Ultrasonic tracking of ply drops in composite laminates

Smith, Robert A.; Nelson, Luke; Mienczakowski, Martin; Wilcox, Paul D.

doi:10.1063/1.4940505

Cited by 21 publications

(35 citation statements)

References 7 publications

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“…This is an exact solution to the one-dimensional wave-propagation problem in laminates and is based on the recursive analytical multi-layer model developed in [4], benchmarked against various other models and experiment as described in [14]. The Hashin (1965) mixture rules for long-fiber composites [16] are used to calculate effective-medium properties for the composite plies; this is based on a fiber volume fraction which is allowed to vary to compensate for ply-thickness variations.…”

Section: Ultrasonic Modelmentioning

confidence: 99%

“…These methods exploit the weak resonances formed by reflections at the periodic resin-layer boundaries between plies in the laminate. In particular, the instantaneous phase in the pulse-echo response appears 'locked' to the resin layers in a way that allows its use to track the plies through undulations and ply drops [14]. Until recently, these methods had been applied mainly to flat, relatively thin specimens manufactured from conventional thermoset fiber-resin systems such as IM7/8552 which has thin inter-ply resin layers in the range 3 to 10 μm.…”

Section: Introductionmentioning

confidence: 99%

“…Until recently, these methods had been applied mainly to flat, relatively thin specimens manufactured from conventional thermoset fiber-resin systems such as IM7/8552 which has thin inter-ply resin layers in the range 3 to 10 μm. In this case, the optimum center frequency and bandwidth of the input pulse is equal to the resonant frequency of the plies [14]. However, recent work on ply tracking through ply drops, tape gaps and tape overlaps has included analysis of more advanced resin systems incorporating resin layers between plies toughened with thermoplastic particles to slow down crack propagation [15].…”

Section: Introductionmentioning

confidence: 99%

“…A desire to increase confidence in the manufacture of complex carbon-fiber composite components [1][2][3] has resulted in improved three-dimensional (3D) ultrasonic characterization methods to determine out-of-plane ply orientation and wrinkling [4][5][6][7][8][9][10][11][12][13][14] as well as in-plane fiber orientation and waviness [7][8][9][10]. These methods exploit the weak resonances formed by reflections at the periodic resin-layer boundaries between plies in the laminate.…”

Section: Introductionmentioning

confidence: 99%

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Phononic band gaps and phase singularities in the ultrasonic response from toughened composites

Smith¹,

Nelson²,

Mienczakowski³

2018

AIP Conference Proceedings

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Abstract. Ultrasonic 3D characterization of ply-level features in layered composites, such as out-of-plane wrinkles and ply drops, is now possible with carefully applied analytic-signal analysis. Study of instantaneous amplitude, phase and frequency in the ultrasonic response has revealed some interesting effects, which become more problematic for 3D characterization as the inter-ply resin-layer thicknesses increase. In modern particle-toughened laminates, the thicker resin layers cause phase singularities to be observed; these are locations where the instantaneous amplitude is zero, so the instantaneous phase is undefined. The depth at which these occur has been observed experimentally to vary with resinlayer thickness, such that a phase-singularity surface is formed; beyond this surface, the ultrasonic response is reduced and significantly more difficult to interpret, so a method for removing the effect would be advantageous. The underlying physics has been studied using an analytical one-dimensional multi-layer model. This has been sufficient to determine that the cause is linked to a phononic band gap in the ultrasound transmitted through multiple equally-spaced partial reflectors. As a result, the phase singularity also depends on input-pulse center frequency and bandwidth. Various methods for overcoming the confusing effects in the data have been proposed and subsequently investigated using the analytical model. This paper will show experimental and modelled evidence of phase-singularities and phase-singularity surfaces, as well as the success of methods for reducing their effects.

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Section: Ultrasonic Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Phononic band gaps and phase singularities in the ultrasonic response from toughened composites

Smith¹,

Nelson²,

Mienczakowski³

2018

AIP Conference Proceedings

Self Cite

View full text Add to dashboard Cite

show abstract

“…The topic of detecting discontinuities and characterizing complex composites parts with bonded components and ply drops has received some recent attention on enhanced ultrasonic NDE techniques [11][12][13]. An example test panel with a bonded pad-up region is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Design and demonstration of automated data analysis algorithms for ultrasonic inspection of complex composite panels with bonds

Aldrin

Forsyth

Welter

2016

AIP Conference Proceedings

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Nondestructive damage characterization of complex aircraft structures by inverse methods: Advances in multiscale models AIP Conference Proceedings 1706, 090007 (2016) Abstract. To address the data review burden and improve the reliability of the ultrasonic inspection of large composite structures, automated data analysis (ADA) algorithms have been developed to make calls on indications that satisfy the detection criteria and minimize false calls. The original design followed standard procedures for analyzing signals for time-of-flight indications and backwall amplitude dropout. However, certain complex panels with varying shape, ply drops and the presence of bonds can complicate this interpretation process. In this paper, enhancements to the automated data analysis algorithms are introduced to address these challenges. To estimate the thickness of the part and presence of bonds without prior information, an algorithm tracks potential backwall or bond-line signals, and evaluates a combination of spatial, amplitude, and time-of-flight metrics to identify bonded sections. Once part boundaries, thickness transitions and bonded regions are identified, feature extraction algorithms are applied to multiple sets of through-thickness and backwall C-scan images, for evaluation of both first layer through thickness and layers under bonds. ADA processing results are presented for a variety of complex test specimens with inserted materials and other test discontinuities. Lastly, enhancements to the ADA software interface are presented, which improve the software usability for final data review by the inspectors and support the certification process.

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Point-cloud acquisition in CFRP composites using ultrasonic location estimation with the phase-shift reference pulse

Ma¹,

Zhou²,

Yang³

et al. 2023

Applied Acoustics

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Ultrasonic tracking of ply drops in composite laminates

Cited by 21 publications

References 7 publications

Phononic band gaps and phase singularities in the ultrasonic response from toughened composites

Phononic band gaps and phase singularities in the ultrasonic response from toughened composites

Design and demonstration of automated data analysis algorithms for ultrasonic inspection of complex composite panels with bonds

Point-cloud acquisition in CFRP composites using ultrasonic location estimation with the phase-shift reference pulse

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