1、Designation:D687421Standard Test Methods forNondestructive Evaluation of the Stiffness of Wood andWood-Based Materials Using Transverse Vibration or StressWave Propagation1This standard is issued under the fixed designation D6874;the number immediately following the designation indicates the year of
2、original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.INTRODUCTIONNondestructive testing methods are used to determine the physical
3、 and mechanical properties ofwood and wood-based materials.These test methods help ensure structural performance of productsmanufactured from a variety of wood species and quality levels of raw materials.These test methodsalso assist in evaluating the influence of environmental conditions on product
4、 performance.Dynamic test methods based on the transverse vibration of a simply or freely supported beam,orthe propagation of a longitudinal stress wave are methods used to nondestructively evaluatewood-based materials.These methods yield results comparable to traditional static test methods,permitt
5、ing standardization of results,interchange and correlation of data,and establishment of acumulative body of information on wood species and products of the world.1.Scope1.1 These test methods cover the non-destructive determi-nation of the following dynamic properties of wood andwood-based materials
6、 from measuring the fundamental fre-quency of vibration:1.1.1 Flexural(see Refs(1-3)2stiffness and apparentmodulus of elasticity(Etv)properties using simply or freelysupported beam transverse vibration in the vertical direction,and1.1.2 Axial stiffness and apparent longitudinal modulus ofelasticity(
7、Esw)using stress wave propagation time in thelongitudinal direction.1.2 The test methods can be used for a broad range ofwood-based materials and products ranging from logs,timbers,lumber,and engineered wood products.1.2.1 The two flexural methods can be applied to flexuralproducts such as glulam be
8、ams and I-joists.1.2.2 The longitudinal stress wave methods are limited tosolid wood and homogeneous grade glulam(e.g.,columns butnot products with distinct subcomponents such as woodI-joists).1.3 The standard recognizes three implementation classesfor each of these test methods.1.3.1 Class IDefines
9、 the fundamental method to achievethe highest degree of repeatability and reproducibility that canbe achieved under laboratory conditions.NOTE1Testing should follow Class I methods to develop training andvalidation data sets for method conversion models(see Annex A2).1.3.2 Class IIMethod with permit
10、ted modifications to theClass I method that can be used to address practical issuesfound in the field,and where practical deviations from theClass I protocol are known and their effects can be accounted.NOTE2Practical deviations include,for example,environmental andtest boundary conditions.Class II
11、methods allow for corrections to testresults to account for quantifiable effect such as machine frame deflec-tions.1.3.3 Class IIIMethod permitting the broadest range ofapplication,with permitted modifications to suit a wider rangeof practical needs with an emphasis on repeatability.NOTE3Online test
12、ing machines implemented to grade/sort lumbermay be treated as Class III.1.4 The standard provides guidance for developing a modelfor estimating a non-destructive test method result(e.g.,staticmodulus of elasticity obtained in accordance with Test Meth-ods D198)from another non-destructive test meth
13、od result(e.g.,dynamic longitudinal modulus of elasticity from mea-surement of longitudinal stress wave propagation time).1These test methods are under the jurisdiction of ASTM Committee D07 onWood and is the direct responsibility of Subcommittee D07.01 on Fundamental TestMethods and Properties.Curr
14、ent edition approved May 1,2021.Published June 2021.Originallyapproved in 2003.Last previous edition approved in 2020 as D6874 20.DOI:10.1520/D6874-21.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright ASTM International,100 Barr Harbor Drive,PO
15、 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 theDevelopment of International Standards,Guides and Recommendations issued by th
16、e World Trade Organization Technical Barriers to Trade(TBT)Committee.11.4.1 The standard covers only models developed from testdata obtained directly from non-destructively testing a repre-sentative sample using one test method,and retesting the samesample following a second test method.1.4.2 Results used for model development shall not beestimated from a model.1.5 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to S
