Non-destructive examination of fibre composite structures by thermal field techniques

McLaughlin, P.; McAssey, Edward V.; Deitrich, Richard

doi:10.1016/0308-9126(80)90046-2

Cited by 21 publications

(12 citation statements)

References 1 publication

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“…For each set of ellipses, the center shows either a maximum or minimum which is the mode l behavior in the vertical direction. Figure 17 was the observed thermoelastic emission pattern at the excitation frequency of 17.l kHz which was predicted to be mode (1,3). The dark blue zone in the center represents the lower stress zone as in Fig.…”

Section: ·mentioning

confidence: 85%

“…Therefore, the image obtained on the screen, which results from adiabatic temperature changes, is point-wise related to the stress field or strain field induced by rapid cyclic loading. For the purpose of obtaining a better 3. EXPERIMENT AL TECHNIQUE emissivity and hence the infrared flux signal, the surface to be examined was descaled and degreased, and a thin, uniform ultra-flat black paint was then applied on the surface of the specimen.…”

Section: Sp a Te Tliermograpliic Syste1nmentioning

confidence: 99%

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Frequency dependent heat generation during vibrothermographic testing of composite materials

1993

NDT & E International

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This investigation concerns the frequency dependent heat generation behavior and the heat generation mechanisms for the thermal patterns of delamination in fiber reinforced composites during a vibrothermographic test, which uses real time thermography as a nondestructive evaluation of a structure or a component excited with mechanical vibration. A local resonance model was proposed in the past to describe the frequency dependent heat generation behavior during a vibrothermographic test, and this model was used as a basis for writing software for calculating the natural frequencies of a plate with the size of delamination. Vibrothermographic tests were performed on three glass-epoxy panels that each contained four different sized simulated delaminations. Comparison between the observed vibrothermal peak frequencies and the natural frequencies predicted by the local resonance model, and investigations of the thermoelastic emission field in the delamination region using SPA TE, were made to determine the validity of the local resonance model. A significant conclusion of the results is that the local resonance is indeed the mechanics model for the frequency dependent heat generation behavior.A careful measurement of the degree of heating of both sides of [0 5 ] glassepoxy panel with delaminations on the 2-3 ply interface, and comparison between the predicted heat patterns generated from a finite difference heat transfer program and observed heat patterns, was made to identify the heat generation mechanism. The results show that the majority of heat generation during vibrothermographic testing results from higher stresses or strains due to local resonance. The heat generation was affected by the combination of the principal strains and shear strain for the lower modes of resonant vibration, and was dominated by the shear strain for the higher modes of resonant vibration.Impact damaged graphite-epoxy panels were also inspected constituting an application of vibrothermography on real damaged components. The degree of heating of the damage were measured through a frequency range, and the damage severity was inspected by ultrasonic C-scan and edge replication. From comparison of two plots of the degree of heating versus exciting frequency, either the area under the curve or the number of vibrothermal peak frequencies, the severity of the damage can be qualitatively identified.

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Section: ·mentioning

confidence: 85%

Section: Sp a Te Tliermograpliic Syste1nmentioning

confidence: 99%

Frequency dependent heat generation during vibrothermographic testing of composite materials

1993

NDT & E International

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“…Xenon flash tubes [11) and pulsed lasers [12) have been used to give short duration/high intensity heat for NDE of thin laminates and coatings. Commercial heat guns [4,7,13,14] have also been used with limited success because they produce nonuniform surface temperatures.…”

Section: Heating Methodsmentioning

confidence: 99%

“…A surface crack can be adequately detected with heat intensities of one to three solar constants. Due to convective cooling from the surface, there is a limit to the size of zone in front of the heat source in which cracks can be detected [4,14,22]. This zone is about 10 to 20 mm for glass/epoxy and 25 to 50 mm for high conductivity graphite/epoxy.…”

Section: Surface Cracksmentioning

confidence: 99%

“…Several techniques are in use in laboratory, manufacturing quality ccntrol, and field inspection applications. The purpose of this paper is to present the capabilities of the externally applied thermal field (EATF) [4) (also called passive [5) thermographic NDE method, to discuss the applications for which it seems best suited, to describe its limitations, and to highlight directions of further development.…”

Section: Department Of Mechanical Engineeringmentioning

confidence: 99%

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Defect detection and quantification in laminated composites by EATF (Passive) thermography

1993

NDT & E International

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Defect Detection and Quantification in Laminated Composites by EATF (Passive) Thermography

McLaughlinJr.

1988

Review of Progress in Quantitative Nondestructive Evaluation

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Non-destructive examination of fibre composite structures by thermal field techniques

Cited by 21 publications

References 1 publication

Frequency dependent heat generation during vibrothermographic testing of composite materials

Frequency dependent heat generation during vibrothermographic testing of composite materials

Defect detection and quantification in laminated composites by EATF (Passive) thermography

Defect Detection and Quantification in Laminated Composites by EATF (Passive) Thermography

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