1、Designation: D5536 17Standard Practice forSampling Forest Trees for Determination of Clear WoodProperties1This standard is issued under the fixed designation D5536; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe everyday use of wood for many different purposes creates a continual need for data on itsmechanical properties. Small cl
3、ear specimen testing to characterize a species has historically beenemployed for such property determination, and related methods of test are outlined in Test MethodsD143.Because wood is a biological material, its mechanical properties are subject to considerable naturalvariation. Thus, the results
4、of tests to evaluate the mechanical properties of a species depend to a greatextent upon how the forest trees are sampled for test material. Ideally, if the results of mechanicalproperty evaluations are to be representative of the forest sampled, probability sampling of materialssuch as outlined in
5、Practice E105 must be used. However, true probability sampling of the forest treesfor determination of mechanical properties can be extremely complex and expensive because of thebroad geographic range and topographic conditions under which a tree species grows. In someinstances, direct probability s
6、ampling may be impractical, necessitating the need for alternativesampling procedures.2,31. Scope1.1 This practice offers two alternative physical samplingprocedures: cruciform sampling and random sampling. Thechoice of procedure will depend upon the intended use for thetest results, the resources a
7、vailable for sampling and testing,and the availability of existing data on the mechanical proper-ties and specific gravity of the species of interest.1.2 A third procedure, double sampling, is included primar-ily by reference. This procedure applies the results of cruciformor random samples through
8、correlation to improve or updateproperty values.1.3 UnitsThe values stated in inch-pound units are to beregarded as standard. The values given in parentheses aremathematical conversions to SI units that are provided forinformation only and are not considered standard.1.4 This standard does not purpo
9、rt to address all of thesafety concerns, 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.1.5 This international standard
10、was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Refere
11、nced Documents2.1 ASTM Standards:4D9 Terminology Relating to Wood and Wood-Based Prod-uctsD143 Test Methods for Small Clear Specimens of TimberD1038 Terminology Relating to Veneer and PlywoodD2555 Practice for Establishing Clear Wood Strength ValuesE105 Practice for Probability Sampling of Materials
12、3. Terminology3.1 Definitions:1This practice is under the jurisdiction of ASTM Committee D07 on Wood andis the direct responsibility of Subcommittee D07.08 on Forests.Current edition approved Aug. 1, 2017. Published September 2017. Originallyapproved in 1994. Last previous edition approved in 2015 a
13、s D5536 15. DOI:10.1520/D5536-17.2Bendtsen, B. A., Freese, F., and Ethington, R. L., “A Forest Sampling Methodfor Wood Strength,” Forest Products Journal, Vol 20, No. 11, 1970, pp. 3847.3Pearson, R. G., and Williams, E. J., “A Review of Methods for Sampling ofTimber,” Forest Products Journal, Vol 8,
14、 No. 9, 1958, pp. 263268.4For referenced 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.Copyright ASTM International, 100 Ba
15、rr Harbor Drive, PO 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 Recom
16、mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.1.1 For definitions of terms used in this standard, refer toTerminologies D9 and D1038.4. Significance and Use4.1 This practice covers procedures of sampling for obtain-ing small, clear wood specimens wh
17、ich, when tested inaccordance with Test Methods D143 and, in conjunction withfull-size product tests, will provide mechanical properties foruse in deriving design properties for lumber, panels, poles,house logs, and other products.4.2 Data obtained by testing specimens sampled in accor-dance with th
18、ese methods also provide information on theinfluence on mechanical properties of such factors as density,locality of growth, position in cross section, height in the tree,and moisture content.4.3 Cruciform sampling is of principal value when informa-tion is desired on the influence on mechanical pro
19、perties ofheight in the tree; of age or radial position in the tree; of rateof growth; the change from sapwood to heartwood; therelationships between mechanical properties and factors suchas specific gravity; and making general comparisons betweenspecies for purposes of rating or selecting species f
20、or specificend-use products. Cruciform sampling does not provide unbi-ased estimates of mean values, percentile or other descriptivestatistics, or a means of associating statistical confidence withestimates of descriptive statistics.4.4 Double sampling is used when it is desired to improveor update
21、existing estimates of mechanical property values thatare the basis for establishing allowable design stresses forstress-graded lumber, plywood, poles and piling, and otherwood products. The method involves predicting one propertyby carefully observing a well-correlated auxiliary property thatis pres
22、umably easier or cheaper to measure. A sample estimateof the auxiliary property is obtained with a high degree ofprecision by representatively sampling the population. Asmaller independent sample or a subsample of the large sampleis used to establish a relationship between the auxiliaryproperty and
23、the property for which an estimate is desired. Asapplied to sampling a forest, double sampling has employedspecific gravity to predict mechanical properties. The double-sampling method provides unbiased estimates of mean me-chanical property values and an approximation method forestimating percentil
24、e values. Statistical confidence may beassociated with the estimates of the means but not thepercentile values.4.5 Random sampling is used when probability estimates ofdescriptive statistics and property distributional characteristicsare desired as the basis for establishing allowable designstresses
25、 for lumber and other stress-rated products. It isapplicable when data for a species do not exist or when existingestimates are believed no longer applicable because of achanging forest character. Random sampling provides betterprobability estimates than double sampling and is less expen-sive and qu
26、icker if sampling and testing must be completed toestablish mechanical property-specific gravity regressions forthe double-sampling method.5. Authentic Identification5.1 The material shall be from trees selected in the forest byone qualified to identify the species and to select the trees.Where nece
27、ssary, herbarium samples such as leaves, fruit,twigs, and bark shall be obtained to ensure positive identifica-tion.6. Cruciform Sampling Primary Method6.1 The standard methods for preparing small, clear speci-mens of timber, primary method, provide for cutting the logsections (divided into and iden
28、tified as bolts) systematicallyinto sticks of nominal 212 by 212 in. (64 by 64 mm) in crosssection, that are later surfaced to provide the test specimens 2by 2 in. (51 by 51 mm) in cross section, on which the systemis based. These methods have served as a basis for theevaluation of the various mecha
29、nical and related physicalproperties of the clear wood of different species of wood. Thesemethods have been extensively used, and a large amount ofdata based on them have been obtained and published.6.1.1 The 2 by 2 in. (51 by 51 mm) test specimen has theadvantage that it embraces a number of growth
30、 rings, is lessinfluenced by earlywood and latewood differences than smallerspecimens, and is large enough to represent a considerableproportion of the material.6.1.2 The choice of specimen size may be influenced by theobjectives of sampling and by the rate of growth of thematerial. Radial property
31、gradients are primarily influenced byage, and large specimens that encompass several rings maymask the age influence. Height gradients must be evaluated byspecimens from the same annual ring because of age influence.Thus, small specimens are preferred for measuring both radialand height gradients. W
32、hen the purpose of sampling is toestimate clear wood properties, large specimens that include anumber of annual rings are preferred. Even with 2 by 2 in. (51by 51 mm) specimens, fast rates of growth will result in fewrings per specimen. Regardless of the purpose of sampling, theanalysis and reportin
33、g of data may require careful consider-ation of the character of the specimen.6.2 Selection of Number of TreesFor each species to betested, select the number and the character of the trees toaccomplish the purpose of the sampling. For traditional me-chanical property data base development, a minimum
34、 of fivetrees have usually been selected that have been judged “rep-resentative” of the trees harvested of the species. Note that ifunbiased estimates and statistical confidence statements arerequired, other methods are needed (Section 4).6.3 Selection and Number of BoltsThe material of eachspecies
35、selected for test shall be representative of the clear,straight-grained wood in the merchantable bole of the tree. Atraditional method of selection is shown in Appendix X2. Notethat the sampling permits varying the intensity of sampling bytree (in accordance with Appendix X2) if the resulting data w
36、illsupport the anticipated analysis. X2.1 illustrates merchantablesection and bolt labeling.6.4 Substitution of Flitches for Bolts:6.4.1 In cases where the logs or bolts are over 60 in.(1.52 m) in diameter, a single flitch 6 in. (15 cm) in thickness,D5536 172taken through the pith representing the f
37、ull diameter of the log,may be substituted, in the same length, for the full log or boltspecified in 6.3.6.4.2 Where orientation of test specimen to geographicfeatures is considered critical, flitch shall maintain the coordi-nates regarded as important in the specimen of 6.9.6.5 Selection for Site R
38、epresentationInferences in analysisthat relate to geographic distribution or site-specific featuresmust be anticipated in selecting both the sample numbers andsources. The number of trees shall conform to 6.2 and 6.3.Ifthe analysis requires statistical inferences, random sampling(Section 8) is one m
39、ethod.6.6 Field Marking:6.6.1 Field marking procedures shall ensure identification oftrees, bolts, and shipment. Appendix X2 provides a traditionalmethod.6.6.2 If the orientation of test specimens to geographical orbolt features is critical, maintenance of cardinal point orienta-tion is recommended.
40、6.7 Field Descriptions:6.7.1 Complete field notes describing the material shall befully and carefully made by the collector. These notes shall besufficient to supply documentation similar to that in TableX1.1, with actual content chosen as appropriate for theobjectives of the study.6.7.2 Photographs
41、 of the standing trees selected should betaken when practicable.6.8 Preparation for ShipmentMaintenance of moisturecontent of the material and of all labeling documentation is arequirement. Paragraph X2.3 provides traditional guidelines.6.9 Sawing and Marking of Bolts and Test SticksSectionsof logs
42、(consisting of two bolts) shall be marked and sawn into212 by 212 in. (64 by 64 mm) sticks. Marking of bolts andsticks shall maintain continuity to the tree, and shipment.Consistency with 6.6 shall be maintained. X2.1 X2.4document the traditional procedures.6.10 Matching for Tests of Dry Material:6.
43、10.1 If one purpose of sampling is to provide comparisonof green and dry properties, provisions may be made formatching of specimens within the tree. The traditional ap-proach is as follows:6.10.2 The collection of the material (Section 6) has beenarranged to provide for tests of both green and dry
44、specimensthat are closely matched by selection from adjacent parts of thesame tree. The 8 ft (2.44 m) long sections, after being markedin accordance with 6.9, shall be sawn and marked in 212 by212 in. by 8 ft (64 by 64 mm by 2.44 m) sticks. Each 212 by212 in. by 8 ft (64 by 64 mm by 2.44 m) stick sh
45、all then be cutinto two 4 ft (1.22 m) pieces, making sure that each part carriesthe proper designation and bolt letter.6.10.3 Some of the 212 by 212 in. by 4 ft (64 by 64 mm by1.22 m) sticks from each 8 ft (2.44 m) section are to providespecimens to be tested green (unseasoned) and the remainingones
46、 are to be dried and tested. To afford matching, the 4 ft(1.22 m) sticks of one bolt shall be interchanged with the 4 ft(1.22 m) sticks of the next adjacent bolt from the same tree toform two composite bolts, each being complete and beingmade of equal portions of the adjacent 4 ft (1.22 m) bolts. Th
47、esticks from one of these composite bolts shall be tested greenand those from the other shall be tested after drying. Thus, thesticks of each composite bolt shall be regarded as if they werefrom the same bolt. X2.5 illustrates a method of formingcomposite bolts.6.10.4 The traditional procedure provi
48、des for end-to-endmatching (end matching) of sticks to be tested dry with thoseto be tested green, which is to be preferred when practicable. If,because of the nature of the material, end matching is notpracticable, side matching may be used.7. Cruciform Sampling Secondary Method7.1 The cruciform se
49、condary method is intended for use inevaluating the properties of wood only when relatively smalltrees, generally less than 12 in. (30 cm) in diameter whenmeasured approximately 412 ft (1.37 m), diameter breastheight, are available to provide the test specimens and onlywhen such trees because of crook, cross grain, knots, or otherdefects are of such quality that the longer clear, straight-grained specimens required by the primary method cannotreasonably be obtained. Whenever possible, the procedure forthe primary method shall be used regardless of the size o
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