1、Designation:D304317Standard 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 parentheses indi
2、cates 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 plywood,w
3、aferboard,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 CLarge Panel Test7Method DFlexure Test for Quality Assurance8The choice of method will be dictated by the
4、 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 caused by density varia
5、tions,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 preferred where size of test
6、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 uniform with respect to elastic
7、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 studies and to test
8、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 panel,in control
9、led 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 canbe projected re
10、adily 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,Large Panel TestThis method is i
11、deallysuited 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 sizeand span above certain minimums are quite flexible.It
12、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 method uses small specimens in acenter-point simple span test
13、 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 All methods can be used to determine modulus ofelasticity with
14、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 in Appendix X1 or corrections are made inother ways.These errors a
15、re 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.1.8 This standard does not purport to address all of thesafety concerns,
16、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.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.15,2017.Published December 2017.Originallyapproved in 1972.Last previous edition approved in 2011 as
