1、Designation: D3043 17Standard Test Methods forStructural Panels in Flexure1This standard is issued under the fixed designation D3043; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenthese
2、s indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods determine the flexural properties ofstrips cut from structural panels or panels up to 4 by 8 ft in size.Structural panels in use include
3、 plywood, waferboard, orientedstrand board, and composites of veneer and of wood-basedlayers. Four methods of tests are included:SectionsMethod ACenter-Point Flexure Test 5Method BTwo-Point Flexure Test 6Method CLarge Panel Test 7Method DFlexure Test for Quality Assurance 8The choice of method will
4、be dictated by the purpose of thetest, type of material, and equipment availability. All methodsare applicable to material that is relatively uniform in strengthand stiffness properties. Only Method C should be used to testmaterial suspected of having strength or stiffness variationswithin a panel c
5、aused by density variations, knots, knot-holes,areas of distorted grain, fungal attack, or wide growth varia-tions. However, Method B may be used to evaluate certainfeatures such as core gaps and veneer joints in plywood panelswhere effects are readily projected to full panels. Method Cgenerally is
6、preferred where size of test material permits.Moments applied to fail specimens tested by MethodA, B or Din which large deflections occur can be considerably largerthan nominal. An approximate correction can be made.1.2 Method A, Center-Point Flexure TestThis method isapplicable to material that is
7、uniform with respect to elastic andstrength properties. Total deflection, and modulus of elasticitycomputed from it, include a relatively constant componentattributable to shear deformation. It is well suited to investi-gations of many variables that influence properties uniformlythroughout the pane
8、l in controlled studies and to test small,defect-free control specimens cut from large panels containingdefects tested by the large-specimen method.1.3 Method B, Two-Point Flexure TestThis method, likeMethodA, is suited to the investigation of factors that influencestrength and elastic properties un
9、iformly throughout the panel,in controlled studies, and to testing small, defect free controlspecimens cut from large specimens tested by Method C.However, it may be used to determine the effects of fingerjoints, veneer joints and gaps, and other features which can beplaced entirely between the load
10、 points and whose effects canbe projected readily to full panel width. Deflection andmodulus of elasticity obtained from this method are related toflexural stress only and do not contain a shear component.Significant errors in modulus of rupture can occur whennominal moment is used (see Appendix X1)
11、.1.4 Method C, Large Panel TestThis method is ideallysuited for evaluating effects of knots, knot-holes, areas ofsloping grain, and patches for their effect on standard full-sizepanels. It is equally well suited for testing uniform or clearmaterial whenever specimen size is adequate. Specimen sizean
12、d span above certain minimums are quite flexible. It ispreferred when equipment is available.1.5 Method D, Flexure Test for Quality AssuranceThismethod, like Method A, is well suited to the investigation offactors that influence bending strength and stiffness properties.Also like Method A, this meth
13、od uses small specimens in acenter-point simple span test configuration. This method uses aspan to depth ratio, specimen width, test fixture and test speedthat make the method well suited for quality assurance. Themethod is frequently used for quality assurance testing oforiented strand board.1.6 Al
14、l methods can be used to determine modulus ofelasticity with sufficient accuracy. Modulus of rupture deter-mined by Methods A, B or D is subject to errors up to andsometimes exceeding 20 % depending upon span, loading, anddeflection at failure unless moment is computed in the rigorousmanner outlined
15、 in Appendix X1 or corrections are made inother ways. These errors are not present in Method C.1.7 When comparisons are desired between results of speci-men groups, it is good practice to use the same method of testfor all specimens, thus eliminating possible differences relat-able to test method.1.
16、8 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1
17、These methods are under the jurisdiction of ASTM Committee D07 on Woodand are the direct responsibility of Subcommittee D07.03 on Panel Products.Current edition approved Nov. 15, 2017. Published December 2017. Originallyapproved in 1972. Last previous edition approved in 2011 as D3043 00 (2011).DOI:
18、 10.1520/D3043-17.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDe
19、velopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.11.9 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision
20、 on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D2395 Test Methods for Density and Specific Gravity (Rela-tive Density) of Wood and W
21、ood-Based MaterialsD4442 Test Methods for Direct Moisture Content Measure-ment of Wood and Wood-Based MaterialsD4761 Test Methods for Mechanical Properties of Lumberand Wood-Base Structural Material3. Significance and Use3.1 These methods give the flexural properties, principallystrength and stiffne
22、ss, of structural panels. These properties areof primary importance in most structural uses of panelswhether in construction for floors, wall sheathing, roofdecking, concrete form, or various space plane structures;packaging and materials handling for containers, crates, orpallets; or structural com
23、ponents such as stress-skin panels.3.2 To control or define other variables influencing flexureproperties, moisture content and time to failure must bedetermined. Conditioning of test material at controlled atmo-spheres to control test moisture content and determination ofspecific gravity are recomm
24、ended. Comparisons of results ofplywood, veneer composites, and laminates with solid wood orother plywood constructions will be greatly assisted if thethickness of the individual plies is measured to permit compu-tation of section properties.4. Control of Moisture Content4.1 Structural panel samples
25、 to be tested at a specificmoisture content or relative humidity shall be conditioned toapproximate constant mass in controlled atmospheric condi-tions before testing. For structural panels used under dryconditions, a relative humidity of 65 6 5 % at a temperature of68 6 6F (20 6 3C) is recommended.
26、5. Method ACenter-Point Flexure Test5.1 SummaryAconventional compression testing machineis used to apply and measure a load at mid-span of a smallflexure specimen; and the resulting deflection at mid span ismeasured or recorded. The test proceeds at a constant rate ofhead motion until either suffici
27、ent deflection data in the elasticrange have been gathered or until specimen failure occurs. Thespecimen is supported on reaction bearings which permit thespecimen and bearing plate to roll freely over the reactions asthe specimen deflects.5.2 Test SpecimenThe test specimen shall be rectangularin cr
28、oss section. The depth of the specimen shall be equal to thethickness of material, and the width shall be 1 in. (25 mm) fordepths less than14 in. (6 mm) and 2 in. (50 mm) for greaterdepths (Note 1). When the principal direction of the face plies,laminations, strands, or wafers is parallel to the spa
29、n, the lengthof the specimen (Note 2) shall be not less than 48 times thedepth plus 2 in.; when the principal direction of the face plies,laminations, strands, or wafers is perpendicular to the span, thespecimen length shall be not less than 24 times the depth plus2 in. (Note 3).NOTE 1In certain spe
30、cific instances, it may be necessary or desirableto test specimens having a width greater than 1 or 2 in. (25 or 50 mm). Toeliminate plate action when wider specimens are tested, the specimenwidth shall not exceed one third of the span length and precaution shall betaken to ensure uniform bearing ac
31、ross the entire width of the specimen atthe load and reaction points.NOTE 2In cutting specimens to meet the length requirement, it is notintended that the length be changed for small variations in thickness.Rather, it is intended that the nominal thickness of the material under testshould be used fo
32、r determining the specimen length.5.2.1 MeasurementsMeasure specimen thickness at mid-span at two points near each edge and record the average.Measure to the nearest 0.001 in. (0.02 mm) or 0.3 %. Measurewidth at mid-span to the nearest 0.3 %.5.2.1.1 When needed for interpretation of test results for
33、plywood, veneer composites, and laminates measure thicknessof each layer to the nearest 0.001 in. (0.02 mm) at mid-span ateach edge and record the average.5.3 SpanThe span shall be at least 48 times the nominaldepth when the principal direction of the face plies,laminations, strands, or wafers of th
34、e test specimen is parallelto the span and at least 24 times the nominal depth when theprincipal direction of the face plies, laminations, strands, orwafers is perpendicular to the span (Note 3).NOTE 3Establishment of a span-depth ratio is required to allow anaccurate comparison of test values for m
35、aterials of different thicknesses. Itshould be noted that the span is based on the nominal thickness of thematerial and it is not intended that the spans be changed for smallvariations in thickness.5.4 End SupportsReaction points shall be capable offreely compensating for warp of the test specimen b
36、y turninglaterally in a plane perpendicular to the specimen length so asto apply load uniformly across its width. Design of endsupports shall place the center of rotation near the neutral axisof the specimen of average thickness. Construction is shown indetail in Fig. 1. Bearing points shall be roun
37、ded where theycontact the specimen.5.4.1 Use of bearing plates is generally recommended and isrequired wherever significant local deformation may occur.5.4.2 Use of roller bearings or plates and rollers to precludefriction forces between end support and specimen is recom-mended in addition to the re
38、quirement of lateral compensation.Construction of a suitable end support using small rollerbearings in conjunction with a plate which clips to the end ofthe specimen is illustrated in Fig. 2 and Fig. 3. The use of alarge ball bearing to provide lateral compensation for warp isalso illustrated. This
39、method is particularly recommended forthin specimens and small loads.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
40、website.D3043 1725.4.3 As the specimen deflects during test, loads no longeract in the direction assumed in formulas for calculatingproperties. For a discussion of these errors, their effects, andmethods for reducing them, refer to Appendix X1.5.5 Loading BlockA loading block having a radius ofcurva
41、ture of approximately one and one-half times the depth ofthe test specimen for a chord length of not less than twice thedepth of the specimen shall be used. In cases where excessivelocal deformation may occur, suitable bearing plates shall beused. Radius of curvature of bearing plate or block shall
42、not beso large as to cause bridging as the specimen bends.5.6 Loading ProcedureApply the load with a continuousmotion of the movable head throughout the test. The rate ofload application shall be such that the maximum fiber strainrate is equal to 0.0015 in./in. (mm/mm) per min within apermissible va
43、riation of 625 %. Load shall be measured to anaccuracy of 61 % of indicated value or 0.4 percent of fullscale, whichever is larger. Calculate the rate of motion of themovable head as follows:N 5 zL2/6d (1)where:N = rate of motion of moving head, in./min (mm/min),L = span, in. (mm),d = depth of beam,
44、 in. (mm), andz = unit rate of fiber strain, in./in.min (mm/mmmin) ofouter fiber length = 0.0015.Inch-Pound (in.)Metric Equiva-lents, (mm)Inch-Pound (in.)Metric Equiva-lents, (mm)116 1.5 114 3218 3112 38316 525014 62116 5238 10 3 761332 10.3 512 14012 12 6 15278 23 12 3051516 24 24 610125FIG. 1 Appa
45、ratus for Static Bending Test Showing Details ofLaterally Adjustable SupportsD3043 1735.6.1 Measure the elapsed time from initiation of loading tomaximum load and record to the nearest12 min.5.7 Measurement of DeflectionTake data for load-deflection curves to determine the modulus of elasticity,prop
46、ortional limit, work to proportional limit, work to maxi-mum load, and total work. Take deflections by the methodsindicated in Fig. 4 or Fig. 5, and take readings to the nearest0.001 in. (0.02 mm). Choose increments of load so that not lessthan 12 and preferably 15 or more readings of load anddeflec
47、tion are taken to the proportional limit.5.7.1 Deflections also may be measured with transducer-type gages and plotted simultaneously against load. In thiscase, record deflection to an accuracy of at least 112 %ofdeformation at proportional limit and the recorded trace belowthe proportional limit sh
48、all be at least 212 in. (64 mm) long or14 of full scale measured on the deformation axis, whichever islarger. Similar requirements apply to the load axis.5.8 Calculations:5.8.1 Calculate specimen bending stiffness as follows:EI 5 L3/48!P/! (2)where:EI = modulus of elasticity, psi (MPa) moment of ine
49、rtia,in.4(or mm4),P/ = slope of loaddeflection curve, lbf/in. (N/mm),I = moment of inertia, in.4(mm4), andL = span, in. (mm).5.8.1.1 Moment of inertia used in the computations in 5.8.1may be calculated in several different ways depending upon therequirements of the investigation. It may be based on the entirecross section, may include only the moment of inertia of layersparallel to span, or may include all layers weighted in accor-dance with modulus of elasticity in the direction of bendingstress. State clearly the method employed i
