1、Designation: E2581 14Standard Practice forShearography of Polymer Matrix Composites and SandwichCore Materials in Aerospace Applications1This standard is issued under the fixed designation E2581; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This pr
3、actice describes procedures for shearography ofpolymer matrix composites and sandwich core materials madeentirely or in part from fiber-reinforced polymer matrix com-posites. The composite materials under consideration typicallycontain continuous high modulus (greater than 20 GPa (3106psi) fibers, b
4、ut may also contain discontinuous fiber, fabric, orparticulate reinforcement.1.2 This practice describes established shearography proce-dures that are currently used by industry and federal agenciesthat have demonstrated utility in quality assurance of polymermatrix composites and sandwich core mate
5、rials during productprocess design and optimization, manufacturing processcontrol, after manufacture inspection, and in service inspec-tion.1.3 This practice has utility for testing of polymer matrixcomposites and sandwich core materials containing but notlimited to bismaleimide, epoxy, phenolic, po
6、ly(amideimide),polybenzimidazole, polyester (thermosetting andthermoplastic), poly(ether ether ketone), poly(ether imide),polyimide (thermosetting and thermoplastic), poly(phenylenesulfide), or polysulfone matrices; and alumina, aramid, boron,carbon, glass, quartz, or silicon carbide fibers. Typical
7、 as-fabricated geometries include uniaxial, cross-ply and angle-plylaminates; as well as honeycomb and foam core sandwichmaterials and structures.1.4 This practice does not specify accept-reject criteria andis not intended to be used as a means for approving polymermatrix composites or sandwich core
8、 materials for service.1.5 To ensure proper use of the referenced standards, thereare recognized nondestructive testing (NDT) specialists thatare certified according to industry and company NDT specifi-cations. It is recommended that an NDT specialist be a part ofany composite component design, qual
9、ity assurance, in-servicemaintenance, or damage examination activity.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the
10、applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C274 Terminology of Structural Sandwich ConstructionsD3878 Terminology for Composite MaterialsD5687/D5687M Guide for Preparation of Flat CompositePanels with Processing Guidelines for Specimen Prepara-ti
11、onE543 Specification for Agencies Performing NondestructiveTestingE1309 Guide for Identification of Fiber-ReinforcedPolymer-Matrix Composite Materials in DatabasesE1316 Terminology for Nondestructive ExaminationsE1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials i
12、n DatabasesE1471 Guide for Identification of Fibers, Fillers, and CoreMaterials in Computerized Material Property DatabasesE2533 Guide for Nondestructive Testing of Polymer MatrixComposites Used in Aerospace ApplicationsE2982 Guide for Nondestructive Testing of Thin-WalledMetallic Liners in Filament
13、-Wound Pressure Vessels Usedin Aerospace ApplicationsF1364 Practice for Use of a Calibration Device to Demon-strate the Inspection Capability of an InterferometricLaser Imaging Nondestructive Tire Inspection System2.2 ASNT Standards:3SNT-TC-1A Recommended Practice for Personnel Qualifi-cation and Ce
14、rtification in Nondestructive Testing1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.10 onSpecialized NDT Methods.Current edition approved Oct. 1, 2014. Published December 2014. Originallyapproved in 2007.
15、 Last previous edition approved as E2581-07. DOI: 10.1520/E2581-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM we
16、bsite.3Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1ANSI/ASNT CP-189 Standard for Qual
17、ification and Certifi-cation of Nondestructive Testing Personnel2.3 AIA Document:4NAS-410 Certification and Qualification of NondestructiveTest Personnel2.4 BSI Document:5EN 60825-1 Safety of Laser Products - Part 1: EquipmentClassification, Requirements, and Users Guide2.5 LIA Document:6ANSI Z136.1
18、-2000 Safe Use of Lasers2.6 Federal Standards:721 CFR 1040.10 Laser products21 CFR 1040.11 Specific purpose laser products29 CFR 1910.95 Occupational Noise Exposure3. Terminology3.1 DefinitionsDefinition of terms related to structuralsandwich constructions, NDT, and composites appearing inTerminolog
19、ies C274, E1316, and D3878, respectively, shallapply to the terms used in this standard.3.2 Definitions of Terms Specific to This Standard:3.2.1 aerospaceany component that will be installed on asystem that flies.3.2.2 beam splitteran optical element capable of splittinga single beam of coherent las
20、er light into two beams. Beamsplitters are key elements of Michelson Type Image ShearingInterferometers.3.2.3 cognizant engineering organizationthe company,agency, or other authority responsible for the design or afterdelivery, end use of the system or component for which laserholographic or laser s
21、hearographic examination is required; inaddition to design personnel, this may include personnel frommaterial and process engineering, stress anaylsis, NDT, orquality groups and others as appropriate.3.2.4 coherent light sourcea light source that convertselectrical energy to a monochromatic beam of
22、light havinguniform phase over a minimum specified length known as thecoherent length.3.2.5 componentthe part(s) or element(s) of a systemdescribed, assembled, or processed to the extent specified bythe drawing.3.2.6 composite materialsee Terminology D3878.3.2.7 composite componenta finished part co
23、ntainingcomposite material(s) that is in its end use application configu-ration and which has undergone processing, fabrication, andassembly to the extent specified by the drawing, purchaseorder, or contract.3.2.8 core crusha collapse, distortion, or compression ofcore material in a sandwich structu
24、re.3.2.9 core separationa partial or complete breaking ofhoneycomb core node bonds.3.2.10 disbond, unbond see Terminology D3878.3.2.11 de-correlationloss of shearography phase datacaused by test part deformation exceeding the resolution of theshearing interferometer or motion occurs between the test
25、object and shearing interferometer during data acquisition.4Available from Aerospace Industries Association of America, Inc. (AIA), 1000Wilson Blvd., Suite 1700,Arlington, VA22209-3928, http:/www.aia-aerospace.org.5Available from British Standards Institution (BSI), 389 Chiswick High Rd.,London W4 4
26、AL, U.K., http:/.6Available from the Laser Institute ofAmerica, 13501 Integrity Drive, Suite 128,Orlando FL 32826.7Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.FIG. 1 Schematic diagra
27、m of a Michelson type shearing interferometer shown with a shearography calibration device consisting of ametal plate with a machined flat bottomed hole creating a deformable plate with a precision mechanical mechanism for loading at thecenter point.E2581 1423.2.12 delaminationsee Terminology D3878.
28、3.2.13 displacement derivatives (w/x) rate of spatialdisplacement change, where w is the surface displacement andx is the surface coordinates.3.2.14 fringe patterna set of lines in a subtraction orwrapped phase shearogram that represents the locus of equalout-of-plane deformation derivative.3.2.15 i
29、mpact damagefracturing of epoxy matrix, fiberbreakage, inter-laminar delamination of monolithiccomposites, composite sandwich structure face sheets due toimpact, characterized by visible dimple surface compression,or fiber breakage caused by impact strike and non-visiblesubsurface matrix cracking an
30、d delamination.3.2.16 inclusionforeign objects or material including butnot limited to particles, chips, backing films, razor blades, ortools of varying sizes which are inadvertently left in acomposite lay-up.3.2.17 indicationthe observation or evidence of a condi-tion resulting from the shearograph
31、ic examination that requiresinterpretation to determine its significance, characterized bydimensions, area, s/n ratio, or other quantitative measurement.3.2.18 laser shearography inspection, shearographyinspection, shearographyinspection method utilizing inter-ferometric imaging of deformation deriv
32、atives compared be-tween different strain states and designed to reveal non-homogeneities, material changes and structural defectsthroughout the volume of the material.3.2.19 out-of-plane displacementthe local deformation ofa test part, normal to the surface, caused by the application ofan engineere
33、d force acting on a non-homogeneity or defect ina composite material.3.2.20 polymer matrix compositeany fiber-reinforcedcomposite lay-up consisting of laminae (plies) with one ormore orientations with respect to some reference direction thatare consolidated by press, vacuum bagging, or autoclave toy
34、ield an engineered part article or structure.3.2.21 porositycondition of trapped pockets of air, gas, orvoid within solid materials, usually expressed as a percentageof the total nonsolid volume (solid + nonsolid) of a unitquantity of material.3.2.22 sandwich core materialan engineered part, article
35、,or structure made up of two or more sheets of compositelaminate, metal, or other material designed to support in-planetensile or compressive loads, separated by and bonded to innercore(s) material(s) designed to support normal compressiveand tensile loads such as metal or composite honeycomb, opena
36、nd closed cell foam, wave formed material, bonded compositetubes, or naturally occurring material such as end grain balsawood.3.2.23 scan plana designed sequence of steps for posi-tioning and adjusting a shearography camera to accomplish adesired inspection. Scan plans shall include camera field ofv
37、iew, percentage of image overlap, position sequences for eacharea to be tested, test number, and location in a coordinatesystem appropriate for test object geometry and access.3.2.24 shearogramthe resulting image from the complexarithmetic combination of interferograms made with an imageshearing int
38、erferometer and presented for interpretation invarious image processing algorithms including wrapped phasemaps (static or real-time), unwrapped phase maps, integrated,Doppler shift map.3.2.25 shearography camera, shear cameraan imageshearing interferometer used for shearography nondestructivetesting
39、, usually including features for adjustment of focus, iris,zoom, shear vector, and projection and adjustment of coherentlight onto the test object area to be inspected.3.2.26 shear vectorthe separation vector between twoidentical images of the target in the output of an image shearinginterferometer.
40、 The Shear vector is expressed in degrees ofangle from the X axis, with a maximum of 90, with + being inthe positive Y direction and in the negative Y direction. Theshear distance between identical points in the two shearedimages expressed in inches or mm. (See Fig. 2 shear vectorFIG. 2 Shear vector
41、 angle convention: Starting with the shear camera adjusted for a 0 shear condition, the sheared image is moved tothe right (+X) or up/down, never adjusted in the direction of X. For a +45 shear vector, the image is moved in the +X and +Y direc-tion. For 60 shear vector, the image is adjusted in the
42、+X and Y directions. The convention allows determination of deformation di-rection from the unwrapped phase map.E2581 143angle convention).3.2.27 stressing devicethe means to apply a measurableand repeatable engineered stress to the test object duringshearography inspection. The applied stress may b
43、e in the formof a partial vacuum, pressure, heat, vibration, magnetic field,electric field, microwave, or mechanical load. Also referred toas excitation or excitation method.3.2.28 voidan empty, unoccupied space in laminate. Voidsare associated with bridging and resin starved areas.4. Summary of Pra
44、ctice4.1 Shearography nondestructive inspection refers to the useof an image shearing interferometer to image local out-of-planedeformation derivatives on the test part surface in response toa change in the applied engineered load. Shearography imagestend to show only the local deformation on the ta
45、rget surfacedue to the presence of a surface or subsurface flaw,delaminations, core damage, or core splice joint separations, aswell as impact damage.4.2 Typical applied loads to the test part are dependant onthe test part material reaction to the induced load.The optimumload type and magnitude depe
46、nd on the flaw type and flawdepth and are best determined before serial testing by makingtrial measurements. Care is taken to ensure that the magnitudeof the applied load is acceptably below the damage threshold ofa given test article. The applied load can be any of thefollowing: heat, mechanical vi
47、bration, acoustic vibration, pres-sure and vacuum, electric fields, magnetic fields, microwave,or mechanical load.4.3 Shearography NDT systems use a common pathMichelson, birefringant, or beam splitter type shearing inter-ferometer for imaging defects. Some of the most currenttechnology shearography
48、 cameras often use a Michelson typeinterferometer, Fig. 1, with phase stepping capability. Theshearography NDT procedure consists of illuminating a testarticle with fixed frequency laser light before and after a smallproof load is applied.Amirror (the tilt mirror), or other opticaldevice is precisel
49、y adjusted to induce an offset, or shearedimage, of the test article with respect to a second image of thepart. The amount of image shear is a vector quantity with anassociated direction, angle, and distance (see Fig. 2). The shearvector, among other factors, determines the sensitivity of theinterferometer to surface displacement derivatives, w/ x. Thetwo sheared images of the test image are focused onto the CCDcamera. Light from pairs of points in each sheared imageinterfere with each other, causing interference at eve
