1、Designation: D2718 00 (Reapproved 2011)1D2718 18Standard Test Methods forStructural Panels in Planar Shear (Rolling Shear)1This standard is issued under the fixed designation D2718; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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.1 NOTEEq 2 and Eq 4 were corrected editorially in April 2017.1. Scope1.1 These test methods determine the shear propert
3、ies of structural panels associated with shear distortion of the planes parallelto the edge planes of the panels. Both shear strength and modulus of rigidity may be determined. Primarily, the tests measure theplanar shear (rolling shear) strength developed in the plane of the panel.1.2 Structural pa
4、nels in use include plywood, waferboard, oriented strand board, include, but are not limited to, structuralplywood, oriented strand board (OSB), and composites of veneer and of wood-based layers.1.3 Two test methods are included:1.3.1 Test Method APlanar shear loaded by plates.1.3.2 Test Method BPla
5、nar shear induced by five-point bending.1.3.3 The choice of method will be dictated by the purpose of the test and equipment available.1.3.4 Test Method A, Planar Shear Loaded by PlatesThis test method uses a rectangular panel section adhered between steelplates with protruding knife edges to create
6、 load at the panel faces. This test method has been used to develop shear propertiesof plywood and oriented strand board for the purpose of confirming design values. This test method does not produce pure shear,but the specimen length is prescribed so that the secondary stresses have a minimum effec
7、t. The method determines shear strengthand modulus of rigidity.1.3.5 Test Method B, Planar Shear Induced by Five-Point BendingPlanar shear stress is induced on the panel while loadedin bending using two continuous spans. This test method determines planar shear strength consistent with panel applica
8、tions undertransverse loading. This test method is able to determine shear strength at any moisture condition.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safet
9、y safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Develop
10、ment of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D2395 Test Methods for Density and Specific Gravity (Relative Density) of Wood and Wood-Based MaterialsD4442 Test M
11、ethods for Direct Moisture Content Measurement of Wood and Wood-Based Materials3. Significance and Use3.1 Planar shear (rolling shear) characteristics of structural panels determined by these test methods are essential for the rigorousdesign of various glued wood-panel structural components, such as
12、 box beams, folded plate roofs, and stressed skin panels. Planarshear also may govern the design at low span-depth ratios encountered in floors subjected to high concentrated loads, concreteforms at high pouring pressures, and bulk storage structures.1 This test method is under the jurisdiction of A
13、STM Committee D07 on Wood and is the direct responsibility of Subcommittee D07.03 on Panel Products.Current edition approved Nov. 1, 2011Nov. 1, 2018. Published November 2011November 2018. Originally approved in 1969. Last previous edition approved in 20002011as D2718 00 (2006).(2011)1. DOI: 10.1520
14、/D2718-00R11E01.10.1520/D2718-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM
15、 standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all
16、 cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2 The modulus of rigidity determined from Test MethodAis a composite of th
17、e entire specimen acting as a unit. For plywoodpanels for which the ratio between the shear moduli of the plies with grain oriented parallel and perpendicular to the shear forcesis known, the rolling shear modulus of the perpendicular plies can be calculated.3.3 Veneer produced by slicing or rotary
18、peeling may contain fine checks or separations parallel to the grain on the knife sideof the veneer that are produced as the knife is forced through the wood. These checks are termed “knife checks” to distinguishthem from occasional checks that may be formed on the opposite side of the veneer by for
19、ces at the compression bar, and fromchecks caused by drying. Knife checks can have a significant effect on rolling shear properties in plywood panels and may be ofsignificance in other veneer containing panels. Test MethodArequires (when applicable) the testing of matching specimens havingknife chec
20、ks oriented both open and closed wherever possible (see Fig. 1).3.4 To control or define other variables influencing rolling shear, these test methods require determination of moisture content,specific gravity, and elapsed time-to-failure. Conditioning of test material in controlled atmospheres, det
21、ermination of depth ofknife checks (when applicable), and determination of percent of wood and plywood glueline failure (when applicable) arerecommended.4. Control of Moisture Content4.1 The structural panel samples to be tested at specific moisture contents or equilibrium relative humidities shall
22、be conditionedto approximately constant weight in controlled atmospheric conditions before gluing to plates. For approximating moistureconditions of structural panel used under dry conditions a relative humidity of 65 6 2 % at a temperature of 68 6 6F (20 6 3C)is recommended. Specimens When using Te
23、st MethodA, specimens shall be tested without undue delay after the adhesive is cured.Testing in similarly controlled atmospheres is recommended wherever possible.Test Method APlanar Shear Loaded by Plates5. Scope5.1 The specimen having the form of a rectangular flat plate is bonded between steel pl
24、ates beveled at opposite ends of thespecimen to provide knife edges for loading the plate at the face bonded to the specimen. The knife edges project beyond the endsof the specimen. This test method is conducted by loading the knife edges in compression at a uniform rate while a suitable gagemeasure
25、s slip between the plates due to specimen deformation. Shear strength is computed from maximum load, and effectiveshear modulus for the specimen is determined from a plot of load versus slip.5.2 This international standard was developed in accordance with internationally recognized principles on sta
26、ndardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.6. Test Specimen6.1 Specimen thickness shall be that of the material. Specimens from mate
27、rial that is expected to vary significantly within thespecimen due to growth or manufacturing features or from other causes shall be 6 in. (15 cm) wide by 18 in. (45 cm) long or larger(a) Knife Checks Open(b) Knife Checks ClosedFIG. 1 Orientation of Knife Checks in PlywoodD2718 182as shown in Fig. 2
28、. This size is recommended for uniform material as well. However, smaller specimens of uniform material maybe used if these are not less than four times the thickness in width nor twelve times the thickness in length.6.2 From each sample of panels containing veneer, two matching specimens shall be c
29、ut. Knife edges of loading plates for onespecimen of each matching pair shall be oriented perpendicular to one of the primary panel directions or for plywood to causeopening of knife checks during test as shown in Fig. 1(a). Knife edges of plates loading the other specimen shall be positionedperpend
30、icular to one of the primary panel directions or for plywood to cause knife checks to close during test as shown in Fig.1(b). Proper plywood orientation may be determined from check depth specimens described in 16.3. It may not be possible to testsamples having two or more plies stressed in rolling
31、shear in both “open” and “closed” orientations if these plies are oriented inopposite directions causing a “checks open” failure regardless of direction of loading.6.3 Specimen length and width shall be measured to the nearest 0.01 in. (0.25 mm) and thickness to the nearest 0.001 in. (0.025mm). When
32、 applicable, the direction of knife checks in plies having grain perpendicular to its length shall be determined and thespecimens marked for position of knife edges. At the time specimens are cut matching samples for determination of moisturecontent and specific gravity in accordance with 16.1 and 1
33、6.2 shall be obtained. When measurement of knife checks is includedas discussed in 16.3, a sample for this measurement also may be cut at this time.7. Loading7.1 Figs. 1 and 2 illustrate the specimen and suitable loading plates and blocks for loading the knife edges of the plates. Thespecimen shall
34、be loaded by steel plates bonded to both faces of the specimen with an adhesive sufficiently rigid to precludecontribution of adhesive creep to measured deformation. Width of plates shall be that of the specimen. One end of each plate shallbe provided with a knife edge projecting 14 in. (6 mm) beyon
35、d the end of the specimen at one end and flush with the surface gluedto the specimen. The other end of the plate shall be square and flush with the end of the specimen. Knife edges of the two platesshall be at opposite ends of the specimen and shall be oriented to load the specimen in the desired di
36、rection in relation to the knifechecks. Planar shear properties of structural panels should be determined in both directions. Plates for specimens 18 in. (45 cm)long shall be 1 in. (2.5 cm) thick. The thickness of plates for shorter specimens may be reduced proportionately. Loading of at leastone V-
37、block shall provide for uniform load distribution along the knife edge by loading through a pivot having its axisperpendicular to the knife edge and centered along it. Pivots permitting rotation about an axis parallel to the knife edge or sphericalseats free to pivot in this manner shall not be used
38、 as they create unstable loading which may cause violent ejection of the specimenfrom the machine and hazard to operating personnel. The V-blocks shall be vertically positioned in the machine, one above theother, causing the forces applied to the specimen to act parallel to the axis of the machine.
39、The specimen itself will be slightlyinclined when placed in the machine. A means of holding the plates in an upright position after the specimen has sheared apartis desirable as a complete separation of the specimen permits the plates to be thrown out of the machine with attendant hazard tothe opera
40、tor.7.2 Load shall be applied continuously throughout the test at constant rate of cross-head motion to normally produce failure inthe range of 3 to 12 min elapsed time from beginning of loading. For plywood, the approximate speed may be determined asfollows:NOTE 1The “V” block is supported on a sea
41、t that provides rotation about the axis perpendicular to the knife edge only.Metric Equivalentsin. 6 18mm 15 45FIG. 2 Planar (Rolling) Shear Test Using a Dial Gage for Measuring Plate SlipD2718 183N 50.0075(T? 1R(T! (1)where:N = crosshead speed, in./min (cm/min),T| = total thickness of plies having
42、grain parallel to direction of shear force, in. (cm),R = 8 (assumed ratio of shear modulus of parallel plies to shear modulus of perpendicular plies), andT = total thickness of plies having grain perpendicular to the direction of shear force, in. (cm).7.2.1 Elapsed time from beginning of load applic
43、ation to failure of each specimen shall be measured and recorded to the nearesthalf minute. Machine speeds calculated by the above formula will normally produce failure in the range of 3 to 12 min elapsedtime from the beginning of loading. Should elapsed time to failure fall greatly outside this ran
44、ge, machine speed should be modifiedto obtain times within this range.7.3 Both epoxy and polyvinyl adhesives have been found satisfactory for bonding steel plates to specimens. Minimum requiredsurface preparation of steel plates consists of removal of residual adhesive. This can be accomplished most
45、 easily by mild heatingof the plate and any portion of the specimen remaining from the previous test in an oven which weakens the bond to the steelsufficiently to permit peeling the remaining wood and adhesive from the plate. The residual adhesive may be scraped off with asharp-edged tool. Further d
46、egreasing and cleaning has frequently been found necessary in addition to the above to ensure adequatebond strength. Curing the adhesive at a slightly elevated temperature has also been helpful.8. Measurement of Deformation8.1 Slip between the steel plates during load application shall be measured t
47、o at least the nearest 0.0001 in. (0.002 mm) at noless than twelve and preferably more equally spaced increments of load to proportional limit from which a load-deformation curveshall be plotted. Slip can be measured with a dial gage as illustrated in Figs. 2 and 3 or with appropriate automatic meas
48、uring andrecording equipment. Gage geometry and position on the specimen shall be such as to minimize any effects of unsymmetricalloading or deformation.FIG. 3 Planar (Rolling) Shear Specimen Ready for TestingD2718 1849. Calculation9.1 Shear stress shall be calculated as follows:fv 5PL W! (2)where:f
49、v = shear stress, psi (N/mm),P = maximum or proportional limit load (force), lbf (N),W = specimen width, in. (mm), andL = specimen length, in. (mm).Maximum shear stress obtained from specimens having final failure of the bond between the plate and the specimen shall beregarded as defective and shall be clearly indicated in the report of results.9.2 Effective modulus of rigidity for the specimen acting as a unit shall be calculated as follows:G 5P/!t/LW!# (3)where:G = apparent modulus of rigidity for the entire specimen, psi (N/mm),t = specimen thickne
