation in an isotropic aluminium Al6082-T6 plate

PRASAD,

Jombo,

Ismail

et al. 2023

Preprint

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The ability to guarantee reliable and damage-tolerant operation of structures is critical to their safe operation. Various non-destructive evaluation (NDE) techniques, such as ultrasonics, acoustic emission, thermography, acousto-ultrasonics (AU), among others could potentially provide a means of inspecting cracks, defects and damage responses in structures. The main aim of this study is to look into the physical problem of AU wave propagation through an isotropic plate and its analytical validation, using wave dispersion concept. The experimental investigation was conducted on aluminium Al6082-T6 alloy plate specimen. Wave propagation speed on top and bottom surfaces of the plate was investigated. The variation of the wave speed and attenuation with frequency were identified. From the results obtained experimentally, the wave dispersion was verified analytically. Interestingly, Lamb waves were discovered to be the dominating AU waves. The wave was appreciably non-dispersive in the frequency extent from 150 kHz to 1 MHz and the attenuation coefficient was increased with the frequency. This finding provides a significant breakthrough to the implementation of acousto- ultrasonics in the non- destructive testing applications, such as accessing the damage in composite structures, including wind turbine blades. AU has an active sensing mechanism, providing an edge over acoustic emission (AE) method which is a passive mode of damage sensing and detection, as external loading is needed for the damage sensing.

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Section: Introductionmentioning

confidence: 99%

Determination of acousto-ultrasonic wave propagation in an isotropic aluminium Al6082-T6 plate

PRASAD,

Jombo,

Ismail

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Hence, a bulk wave generated at one side of a plate and incident upon the base of the slot is likely to generate a Rayleigh wave by mode conversion, the presence of the surface wave being indicative of the surface discontinuity. Because this Rayleigh wave would not be present in the absence of a slot, this mechanism has been proposed as a sensitive means for the detection of surface defects (14,15). Note that reflection of Rayleigh waves is the most common method for crack detection of this type, but research has shown that sizing of the defect is not convenient using reflection only (16).…”

Section: Introductionmentioning

confidence: 99%

A pulsed photoacoustic investigation of ultrasonic mode conversion

Hutchins¹,

Nadeau²,

Cielo³

1986

Can. J. Phys.

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Experiments have been undertaken into the generation and detection of ultrasonic transients in metals over a 40-MHz bandwidth, using pulsed-laser generation and interferometric detection. Longitudinal, shear, and surface waves have been investigated, and their form compared favorably to theory. The techique has been used to study the interactionof surfaceand bulk waves with slots in the surface of aplate. It has been shown that significant mode conversion occurred from surface to bulk waves and vice versa. The significance of this result to nondestructive testing is discussed.On a entrepris des experiences sur la generation et la detection de transients ultrasoniques dans les metaux, dans une bande de 40MHz de largeur, en utilisant la generation par laser pulse et la detection interf6romCtrique. On a Ctudit les ondes longitudinales, les ondes de cisaillement et les ondes de surface; la forme de ces ondes se compare favorablement A la forme thtorique. La technique a CtC utilisie pour etudier I'interaction d'ondes de surfaces et de volume avec des fentes dans la surface d'une plaque. On a montre qu'il se produit un conversion de mode importante, des ondes de surface aux ondes de volume et rkciproquement. L'importance de ce rtsultat pour les tests non destructifs sera discutie.[Traduit par la revue]Can. J. Phys. 64. 1334 (1986)

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“…12 The arrangement enabled measurement systems, modeling, transducers, films with initial thicknesses ranging from 1000 resolution, and accuracy have been reported in to 1200 mm to be easily knife-cast directly on the the literature. [24][25][26] The specific case regarding the aluminum substrate using a thickness-calibrated capabilities and limitations of ultrasonic TDR for glass casting knife assembly (not shown). When applications in membrane science was described the cast film has contacted the aluminum subby Bond et al 27 strate, a signal is sent from the pulser-receiver (Panametrics Model 5072) to the ultrasonic transducer (Panametrics Type V111, 0.5-in.…”

Section: Introductionmentioning

confidence: 99%

Use of ultrasonic time-domain reflectometry for real-time measurement of thickness changes during evaporative casting of polymeric films

Kools

Konagurthu

Greenberg

et al. 1998

J. Appl. Polym. Sci.

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ABSTRACT:The dry-cast membrane-formation process is a principal technique by which asymmetric porous membranes as well as dense films can be obtained. Much insight into the fundamental nature of this process can be obtained via real-time measurements of mass and thickness changes. The former requires an equation of state for the density to obtain the average instantaneous film thickness. Optical techniques for the latter such as interferometry and reflectometry usually require transparent samples and good reflecting surfaces; in many cases, such characteristics cannot be obtained. In this article, we report the adaptation of ultrasonic time-domain reflectometry (TDR) for real-time, noninvasive measurement of thickness changes of polymeric films. Ultrasonic TDR does not depend on optical characteristics and is based upon the reflection of longitudinal plane waves at the interface between two media with different acoustic impedances. The technique utilizes the acoustic velocity, which, in general, is a function of temperature and composition. Representative ultrasonic-TDR thickness data are presented for the cellulose acetate (CA) -acetone, CA-acetone-water, and polysulfone (PSf) -tetrahydrofuran systems. Values are compared to those obtained independently using a direct micrometer measurement as well as mass-loss data. In general, the results are in excellent agreement with a maximum error of less than 5%. In addition to overall changes in thickness, preliminary data indicate that ultrasonic TDR can be used to locate the interface between the polymer solution and an opaque solidified region. The latter is a characteristic of polymer systems that undergo a phase separation during solidification. Ultrasonic TDR thus appears to be a promising technique that can be applied to a wide range of polymer systems.

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Crack Characterisation in Turbine Disks

Cited by 5 publications

References 4 publications

Determination of acousto-ultrasonic wave propagation in an isotropic aluminium Al6082-T6 plate

Determination of acousto-ultrasonic wave propagation in an isotropic aluminium Al6082-T6 plate

A pulsed photoacoustic investigation of ultrasonic mode conversion

Use of ultrasonic time-domain reflectometry for real-time measurement of thickness changes during evaporative casting of polymeric films

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