ASTM D3044-1994(2006) Standard Test Method for Shear Modulus of Wood-Based Structural Panels《木基结构板剪切模数的标准试验方法》.pdf

1、Designation: D 3044 94 (Reapproved 2006)Standard Test Method forShear Modulus of Wood-Based Structural Panels1This standard is issued under the fixed designation D 3044; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l

2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers determination of the shearmodulus of wood-based structural panels associated with sheardistort

3、ion in the plane of the panels. The method is applicableto all types of wood-based structural panels. The grain direc-tion or orientation of the individual plies, laminations, or layersshall be parallel or perpendicular to the edge of the testspecimen. If the plies, laminations, or layers are of dif

4、ferentmaterial or elastic properties, the method gives the effectiveshearing modulus. Wood-based structural panels in use includeplywood, waferboard, oriented strand board, and composites ofveneer and of wood-based layers.NOTE 1This test method is primarily designed for material in whichthe grain or

5、 orientation of the individual plies, laminations, or layers isparallel or perpendicular to the edge of the specimen. It may be used,however, for plywood specimens in which the grain is at 45 to thespecimen edges if a four-ply panel with all plies of the same thickness isused. The controlling condit

6、ion is that the EI (modulus ofelasticity 3 moment of inertia) values along both diagonals shall be equal.1.2 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

7、 health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 2395 Test Methods for Specific Gravity of Wood andWood-Based MaterialsD 4442 Test Methods for Direct Moisture Content Measure-ment of Wood and Wood-Base Materials3.

8、Summary of Test Method3.1 The test consists of twisting a square plate of material byapplying loads at the ends of one diagonal and supporting theplate at the ends of the other diagonal. From theory on theflexure of flat plates the deflections of the plate under thisloading is related to the shear m

9、odulus of the plate. Deflectionsof the plate at points on the diagonal are measured relative toits center. The shear modulus of the specimen is determinedfrom load-deflection data. The shear modulus obtained is thatassociated with shearing distortion in the plane of the plate. Aphotograph of testing

10、 apparatus and a deflection measuringdevice is given in Fig. 1.4. Significance and Use4.1 This test method is most useful for determining themoduli of rigidity of orthotropic materials for which moduli ofrigidity cannot be computed from elastic moduli and Poissonsratios. The shear modulus determined

11、 by this method appearsin the equation governing the bending of a plate. This is themodulus that is needed in discussing the deflection andbuckling of plates.5. Control of Moisture Content5.1 The structural panel samples to be tested at specificmoisture contents or equilibrium relative humidities sh

12、all beconditioned to approximately constant mass in controlledatmospheric conditions. For approximating moisture condi-tions of panels used under dry conditions, a relative humidityof 65 6 2 % at a temperature of 68 6 6F (206 3C) isrecommended. Specimens shall be tested without undue delayafter cond

13、itioning. Testing in similarly controlled atmosphereis recommended whenever possible.6. Test Specimen6.1 The test specimen shall be square, with the thicknessequal to the thickness of the material, and the length and widthnot less than 25 nor more than 40 times the thickness. Thethickness, length, a

14、nd width of each specimen shall be mea-sured to an accuracy of not less than6 0.3 %. Care shall betaken to avoid obtaining test specimens with initial curvature.1This test method is under the jurisdiction of ASTM Committee D07 on Woodand is the direct responsibility of Subcommittee D07.03 on Panel P

15、roducts.Current edition approved Oct. 1, 2006. Published October 2006. Originallyapproved in 1972. Last previous edition approved in 2000 as D 3044 94 (2000).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of A

16、STMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Loading Procedure7.1 Support the test specimen on supports having a radius ofcurvatur

17、e not greater than14 in. (6 mm) on the opposite endsof a plate diagonal, and loaded in a similar manner on theopposite ends of the other diagonal. In order that the loads areapplied at the corners, first attach metal plates as shown in Fig.1. Fig. 1 also shows suggested apparatus for applying load a

18、ndmeasuring deflection. Apply the load with a continuous anduniform motion of the movable head at a rate of 0.012 timesthe length of the plate in inches or millimetres, expressed ininches or millimetres per minute, within a permissible variationof 625 %.7.2 The load applied shall be accurate to with

19、in 1 %.8. Deflection Measurements8.1 Measure the deflections to the nearest 0.001 in. (0.02mm) of points on each diagonal relative to the center of theplate. These measurements preferably shall be made near thequarter-points of the diagonals, and if other points than theseare chosen, take care to av

20、oid locations near the concentratedloads at the plate corners. Apparatus used to measure the platedeflection should be supported on the plate to ensure accuratemeasurements. Do not stress the plate beyond its elastic range,and choose increments of load so that not less than 12 andpreferably 15 load-

21、deflection readings are taken. To eliminatethe effects of slight initial curvature obtain two sets of data, thesecond set with the panel rotated 90 about an axis through thecenter of the plate and perpendicular to the plane of the panel.Average the two results to obtain the shear modulus for theplat

22、e. A satisfactory arrangement for measuring relative deflec-tions is indicated in Fig. 1; the dial readings in this case givetwice the average deflections relative to the panel center of thefour points at which the dial and dial stem supports touch thepanel.9. Calculation9.1 Calculate the shearing m

23、odulus of elasticity as follows:G 5 3u2P/2h3Dwhere:G = shearing modulus, psi (or MPa),P = load applied to each corner, lbf (or N),h = thickness of the plate, in. (or mm),D = deflection relative to the center, in. (or mm), andu = distance from the center of the panel to the point wherethe deflections

24、 are measured, in. (or mm).NOTE 2The value of P/D is generally taken as the slope of theload-deflection curve.10. Variables Influencing Shear Modulus10.1 Moisture ContentCut a moisture content samplehaving minimum area of 4 in,2(26 cm2) from the clear areas ofthe specimens and weigh immediately afte

25、r each test. Whereadditional tests are to be made on the plate, a satisfactorymoisture content specimen may be provided at the time thespecimens are originally cut, in which case subject thesespecimens to the same conditioning as the plate. If inspectionof the edges reveals the presence of a knot in

26、 any ply of aplywood panel, select a second specimen. Moisture contentspecimens also serving as specific gravity specimens shall befree of voids. Moisture content determinations shall be made inaccordance with Test Methods D 4442.10.2 Specific GravitySpecific gravity determination shallbe made in ac

27、cordance with Test Methods D 2395. Thespecimen may be the same as that for moisture contentdetermination but must be at least 2 in.3(33 cm3) in volume,and be free of visible knots or voids.NOTE 3The moisture content and specific gravity as determinedabove are the average values. In plywood made up o

28、f thin veneers, theFIG. 1 Shear Modulus Test of Structural Panel Showing Method of Loading and Observing the Deflections Along the DiagonalsD 3044 94 (2006)2glue may constitute a significant part of the total mass, and as a result thecalculated specific gravities and moisture contents may vary subst

29、antiallyfrom the true values for the veneers. In some instances it may be desirableto take this into account.11. Report11.1 The structural panel specimen shall be described as tospecies, construction, and adhesive type used in its manufac-ture. Data for individual specimens and specimen averagesshal

30、l include:11.1.1 Panel thickness,11.1.2 Moisture content,11.1.3 Specific gravity,11.1.4 Modulus of rigidity, and11.1.5 Load-deflection diagrams.11.2 When specified, additional data shall include, but arenot limited to the maximum applied load, grade, and manufac-turing characteristics, which may inf

31、luence results.12. Precision and Bias12.1 The precision and bias of this test method have not yetbeen determined, but when data are available, a precision andbias statement will be included.13. Keywords13.1 shear modulus; structural panel; woodASTM International takes no position respecting the vali

32、dity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subj

33、ect to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquar

34、ters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standar

35、d is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 3044 94 (2006)3