1、Designation: D 3043 00 (Reapproved 2006)Standard Test Methods forStructural Panels in Flexure1This standard is issued under the fixed designation D 3043; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、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 These test methods determine the flexural properties ofstrips cut from structural panels or panels up to 4 by 8 ft in size.Structural
3、panels in use include 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 CPure Moment Test 7Method DFlexure Test for Quality Assurance 8The c
4、hoice of method will be dictated by the purpose of thetest, type of material, and equipment availability. All methodsare applicable to material that is relative uniform in strengthand stiffness properties. Only Method C should be used to testmaterial suspected of having strength or stiffness variati
5、onswithin a panel caused 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. Me
6、thod Cgenerally is 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 t
7、o material that is 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 uniformly
8、throughout the panel 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 el
9、astic properties uniformly 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 entire
10、ly between the load 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 use
11、d (see Appendix X1).1.4 Method C, Pure Moment 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 adequa
12、te. Measured defor-mation and elastic constants are free of shear deformationeffects; and panels can be bent to large deflections withoutincurring errors from horizontal force components occurring inother methods. Specimen size and span above certain mini-mums are quite flexible. It is preferred whe
13、n equipment isavailable.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 method uses small specimens in acenter-point simple span test configurati
14、on. 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 All methods can be used to determine modulus ofelasticity with sufficie
15、nt 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 in Appendix X1 or corrections are made inother ways. These errors ar
16、e 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.1These methods are under the jurisdiction of ASTM Committee D07 on Wood
17、and are the direct responsibility of Subcommittee D07.03 on Panel Products.Current edition approved Oct. 1, 2006. Published October 2006. Originallyapproved in 1972. Last previous edition approved in 2000 as D 3043 00e1.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho
18、cken, PA 19428-2959, United States.1.8 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 and health practices and determine the applica-bility of regulatory limit
19、ations 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 MaterialsD 4761 Test Methods for Mechanical Properties of Lumberand Wood-Base Stru
20、ctural Material3. Significance and Use3.1 These methods give the flexural properties, principallystrength and stiffness, of structural panels. These properties areof primary importance in most structural uses of panelswhether in construction for floors, wall sheathing, roof deck-ing, concrete form,
21、or various space plane structures; packag-ing and materials handling for containers, crates, or pallets; orstructural components 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
22、test material at controlled atmo-spheres to control test moisture content and determination ofspecific gravity are recommended. Comparisons of results ofplywood, veneer composites, and laminates with solid wood orother plywood constructions will be greatly assisted if thethickness of the individual
23、plies is measured to permit compu-tation of section properties.4. Control of Moisture Content4.1 Structural panel samples to be tested at a specificmoisture content or relative humidity shall be conditioned toapproximate constant mass in controlled atmospheric condi-tions before testing. For structu
24、ral panels used under dryconditions, a relative humidity of 65 6 5 % at a temperature of68 6 6F (20 6 3C) is recommended.5. Method ACenter-Point Flexure Test5.1 SummaryA conventional compression testing ma-chine is used to apply and measure a load at mid-span of asmall flexure specimen; and the resu
25、lting deflection at mid spanis measured or recorded. The test proceeds at a constant rate ofhead motion until either sufficient deflection data in the elasticrange have been gathered or until specimen failure occurs. Thespecimen is supported on reaction bearings which permit thespecimen and bearing
26、plate to roll freely over the reactions asthe specimen deflects.5.2 Test SpecimenThe test specimen shall be rectangularin cross 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 g
27、reaterdepths (Note 1). When the principal direction of the face plies,laminations, strands, or wafers is parallel to the span, 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 per
28、pendicular to the span, thespecimen length shall be not less than 24 times the depth plus2 in. (Note 3).NOTE 1In certain specific 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 teste
29、d, the specimenwidth shall not exceed one third of the span length and precaution shall betaken to ensure uniform bearing across 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
30、 small variations in thickness.Rather, it is intended that the nominal thickness of the material under testshould be used for 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.
31、(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 forplywood, 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 shal
32、l be at least 48 times the nominaldepth when the principal direction of the face plies, lamina-tions, strands, or wafers of the test specimen is parallel to thespan and at least 24 times the nominal depth when the principaldirection of the face plies, laminations, strands, or wafers isperpendicular
33、to the span (Note 3).NOTE 3Establishment of a span-depth ratio is required to allow anaccurate comparison of test values for materials 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 small
34、variations in thickness.5.4 End SupportsReaction points shall be capable offreely compensating for warp of the test specimen by 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 nea
35、r the neutral axisof the specimen of average thickness. Construction is shown indetail in Fig. 1. Bearing points shall be rounded 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 be
36、arings or plates and rollers to precludefriction forces between end support and specimen is recom-mended in addition to the requirement 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 illus
37、trated in Fig. 2 and Fig. 3. The use of alarge ball bearing to provide lateral compensation for warp isalso illustrated. This method is particularly recommended forthin specimens and small loads.5.4.3 As the specimen deflects during test, loads no longeract in the direction assumed in formulas for c
38、alculating2For 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 website.D 3043 00 (2006)2properties. For a discussion of th
39、ese errors, their effects, andmethods for reducing them, refer to Appendix X1.5.5 Loading BlockA loading block having a radius ofcurvature 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
40、where excessivelocal deformation may occur, suitable bearing plates shall beused. Radius of curvature of bearing plate or block shall 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 rat
41、e ofload application shall be such that the maximum fiber strainrate is equal to 0.0015 in./in. (mm/mm) per min within apermissible variation of6 25 %. 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 th
42、emovable 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, 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 Equiv
43、a-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 Apparatus for Static Bending Test Showing Details ofLaterally Adjustable SupportsD 3043 00 (2006)35.6.1 Measure the elapsed time from initiation of loading tomaximum load
44、 and record to the nearest12 min.5.7 Measurement of DeflectionTake data for load-deflection curves to determine the modulus of elasticity,proportional 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 read
45、ings 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 anddeflection are taken to the proportional limit.5.7.1 Deflections also may be measured with transducer-type gages and plotted simultaneously against load. In thiscas
46、e, record deflection to an accuracy of at least 112 %ofdeformation at proportional limit and the recorded trace belowthe proportional limit shall 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
47、Calculations:5.8.1 Calculate specimen bending stiffness as follows:EI 5 L3/48!P/D! (2)where:EI = modulus of elasticity, psi (MPa) 3 moment of iner-tia, in.4(or mm4),P/D = 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 u
48、sed 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 modulu
49、s of elasticity in the direction of bendingstress. State clearly the method employed in the report.5.8.2 Calculate maximum moment (SbI/c) by the followingequation:SbI/c 5 PL/4 (3)FIG. 2 Reaction Bearing for Small Flexure Test SpecimensD 3043 00 (2006)4where:SbI/c = maximum moment, lbfin. (Nmm),Sb= modules of rupture, psi (MPa),P = maximum load, lbf (N), andc = distance from neutral axis to extreme fiber, in.(mm).6. Method BTwo-Point Flexure Test6.1 SummaryThe ends of a two-point flexure specimenare supported on special reaction bea
