1、Designation:D304300(Reapproved 2011)Standard 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
2、 parentheses 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
3、include plywood,waferboard,orientedstrand board,and composites of veneer and of wood-basedlayers.Four methods of tests are included:SectionsMethod ACenter-Point Flexure Test5Method BTwo-Point Flexure Test6Method CPure Moment Test7Method DFlexure Test for Quality Assurance8The choice of method will b
4、e dictated by the purpose of thetest,type of material,and equipment availability.All meth-ods are applicable to material that is relative uniform instrength and stiffness properties.Only Method C should beused to test material suspected of having strength or stiffnessvariations within a panel caused
5、 by density variations,knots,knot-holes,areas of distorted grain,fungal attack,or widegrowth variations.However,Method B may be used toevaluate certain features such as core gaps and veneer jointsin plywood panels where effects are readily projected to fullpanels.Method C generally is preferred wher
6、e size of testmaterial permits.Moments applied to fail specimens testedby Method A,B or D in which large deflections occur canbe considerably larger than nominal.An approximate correc-tion can be made.1.2 Method A,Center-Point Flexure TestThis method isapplicable to material that is uniform with res
7、pect 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 panel in controlled stud
8、ies 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 uniformly throughout the
9、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 points and whose effects ca
10、nbe 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).1.4 Method C,Pure Moment Test
11、This 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.Measured defor-mation and elastic constants are fre
12、e 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 when equipment isavailable.1.5 Method D,Flexure Test for Qual
13、ity 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 configuration.This method uses aspan to depth ratio,specimen width,test f
14、ixture 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 sufficient accuracy.Modulus of rupture deter-mined by Methods A,B or D is
15、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 are not present in Method C.1.7 When comparisons are desired between result
16、s 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 Woodand are the direct responsibility of Subcommittee D07.03 on Panel Products.Current edition approved Nov.1,2011.Published November 2011.Originallyapproved in 1972.Last previous edition approved in 2000 as D3043 00(2006).DOI:10.1520/D3043-00R11.Copyright ASTM International,100