WO1997039306A1 - Appareil permettant d'analyser une rupture dans une structure deformable - Google Patents

Appareil permettant d'analyser une rupture dans une structure deformable Download PDF

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Publication number
WO1997039306A1
WO1997039306A1 PCT/US1997/005300 US9705300W WO9739306A1 WO 1997039306 A1 WO1997039306 A1 WO 1997039306A1 US 9705300 W US9705300 W US 9705300W WO 9739306 A1 WO9739306 A1 WO 9739306A1
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WO
WIPO (PCT)
Prior art keywords
ofthe
separation
bulge
pressure
area
Prior art date
Application number
PCT/US1997/005300
Other languages
English (en)
Inventor
John W. Newman
Original Assignee
Laser Technology, Inc.
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 Laser Technology, Inc. filed Critical Laser Technology, Inc.
Priority to AU24299/97A priority Critical patent/AU2429997A/en
Publication of WO1997039306A1 publication Critical patent/WO1997039306A1/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
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/021—Interferometers using holographic techniques
    • G01B9/025—Double exposure technique
    • 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
    • G01B11/161—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means
    • G01B11/162—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means by speckle- or shearing interferometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M17/00—Testing of vehicles
    • G01M17/007—Wheeled or endless-tracked vehicles
    • G01M17/02—Tyres
    • G01M17/027—Tyres using light, e.g. infrared, ultraviolet or holographic techniques

Definitions

  • the present invention relates to nondestructive testing, and more particularly, nondestructive testing for analyzing a separation in the material of a deformable structure.
  • Separations can occur in the material of a deformable structure that can reduce the strength of the structure. Often, visual inspection alone cannot determine the existence ofthe separation in the deformable structure. Therefore, there is a need for devices that can determine if a separation has occurred in the material of a deformable
  • tires can develop separations within the body ofthe tire during use. Whether or not the tire can be retreaded for additional use depends on the size and location of such separation in the tire Therefore, there is a need for apparatuses that determine size and location of separations in the material of a tire
  • the present invention is a method for determining the present invention
  • location of a separation in the material of a deformable structure comprising the steps of: means for varying pressure in a vicinity of the test object to a plurality of predetermined pressures, thereby creating a bulge in a surface of the test object due
  • the present invention is a method for determining the location of a separation in the material of a deformable structure comprising the steps of: means for varying pressure in a vicinity ofthe test object; means for generating a plurality of interferograms ofthe test object, while the pressure near the test object is varied; and means for electronically storing said interferograms and for determining a change in the cross section of a bulge in a surface of the test object in said interferograms, with respect to changes in pressure.
  • FIG. 1 is a cross sectional view of a deformable structure in the form of a tire
  • FIG. 2 is a partial cross-sectional view of the tire from FIG. 1, illustrating the separations ofthe material in the tire at different deformation conditions;
  • FIG. 3 is a cross sectional view of the time from FIG. 1 in a plane z ⁇ illustrating the
  • FIG. 4 is a chart illustrating the growth ofthe cross-sectional area ofthe bulges in the material of the tire in FIG. 1, in relation to the decrease in pressure surrounding the separations;
  • FIG. 5 is a block diagram illustrating an embodiment of an apparatus ofthe present invention for detecting the separations in the tire illustrated in FIG. 1 ; and
  • FIG. 6 is a diagram illustrating an interferogram image generated by the apparatus in FIG. 5.
  • FIG. 1 there is shown a
  • the tire 10 generally comprises sidewalls
  • a first separation 31 exists in the material of the tire 10 above the belts 25.
  • the bulges 41 and 42 are the flexing of material in the tire 10 in the direction z directly over the
  • the bulges 41 and 42 When the bulges 41 and 42 are viewed in a cross-sectional plane that is perpendicular to the surface 28, the bulges 41 and 42 appear as a dome shape in the inner surface 28 of the tire 10, as
  • the bulges 41 and 42 When the bulges 41 and 42 are viewed in a cross-sectional plane that is parallel to the surface 28 and is offset in the z direction from surface 28 a distance of z, the bulges 41 and 42 appear as a generally circular area, as shown in FIG. 3.
  • One method of creating a deformed condition in a deformable structure to analyze separations is to reduce the pressure in the vicinity ofthe separations.
  • this specification will refer to the reduction of pressure for the creation of a deformed condition in the deformable structure.
  • the present specification will refer to the reduction of pressure for the creation of a deformed condition in the deformable structure.
  • inner surface provides a convenient surface for measuring the cross sectional area of bulges; however, other surfaces can also be observed to determine the cross sectional
  • a discovery of the present invention is that the depth of a separation within a
  • deformable body is related to the change in the area ofthe bulge in the plane z, per
  • the area of a bulge in a plane parallel to the surface will cease increasing with a decrease in pressure on the surface once the area ofthe bulge in the plane parallel to the surface is approximately the same as the area of the separation
  • the change in the area of a bulge in the plane parallel to the surface per reduction of the pressure on the surface adjacent to the separation is related to the depth ofthe separation, the modulus ofthe elasticity ofthe material being tested, and
  • the depth of a separation is inversely proportional to the
  • the separation is located more deeply inside the object. Also, the area or diameter of the bulge in a
  • the separations 3 1 and 32 have the same area, but separation 31 is located at a deeper depth from the inner surface 28 than separation 32.
  • the area ofthe bulges 41 and 42 in the plane z are plotted in FIG. 4 in relation to the pressure against the inner surface 28 in the area ofthe separations 31 and 32.
  • the area A 1H5 of the bulge 41 in the plane z is plotted at pressure readings P, ⁇ as the curve 51.
  • the area B,. 6 ofthe bulge 42 in the plane z is plotted in relationship to P, ⁇ as the curve 52.
  • Separations 31 and 32 have the same area; and therefore the maximum cross-sectional area that the bulges 41 and 42 reach is approximately the same.
  • the curve 52 for the bulge 42 reaches the maximum cross-sectional area in the plane z, at a lower pressure than the curve 51 for the bulge 41.
  • the cross-sectional area 51 ofthe bulge 41 in the plane z begins at a greater pressure drop than the cross-sectional area 52 for the bulge 42, and requires a greater change in the pressure drop than the bulge 42 to reach the maximum area cross-sectional area.
  • a predetermined curve representing a bulge cross sectional area at various pressures can be obtained for specific known separation sizes and depths in a reference deformable structure having a particular modulus of elasticity.
  • curves are obtained from reference deformable structures having different separation sizes and depths, then the curves derived from a test deformable structure having the same modulus of elasticity can be compared with the predetermined curves from the reference deformable structures to determine the size and depth of separations in the test deformable structure.
  • the inner surface 28 of the tire 10 in the vicinity of the separations 31 and 32 is subjected to a plurality of pressures and the cross sectional area ofthe bulges 41 and 42 is plotted against the corresponding pressure.
  • the curve created by plotting the cross sectional areas of the bulges 41 and 42 against pressure is compared to curves generated by plotting the cross sectional areas of bulges in test tires having the same modulus of elasticity and various separation sizes and depths, that are subjected to corresponding pressures.
  • the separation in the test tire 10 corresponds to the size and depth ofthe separation in the reference tire that generated the matching curve.
  • sectional area ofthe bulge at a predetermined pressure will vary with the depth ofthe
  • the same modulus of elasticity and the same size separation can be compared with the cross sectional areas ofthe bulges in the reference deformable structures to determine the depth ofthe separation in the test deformable structure.
  • the area ofthe inner surface 28 ofthe tire 10 in the vicinity of the separations 31 and 32 is subjected to a predetermined pressure, and the cross sectional area of the bulges 41 and 42 is measured.
  • the areas ofthe separations 31 and 32 in the test tire 10 can be found by inspection methods such as x-ray or by reducing the pressure against the inner surface 23 in the vicinity ofthe separations 31 and 32 until the cross sectional area ofthe bulges 41 and 42 reaches a maximum.
  • the areas ofthe separations 31 and 32 are approximated by the maximum achieved area of the bulges 41 and 42 in the plane z, when the plane z, is relatively close to the
  • a bulge from the test tire 10 matches a particular cross sectional area of a bulge from one of the reference tires, then the depth of the separation in the test tire 10
  • predetermined depth can be subjected to pressure changes to determine at what pressure the bulge crosses the plane z.
  • the pressure at which a bulge in a test deformable structure crosses the plane z can be compared with the pressure at which a bulge in the reference deformable structure, having the same size separation and modulus of elasticity, crosses the plane z, to determine if the separation in the test deformable structure is above or below the depth of the separation in the reference deformable structure.
  • the pressure in the area of the inner surface 28 of the tire 10 is reduced in the vicinity ofthe separations 31 and 32 until the bulges 41 and 42 cross the plane z,
  • the areas ofthe separations 31 and 32 in the test tire 10 can be found by
  • the shearography device 100 includes a laser illuminator 1 10, a shearography camera 120, and an image processor 130.
  • the illuminator 1 10 includes a laser 1 1 1 that provides coherent light through a fiber optic cable 1 13 into a fiber optic illuminator 1 15.
  • the coherent laser light from the laser 1 11 is projected by the fiber optic illuminator 1 15 onto the inside surface 28 ofthe tire 10.
  • the shearography camera 120 includes an image shearing device 127, a lens 125, and a video camera 123.
  • the image shearing device 127 shears the image received by the shearography camera 120 and passes that dual image through the lens 125 to create an interferogram.
  • the interferogram creates a dual image ofthe coherent light
  • the interferogram is
  • FIG. 6 illustrates the interferogram for bulge 41, bulge 42 and other bulges in the inner surface 28 of the tire 10 will have a similar interferogram. Due to the splitting of images by the image shearing device 127 for interference purposes, the
  • bulge 41 will be displayed in an interferogram as two groups of concentric rings 141 and 151.
  • the cross-sectional area of the bulge 41 in the plane z, for a particular pressure can be determined by measuring the area within the outermost concentric ring 141 a or 151 a for either group of concentric rings 141 or 151
  • the change in the area of the bulge 41 per change in pressure can be calculated.
  • the maximum area ofthe bulge 41 in the plane z can be determined by comparing the area ofthe bulge 41 in each interferogram Using change of area of
  • the shearography camera 120 is positioned to view the inside surface 28 ofthe tire 10.
  • a separation found to be shallow, relative to the camera 120 is a separation that is deep relative to the tire tread 24, while a separation found to be
  • the processor or computer 130 can also be programmed to store each interferogram in its memory and automatically analyze each interferogram to determine
  • the processor 130 analyzes each
  • the processor 130 uses the area ofthe bulges 31 and 32 form the interferograms to determine the area for each separation 31 and 32 and the change in the area ofthe bulges 41 and 42 in the plane z, per reduction in the pressure. Then, the processor 130 can use the area for each separation 31 and 32 and the change in the area of the bulges 41 and 42 in the plane z, per reduction in the pressure, with the present invention to calculate the depth ofthe separation 31 and 32.
  • the forces inducing deformation in the deformable structure can progress from greater deformation to lesser deformation or from lesser

Abstract

Une structure déformable (10) subit à plusieurs reprises une réduction de pression, ce qui provoque un renflement (41, 42) dans la surface (24) de la structure déformable au-dessus d'une rupture (31, 32) dans cette structure déformable. Un dispositif de mesure de cisaillement (110, 120) mesure la surface de la coupe transversale du renflement (41, 42) sur un plan parallèle à la surface de la structure déformable pour chaque réduction de pression. Lorsque la surface de la coupe transversale du renflement ne s'accroît pas sous l'effet d'une réduction de pression, la surface de la coupe transversale du renflement (41, 42) est voisine de la zone de la rupture. Un processeur (130) détermine la zone de la rupture et calcule la profondeur de celle-ci à partir de la modification de la surface de la coupe transversale du renflement sous l'effet du changement de pression.
PCT/US1997/005300 1996-04-17 1997-04-08 Appareil permettant d'analyser une rupture dans une structure deformable WO1997039306A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU24299/97A AU2429997A (en) 1996-04-17 1997-04-08 Apparatus for analyzing a separation in a deformable structure

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US63366996A 1996-04-17 1996-04-17
US08/633,669 1996-04-17
US78585097A 1997-01-21 1997-01-21
US08/785,850 1997-01-21

Publications (1)

Publication Number Publication Date
WO1997039306A1 true WO1997039306A1 (fr) 1997-10-23

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ID=27091953

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/005300 WO1997039306A1 (fr) 1996-04-17 1997-04-08 Appareil permettant d'analyser une rupture dans une structure deformable

Country Status (2)

Country Link
AU (1) AU2429997A (fr)
WO (1) WO1997039306A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6959602B2 (en) 2002-03-19 2005-11-01 Millipore Corporation Ultrasonic detection of porous medium characteristics
US7160820B2 (en) 2001-05-15 2007-01-09 International Superconductivity Technology Center, The Juridical Foundation Method of preparing oxide crystal film/substrate composite and solution for use therein

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5007738A (en) * 1990-03-14 1991-04-16 Grant Ralph M Interferometric test standard

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5007738A (en) * 1990-03-14 1991-04-16 Grant Ralph M Interferometric test standard

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7160820B2 (en) 2001-05-15 2007-01-09 International Superconductivity Technology Center, The Juridical Foundation Method of preparing oxide crystal film/substrate composite and solution for use therein
US6959602B2 (en) 2002-03-19 2005-11-01 Millipore Corporation Ultrasonic detection of porous medium characteristics

Also Published As

Publication number Publication date
AU2429997A (en) 1997-11-07

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