WO2014104983A1 - Procédé et appareil de mesure d'épaisseur d'une sonde durant un essai de traction - Google Patents

Procédé et appareil de mesure d'épaisseur d'une sonde durant un essai de traction Download PDF

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Publication number
WO2014104983A1
WO2014104983A1 PCT/SI2012/000067 SI2012000067W WO2014104983A1 WO 2014104983 A1 WO2014104983 A1 WO 2014104983A1 SI 2012000067 W SI2012000067 W SI 2012000067W WO 2014104983 A1 WO2014104983 A1 WO 2014104983A1
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WO
WIPO (PCT)
Prior art keywords
probe
matrix
thickness
values
pix
Prior art date
Application number
PCT/SI2012/000067
Other languages
English (en)
Inventor
Blaz JAPELJ
Original Assignee
Sieva, Podjetje Za Razvoj In Trzenje V Avtomobilski Industriji, D.O.O.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sieva, Podjetje Za Razvoj In Trzenje V Avtomobilski Industriji, D.O.O. filed Critical Sieva, Podjetje Za Razvoj In Trzenje V Avtomobilski Industriji, D.O.O.
Priority to PCT/SI2012/000067 priority Critical patent/WO2014104983A1/fr
Priority to PCT/SI2013/000087 priority patent/WO2014104986A1/fr
Publication of WO2014104983A1 publication Critical patent/WO2014104983A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G01N3/06—Special adaptations of indicating or recording means
    • G01N3/068—Special adaptations of indicating or recording means with optical indicating or recording means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/0641—Indicating or recording means; Sensing means using optical, X-ray, ultraviolet, infrared or similar detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/0641—Indicating or recording means; Sensing means using optical, X-ray, ultraviolet, infrared or similar detectors
    • G01N2203/0647—Image analysis

Definitions

  • the present invention refers to a process and apparatus for measuring of thickness of a probe during a tension test.
  • the aim of the invention is to enable accurate and reliable measuring of thickness of a probe during a tensioning test at least in the location of minimal cross-section of said probe.
  • a tension test as such is intended for the purposes of determining and/or examining of physical properties of materials, in particular tensile strength, upper elastic limit, contraction or the like.
  • a probe consisting of a known material and hawing known and standardized dimensions is fastened within a tension testing apparatus having a fixed jaw and a displaceable jaw, in which said probe is fastened.
  • Said displaceable jaw can be displaced apart from said fixed jaw, by which the probe is tensioned.
  • the tension force acting to the probe is permanently measured as well as deformation thereof, in particular strain and contraction.
  • One of known methods for measuring thickness of the probe provides measuring of a diameter of the probe by means of suitable measuring instrument prior to performing the test, upon which the probe is tensioned and the diameter of such deformed probe is measured. On such basis, conclusions are then made about changing of the thickness during the test, which is not really reliable, in particular since also the thickness prior to testing and after that can actually be measured on different locations along the probe. Moreover, results of such measuring are not automatically and independently collected, which reduces accuracy of such measuring.
  • a further approach provides use of two laser beams, which are directed towards each other and perpendicularly with respect to the longitudinal axis of the probe, which is then exposed to said beams in two points located in the diametrical plane thereof.
  • the probe is tensioned, it is also extended, and both points, which are initially exposed to said beams, are displaced along such extending probe. Consequently, such measuring us also not performed always in the same location on the probe, since the measuring location is permanently displaced along the probe during the test, which systematically introduces certain discrepancies into said measuring, and such obtained results are never quite reliable.
  • the third approach provides monitoring of the thickness by means of two video cameras, and change of thickness of the probe is permanently monitored and calculated by means of triangulation.
  • two cameras, two supporting stands and other required equipment leads to essentially complicated concept of the measuring apparatus as such, which essentially increases the price and also the risk of malfunction.
  • the initially raised problem is solved by means of features of a measuring apparatus as well as of process, which are included in independent patent claims including the embodiments according to dependent claims.
  • Fig. 1 is a schematically presented perspective view of an apparatus for measuring of thickness of a probe according to the invention.
  • Fig. 2 is a probe, which is suitable for such measuring.
  • the present invention refers to an apparatus for measuring of thickness of a probe 2 during a tension test, wherein such apparatus comprises a tension testing device 1 with a fixed jaw 1 1 and a movable jaw 12, which are arranged above each other and adapted to hold each disposable standardized probe 2 having a measuring area defined by means of a diameter D mm and the length L mm , such that the longitudinal axis 20 of the probe 2 extends at least approximately in the vertical direction.
  • the apparatus further comprises a video camera 3, which is adapted for monitoring the probe 2 during tensioning thereof and is arranged in the area of the tensioning device 1 appropriately apart from the probe 2, such that the optical axis 30 of the camera 3 is directed towards the longitudinal axis 20 of the probe 2 and perpendicularly with respect to said longitudinal axis 20 of the probe 2.
  • said video camera 3 is suitable for generating video recordings in the format "jpeg" i.e. 24-bit RGB format, and is optionally for the purposes of transmission of data interconnectable with a corresponding computer 4, which is adapted to receive, store, process and optionally also to display and/or to export the data received from the side of the previously mentioned video camera 3.
  • the apparatus comprises a screen 5, which is suitable to provide contrast relative to the probe 2 and is arranged in the area of said tensioning apparatus 1 adjacent to the probe 2 and at appropriate distance apart from it, namely diametrically opposite to the video camera 3 with respect to the longitudinal axis 20 of the probe 2, wherein said screen 5 is intended to provide a contrast background behind the probe 2, when recorded by means of video camera 3 and is appropriately colored relative to each disposable surface of each corresponding probe 2.
  • the apparatus according to the invention is furnished with a computer 4, which is suitable for cooperating with said video camera 3 and is adapted for
  • - n is a number of columns of the input picture; ii) calculating average value x of pixels e.g. in a row corresponding to integer of m/2 according to the formula (I)
  • D P ix 2 - i (IV); v) determining the length Z pix , along which said measuring of reduction of the thickness of the probe 2 is performed, wherein the ratio of original values of the diameter and the measuring length of the probe 2 according to formula (V) is calculated
  • the computer 4 is further adapted to eliminate each errors due to image noise, by anticipating that said error is statistically distributed in accordance with the Gauss distribution curve, and 2/3 of the matrix DD pix are taken into consideration by calculating thickness of the probe 2, wherein i) a histogram is created with such number of intervals, which corresponds to L pix - 1 , while two abscise axis values of the histogram correspond to minimum and maximum value of the matrix DD plx , by which a further matrix G is created with the size L pix - 1, in which the first column comprises values on the abscise axis of said histogram, and the second column comprises correlated values on the ordinate axis of said histogram, wherein the maximum value in said second column is G max , upon which the values in said second column are numerically integrated in order to obtain a curve similar to "error function"; ii) all values of the matrix G, are reviewed by means of the "for loop
  • the computer 4 is further adapted for calculating average thickness D A VG of the probe 2 in accordance with formula (VII):
  • the computer 4 is further adapted for determining the thickness D AVG of the probe 2 as the minimum value of the matrix G zaJzracun .
  • Apparatus according to the invention further comprises a bright, in particular white colored screen 5, while the probe 2 is darkened on its surface, in particular in the area of its diametrical plane, which extends throughout the longitudinal axis 20 of the probe 2 and at the same time also perpendicularly with respect to the optical axis 30 of the video camera 3.
  • the invention further refers to a process for measuring of thickness of a probe 2 during a tension test, wherein each disposable standardized probe 2 having a measuring area defined by means of a diameter D mm and the length L mm is fastened into a tension testing device 1 furnished with at least one fixed jaw 1 1 and a movable jaw 12, which are arranged above each other and adapted to hold said probe 2, such that the longitudinal axis 20 of the probe 2 extends at least approximately in the vertical direction, and wherein said probe 2 in such fastened state and during tensioning thereof is recorded by means of a video camera 3, which is arranged in the area of the tensioning device 1 at appropriate distance apart from the probe 2, such that the optical axis 30 of the camera 3 is directed towards the longitudinal axis 20 of the probe 2 and perpendicularly with respect to said longitudinal axis 20 of the probe 2, and in addition to that, said video camera 3 is suitable for generating video recordings in the format "jpeg" i.e. 24-bit RGB format, and is optionally for the purposes of transmission of data
  • the process according to the invention provides that prior to recording by said video camera 3 a screen 5 is arranged adjacent to said probe 2, which is suitable to provide a contrast relative to the probe 2 and is arranged in the area of said tensioning device 1 adjacent to the probe 2 and at appropriate distance apart from it, namely diametrically opposite to the video camera 3 with respect to the longitudinal axis of the probe 2, wherein said screen 5 is intended to provide a contrast background behind the probe 2 during recording by means of video camera 3 and is appropriately colored relative to each disposable surface of each corresponding probe 2.
  • the invention provides that the computer 4 cooperating with said video camera 3 is further adapted for i) converging each particular input picture of the measuring area L of the probe 2 as received from the video camera 3, from the " peg i.e. 24- byte RGB format into a matrix A consisting of 8-byte digits with values 0- 256 corresponding to each particular points i.e. pixels, wherein the dimensions of said matrix A are m x «, and wherein
  • - n is a number of columns of the input picture; calculating an average value x of pixels e.g. in a row corresponding :ger of m/2 according to the formula (I)
  • the value XQ corresponds to a value in the line and the column j in said matrix
  • the average value x corresponds to the average values in the row ; iii) comparing each disposable values of pixels, wherein in the row
  • a ⁇ x j 0 ⁇ n ⁇ x; B ⁇ [ ⁇ j-l, j ⁇ , ⁇ x , Xj ⁇ ],
  • xi (* - «,)/* ! (Ill) upon which analogously also the value x 2 of the second line is determined, and the thickness of the probe 2 in pixels is calculated by means of formula (IV) on the basis of the difference v) determining the length Z, pix , along which said measuring of reduction of the thickness of the probe 2 is performed, wherein the ratio of original values of the diameter D mm and the measuring length L mm of the probe 2 according to formula ( V) is calculated
  • R D nm /L mm (V) and the length L pix in pixels is determined by means of formula (VI) on the basis of thickness D pix in pixels and the previously mentioned ratio R
  • L pix D p R (VI), by means of which for the purposes of further measuring of the thickness of the probe 2 then a sub-matrix W of size L pix x n is created, wherein the first row of said sub-matrix is the row numbered (m - L pix )/2 of the original matrix A, and the step of determining the thickness of the probe 2 is then repeated in each row of said sub-matrix W, so that in each row of the sub- matrix W the thickness Z> pix of the probe 2 in pixels is determined, and for each image generated by means of the video camera 3 then a matrix DD pix of size Xpj x x 1 is created.
  • the computer 4 is further used for the purposes of eliminating errors due to image noise, by anticipating that said error is statistically distributed in accordance with the Gauss distribution curve, and 2/3 of the matrix DD pix are taken into consideration by calculating thickness of the probe 2, wherein i) a histogram is created with such number of intervals, which corresponds to L pix - 1 , while two abscise axis values of the histogram correspond to minimum and maximum value of the matrix DD pix , by which a further matrix G is created with the size L p j x - 1 , in which the first column comprises values on the abscise axis of said histogram, and the second column comprises correlated values on the ordinate axis of said histogram, wherein the maximum value in said second column is G max , upon which the values in said second column are numerically integrated in order to obtain a curve similar to "error function";
  • an average thickness D AVG of the probe 2 is determined in accordance with formula (VII):
  • each thickness of the probe 2 is determined on the basis of the minimum value of the matrix (G za _ izracun ).
  • each particular scalar value of each particular image is transformed into a matrix of values of the thickness D jzrac , on the basis of which then also a contraction can be calculated by means of Formula ( VIII)
  • the apparatus and process according to the invention enable permanent monitoring of the thickness of the probe 2 on the same location on the probe 2 during the tension test, when the probe 2 is fastened within the tension testing device 1 and exposed to each known and measured force, and also to calculate a relative contraction and other physical properties of the material of the probe 2. All the data is permanently and independently recorded, and such retrieved data about identified changes during the whole testing up to destruction of the probe 2 can later serve as an input data for the purposes of simulating various loading examples in the finite element analysis, by which stresses and deformations in mechanically loaded parts can be foreseen not only in the area of elastic deformations but also in the area of plastic deformations.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)

Abstract

L'invention concerne un appareil de mesure d'épaisseur d'une sonde (2) durant un essai de traction, qui comprend un dispositif de tensionnement (1) doté d'une mâchoire fixe (11) et d'une mâchoire amovible (12), disposées l'une au-dessus de l'autre et conçues pour serrer des sondes (2) standardisées en appliquant de la tension, ainsi qu'une caméra vidéo (3), disposée dans la zone dudit dispositif de tensionnement (1) à une distance appropriée de la sonde (2), de sorte que l'axe optique (30) de la caméra vidéo (3) s'étende vers l'axe longitudinal (20) de la sonde (2), de manière rectangulaire par rapport audit axe longitudinal (20) de la sonde (2). L'appareil comprend en outre un écran (5) qui forme un arrière-plan contrastant derrière la sonde (2) et disposé du côté opposé de la sonde (2) par rapport à ladite caméra vidéo (3), ainsi qu'un ordinateur (4) conçu pour récupérer, sauvegarder et traiter des données reçues à partir de la caméra vidéo (3).
PCT/SI2012/000067 2012-12-27 2012-12-27 Procédé et appareil de mesure d'épaisseur d'une sonde durant un essai de traction WO2014104983A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/SI2012/000067 WO2014104983A1 (fr) 2012-12-27 2012-12-27 Procédé et appareil de mesure d'épaisseur d'une sonde durant un essai de traction
PCT/SI2013/000087 WO2014104986A1 (fr) 2012-12-27 2013-12-23 Extensomètre vidéo

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/SI2012/000067 WO2014104983A1 (fr) 2012-12-27 2012-12-27 Procédé et appareil de mesure d'épaisseur d'une sonde durant un essai de traction

Publications (1)

Publication Number Publication Date
WO2014104983A1 true WO2014104983A1 (fr) 2014-07-03

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PCT/SI2012/000067 WO2014104983A1 (fr) 2012-12-27 2012-12-27 Procédé et appareil de mesure d'épaisseur d'une sonde durant un essai de traction
PCT/SI2013/000087 WO2014104986A1 (fr) 2012-12-27 2013-12-23 Extensomètre vidéo

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Application Number Title Priority Date Filing Date
PCT/SI2013/000087 WO2014104986A1 (fr) 2012-12-27 2013-12-23 Extensomètre vidéo

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104482840A (zh) * 2014-11-20 2015-04-01 航天海鹰(镇江)特种材料有限公司 用于检测复合材料壁板贴模间隙的施力装置及检测方法
FR3093175A1 (fr) * 2019-02-21 2020-08-28 Safran Aircraft Engines Systeme de mesure d’une deformation de surface en flexion d’un materiau
WO2020263558A1 (fr) * 2019-06-25 2020-12-30 Illinois Tool Works Inc. Système d'extensomètre vidéo avec écran arrière réfléchissant
WO2020263559A1 (fr) * 2019-06-25 2020-12-30 Illinois Tool Works Inc. Correction de luminosité et de contraste pour systèmes et procédés d'extensomètre vidéo
EP2990775B1 (fr) * 2014-08-28 2021-03-03 The Boeing Company Systèmes et procédés de détection de croissance de fissure
US20210404929A1 (en) * 2020-06-29 2021-12-30 Illinois Tool Works Inc. Thickness correction for video extensometer systems and methods

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104330315A (zh) * 2014-11-06 2015-02-04 重庆戴卡捷力轮毂制造有限公司 拉伸试棒延伸率快速测量装置

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US5033096A (en) * 1987-04-22 1991-07-16 John Lysaght (Australia) Limited Non-contact determination of the position of a rectilinear feature of an article
JP2000146787A (ja) * 1998-11-05 2000-05-26 Nippon Steel Corp 引張り試験の絞り計測方法
US20030182069A1 (en) * 2002-02-08 2003-09-25 Banes Albert J. Method and system for measuring properties of deformable material specimens

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5033096A (en) * 1987-04-22 1991-07-16 John Lysaght (Australia) Limited Non-contact determination of the position of a rectilinear feature of an article
JP2000146787A (ja) * 1998-11-05 2000-05-26 Nippon Steel Corp 引張り試験の絞り計測方法
US20030182069A1 (en) * 2002-02-08 2003-09-25 Banes Albert J. Method and system for measuring properties of deformable material specimens

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2990775B1 (fr) * 2014-08-28 2021-03-03 The Boeing Company Systèmes et procédés de détection de croissance de fissure
CN104482840A (zh) * 2014-11-20 2015-04-01 航天海鹰(镇江)特种材料有限公司 用于检测复合材料壁板贴模间隙的施力装置及检测方法
FR3093175A1 (fr) * 2019-02-21 2020-08-28 Safran Aircraft Engines Systeme de mesure d’une deformation de surface en flexion d’un materiau
US11231265B2 (en) 2019-02-21 2022-01-25 Safran Aircraft Engines System for measuring a bending deformation of a surface of a material
WO2020263558A1 (fr) * 2019-06-25 2020-12-30 Illinois Tool Works Inc. Système d'extensomètre vidéo avec écran arrière réfléchissant
WO2020263559A1 (fr) * 2019-06-25 2020-12-30 Illinois Tool Works Inc. Correction de luminosité et de contraste pour systèmes et procédés d'extensomètre vidéo
US11803943B2 (en) 2019-06-25 2023-10-31 Illinois Tool Works Inc. Brightness and contrast correction for video extensometer systems and methods
JP7539934B2 (ja) 2019-06-25 2024-08-26 イリノイ トゥール ワークス インコーポレイティド ビデオ伸び計システム及び方法の輝度及びコントラストの補正
US20210404929A1 (en) * 2020-06-29 2021-12-30 Illinois Tool Works Inc. Thickness correction for video extensometer systems and methods
US11867668B2 (en) * 2020-06-29 2024-01-09 Illinois Tool Works Inc. Thickness correction for video extensometer systems and methods
US20240142355A1 (en) * 2020-06-29 2024-05-02 Illinois Tool Works Inc. Thickness correction for video extensometer systems and methods

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