ASTM D143-2014 Standard Test Methods for Small Clear Specimens of Timber《木材无疵小试样的标准试验方法》.pdf

1、Designation: D143 09D143 14Standard 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 pa

2、rentheses indicates 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 g

3、reat 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 preparation of these methods for testing small clear specimens, consideration was gi

4、ven 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 thousands of tests made under a single comprehensive plan by the U.S. ForestS

5、ervice, the former Forest Products Laboratories of Canada (now Forintek Canada Corp.), FPInnovations), and other similar organizations, these test methods naturally conform closely to themethods used by those institutions. These test methods are the outgrowth of a study of bothAmericanand European e

6、xperience and methods. The general adoption of these test methods will tend towarda world-wide unification of results, permitting an interchange and correlation of data, and establishingthe basis for a cumulative body of fundamental information on the timber species of the world.Descriptions of some

7、 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 physical properties of differentspecies of wood, and a la

8、rge 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 smaller size specimens, and is largeenough to represent a con

9、siderable 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 required 30 in. (760 mm)length for static bending tests. W

10、ith 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 utilizes a 1 by 1-in. (25 by 25-mm) cross section has beenincluded. This cross section is es

11、tablished 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 grain. Toughness and tensionparallel to grain are speci

12、al 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 beyondthe scope of these test methods and should be soug

13、ht 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 reliability available with basic mechanical equipment.1

14、These test methods are under the jurisdiction ofASTM Committee D07 on Wood and are the direct responsibility of Subcommittee D07.01 on Fundamental Test Methodsand Properties.Current edition approved Sept. 1, 2009Feb. 1, 2014. Published October 2009April 2014. Originally approved in 1922. Last previo

15、us edition approved in 20072009 asD143 94 (2007).D143 09. DOI: 10.1520/D0143-09.10.1520/D0143-14.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically p

16、ossible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700,

17、 West Conshohocken, PA 19428-2959. United States11. Scope1.1 These test methods cover the determination of various strength and related properties of wood by testing small clearspecimens.1.1.1 These test methods represent procedures for evaluating the different mechanical and physical properties, co

18、ntrollingfactors such as specimen size, moisture content, temperature, and rate of loading.1.1.2 Sampling and collection of material is discussed in Practice D5536. Sample data, computation sheets, and cards have beenincorporated, which were of assistance to the investigator in systematizing records

19、.1.1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard. When a weight is prescribed, thebasic inch-pound unit of weight (lbf) and t

20、he basic SI unit of mass (Kg) are cited.1.2 The procedures for the various tests appear in the following order:SectionsPhotographs of Specimens 5Control of Moisture Content and Temperature 6Record of Heartwood and Sapwood 7Static Bending 8Compression Parallel to Grain 9Impact Bending 10Toughness 11C

21、ompression Perpendicular to Grain 12Hardness 13Shear Parallel to Grain 14Cleavage 15Tension Parallel to Grain 16Tension Perpendicular to Grain 17Nail Withdrawal 18Specific Gravity and Shrinkage in Volume 19Radial and Tangential Shrinkage 20Moisture Determination 21Permissible Variations 22Calibratio

22、n 231.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced

23、 Documents2.1 ASTM Standards:2D198 Test Methods of Static Tests of Lumber in Structural SizesD2395 Test Methods for Specific Gravity of Wood and Wood-Based MaterialsD3043 Test Methods for Structural Panels in FlexureD3500 Test Methods for Structural Panels in TensionD4442 Test Methods for Direct Moi

24、sture Content Measurement of Wood and Wood-Base MaterialsD4761 Test Methods for Mechanical Properties of Lumber and Wood-Base Structural MaterialD5536 Practice for Sampling Forest Trees for Determination of Clear Wood PropertiesE4 Practices for Force Verification of Testing MachinesE2309 Practices f

25、or Verification of Displacement Measuring Systems and Devices Used in Material Testing Machines3. Summary of Test Methods3.1 The mechanical tests are static bending, compression parallel to grain, impact bending toughness, compressionperpendicular to grain, hardness, shear parallel to grain (Note 1)

26、, cleavage, tension parallel to grain, tension-perpendicular-to-grain,and nail-withdrawal tests. These tests may be made on both green and air-dry material as specified in these test methods. Inaddition, test methods for evaluating such physical properties as specific gravity, shrinkage in volume, r

27、adial shrinkage, andtangential shrinkage are presented.NOTE 1The test for shearing strength perpendicular to the grain (sometimes termed “vertical shear”) is not included as one of the principal mechanicaltests since in such a test the strength is limited by the shearing resistance parallel to the g

28、rain.4. Significance and Use4.1 These test methods cover tests on small clear specimens of wood that are made to provide the following:4.1.1 Data for comparing the mechanical properties of various species,2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Se

29、rvice at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.D143 1424.1.2 Data for the establishment of correct strength functions, which in conjunction with results of tests of timbers in structuralsizes (see Test M

30、ethods D198 and Test Methods D4761), afford a basis for establishing allowable stresses, and4.1.3 Data to determine the influence on the mechanical properties of such factors as density, locality of growth, position incross section, height of timber in the tree, change of properties with seasoning o

31、r treatment with chemicals, and change fromsapwood to heartwood.5. Photographs of Specimens5.1 Four of the static bending specimens from each species shall be selected for photographing, as follows: two average growth,one fast growth, and one slow growth. These specimens shall be photographed in cro

32、ss section and on the radial and tangentialsurfaces. Fig. 1 is a typical photograph of a cross section of 2 by 2-in. (50 by 50-mm) test specimens, and Fig. 2 is the tangentialsurface of such specimens.6. Control of Moisture Content and Temperature6.1 In recognition of the significant influence of te

33、mperature and moisture content on the strength of wood, it is highly desirablethat these factors be controlled to ensure comparable test results.6.2 Control of Moisture ContentSpecimens for the test in the air-dry condition shall be dried to approximately constant weightbefore test. Should any chang

34、es in moisture content occur during final preparation of specimens, the specimens shall bereconditioned to constant weight before test. Tests shall be carried out in such manner that large changes in moisture content willnot occur. To prevent such changes, it is desirable that the testing room and r

35、ooms for preparation of test specimens have somemeans of humidity control.6.3 Control of TemperatureTemperature and relative humidity together affect wood strength by fixing its equilibrium moisturecontent. The mechanical properties of wood are also affected by temperature alone. When tested, the sp

36、ecimens shall be at atemperature of 68 + 6F (20 + 3C). The temperature at the time of test shall in all instances be recorded as a specific part of thetest record.7. Record of Heartwood and Sapwood7.1 Proportion of SapwoodThe estimated proportion of sapwood present should be recorded for each test s

37、pecimen.8. Static Bending8.1 Size of SpecimensThe static bending tests shall be made on 2 by 2 by 30 in. (50 by 50 by 760 mm) primary methodspecimens or 1 by 1 by 16 in. (25 by 25 by 410 mm) secondary method specimens. The actual height and width at the center andthe length shall be measured (see 22

38、.2).FIG. 1 Cross Sections of Bending Specimens Showing Different Rates of Growth of Longleaf Pine (2 by 2-in. (50 by 50-mm) Speci-mens)D143 1438.2 Loading Span and SupportsUse center loading and a span length of 28 in. (710 mm) for the primary method and 14 in.(360 mm) for the secondary method. Thes

39、e spans were established in order to maintain a minimum span-to-depth ratio of 14. Bothsupporting knife edges shall be provided with bearing plates and rollers of such thickness that the distance from the point of supportto the central plane is not greater than the depth of the specimen (Fig. 3). Th

40、e knife edges shall be adjustable laterally to permitadjustment for slight twist in the specimen (Note 2).NOTE 2Details of laterally adjustable supports may be found in Fig. 1 of Test Methods D3043.8.3 Bearing BlockAbearing block of the form and size of that shown in Fig. 4 shall be used for applyin

41、g the load for primarymethod specimens. A block having a radius of 112 in. (38 mm) for a chord length of not less than 2 in. (50 mm) shall be used forsecondary method specimens.8.4 Placement of Growth RingsThe specimen shall be placed so that the load will be applied through the bearing block to the

42、tangential surface nearest the pith.8.5 Speed of TestingThe load shall be applied continuously throughout the test at a rate of motion of the movable crossheadof 0.10 in. (2.5 mm)/min (see 22.3), for primary method specimens, and at a rate of 0.05 in. (1.3 mm)/min for secondary methodspecimens.FIG.

43、2 Tangential Surfaces of Bending Specimens of Different Rates of Growth of Jeffrey Pine 2 by 2-in. (50 by 50 by 760-mm) Speci-mensFIG. 3 Static Bending Test Assembly Showing Test Method of Load Application, Specimen Supported on Rollers and Laterally Adjust-able Knife Edges, and Test Method of Measu

44、ring Deflection at Neutral Axis by Means of Yoke and Dial Attachment (Adjustable scalemounted on loading head is used to measure increments of deformation beyond the dial capacity.)Displacement Measurement DeviceD143 1448.6 Load-Deflection Curves:8.6.1 Load-deflection At a minimum, the load-deflecti

45、on curves shall be recorded to or beyond and the test continued up to themaximum load for all static bending tests. The curves shall be continued to a 6 in. (150 mm) deflection, or until the specimen failsto support a load of 200 lbf (890 N) for primary method specimens, and to a 3 in. (76 mm) defle

46、ction, or until the specimen failsto support a load of 50 lbf (220 N) for secondary method specimens.If required for the purposes of the study, it shall be permittedto continue both loading and the load-deflection measurement beyond the maximum load.NOTE 3One situation where the user may choose to c

47、ontinue the test and the load-deflection measurements beyond the maximum load is if the totalenergy under the flexural load-deflection curve is a parameter of concern. In these instances for primary method specimens, it has been customary tocontinue the test and record the load-deflection curve beyo

48、nd the maximum load to a 6 in. (152 mm) deflection or until the specimen fails to support aload of 200 lbf (890 N). For secondary method specimens, it has been customary to continue loading to a 3 in. (76 mm) deflection, or until the specimenfails to support a load of 50 lbf (222 N).8.6.2 Deflection

49、s of the neutral plane at the center of the length shall be taken with respect to points in the neutral plane abovethe supports. Alternatively, deflection may be taken relative to the tension surface at midspan. However, take care to ensure thatvertical displacements which may occur at the reactions are accounted for.8.6.3 Within the proportional limit, deflection readings shall be taken to 0.001 in. (0.02 mm). with a yoke-mounted displacementmeasurement device capable of at least a Class B rating when evaluated in accordance with Practice E2309.After the propo