A Laboratory Laser-Ultrasonic Instrument for Measuring the Mechanical Properties of Paper Webs

Lafond, Emmanuel; Ridgway, Paul; Jackson, Ted; Habeger, C. C; Russo, R.E.

doi:10.1063/1.1570330

Cited by 4 publications

(5 citation statements)

References 11 publications

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“…For the copy paper specimen, two important parameters for industrial processing: flexural rigidity (FR) and shear rigidity (SR), can be obtained from the A0 dispersion curve. The extracted FR ( 1.8E-3 N•m ) and SR ( 3.6E4 N/m ) for this paper sample along the MD and measurements on the other paper specimens are consistent with the contact ultrasonics measurements [11] and previous laser ultrasonics measurements [10].…”

supporting

confidence: 87%

“…The optical layout of our LU system is described in references [8][9][10]. Briefly, broadband ultrasonic waves are generated by a pulsed, point focused laser beam that is obtained from a 1064 or 532 nm Nd:YAG laser.…”

mentioning

confidence: 99%

“…From the obtained time-domain waveform, a technique, like phase velocity calculation, can be used to obtain indirectly the phase velocity dispersion curve as a function of frequency [8][9][10]. Using a fit to this curve one can extract the physical properties of the sample.…”

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confidence: 99%

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Noncontact determination of elastic moduli by two-dimensional Fourier transformation and laser ultrasonic technique

Zhang

Jackson

Lafond

2005

Review of Scientific Instruments

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Broadband laser ultrasonics and two dimensional Fourier transformation are used to characterize the properties of varieties of foils and plates. Laser ultrasonics generation is achieved by use of a pulsed laser which deposits pulsed laser energy on the surface of the specimen. The displacement amplitude of the resulting broadband ultrasonic modes are monitored using a two wave mixing photo-refractive interferometer. By applying a two dimensional Fourier transformation to the detected spatial and temporal displacement waveforms, the images of density of state (DOS) for the excited ultrasounds are obtained. Results are presented for a 150 µm thick paper sample, a 52.8 µm stainless steel foil and a 1.27 mm thick aluminum plate. The DOS image demonstrates the ability to measure the properties of each generated ultrasonic modes and provides a direct, non destructive, measure of elastic moduli of the tested specimens.Techniques that have been used successfully for non-destructive elastic properties evaluation in films fall into two basic categories [1]: laser based ultrasonic methods [2-4] and techniques utilizing Brillouin scattering [5][6][7]. In laser ultrasonics (LU) experiments, ultrasonic waves are externally generated, and either the dispersion of surface propagation modes is measured or the acoustic pulses propagating out of the plane of the specimens are monitored. Brillouin scattering probes the thermally induced vibration modes and measures their dispersions.The LU metrology uses pulsed laser irradiation to induce ultrasounds in a test object via three mechanisms: thermal-elastic, ablation and plasma. The resulting ultrasonic wave packets are often measured in a non-contact, nondestructive manner using an optical interferometer. LU techniques can provide information about the mechanical, thermal, and electronic properties of materials, and can also be used to detect surface and subsurface flaws in structures [2].LU often monitors an ultrasonic waveform in the time domain. From the obtained time-domain waveform, a technique, like phase velocity calculation, can be used to obtain indirectly the phase velocity dispersion curve as a function of frequency [8][9][10]. Using a fit to this curve one can extract the physical properties of the sample. The conventional technique to obtain phase velocity dispersion requires skill, knowledge and knowhow in data processing. In addition, previous knowledge of material properties is also necessary.In this letter, we describe a two dimensional fast Fourier transformation (2D FFT) technique to avoid most problems confronted by the conventional method. It is implemented by taking incremental measurements in separation distance between ultrasound emitter and receiver to obtain a second spatial dimension, correspond to wavevector ( k ) domain in Fourier transformation. The method automatically produces density of state ( DOS ) image as function of frequency ( f ) and wavevector for the generated ultrasounds with minimum human involvement in the process. The DOS image not only b...

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confidence: 87%

mentioning

confidence: 99%

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Noncontact determination of elastic moduli by two-dimensional Fourier transformation and laser ultrasonic technique

Zhang

Jackson

Lafond

2005

Review of Scientific Instruments

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“…A disadvantage of out-of-plane velocity measurement is that the low-frequency sensitivity is much lower than in the case of interferometers which measure displacement, such as the Two-Wave Mixing (TWM) photo-refractive interferometer developed at IPST at Georgia Tech for use on stationary paper and paperboard [17][18]. The TWM-based instrument is, however, too sensitive to a fast and continuous motion of the object along the direction of the detection beam.…”

Section: Signal Analysismentioning

confidence: 97%

A Sensor for Laser Ultrasonic Measurement of Elastic Properties of Moving Paper

Ridgway¹,

Russo²,

Lafond³

et al. 2005

AIP Conference Proceedings

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ABSTRACT. An automated, non-contact, non-destructive sensor has been developed for measurement of sheet flexural and shear rigidity in paper manufacturing. It was tested on a pilot web handler at web speeds up to 25.4 m/s. A model equation was fitted to the frequency dependence of the phase velocity of A o mode Lamb waves. Ultrasound was generated in paper with a pulsed Nd:YAG laser and detected with a Mach-Zehnder interferometer coupled with a scanning mirror/timing system to compensate for paper motion.

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“…Paper labels are soft and breathable, 6 and label separation is the key in the label handling. 7,8 None of the existing label handling technologies can separate a single paper label from stacked paper labels satisfying reliability 99.99% and production efficiency less than 1 s. A method for separation of stacked paper labels based on airflow induction is proposed in the paper, which utilizes airflow to induce the preseparation of the labels.…”

Section: Introductionmentioning

confidence: 99%

Airflow‐induced high‐speed separation method for stacked paper labels and its mechanism

Huang

et al. 2020

Packag Technol Sci

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An airflow‐induced separation method for stacked paper labels is proposed with a stream of compressed air used to jet vertically onto the side of the stacked labels and force constraints applied to the two ends of the labels. Its mechanism is revealed that the viscous force caused by airflow is the main driving force for the initial separation of labels and the vertical force is the main factor for the formation of successive separation channels. Theoretical and experimental analyses are implemented to ensure the effects of airflow velocity, label characteristics, label stress, and other factors on label separation and show that a stable separation gap can be generated with separation efficiency of more than 3600 sheets per minute and reliability of 99.99%. A complete airflow‐induced label separation device is designed, which can be integrated into the existing packaging machine, and the physical feasibility of the stack label separation method is verified by experiments.

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A Laboratory Laser-Ultrasonic Instrument for Measuring the Mechanical Properties of Paper Webs

Cited by 4 publications

References 11 publications

Noncontact determination of elastic moduli by two-dimensional Fourier transformation and laser ultrasonic technique

Noncontact determination of elastic moduli by two-dimensional Fourier transformation and laser ultrasonic technique

A Sensor for Laser Ultrasonic Measurement of Elastic Properties of Moving Paper

Airflow‐induced high‐speed separation method for stacked paper labels and its mechanism

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