WO1991017435A1 - Method and device for continuously determining the modulus of elasticity of advancing flexible material - Google Patents

Method and device for continuously determining the modulus of elasticity of advancing flexible material Download PDF

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Publication number
WO1991017435A1
WO1991017435A1 PCT/FR1991/000355 FR9100355W WO9117435A1 WO 1991017435 A1 WO1991017435 A1 WO 1991017435A1 FR 9100355 W FR9100355 W FR 9100355W WO 9117435 A1 WO9117435 A1 WO 9117435A1
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Prior art keywords
distance
transducer
air
elasticity
ultrasonic
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Application number
PCT/FR1991/000355
Other languages
French (fr)
Inventor
Guy Bonnet
Olivier Lebaigue
Original Assignee
Centre Technique De L'industrie Des Papiers, Cartons Et Celluloses
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Publication of WO1991017435A1 publication Critical patent/WO1991017435A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/34—Paper
    • G01N33/343—Paper pulp
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/07—Analysing solids by measuring propagation velocity or propagation time of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/01—Indexing codes associated with the measuring variable
    • G01N2291/011—Velocity or travel time
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/023—Solids
    • G01N2291/0237—Thin materials, e.g. paper, membranes, thin films
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/02854—Length, thickness
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/042—Wave modes
    • G01N2291/0427—Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/10—Number of transducers
    • G01N2291/102—Number of transducers one emitter, one receiver
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/10—Number of transducers
    • G01N2291/103—Number of transducers one emitter, two or more receivers

Definitions

  • the invention in the making of which took part the Grenoble Institute of Mechanics on behalf of the Association for the Development of Research with Universities, Public, Scientific and Cultural Establishments of Grenoble, relates to a process to determine the mechanical characteristics, and more specifically the coefficient of elasticity of a non-rigid material in movement. It also relates to a device capable of enabling this measurement to be carried out.
  • non-rigid material any type of material capable of diffusing a wave of determined frequency, over a minimum distance of at least ten centimeters.
  • a second sensor (4) is positioned on the side opposite to said material (1) by means of which the wave transmitted by said material is picked up.
  • This method is not satisfactory taking into account on the one hand, that one cannot overcome the significant background noise detected by the second sensor, and significantly altering the accuracy of the measurement, and d on the other hand, the fact that the measurement is based on the determination of the amplitude of the wave scattered by the material, which is relatively complex to interpret with a view to obtaining the coefficient of elasticity of said material.
  • E denotes the modulus of elasticity or Young's modulus of the material, D its density, and • ••> the Poisson's ratio of this material.
  • the invention consists in determining the propagation speed of a wave train ultrasonic over a determined distance without implying any contact between on the one hand, the device generating the wave train and the sensor device of the wave train diffused by the material and on the other hand the material itself said. This eliminates any sort of coupling agent, prohibitive for the use of such a process on a production line.
  • the invention also relates to a device for implementing the method thus described.
  • This device is characterized in that it consists of: - a generator of ultrasonic signals associated with an amplifier and a transducer, in order to emit in the air towards the moving material and in a direction other than normal to the plane defined by the material, ultrasonic wave trains of fixed fixed frequency, between 100 and 800 kHz;
  • a second transducer capable of picking up the ultrasonic waves diffused in the air by the material at these frequencies
  • an amplifier connected to the second transducer, capable of amplifying the analog signals emitted by the latter;
  • a digitizing device connected to said amplifier, and capable of storing, as a function of time, the different ultrasonic wave trains picked up by the second transducer as well as the amplitude of these;
  • - a calculator capable of carrying out the various calculations necessary to arrive at the value of the elastic coeffi ⁇ cient of the material, from the measurement of the propagation durations for several distances.
  • These calculations include in particular an averaging over time on several signals, in order to reduce the background noise.
  • the device further comprises a third transducer, located downstream relative to the direction of travel of the material and relative to the other transducers, but at a distance at most equal to forty centimeters from the point impact of the ultrasonic waves diffused in the air by the material, this second transducer being as in the previous case associated with an amplifier and a digitizing member connected to the same computer in order to obtain more precisely the value of the elastic coefficient of the material.
  • FIGS 1 and 2 show the known devices of the prior art.
  • Figure 3 is a schematic representation of the device according to the invention.
  • Figure 4 is a schematic representation of another embodiment of this device.
  • FIG. 5 is a graphic representation of the detection of the ultrasonic wave trains by the second sensor as a function of time.
  • FIG. 6 is a block diagram of the operation of the device according to the invention.
  • a device capable of obtaining the measurement of the coefficient of elasticity (Young's modulus E) of a paper in the form of a moving sheet.
  • the density ⁇ of this paper is known.
  • the device according to the invention firstly comprises a generator of ultrasonic signals
  • This scattered wave is picked up by a second transducer (11) at a distance d from the point of impact of the exciter wave on the sheet of paper (1).
  • This distance d can typically be of the order of thirty centimeters.
  • This distance d is at least ten centimeters, because the detected direct wave is followed by a train, which if this distance is less than ten centimeters, risks causing an overlap between the direct wave and the scattered wave detected.
  • this distance cannot exceed forty centimeters, the signal of the diffused wave being then too tenuous to be exploitable.
  • This second sensor (11) / which delivers analog signals corresponding to the received waves, transmits these signals to an amplifier (14) associated with a bandpass filter, capable, in known manner, of amplifying the analog signals corresponding to a range of determined frequencies. These signals are then transmitted to an oscilloscope (15) with digital memory or transient analyzer, which itself transforms the analog signals into digital signals and which, in known manner, makes it possible to measure the date on which the signals were picked up by said signal. sensor (11). In addition, it stores in memory the different trains of scattered waves picked up by the sensor (11).
  • - d corresponds as already said to the distance par ⁇ traveled by said waves in the material étu ⁇ dié, obtained by calibration for a given relative position of the sensors;
  • - t - t_ represents the duration of propagation of the waves between the two points defined above, ie the total duration of propagation of the waves between the generator (12) and the sensor (11) minus the duration t a propagation of waves in the air; this latter value is obtained by calibration for a given relative position of the sensors.
  • t 0 corresponds to the original time given by the generator of ultrasonic waves (12) and transmitted directly to the oscilloscope during the emission of the excitation wave trains.
  • FIG. 5 gives a graphical representation of the waves detected as a function of time.
  • the amplitude in arbitrary scale of these waves is shown on the ordinate, and the detection time in milli-seconds on the abscissa.
  • a first train of waves is thus observed corresponding to the direct path in the air of the ultrasonic waves emitted by the first sensor (10) and picked up by the second sensor (11). In fact, these waves are captured before the waves scattered by the material are. These correspond to the second wave train. From such a representation, the average value of the propagation time of the waves in the material is obtained, and thus the speed and then the Young's module.
  • the example described corresponds to ultrasonic waves of frequency 500 kHz whose propagation speed was measured on dry kraft paper. Typically we obtain as propagation speed 690 ms -1 .
  • the device is provided with a third sensor (17), located downstream in the direction of movement of the sheet, and relative to the first two sensors (10,11) .
  • This third sensor (17) is very similar to the second sensor, connected to an amplifier. and the digital memory oscilloscope (15).
  • This sensor is located at a distance d__ from the point of impact of the exciting ultrasonic waves, that is to say si ⁇ killed about twenty to forty centimeters from this point of impact.
  • d__ from the point of impact of the exciting ultrasonic waves, that is to say si ⁇ killed about twenty to forty centimeters from this point of impact.
  • the second sensor it detects the waves diffused by the sheet of scrolling paper and, being associated with the digital oscilloscope (15), makes it possible to measure the duration of propagation t___ of the waves in the paper between these two points.
  • the computer or microcomputer (16) then performs the following calculation:
  • the device and the method in accordance with the invention make it possible to dispense with any contact between the sensors and the sheet of material in movement, and therefore the hazards linked to the calculation based on the ampli ⁇ tude of waves received.
  • the advantageous embodiment of the invention overcomes background noise, a feature which was not possible with the devices known to date.
  • the method and the device described are perfectly suited to the measurement of the coefficient of elasticity of paper, film, as well as any non-rigid anisotropic material, such as in particular fabrics.

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  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Medicinal Chemistry (AREA)
  • Food Science & Technology (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)

Abstract

The method enables a measurement of the modulus of elasticity of an advancing flexible material to be made accurately and in a contactless fashion. The method involves: firstly, transmitting through the air towards the material an ultrasonic wave train having a set frequency, the time of transmission of said wave train being the zero point of times to; sensing the ultrasonic waves scattered through the air by the material at a distance d; measuring the wave train's propagation time t over distance d; and finally, deducing from this measurement the wave train's propagation speed in the material, which is, in a known manner, proportional to the square root of the ratio between the modulus of elasticity and the density of said material. Applications: paper industry.

Description

PROCEDE ET DISPOSITIF POUR DETERMINER EN CONTINU LE COEFFICIENT D'ELASTICITE D'UN MATERIAU NON RIGIDE EN DEFILEMENT. METHOD AND DEVICE FOR CONTINUOUSLY DETERMINING THE COEFFICIENT OF ELASTICITY OF A NON-RIGID CUTTING MATERIAL.
L'invention, à la réalisation de laquelle a parti¬ cipé l'Institut de Mécanique de Grenoble pour le compte de l'Association pour le Développement des Recherches auprès des Universités, Etablissements Publics, Scien¬ tifiques et Culturels de Grenoble, concerne un procédé pour déterminer les caractéristiques mécaniques, et plus spécifiquement le coefficient d'élasticité d'un matériau non rigide en défilement. Elle concerne également un dispositif apte à permettre la réalisation de cette mesure.The invention, in the making of which took part the Grenoble Institute of Mechanics on behalf of the Association for the Development of Research with Universities, Public, Scientific and Cultural Establishments of Grenoble, relates to a process to determine the mechanical characteristics, and more specifically the coefficient of elasticity of a non-rigid material in movement. It also relates to a device capable of enabling this measurement to be carried out.
Par "matériau non rigide" , on entend tout type de matériau susceptible de diffuser une onde de fréquence déterminée, sur une distance minimum d'au moins dix centimètres .By "non-rigid material" is meant any type of material capable of diffusing a wave of determined frequency, over a minimum distance of at least ten centimeters.
Bien que la description qui va suivre concerne essentiellement la mesure du coefficient d'élasticité d'une feuille de papier en défilement, l'invention ne saurait se limiter à ce seul matériau, et il va de soi qu'elle s'applique également à tout autre matériau non rigide, tel que notamment les films, les tissus, les cartons, etc...Although the description which follows essentially relates to the measurement of the coefficient of elasticity of a sheet of paper in movement, the invention cannot be limited to this single material, and it goes without saying that it also applies to any other non-rigid material, such as in particular films, fabrics, cardboard, etc.
Dans le cadre de l'industrie papetière, la déter- mination de telles grandeurs physiques, et notamment du module d'Young s'avère de grande importance, particuliè¬ rement lors de la fabrication proprement dite du papier. En effet, la connaissance de ces grandeurs, en permanen¬ ce permet de faire varier les paramètres de fabrication quasiment immédiatement en fonction de la qualité et des caractéristiques que l'on désire obtenir. Afin de mesurer de telles caractéristiques, on a tout d'abord proposé de mesurer l'amplitude d'une onde ultra-sonore transmise à travers le matériau (1) dont on désire connaître le coefficient d'élasticité. Pour ce faire, et comme on peut le voir sur la figure 1, on envoie en direction du matériau ( 1) par 1'intermédiaire d'un capteur approprié (2), une onde ultra-sonore de fréquence déterminée, cette onde franchissant une cer¬ taine distance (3) dans l'air avant d'exciter le maté- riau. On positionne du coté opposé audit matériau (1) un second capteur (4) au moyen duquel, on capte l'onde transmise par ledit matériau. Ce procédé ne donne pas satisfaction compte-tenu d'une part, que l'on.ne peut s'affranchir du bruit de fond important déte.cté par le second capteur, et altérant de manière significative la précision de la mesure, et d'autre part du fait que la mesure repose sur la détermination de l'amplitude de l'onde diffusée par le matériau, relativement complexe à interpréter en vue de l'obtention du coefficient d'élas- ticité dudit matériau.In the context of the paper industry, the determination of such physical quantities, and in particular of the Young module, proves to be of great importance, particularly during the actual production of paper. Indeed, the knowledge of these quantities, in permanence, this makes it possible to vary the manufacturing parameters almost immediately as a function of the quality and characteristics which it is desired to obtain. In order to measure such characteristics, it was first proposed to measure the amplitude of an ultrasonic wave transmitted through the material (1) for which the elasticity coefficient is desired. To do this, and as can be seen in FIG. 1, an ultrasonic wave of determined frequency is sent towards the material (1) by means of an appropriate sensor (2), this wave crossing a certain distance (3) in the air before exciting the material. A second sensor (4) is positioned on the side opposite to said material (1) by means of which the wave transmitted by said material is picked up. This method is not satisfactory taking into account on the one hand, that one cannot overcome the significant background noise detected by the second sensor, and significantly altering the accuracy of the measurement, and d on the other hand, the fact that the measurement is based on the determination of the amplitude of the wave scattered by the material, which is relatively complex to interpret with a view to obtaining the coefficient of elasticity of said material.
On a alors proposé de mesurer la vitesse de dif¬ fusion des ondes ultra-sonores au moyen de palpeurs situés au contact du matériau (figure 2). Un premier palpeur (6), associé à un générateur d'ondes ultra-sono¬ res (5) excite le matériau (1). Cette excitation, diffu¬ sée par le matériau (1), est détectée et un second pal¬ peur (8), situé à une distance _1 connue dudit premier palpeur (.6), et associé à un capteur (7). Par mesure de la durée t de la diffusion du train d'ondes ultra-sono¬ res entre les deux palpeurs (6,8), on remonte à la vi¬ tesse de propagation et donc de manière connue, au modu¬ le d'élasticité du matériau selon l'expression :It was then proposed to measure the speed of diffusion of the ultrasonic waves by means of sensors located in contact with the material (FIG. 2). A first probe (6), associated with an ultrasonic wave generator (5) excites the material (1). This excitation, diffused by the material (1), is detected and a second fear (8), located at a known distance _1 from said first probe (.6), and associated with a sensor (7). By measuring the duration t of the diffusion of the ultrasonic wave train between the two probes (6,8), we go back to the propagation speed and therefore in known manner, to the modu¬ elasticity of the material according to the expression:
1 v =1 v =
(1 - 0 - )(1 - 0 -)
Ç où E désigne le module d'élasticité ou module d'Young du matériau, D sa masse volumique, et •••> le coeffi¬ cient de Poisson de ce matériau.VS where E denotes the modulus of elasticity or Young's modulus of the material, D its density, and • ••> the Poisson's ratio of this material.
Bien entendu, cette expression peut-être générali¬ sée dans le cas d'un matériau anisotrope.Of course, this expression may be generalized in the case of an anisotropic material.
Si certes ce type de dispositif permet d'apprécier de manière plus précise la valeur du coefficient d'élas- ticité d'un matériau non rigide, en revanche, son mode d'utilisation s'avère peu pratique, du fait que les palpeurs doivent être en contact permanent avec le maté¬ riau, ce contact étant réalisé par exemple par le biais d'une roulette, risquant à tout instant de ^détériorer le matériau. En outre, dans certaines applications particu¬ lières, telles que notamment dans le cadre de la fabri¬ cation de papier, il est nécessaire de ménager dans un rouleau moteur, ou un rouleau moteur et un rouleau de renvoi, voire dans deux rouleaux de renvoi, un espace destiné à permettre l'adaptation et le positionnement des palpeurs, d'où le caractère peu pratique de ce type de procédé et donc du dispositif associé. On a décrit un tel dispositif dans le document US - A - 4 291 577.While this type of device allows a more precise appreciation of the value of the coefficient of elasticity of a non-rigid material, on the other hand, its mode of use proves to be impractical, owing to the fact that the probes must be in permanent contact with the maté¬ riau, this contact being made for example by means of a roller, risking ^ damaging the material at any time. In addition, in certain particular applications, such as in particular in the context of the manufacture of paper, it is necessary to provide in a drive roller, or a drive roller and a deflection roller, or even in two deflection rollers. , a space intended to allow the adaptation and positioning of the probes, hence the impracticality of this type of process and therefore of the associated device. Such a device has been described in document US-A-4,291,577.
On a également proposé par exemple dans le document US-A-3 720 098, un dispositif apte à mesurer la vitesse de propagation des ultra-sons dans un échantillon, afin de déterminer certaines grandeurs physiques, parmi les¬ quelles le module d'Young E. Néanmoins, si certes les valeurs obtenues sont relativement précises, en revan¬ che, ce dispositif nécessite l'utilisation d'un agent couplant interposé entre l'émetteur et/ou le capteur d'ultra-sons et le support-échantillon analysé, afin de s'affranchir de l'amortissement des ultra-sons dans l'air. De la sorte, ce dispositif et le procédé d'utili¬ sation ne peuvent être utilisés directement sur une chaîne de fabrication, réduisant ainsi considérablement leur intérêt. L'invention vise à pallier ces différents incon¬ vénients . Elle vise un procédé apte à permettre la me¬ sure du coefficient d'élasticité d'un matériau non rigi¬ de en défilement, et ce de manière précise et sans con- tact.We have also proposed, for example in document US-A-3,720,098, a device capable of measuring the speed of propagation of ultrasound in a sample, in order to determine certain physical quantities, among which the Young's modulus. E. Nevertheless, if the values obtained are relatively precise, on the other hand, this device requires the use of a coupling agent interposed between the transmitter and / or the ultrasonic sensor and the sample support analyzed. , in order to get rid of the damping of ultrasound in the air. In this way, this device and the method of use cannot be used directly on a production line, thus considerably reducing their advantage. The invention aims to overcome these various drawbacks. It relates to a process capable of allowing the measurement of the coefficient of elasticity of a material which is not rigid in running, and this in a precise and contactless manner.
Ce procédé se caractérise en ce qu'il consiste :This process is characterized in that it consists:
- tout d'abord, à émettre dans l'air en direction dudit matériau et sous incidence autre que la normale au plan de celui-ci, un train d'ondes ultra-sonores de fréquence fixe et déterminée, la date d'émission dudit train d'ondes définissant l'origine des temps t_ ;- first of all, to emit into the air towards said material and under incidence other than normal to the plane thereof, a train of ultrasonic waves of fixed and determined frequency, the date of emission of said train of waves defining the origin of times t_;
- à capter, une distance d comprise entre dix et quarante centimètres du lieu d'impact du train d'ondes ultra-sonores sur le matériau, les ondes ultra-sonores diffusées dans l'air par celui-ci ;- to capture, a distance d between ten and forty centimeters from the place of impact of the train of ultrasonic waves on the material, the ultrasonic waves diffused in the air by the latter;
- à mesurer la durée t de propagation du train d'ondes entre le temps origine 0 et la date de détec¬ tion du train d'ondes diffusées à la distance d ; - à déterminer par étalonnage la durée ta du par¬ cours du train d'ondes dans l'air ;to measure the duration t of propagation of the wave train between the time of origin 0 and the date of detection of the train of waves diffused at distance d; - to determine by calibration the duration t a of the course of the wave train in the air;
- et enfin, à déduire de cette mesure, la vitesse de propagation du train d'ondes dans le matériau, vites¬ se qui est de manière connue proportionnellement à la racine carrée du rapport du module d'élasticité (module d'Young) sur la masse volumique du matériau.- and finally, to deduce from this measurement, the speed of propagation of the wave train in the material, vites¬ which is in known manner proportional to the square root of the ratio of the modulus of elasticity (Young's modulus) on the density of the material.
Dans ce calcul de la vitesse de propagation du train d'ondes, la distance parcourue par le train d'on- des dans l'air doit être déterminée par étalonnage préa¬ lable, ce qui permet d'obtenir la distance réellement parcourue dans le matériau.In this calculation of the propagation speed of the wave train, the distance traveled by the wave train in the air must be determined by prior calibration, which makes it possible to obtain the distance actually traveled in the material.
En d'autres termes, l'invention consiste à déter- miner la vitesse de propagation d'un train d'ondes ultra-sonores sur une distance déterminée et ce, sans impliquer un quelconque contact entre d'une part, le dispositif générateur du train d'ondes et le dispositif capteur du train d'ondes diffusées par le matériau et d'autre part le matériau proprement dit. On s'affranchit de la sorte de tout agent couplant, rédhibitoire pour l'utilisation d'un tel procédé sur une chaîne de fabri¬ cation.In other words, the invention consists in determining the propagation speed of a wave train ultrasonic over a determined distance without implying any contact between on the one hand, the device generating the wave train and the sensor device of the wave train diffused by the material and on the other hand the material itself said. This eliminates any sort of coupling agent, prohibitive for the use of such a process on a production line.
Dans une variante avantageuse de l'invention, on capte de manière supplémentaire dans la limite des qua¬ rante centimètres définis précédemment, mais à une dis¬ tance d_ supérieure à la distance d séparant le point d'impact du train d'ondes excitateur du point de premier captage, les ondes ultra-sonores diffusées par le maté¬ riau dans l'air, et l'on détermine la durée t_[_ de propa¬ gation du train d'ondes dans le matériau depuis le temps origine t0 ; on déduit alors des mesures ainsi effec¬ tuées la vitesse de propagation du train d'ondes dans le matériau sur le trajet d' - d, selon l'expression :In an advantageous variant of the invention, it is additionally captured within the limit of the forty-one centimeters defined above, but at a distance d_ greater than the distance d separating the point of impact of the excitation wave train from point of first capture, the ultrasonic waves diffused by the material in the air, and the duration t _ [_ of propagation of the wave train in the material since the origin time t 0 is determined ; we then deduce from the measurements thus made the propagation speed of the wave train in the material on the path from - d, according to the expression:
Figure imgf000007_0001
Figure imgf000007_0001
De la sorte, cette double mesure permet de s'af¬ franchir de la quasi-totalité du bruit de fond généré par les ondes parasites diffusées par le matériau, et surtout d'éliminer par différence la nécessité de con- naître la durée du trajet des ondes dans l'air.In this way, this double measurement makes it possible to overcome almost all of the background noise generated by the parasitic waves diffused by the material, and above all to eliminate by difference the need to know the duration of the journey. waves in the air.
L'invention concerne également un dispositif pour la mise en oeuvre du procédé ainsi décrit. Ce dispositif se caractérise en ce qu'il se compose : - d'un générateur de signaux ultra-sonores associé à un amplificateur et un transducteur, en vue d'émettre dans l'air en direction du matériau en défilement et selon une direction autre que la normale au plan défini par le matériau, des trains d'ondes ultra-sonores de fréquence fixe déterminée, comprise entre 100 et 800 kHz;The invention also relates to a device for implementing the method thus described. This device is characterized in that it consists of: - a generator of ultrasonic signals associated with an amplifier and a transducer, in order to emit in the air towards the moving material and in a direction other than normal to the plane defined by the material, ultrasonic wave trains of fixed fixed frequency, between 100 and 800 kHz;
- d'un second transducteur, apte à capter les ondes ultra-sonores diffusées dans l'air par le matériau à ces fréquences ;- a second transducer, capable of picking up the ultrasonic waves diffused in the air by the material at these frequencies;
- d'um amplificateur, connecté au second transduc- teur, apte à amplifier les signaux analogiques émis par celui-ci ;- an amplifier, connected to the second transducer, capable of amplifying the analog signals emitted by the latter;
- d'un organe de numérisation, relié audit amplifi¬ cateur, et apte à stocker en fonction du temps les dif¬ férents trains d'ondes ultra-sonores captées par le second transducteur ainsi que l'amplitude de ceux-ci ;- a digitizing device, connected to said amplifier, and capable of storing, as a function of time, the different ultrasonic wave trains picked up by the second transducer as well as the amplitude of these;
- d'un calculateur, apte à effectuer les différents calculs nécessaires pour aboutir à la valeur du coeffi¬ cient d'élasticité du matériau, à partir de la mesure des durées de propagation pour plusieurs distances. Ces calculs comprennent en particulier une moyennage dans le temps sur plusieurs signaux, en vue de diminuer le bruit de fond.- a calculator, capable of carrying out the various calculations necessary to arrive at the value of the elastic coeffi¬ cient of the material, from the measurement of the propagation durations for several distances. These calculations include in particular an averaging over time on several signals, in order to reduce the background noise.
Dans une forme de réalisation avantageuse, le dis- positif comprend en outre un troisième transducteur, situé en aval par rapport au sens de défilement du maté¬ riau et par rapport aux autres transducteurs, mais à une distance au plus égale à quarante centimètres du point d'impact des ondes ultra-sonores diffusées dans l'air par le matériau, ce second transducteur étant comme dans le cas précédent associé à un amplificateur et un organe de numérisation relié au même calculateur en vue d'ob¬ tenir de manière plus précise la valeur du coefficient d'élasticité du matériau. La manière dont l'invention peut être réalisée et les avantages qui en découlent ressortiront mieux de l'exemple de réalisation qui suit, donné à titre indica¬ tif et non limitatif, à l'appui des figures annexées.In an advantageous embodiment, the device further comprises a third transducer, located downstream relative to the direction of travel of the material and relative to the other transducers, but at a distance at most equal to forty centimeters from the point impact of the ultrasonic waves diffused in the air by the material, this second transducer being as in the previous case associated with an amplifier and a digitizing member connected to the same computer in order to obtain more precisely the value of the elastic coefficient of the material. The manner in which the invention can be implemented and the advantages which result therefrom will emerge more clearly from the embodiment which follows, given by way of non-limiting indication, in support of the appended figures.
Les figures 1 et 2 représentent les dispositifs connus de 1'art antérieur.Figures 1 and 2 show the known devices of the prior art.
La figure 3 est une représentation schématique du dispositif conforme à l'invention. La figure 4 est une représentation schématique d'une autre forme de réalisation de ce dispositif.Figure 3 is a schematic representation of the device according to the invention. Figure 4 is a schematic representation of another embodiment of this device.
La figure 5 est une représentation graphique de la détection des trains d'ondes ultra-sonores par le second capteur en fonction du temps . La figure 6 est un schéma synoptique du fonctionne¬ ment du dispositif conforme à l'invention.FIG. 5 is a graphic representation of the detection of the ultrasonic wave trains by the second sensor as a function of time. FIG. 6 is a block diagram of the operation of the device according to the invention.
Selon l'invention, il va être décrit un dispositif apte à obtenir la mesure du coefficient d'élasticité (module d'Young E) d'une papier en forme de feuille en défilement. La masse volumique Ç de ce papier est connue. Néanmoins, si celle-ci n'est pas connue, la con¬ naissance du grammage G permet d'aboutir à la valeur de la rigidité extensionnelle S = E.e, où e désigne l'épaisseur de la feuille, (mieux connue sous l'expres¬ sion en langue anglaise extensional stiffness) via la relation :According to the invention, a device will be described capable of obtaining the measurement of the coefficient of elasticity (Young's modulus E) of a paper in the form of a moving sheet. The density Ç of this paper is known. However, if this is not known, the knowledge of the grammage G makes it possible to arrive at the value of the extensional stiffness S = Ee, where e denotes the thickness of the sheet, (better known as expression in English language extensional stiffness) via the relation:
S v2G 1 - ^ 2S v 2 G 1 - ^ 2
Le disposisitif conforme à l'invention comprend tout d'abord un générateur de signaux ultra-sonoresThe device according to the invention firstly comprises a generator of ultrasonic signals
(12), délivrant des trains de tels signaux de fréquence cinq cents 500 kilohertz (kHz). On peut toutefois choisir une fréquence comprise entre 100 et 800 kHz. On peut difficilement descendre en deçà de 100 kHz, sans- risque d'obtenir un faisceau d'ondes trop élargi, et partant, inexploitable. De même, si la fréquence dépasse 800 kHz, la proportion de propagation d'ondes dans l'air devient trop importante pour permettre une détermination correcte et précise des caractéristiques recherchées.(12), delivering trains of such frequency signals five hundred 500 kilohertz (kHz). However, you can choose a frequency between 100 and 800 kHz. We can hardly fall below 100 kHz, without the risk of obtaining a wave beam that is too broad, and therefore unusable. Likewise, if the frequency exceeds 800 kHz, the proportion of propagation of waves in the air becomes too great to allow a correct and precise determination of the desired characteristics.
Ces signaux sont ensuite amplifiés de manière con¬ ventionnelle au moyen d'un amplificateur (13), puis générés dans l'air par un capteur adapté (10). La direc¬ tion principale des signaux émis par le capteur (10) forme un angle voisin de 45e par rapport au plan défini par la feuille de papier en défilement (1). La distance séparant le capteur (10) de la feuille (1) e.st_ au plus égale à dix centimètres. En effet, si l'on exède cette distance, la déperdition de signal excitateur devient trop importante pour obtenir un signal diffusé exploita¬ ble. Cette excitation ultra-sonore est transmise à la feuille sous la forme d'ondes dites "de plaque". Ces ondes de plaque se propagent dans le matériau selon une vitesse fonction d'une part, du module d'élasticité du matériau ou module d'Young E et d'autre part, de la masse volumique de la feuille de papier, et créent de part et d'autre de la feuille une onde diffusée.These signals are then amplified conventionally by means of an amplifier (13), then generated in the air by a suitable sensor (10). The main direction of the signals emitted by the sensor (10) forms an angle close to 45 e with respect to the plane defined by the sheet of scrolling paper (1). The distance between the sensor (10) and the sheet (1) is not more than ten centimeters. In fact, if this distance is exceeded, the loss of the excitatory signal becomes too great to obtain an exploitable signal. This ultrasonic excitation is transmitted to the sheet in the form of so-called "plate" waves. These plate waves propagate in the material at a speed which depends on the one hand, on the elastic modulus of the material or Young's modulus and on the other hand, on the density of the paper sheet, and create on either side of the sheet a scattered wave.
Cette onde diffusée est captée par un second trans¬ ducteur (11) à une distance d du point d'impact de l'on¬ de excitatrice sur la feuille de papier (1). Cette dis¬ tance d peut typiquement être de l'ordre de trente cen- timètres. Cette distance d est d'au moins dix centimè¬ tres, du fait que l'onde directe détectée est suivie d'une traine, qui si cette distance est inférieure à dix centimètres, risque de provoquer un chevauchement entre l'onde directe et l'onde diffusée détectée. Toutefois, cette distance ne peut excéder quarante centimètres, le signal de l'onde diffusée étant alors trop ténu pour être exploitable. Ce second capteur (11)/ qui délivre des signaux analogiques correspondant aux ondes captées, transmet ces signaux à un amplificateur (14) associé à un filtre passe-bande, apte, de manière connue, à amplifier les signaux analogiques correspondant à une gamme de fré¬ quences déterminées. Ces signaux sont alors transmis à un oscilloscope (15) à mémoire numérique ou analyseur de transitoire, qui assure lui-même la transformation des signaux analogiques en signaux numériques et qui, de manière connue, permet de mesurer la date de captage des signaux par ledit capteur (11). En outre, il stocke en mémoire les différents trains d'ondes diffusées captés par le capteur (11).This scattered wave is picked up by a second transducer (11) at a distance d from the point of impact of the exciter wave on the sheet of paper (1). This distance d can typically be of the order of thirty centimeters. This distance d is at least ten centimeters, because the detected direct wave is followed by a train, which if this distance is less than ten centimeters, risks causing an overlap between the direct wave and the scattered wave detected. However, this distance cannot exceed forty centimeters, the signal of the diffused wave being then too tenuous to be exploitable. This second sensor (11) / which delivers analog signals corresponding to the received waves, transmits these signals to an amplifier (14) associated with a bandpass filter, capable, in known manner, of amplifying the analog signals corresponding to a range of determined frequencies. These signals are then transmitted to an oscilloscope (15) with digital memory or transient analyzer, which itself transforms the analog signals into digital signals and which, in known manner, makes it possible to measure the date on which the signals were picked up by said signal. sensor (11). In addition, it stores in memory the different trains of scattered waves picked up by the sensor (11).
Les signaux ainsi détectés et transformés sont alors exploités par un microordinateur (16) d'un type en soi connu, apte à réaliser le calcul suivant :The signals thus detected and transformed are then used by a microcomputer (16) of a type known per se, capable of carrying out the following calculation:
Figure imgf000011_0001
dans lequel :
Figure imgf000011_0001
in which :
- v désigne la vitesse de propagation des ondes ultra-sonores dans la feuille de papier ;- v denotes the speed of propagation of the ultrasonic waves in the sheet of paper;
- d correspond comme déjà dit à la distance par¬ courue par lesdites ondes dans le matériau étu¬ dié, obtenue par étalonnage pour une position relative donnée des capteurs ; - t - t_ représente la durée de propagation des ondes entre les deux points définis ci-dessus, c'est à dire la durée totale de propagation des ondes entre le générateur (12) et le capteur (11) diminuée de la durée ta de propagation des ondes dans l'air ; cette dernière valeur est obtenue par étalonnage pour une position relative donnée des capteurs. t0 correspond au temps origine donné par le généra¬ teur d'ondes ultra-sonores (12) et transmis directement à l'oscilloscope lors de l'émission des trains d'ondes excitateurs.- d corresponds as already said to the distance par¬ traveled by said waves in the material étu¬ dié, obtained by calibration for a given relative position of the sensors; - t - t_ represents the duration of propagation of the waves between the two points defined above, ie the total duration of propagation of the waves between the generator (12) and the sensor (11) minus the duration t a propagation of waves in the air; this latter value is obtained by calibration for a given relative position of the sensors. t 0 corresponds to the original time given by the generator of ultrasonic waves (12) and transmitted directly to the oscilloscope during the emission of the excitation wave trains.
On constate ainsi que par simple mesure de la durée de propagation des ondes ultra-sonores, on aboutit à la détermination du module d'Young ou module d'élasticité du matériau, dans la mesure où bien entendu, la masse volumique du papier est connue.It can thus be seen that by simple measurement of the duration of propagation of the ultrasonic waves, we arrive at the determination of the Young's modulus or modulus of elasticity of the material, insofar as of course, the density of the paper is known. .
On a donné à la figure 5, une représentation gra¬ phique des ondes détectées en fonction du temps. On a représenté en ordonnées l'amplitude en échelle arbi- traire de ces ondes, et en abscisses le temps de détec¬ tion en milli-secondes. On observe ainsi un premier train d'ondes correspondant au trajet direct dans l'air des ondes ultra-sonores émises par le premier capteur (10) et captées par le second capteur (11). De fait, ces ondes sont captées avant que les ondes diffusées par le matériau ne le soient. Ces dernières correspondent au second train d'ondes. D'une telle représentation, on tire la valeur moyenne de la durée de propagation des ondes dans le matériau et ainsi la vitesse puis le mo- dule d'Young. L'exemple décrit correspond a des ondes ultra-sonores de fréquence 500 kHz dont la vitesse de propagation a été mesurée sur du papier kraft sec. On obtient typiquement comme vitesse de propagation 690 m.s-1.FIG. 5 gives a graphical representation of the waves detected as a function of time. The amplitude in arbitrary scale of these waves is shown on the ordinate, and the detection time in milli-seconds on the abscissa. A first train of waves is thus observed corresponding to the direct path in the air of the ultrasonic waves emitted by the first sensor (10) and picked up by the second sensor (11). In fact, these waves are captured before the waves scattered by the material are. These correspond to the second wave train. From such a representation, the average value of the propagation time of the waves in the material is obtained, and thus the speed and then the Young's module. The example described corresponds to ultrasonic waves of frequency 500 kHz whose propagation speed was measured on dry kraft paper. Typically we obtain as propagation speed 690 ms -1 .
Dans une forme de réalisation avantageuse de l'in¬ vention, on munit le dispositif d'un troisième capteur (17), situé en aval dans le sens de déplacement de la feuille, et par rapport aux deux premiers capteurs (10,11). Ce troisième capteur (17) est, de manière tout à fait similaire au second capteur, relié à un amplifi- cateur, et à l'oscilloscope à mémoire numérique (15). Ce capteur est situé à une distance d__ du point d'impact des ondes ultra-sonores excitatrices, c'est à dire si¬ tuée à environ vingt à quarante centimètres de ce point d'impact. De la même manière que pour le second capteur, il détecte les ondes diffusées par la feuille de papier en défilement et, étant associé à l'oscilloscope numéri¬ que (15), permet de mesurer la durée de propagation t___ des ondes dans le papier entre ces deux points.In an advantageous embodiment of the invention, the device is provided with a third sensor (17), located downstream in the direction of movement of the sheet, and relative to the first two sensors (10,11) . This third sensor (17) is very similar to the second sensor, connected to an amplifier. and the digital memory oscilloscope (15). This sensor is located at a distance d__ from the point of impact of the exciting ultrasonic waves, that is to say si¬ killed about twenty to forty centimeters from this point of impact. In the same way as for the second sensor, it detects the waves diffused by the sheet of scrolling paper and, being associated with the digital oscilloscope (15), makes it possible to measure the duration of propagation t___ of the waves in the paper between these two points.
Le calculateur ou microordinateur (16) effectue alors le calcul suivant :The computer or microcomputer (16) then performs the following calculation:
Figure imgf000013_0001
permettant ainsi de calculer de manière beaucoup plus précise la vitesse de propagation des ondes dans le matériau, en s'affranchissant des incertitudes liées au point d'impact des ondes excitatrices au niveau de la feuille de papier en défilement, du bruit de fond généré par d'autres ondes diffusées par le papier, ainsi que de la durée de propagation des ondes dans l'air, qu'il n'est plus nécessaire de mesurer, notamment par étalon¬ nage.
Figure imgf000013_0001
thus making it possible to calculate in a much more precise manner the speed of propagation of the waves in the material, by overcoming the uncertainties linked to the point of impact of the excitation waves at the level of the sheet of paper in scrolling, of the background noise generated by other waves diffused by the paper, as well as the propagation time of the waves in the air, which it is no longer necessary to measure, in particular by étalon¬ nage.
De la sorte, le dispositif et le procédé conformes à l'invention permettent de s'affranchir de tout contact entre les capteurs et la feuille de matériau en défile¬ ment, et donc des aléas liés au calcul basé sur l'ampli¬ tude des ondes captées. En outre, la forme de réalisa¬ tion avantageuse de l'invention permet de s'affranchir du bruit de fond, particularité qui n'était pas possible avec les dispositifs connus à ce jour.In this way, the device and the method in accordance with the invention make it possible to dispense with any contact between the sensors and the sheet of material in movement, and therefore the hazards linked to the calculation based on the ampli¬ tude of waves received. In addition, the advantageous embodiment of the invention overcomes background noise, a feature which was not possible with the devices known to date.
De la sorte, le procédé et le dispositif décrits sont parfaitement adaptés à la mesure de coefficient d'élasticité de papier, film, ainsi que tout matériau anisotrope non rigide, tel que notamment les tissus. In this way, the method and the device described are perfectly suited to the measurement of the coefficient of elasticity of paper, film, as well as any non-rigid anisotropic material, such as in particular fabrics.

Claims

REVENDICATIONS 1/ Procédé pour mesurer le coefficient d'élasticité d'un matériau non rigide en défilement, caractérisé en ce qu'il consiste : - tout d'abord, à émettre dans l'air en direction dudit matériau et sous incidence autre que la normale au plan de celui-ci, un train d'ondes ultra-sonores de fréquence fixe et déterminée, la date d'émission dudit train d'ondes définissant l'origine des temps t_ ; - à capter, à une distance d comprise entre dix et quarante centimètres du lieu d'impact du train d'ondes ultra-sonores sur le matériau, les ondes ultra-sonores diffusées dans l'air par celui-ci ; CLAIMS 1 / Method for measuring the elasticity coefficient of a non-rigid material in movement, characterized in that it consists: - first of all, in emitting in the air in the direction of said material and under incidence other than the normal to the plane thereof, an ultrasonic wave train of fixed and determined frequency, the date of emission of said wave train defining the origin of the times t_; - to pick up, at a distance d between ten and forty centimeters from the place of impact of the train of ultrasonic waves on the material, the ultrasonic waves diffused in the air by the latter;
- à mesurer la durée t de propagation du train d'ondes entre le temps d'origine t0 et la date de détection du train d'ondes diffusées à la distance d ;- to measure the duration t of propagation of the wave train between the original time t 0 and the date of detection of the wave train broadcast at distance d;
- à déterminer par étalonnage la durée ta du par¬ cours du train d'ondes dans l'air ;- to determine by calibration the duration t a of the course of the wave train in the air;
- et enfin, à déduire de cette mesure, la vitesse de propagation du train d'ondes dans le matériau qui est de manière connue proportionnelle à la racine carrée du rapport du module d'élasticité sur la masse volumique du matériau considéré, selon une expression de la forme :- and finally, to deduce from this measurement, the speed of propagation of the wave train in the material which is in known manner proportional to the square root of the ratio of the modulus of elasticity to the density of the material considered, according to an expression of shape :
Figure imgf000014_0001
2/ Procédé selon la revendication 1, caractérisé en ce que l'on capte de manière supplémentaire dans la limite des quarante centimètres définis précédemment, mais à une distance d_ supérieure à la distance d défi¬ nie précédemment, les ondes ultra-sonores diffusées par le matériau dans l'air, et en ce que l'on détermine la durée t___ de propagation du train d'ondes depuis le temps t0 d'origine, et enfin, en ce que l'on déduit alors des mesures ainsi effectuées la vitesse de propagation du train d'ondes dans le matériau selon une expression de la forme :
Figure imgf000014_0001
2 / A method according to claim 1, characterized in that one collects additionally within the limit of the forty centimeters defined above, but at a distance d_ greater than the distance d Défi¬ denied previously, the ultrasonic waves broadcast by the material in the air, and in that one determines the duration t___ of propagation of the wave train from the original time t 0 , and finally, in that one then deduces from the measurements thus carried out the propagation speed of the wave train in the material according to an expression of the form:
Figure imgf000014_0002
3/ Procédé selon l'une des revendications 1 et 2, caractérisé en ce que la fréquence des ondes ultra-sono¬ res est comprise entre cent et huit cents kilohertz," de préférence voisine de cinq cents kilohertz. 5
Figure imgf000014_0002
3 / Method according to one of claims 1 and 2, characterized in that the frequency of the ultrasonic waves is between one hundred and eight hundred kilohertz, " preferably close to five hundred kilohertz. 5
4/ Dispositif pour la mise en oeuvre du procédé conforme à la revendication 1, caractérisé en ce qu'il se compose :4 / Device for implementing the method according to claim 1, characterized in that it consists of:
- d'un générateur de signaux ultra-sonores (12) associé à un amplificateur (13) et un transducteur (10), en vue d'émettre des trains d'ondes ultra-sonores dans l'air en direction du matériau en défilement (1) et selon une direction autre que la normale au plan défini par le matériau ; - d'un second transducteur (11), pour capter les ondes ultra-sonores diffusées par le matériau (1) dans l'air, et situé à une distance d comprise entre dix et quarante centimètres du point d'impact des ondes ultra¬ sonores sur ledit matériau (1) ; - d'un amplificateur (14), relié au second trans¬ ducteur (11), pour amplifier les signaux analogiques émis par celui-ci ;- an ultrasonic signal generator (12) associated with an amplifier (13) and a transducer (10), with a view to emitting ultrasonic wave trains in the air in the direction of the moving material (1) and in a direction other than normal to the plane defined by the material; - A second transducer (11), to capture the ultrasonic waves diffused by the material (1) in the air, and located at a distance d between ten and forty centimeters from the point of impact of the ultra¬ waves sound on said material (1); - an amplifier (14), connected to the second transducer (11), for amplifying the analog signals emitted by the latter;
- d'un organe de numérisation (15), relié à l'am¬ plificateur (14), pour stocker en fonction du temps t les différents trains d'ondes ultra-sonores captées par le second transducteur (11) et pour mesurer leur ampli¬ tude ;- a digitizing member (15), connected to the amplifier (14), for storing, as a function of time t, the various ultrasonic wave trains picked up by the second transducer (11) and for measuring their amplitude;
- d'un calculateur (16) relié audit oscilloscope (15), pour effectuer les différents calculs nécessaires pour aboutir à la valeur du coefficient d'élasticité du matériau, à partir de la mesure des durées de propaga¬ tion pour une distance donnée, selon une expression de • la forme :- a computer (16) connected to said oscilloscope (15), to perform the various calculations necessary to arrive at the value of the coefficient of elasticity of the material, from the measurement of the propagation times for a given distance, according to an expression of • the form:
t - t, (1 ~ \>2) 5/ Dispositif pour la mise en oeuvre du procédé conforme à la revendication 2, caractérisé en ce qu'il compose :t - t, (1 ~ \> 2 ) 5 / Device for implementing the method according to claim 2, characterized in that it comprises:
- d'un générateur de signaux ultra-sonores (12) associé à un amplificateur (13) et un transducteur (10), en vue d'émettre des trains d'ondes ultra-sonores dans l'air en direction du matériau en défilement (1) et selon une direction autre que la normale au plan défini par le matériau ; - d'un second transducteur (11), pour capter les ondes ultra-sonores diffusées dans l'air par le matériau (1), et situé à une distance d comprise entre dix et quarante centimètres du point d'impact des ondes ultra¬ sonores sur ledit matériau (1) ; - d'un amplificateur (14), relié au second trans¬ ducteur (11), pour amplifier les signaux analogiques émis par celui-ci ;- an ultrasonic signal generator (12) associated with an amplifier (13) and a transducer (10), with a view to emitting ultrasonic wave trains in the air in the direction of the moving material (1) and in a direction other than normal to the plane defined by the material; - A second transducer (11), to capture the ultrasonic waves diffused in the air by the material (1), and located at a distance d between ten and forty centimeters from the point of impact of the ultra¬ waves sound on said material (1); - an amplifier (14), connected to the second transducer (11), for amplifying the analog signals emitted by the latter;
- d'un organe de numérisation (15), relié audit amplificateur (14), pour stocker en fonction du temps t les différents trains d'ondes ultra-sonores captées par le second transducteur (11) et pour mesurer leur ampli¬ tude ;- a digitizing member (15), connected to said amplifier (14), for storing, as a function of time t, the various ultrasonic wave trains picked up by the second transducer (11) and for measuring their amplitude;
- d'un calculateur (16), relié audit oscilloscope (15), pour effectuer les différents calculs nécessaires pour aboutir à la valeur du coefficient d'élasticité du matériau, à partir de la mesure des durées de propaga¬ tion pour une distance donnée ; et en ce q 'il comprend en outre :- a computer (16), connected to said oscilloscope (15), to carry out the various calculations necessary to arrive at the value of the coefficient of elasticity of the material, from the measurement of the propagation times for a given distance ; and in that it further comprises:
- un. troisième transducteur (17), situé en aval par rapport au sens de défilement du matériau, et par rap¬ port aux autres transducteurs (10,11), et à une distance d' du point d'impact des ondes ultra-sonores excitatri¬ ces sur le matériau, la distance d _ étant au plus égale à quarante centimètres, et destiné à capter également les ondes ultra-sonores diffusées dans l'air par le matériau, ce transducteur (17) étant également associé à un amplificateur et un organe de numérisation, et relié audit calculateur (16) en vue d'effectuer les différents calculs nécessaires pour aboutir à la valeur du coeffi- cient d'élasticité du matériau, à partir de la mesure des durées de propagation _ pour une distance donnée d' , selon une expression de la forme :- a. third transducer (17), located downstream relative to the direction of travel of the material, and relative to the other transducers (10,11), and at a distance from the point of impact of the excitatory ultrasonic waves these on the material, the distance d _ being at most equal to forty centimeters, and intended also to pick up the ultrasonic waves diffused in the air by the material, this transducer (17) also being associated with an amplifier and a digitizing member, and connected to said calculator (16) in order to carry out the various calculations necessary to arrive at the value of the coefficient of elasticity of the material, from the measurement of propagation times _ for a given distance of, according to an expression of the form:
Figure imgf000017_0001
Figure imgf000017_0001
6/ Dispositif selon l'une des revendications 4 et 5, caractérisé en ce que l'organe de numérisation (15) est un oscilloscope à mémoire numérique.6 / Device according to one of claims 4 and 5, characterized in that the digitizing member (15) is a digital memory oscilloscope.
Il Dispositif pour mesurer le coefficient d'élas¬ ticité ou module d'Young d'une feuille de papier en défilement, caractérisé en ce qu'il reprend les ensei¬ gnements des revendications 4 et 6. Device for measuring the elasticity coefficient or Young's modulus of a sheet of scrolling paper, characterized in that it incorporates the teachings of claims 4 and 6.
PCT/FR1991/000355 1990-05-02 1991-04-30 Method and device for continuously determining the modulus of elasticity of advancing flexible material WO1991017435A1 (en)

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FR90/05754 1990-05-02

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996011396A1 (en) * 1994-10-06 1996-04-18 Ab Lorentzen & Wettre System for measuring ultrasonically the elastic properties of a moving paper web
WO1996011395A1 (en) * 1994-10-06 1996-04-18 Ab Lorentzen & Wettre System for measuring ultrasonically the elastic properties of a moving paper web
EP1985990A2 (en) * 2007-04-25 2008-10-29 Voith Patent GmbH Ultrasonic method for determining the stiffness of a fibrous material web in thickness direction
DE102011006391A1 (en) * 2011-03-30 2012-10-04 Siemens Aktiengesellschaft Method and device for detecting parameters of a continuous or circulating material web in a material processing machine
CN110849970A (en) * 2019-11-18 2020-02-28 清华大学 Method, device and system for measuring material mechanics attribute information
EP3589943A4 (en) * 2017-03-02 2020-12-16 Abzac Canada Inc. An in-line, contactless and non-destructive method&system for detecting defects in a moving cardboard structure

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69424796D1 (en) * 1993-10-22 2000-07-06 Amcor Ltd DETERMINING THE STRENGTH OF LAYER MATERIALS BY ULTRASONIC TESTING
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JP2010286358A (en) 2009-06-11 2010-12-24 Toshiba Corp Stiffness detector, stiffness detection method, and paper sheet processor including stiffness detector
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3720098A (en) * 1971-03-22 1973-03-13 Atomic Energy Commission Ultrasonic apparatus and method for nondestructively measuring the physical properties of a sample
EP0028540A1 (en) * 1979-11-06 1981-05-13 The Electricity Council Method and apparatus for non-contact acoustic measurement of physical properties of continuously moving metal strip
DE3045581A1 (en) * 1979-12-03 1981-08-27 Institute of Paper Chemistry, Appleton, Wis. DEVICE FOR MEASURING THE SPEED OF SPREADING FROM A MOVING MATERIAL, IN PARTICULAR PAPER, THROUGH ULTRASOUND WAVES
US4574634A (en) * 1984-08-09 1986-03-11 Westvaco Corporation Automatic paper testing apparatus

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5710448A (en) * 1980-06-23 1982-01-20 Sumitomo Metal Ind Ltd Evaluation for strength of refractories

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3720098A (en) * 1971-03-22 1973-03-13 Atomic Energy Commission Ultrasonic apparatus and method for nondestructively measuring the physical properties of a sample
EP0028540A1 (en) * 1979-11-06 1981-05-13 The Electricity Council Method and apparatus for non-contact acoustic measurement of physical properties of continuously moving metal strip
DE3045581A1 (en) * 1979-12-03 1981-08-27 Institute of Paper Chemistry, Appleton, Wis. DEVICE FOR MEASURING THE SPEED OF SPREADING FROM A MOVING MATERIAL, IN PARTICULAR PAPER, THROUGH ULTRASOUND WAVES
US4574634A (en) * 1984-08-09 1986-03-11 Westvaco Corporation Automatic paper testing apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Patent Abstracts of Japan, vol. 6, no. 70 (P-113)(948), 6 mai 1982; & JP-A-5710448 (SUMITOMO KINZOKU KOGYO K.K.) 20 janvier 1982 *

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WO1996011396A1 (en) * 1994-10-06 1996-04-18 Ab Lorentzen & Wettre System for measuring ultrasonically the elastic properties of a moving paper web
WO1996011395A1 (en) * 1994-10-06 1996-04-18 Ab Lorentzen & Wettre System for measuring ultrasonically the elastic properties of a moving paper web
US5808199A (en) * 1994-10-06 1998-09-15 Ab Lorentzen & Wettre System for measuring ultrasonically the elastic properties of a moving paper web
US5847281A (en) * 1994-10-06 1998-12-08 Ab Lorentzen & Wettre System for measuring ultrasonically the elastic properties of a moving paper web
EP1985990A2 (en) * 2007-04-25 2008-10-29 Voith Patent GmbH Ultrasonic method for determining the stiffness of a fibrous material web in thickness direction
EP1985990A3 (en) * 2007-04-25 2012-03-07 Voith Patent GmbH Ultrasonic method for determining the stiffness of a fibrous material web in thickness direction
DE102011006391A1 (en) * 2011-03-30 2012-10-04 Siemens Aktiengesellschaft Method and device for detecting parameters of a continuous or circulating material web in a material processing machine
WO2012130618A2 (en) 2011-03-30 2012-10-04 Siemens Aktiengesellschaft Method and device for detecting parameters of a traversing or circulating material web in a material processing machine
WO2012130618A3 (en) * 2011-03-30 2012-11-22 Siemens Aktiengesellschaft Method and device for detecting parameters of a traversing or circulating material web in a material processing machine
CN103477221A (en) * 2011-03-30 2013-12-25 西门子公司 Method and device for detecting parameters of a traversing or circulating material web in a material processing machine
CN103477221B (en) * 2011-03-30 2015-11-25 西门子公司 The method and apparatus of the parameter of the continous way in test material processing machine or circulating material webs
EP3589943A4 (en) * 2017-03-02 2020-12-16 Abzac Canada Inc. An in-line, contactless and non-destructive method&system for detecting defects in a moving cardboard structure
US11209403B2 (en) 2017-03-02 2021-12-28 Abzac Canada Inc. In-line, contactless and non-destructive method and system for detecting defects in a moving cardboard structure
CN110849970A (en) * 2019-11-18 2020-02-28 清华大学 Method, device and system for measuring material mechanics attribute information
CN110849970B (en) * 2019-11-18 2020-11-27 清华大学 Method, device and system for measuring material mechanics attribute information

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