1、Designation:D14314Standard Test Methods forSmall Clear Specimens of Timber1This standard is issued under the fixed designation D143;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 ind
2、icates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe need to classify wood species by evaluating the physical and mechanical properties of smallclear specimens has always existed.Because of the great variety of s
3、pecies,variability of the material,continually changing conditions of supply,many factors affecting test results,and ease of comparingvariables,the need will undoubtedly continue to exist.In the preparation of these methods for testing small clear specimens,consideration was given bothto the desirab
4、ility of adopting test methods that would yield results comparable to those alreadyavailable and to the possibility of embodying such improvements as experience has shown desirable.In view of the many thousands of tests made under a single comprehensive plan by the U.S.ForestService,the former Fores
5、t Products Laboratories of Canada(now FP Innovations),and other similarorganizations,these test methods naturally conform closely to the methods used by those institutions.These test methods are the outgrowth of a study of both American and European experience andmethods.The general adoption of thes
6、e test methods will tend toward a world-wide unification ofresults,permitting an interchange and correlation of data,and establishing the basis for a cumulativebody of fundamental information on the timber species of the world.Descriptions of some of the strength tests refer to primary methods and s
7、econdary methods.Primarymethods provide for specimens of 2 by 2-in.(50 by 50-mm)cross section.This size of specimen hasbeen extensively used for the evaluation of various mechanical and physical properties of differentspecies of wood,and a large number of data based on this primary method have been
8、obtained andpublished.The 2 by 2-in.(50 by 50-mm)size has the advantage in that it embraces a number of growth rings,is less influenced by earlywood and latewood differences than smaller size specimens,and is largeenough to represent a considerable portion of the sampled material.It is advisable to
9、use primarymethod specimens wherever possible.There are circumstances,however,when it is difficult orimpossible to obtain clear specimens of 2 by 2-in.cross section having the required 30 in.(760 mm)length for static bending tests.With the increasing incidence of smaller second growth trees,and thed
10、esirability in certain situations to evaluate a material which is too small to provide a 2 by 2-in.crosssection,a secondary method which utilizes a 1 by 1-in.(25 by 25-mm)cross section has beenincluded.This cross section is established for compression parallel to grain and static bending tests,while
11、 the 2 by 2-in.cross section is retained for impact bending,compression perpendicular to grain,hardness,shear parallel to grain,cleavage,and tension perpendicular to grain.Toughness and tensionparallel to grain are special tests using specimens of smaller cross section.The user is cautioned that tes
12、t results between two different sizes of specimens are not necessarilydirectly comparable.Guidance on the effect of specimen size on a property being evaluated is beyondthe scope of these test methods and should be sought elsewhere.Where the application,measurement,or recording of load and deflectio
13、n can be accomplished usingelectronic equipment and computerized apparatus,such devices are encouraged,providing they do notlower the standard of accuracy and reliability available with basic mechanical equipment.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 194
14、28-2959.United States1 1.Scope1.1 These test methods cover the determination of variousstrength and related properties of wood by testing small clearspecimens.1.1.1 These test methods represent procedures for evaluat-ing the different mechanical and physical properties,control-ling factors such as s
15、pecimen size,moisture content,temperature,and rate of loading.1.1.2 Sampling and collection of material is discussed inPractice D5536.Sample data,computation sheets,and cardshave been incorporated,which were of assistance to theinvestigator in systematizing records.1.1.3 The values stated in inch-po
16、und units are to beregarded as the standard.The values given in parentheses aremathematical conversions to SI units that are provided forinformation only and are not considered standard.When aweight is prescribed,the basic inch-pound unit of weight(lbf)and the basic SI unit of mass(Kg)are cited.1.2 The procedures for the various tests appear in thefollowing order:SectionsPhotographs of Specimens5Control of Moisture Content and Temperature6Record of Heartwood and Sapwood7Static Bending8Compressio