1、Designation: D143 09Standard 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 parenthes
2、es indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.INTRODUCTIONThe need to classify wood species by evaluating the physical and mechanic
3、al properties of smallclear specimens has always existed. Because of the great variety of species, 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 preparatio
4、n of these methods for testing small clear specimens, consideration was given bothto the desirability 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 tho
5、usands of tests made under a single comprehensive plan by the U.S. ForestService, the former Forest Products Laboratories of Canada (now Forintek Canada Corp.), and othersimilar organizations, these test methods naturally conform closely to the methods used by thoseinstitutions. These test methods a
6、re the outgrowth of a study of both American and Europeanexperience and methods. The general adoption of these test methods will tend toward a world-wideunification of results, permitting an interchange and correlation of data, and establishing the basis fora cumulative body of fundamental informati
7、on on the timber species of the world.Descriptions of some of the strength tests refer to primary methods and secondary 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
8、 physical properties of differentspecies of wood, and a large number of data based on this primary method have been 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 sma
9、ller size specimens, and is largeenough to represent a considerable portion of the sampled material. It is advisable to 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
10、required 30 in. (760 mm)length for static bending tests. With the increasing incidence of smaller second growth trees, and thedesirability in certain situations to evaluate a material which is too small to provide a 2 by 2-in. crosssection, a secondary method which utilizesa1by1-in. (25 by 25-mm) cr
11、oss section has beenincluded. This cross section is established for compression parallel to grain and static bending tests,while 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 g
12、rain. Toughness and tensionparallel to grain are special tests using specimens of smaller cross section.The user is cautioned that test results between two different sizes of specimens are not necessarilydirectly comparable. Guidance on the effect of specimen size on a property being evaluated is be
13、yondthe scope of these test methods and should be sought elsewhere.Where the application, measurement, or recording of load and deflection can be accomplished usingelectronic equipment and computerized apparatus, such devices are encouraged, providing they do notlower the standard of accuracy and re
14、liability available with basic mechanical equipment.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1. Scope1.1 These test methods cover the determination of variousstrength and related properties of wood by testing small clearspecim
15、ens.1.1.1 These test methods represent procedures for evaluat-ing the different mechanical and physical properties, control-ling factors such as specimen size, moisture content, tempera-ture, and rate of loading.1.1.2 Sampling and collection of material is discussed inPractice D5536. Sample data, co
16、mputation sheets, and cardshave been incorporated, which were of assistance to theinvestigator in systematizing records.1.1.3 The values stated in inch-pound units are to beregarded as the standard. The values given in parentheses aremathematical conversions to SI units that are provided forinformat
17、ion 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 Specimens 5Control of Moisture Content and Temperat
18、ure 6Record of Heartwood and Sapwood 7Static Bending 8Compression Parallel to Grain 9Impact Bending 10Toughness 11Compression Perpendicular to Grain 12Hardness 13Shear Parallel to Grain 14Cleavage 15Tension Parallel to Grain 16Tension Perpendicular to Grain 17Nail Withdrawal 18Specific Gravity and S
19、hrinkage in Volume 19Radial and Tangential Shrinkage 20Moisture Determination 21Permissible Variations 22Calibration 231.3 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-pri
20、ate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D198 Test Methods of Static Tests of Lumber in StructuralSizesD2395 Test Methods for Specific Gravity of Wood andWood-Based MaterialsD3043 Test Methods f
21、or Structural Panels in FlexureD3500 Test Methods for Structural Panels in TensionD4442 Test Methods for Direct Moisture Content Measure-ment of Wood and Wood-Base MaterialsD4761 Test Methods for Mechanical Properties of Lumberand Wood-Base Structural MaterialD5536 Practice for Sampling Forest Trees
22、 for Determina-tion of Clear Wood PropertiesE4 Practices for Force Verification of Testing Machines3. Summary of Test Methods3.1 The mechanical tests are static bending, compressionparallel to grain, impact bending toughness, compressionperpendicular to grain, hardness, shear parallel to grain (Note
23、1), cleavage, tension parallel to grain, tension-perpendicular-to-grain, and nail-withdrawal tests. These tests may be made onboth green and air-dry material as specified in these testmethods. In addition, test methods for evaluating such physicalproperties as specific gravity, shrinkage in volume,
24、radialshrinkage, and tangential shrinkage are presented.NOTE 1The test for shearing strength perpendicular to the grain(sometimes termed “vertical shear”) is not included as one of the principalmechanical tests since in such a test the strength is limited by the shearingresistance parallel to the gr
25、ain.4. Significance and Use4.1 These test methods cover tests on small clear specimensof wood that are made to provide the following:4.1.1 Data for comparing the mechanical properties ofvarious species,4.1.2 Data for the establishment of correct strength func-tions, which in conjunction with results
26、 of tests of timbers instructural sizes (see Test Methods D198 and Test MethodsD4761), afford a basis for establishing allowable stresses, and4.1.3 Data to determine the influence on the mechanicalproperties of such factors as density, locality of growth,position in cross section, height of timber i
27、n the tree, change ofproperties with seasoning or treatment with chemicals, andchange from sapwood to heartwood.5. Photographs of Specimens5.1 Four of the static bending specimens from each speciesshall be selected for photographing, as follows: two averagegrowth, one fast growth, and one slow growt
28、h. These speci-mens shall be photographed in cross section and on the radialand tangential surfaces. Fig. 1 is a typical photograph of a crosssection of 2 by 2-in. (50 by 50-mm) test specimens, and Fig. 2is the tangential surface of such specimens.6. Control of Moisture Content and Temperature6.1 In
29、 recognition of the significant influence of temperatureand moisture content on the strength of wood, it is highlydesirable that these factors be controlled to ensure comparabletest results.6.2 Control of Moisture ContentSpecimens for the test inthe air-dry condition shall be dried to approximately
30、constantweight before test. Should any changes in moisture contentoccur during final preparation of specimens, the specimensshall be reconditioned to constant weight before test. Testsshall be carried out in such manner that large changes in1These test methods are under the jurisdiction of ASTM Comm
31、ittee D07 onWood and are the direct responsibility of Subcommittee D07.01 on FundamentalTest Methods and Properties.Current edition approved Sept. 1, 2009. Published October 2009. Originallyapproved in 1922. Last previous edition approved in 2007 as D143 94 (2007).DOI: 10.1520/D0143-09.2For referenc
32、ed 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.D143 092moisture content will not occur. To prevent such changes, it isdes
33、irable that the testing room and rooms for preparation of testspecimens have some means of humidity control.6.3 Control of TemperatureTemperature and relative hu-midity together affect wood strength by fixing its equilibriummoisture content. The mechanical properties of wood are alsoaffected by temp
34、erature alone. When tested, the specimensshall be at a temperature of 68 + 6F (20 + 3C). The tempera-ture at the time of test shall in all instances be recorded as aspecific part of the test record.7. Record of Heartwood and Sapwood7.1 Proportion of SapwoodThe estimated proportion ofsapwood present
35、should be recorded for each test specimen.8. Static Bending8.1 Size of SpecimensThe static bending tests shall bemade on 2 by 2 by 30 in. (50 by 50 by 760 mm) primarymethod specimens or 1 by 1 by 16 in. (25 by 25 by 410 mm)secondary method specimens. The actual height and width atthe center and the
36、length shall be measured (see 22.2).8.2 Loading Span and SupportsUse center loading and aspan length of 28 in. (710 mm) for the primary method and 14in. (360 mm) for the secondary method. These spans wereestablished in order to maintain a minimum span-to-depth ratioof 14. Both supporting knife edges
37、 shall be provided withbearing plates and rollers of such thickness that the distancefrom the point of support to the central plane is not greater thanthe depth of the specimen (Fig. 3). The knife edges shall beadjustable laterally to permit adjustment for slight twist in thespecimen (Note 2).NOTE 2
38、Details of laterally adjustable supports may be found in Fig.1 of Test Methods D3043.8.3 Bearing BlockA bearing block of the form and size ofthat shown in Fig. 4 shall be used for applying the load forFIG. 1 Cross Sections of Bending Specimens Showing Different Rates of Growth of Longleaf Pine (2 by
39、 2-in. (50 by 50-mm) Specimens)FIG. 2 Tangential Surfaces of Bending Specimens of Different Rates of Growth of Jeffrey Pine 2 by 2-in. (50 by 50 by 760-mm)SpecimensD143 093primary method specimens. A block having a radius of 112 in.(38 mm) for a chord length of not less than 2 in. (50 mm) shallbe us
40、ed for secondary method specimens.8.4 Placement of Growth RingsThe specimen shall beplaced so that the load will be applied through the bearingblock to the tangential surface nearest the pith.8.5 Speed of TestingThe load shall be applied continu-ously throughout the test at a rate of motion of the m
41、ovablecrosshead of 0.10 in. (2.5 mm)/min (see 22.3), for primarymethod specimens, and at a rate of 0.05 in. (1.3 mm)/min forsecondary method specimens.8.6 Load-Deflection Curves:8.6.1 Load-deflection curves shall be recorded to or beyondthe maximum load for all static bending tests. The curves shall
42、be continued to a 6 in. (150 mm) deflection, or until thespecimen fails to support a load of 200 lbf (890 N) for primarymethod specimens, and to a 3 in. (76 mm) deflection, or untilthe specimen fails to support a load of 50 lbf (220 N) forsecondary method specimens.8.6.2 Deflections of the neutral p
43、lane at the center of thelength shall be taken with respect to points in the neutral planeabove the supports. Alternatively, deflection may be takenrelative to the tension surface at midspan. However, take careto ensure that vertical displacements which may occur at thereactions are accounted for.8.
44、6.3 Within the proportional limit, deflection readings shallbe taken to 0.001 in. (0.02 mm). After the proportional limit isreached, less refinement is necessary in observing deflections,but it is convenient to read them by means of the dial gage (Fig.3) until it reaches the limit of its capacity, n
45、ormally approxi-mately 1 in. (25 mm). Where deflections beyond 1 in. areencountered, the deflections may be measured by means of thescale mounted on the loading head (Fig. 3) and a wire mountedat the neutral axis of the specimen of the side opposite theyoke. Deflections are read to the nearest 0.01
46、in. (0.2 mm) at0.10 in. (2.5 mm) intervals and also after abrupt changes inload.8.6.4 The load and deflection of first failure, the maximumload, and points of sudden change shall be read and shown onthe curve sheet (Note 3) although they may not occur at one ofthe regular load or deflection incremen
47、ts.NOTE 3See Fig. 5 for a sample static bending data sheet form.FIG. 3 Static Bending Test Assembly Showing Test Method of Load Application, Specimen Supported on Rollers and LaterallyAdjustable Knife Edges, and Test Method of Measuring Deflection at Neutral Axis by Means of Yoke and Dial Attachment
48、 (Adjustablescale mounted on loading head is used to measure increments of deformation beyond the dial capacity.)FIG. 4 Details of Bearing Block for Static Bending TestsD143 0948.7 Description of Static Bending FailuresStatic bending(flexural) failures shall be classified in accordance with theappea
49、rance of the fractured surface and the manner in whichthe failure develops (Fig. 6). The fractured surfaces may beroughly divided into “brash” and “fibrous”, the term “brash”indicating abrupt failure and “fibrous” indicating a fractureshowing splinters.8.8 Weight and Moisture ContentThe specimen shall beweighed immediately before test, and after the test a moisturesection approximately 1 in. (25 mm) in length shall be cut fromthe specimen near the point of failure (see 21.1 and 22.1).9. Compression Parallel to Grain9.1 Size of SpecimensThe compression-parallel-t
