1、Designation: D5536 94 (Reapproved 2010)D5536 15Standard 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 re
2、vision, 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.INTRODUCTIONThe everyday use of wood for many different purposes creates a continual need for data on itsmecha
3、nical properties. Small clear specimen testing to characterize a species has historically beenemployed for such property determination, and related methods of test are outlined in Methods D143.Because wood is a biological material, its mechanical properties are subject to considerable naturalvariati
4、on. Thus, the results 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 materia
5、lssuch as outlined in 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
6、, direct probability sampling may be impractical, necessitating the need for alternativesampling procedures.2, 31. Scope1.1 This practice offers two alternative physical sampling procedures: cruciform sampling and random sampling. The choice ofprocedure will depend upon the intended use for the test
7、 results, the resources available for sampling and testing, and theavailability of existing data on the mechanical properties and specific gravity of the species of interest.1.2 A third procedure, double sampling, is included primarily by reference. This procedure applies the results of cruciform or
8、random samples through correlation to improve or update property values.1.3 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 t
9、he applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:4D143 Test Methods for Small Clear Specimens of TimberD2555 Practice for Establishing Clear Wood Strength ValuesE105 Practice for Probability Sampling of Materials3. Significance and Use3.1 This practice
10、 covers procedures of sampling for obtaining small clear wood specimens which, when tested in accordancewith Methods D143 and, in conjunction with full-size product tests, will provide mechanical properties for use in deriving designproperties for lumber, panels, poles, house logs, and other product
11、s.1 This practice is under the jurisdiction of ASTM Committee D07 on Wood and is the direct responsibility of Subcommittee D07.08 on Forests.Current edition approved May 1, 2010Nov. 1, 2015. Published July 2010December 2015. Originally approved in 1994. Last previous edition approved in 20042010 asD
12、5536 94 (2004). 94(2010). DOI: 10.1520/D5536-94R10.10.1520/D5536-15.2 Bendtsen, B. A., Freese, F., and Ethington, R. L., “A Forest Sampling Method for Wood Strength,” Forest Products Journal, Vol 20, No. 11, 1970, pp. 3847.3 Pearson, R. G., and Williams, E. J., “A Review of Methods for Sampling of T
13、imber,” Forest Products Journal, Vol 8, No. 9, 1958, pp. 263268.4 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM websi
14、te.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 possible to adequately depict all changes accurately, ASTM recommends that users consult prior
15、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, West Conshohocken, PA 19428-2959. United States13.2 Data obtained by testing specimens sample
16、d in accordance with these methods also provide information on the influenceon mechanical properties of such factors as density, locality of growth, position in cross section, height in the tree, and moisturecontent.3.3 Cruciform sampling is of principal value when information is desired on the infl
17、uence on mechanical properties of heightin the tree; of age or radial position in the tree; of rate of growth; the change from sapwood to heartwood; the relationships betweenmechanical properties and factors such as specific gravity; and making general comparisons between species for purposes of rat
18、ingor selecting species for specific end-use products. Cruciform sampling does not provide unbiased estimates of mean values,percentile or other descriptive statistics, or a means of associating statistical confidence with estimates of descriptive statistics.3.4 Double sampling is used when it is de
19、sired to improve or update existing estimates of mechanical property values that arethe basis for establishing allowable design stresses for stress-graded lumber, plywood, poles and piling, and other wood products.The method involves predicting one property by carefully observing a well-correlated a
20、uxiliary property that is presumably easieror cheaper to measure. A sample estimate of the auxiliary property is obtained with a high degree of precision by representativelysampling the population. A smaller independent sample or a subsample of the large sample is used to establish a relationshipbet
21、ween the auxiliary property and the property for which an estimate is desired.As applied to sampling a forest, double samplinghas employed specific gravity to predict mechanical properties. The double-sampling method provides unbiased estimates of meanmechanical property values and an approximation
22、method for estimating percentile values. Statistical confidence may be associatedwith the estimates of the means but not the percentile values.3.5 Random sampling is used when probability estimates of descriptive statistics and property distributional characteristics aredesired as the basis for esta
23、blishing allowable design stresses for lumber and other stress-rated products. It is applicable when datafor a species do not exist or when existing estimates are believed no longer applicable because of a changing forest character.Random sampling provides better probability estimates than double sa
24、mpling and is less expensive and quicker if sampling andtesting must be completed to establish mechanical property-specific gravity regressions for the double-sampling method.4. Authentic Identification4.1 The material shall be from trees selected in the forest by one qualified to identify the speci
25、es and to select the trees. Wherenecessary, herbarium samples such as leaves, fruit, twigs, and bark shall be obtained to ensure positive identification.5. Cruciform SamplingPrimary Method5.1 The standard methods for preparing small clear specimens of timber, primary method, provide for cutting the
26、log sections(divided into and identified as bolts) systematically into sticks of nominal 212 by 212 in. (63 by 63 mm) in cross section, that arelater surfaced to provide the test specimens 2 by 2 in. (50(52 by 5052 mm) in cross section, on which the system is based. Thesemethods have served as a bas
27、is for the evaluation of the various mechanical and related physical properties of the clear wood ofdifferent species of wood. These methods have been extensively used, and a large amount of data based on them have beenobtained and published.5.1.1 The 2 by 2-in. (50(52 by 50-mm)52-mm) test specimen
28、has the advantage that it embraces a number of growth rings, isless influenced by earlywood and latewood differences than smaller specimens, and is large enough to represent a considerableproportion of the material.5.1.2 The choice of specimen size may be influenced by the objectives of sampling and
29、 by the rate of growth of the material.Radial property gradients are primarily influenced by age, and large specimens that encompass several rings may mask the ageinfluence. Height gradients must be evaluated by specimens from the same annual ring because of age influence. Thus, smallspecimens are p
30、referred for measuring both radial and height gradients. When the purpose of sampling is to estimate clear woodproperties, large specimens that include a number of annual rings are preferred. Even with 2 by 2-in. (50(52 by 50-mm)52-mm)specimens, fast rates of growth will result in few rings per spec
31、imen. Regardless of the purpose of sampling, the analysis andreporting of data may require careful consideration of the character of the specimen.5.2 Selection of Number of TreesFor each species to be tested, select the number and the character of the trees to accomplishthe purpose of the sampling.
32、For traditional mechanical property data base development, a minimum of five trees have usually beenselected that have been judged “representative” of the trees harvested of the species. Note that if unbiased estimates and statisticalconfidence statements are required, other methods are needed (Sect
33、ion 3).5.3 Selection and Number of BoltsThe material of each species selected for test shall be representative of the clear,straight-grained wood in the merchantable bole of the tree. A traditional method of selection is shown in Appendix X2. Note thatthe sampling permits varying the intensity of sa
34、mpling by tree (in accordance with Appendix X2A2) if the resulting data willsupport the anticipated analysis. X2.1 illustrates merchantable section and bolt labeling.5.4 Substitution of Flitches for Bolts:5.4.1 In cases where the logs or bolts are over 60 in. (1.5 m) in diameter, a single flitch 6 i
35、n. (150 mm)(15 cm) in thickness,taken through the pith representing the full diameter of the log, may be substituted, in the same length, for the full log or boltspecified in 5.3.D5536 1525.4.2 Where orientation of test specimen to geographic features is considered critical, flitch shall maintain th
36、e coordinatesregarded as important in the specimen of 5.9.5.5 Selection for Site RepresentationInferences in analysis that relate to geographic distribution or site-specific features mustbe anticipated in selecting both the sample numbers and sources. The number of trees shall conform to 5.2 and 5.3
37、. If the analysisrequires statistical inferences, random sampling (Section 7) is one method.5.6 Field Marking:5.6.1 Field marking procedures shall ensure identification of trees, bolts, and shipment. Appendix X2 provides a traditionalmethod.5.6.2 If the orientation of test specimens to geographical
38、or bolt features is critical, maintenance of cardinal point orientationis recommended.5.7 Field Descriptions:5.7.1 Complete field notes describing the material shall be fully and carefully made by the collector. These notes shall besufficient to supply documentation similar to that in Table X1.1, wi
39、th actual content chosen as appropriate for the objectives of thestudy.5.7.2 Photographs of the standing trees selected should be taken when practicable.5.8 Preparation for ShipmentMaintenance of moisture content of the material and of all labeling documentation is arequirement. Paragraph X2.3 provi
40、des traditional guidelines.5.9 Sawing and Marking of Bolts and Test SticksSections of logs (consisting of two bolts) shall be marked and sawn into 212by 212-in. (60(63 by 60-mm)63-mm) sticks. Marking of bolts and sticks shall maintain continuity to the tree, and shipment.Consistency with 5.6 shall b
41、e maintained. Paragraphs A2.1Sections X2.1through A2.4X2.4 document the traditional procedures.5.10 Matching for Tests of Dry Material:5.10.1 If one purpose of sampling is to provide comparison of green and dry properties, provisions may be made for matchingof specimens within the tree. The traditio
42、nal approach is as follows:5.10.2 The collection of the material (Section 5) has been arranged to provide for tests of both green and dry specimens thatare closely matched by selection from adjacent parts of the same tree. The 8-ft (2.4-m) long sections, after being marked inaccordance with 5.9, sha
43、ll be sawn and marked in 212 by 212-in. (60(63 by 60-mm)63-mm) by 8-ft sticks. Each 212 by 212-in. by8-ft stick shall then be cut into two 4-ft (1.2-m) pieces, making sure that each part carries the proper designation and bolt letter.5.10.3 Some of the 212 by 212-in. by 4-ft (60(63 by 60-mm63-mm by
44、1.2-m) sticks from each 8-ft (2.4-m) section are to providespecimens to be tested green (unseasoned) and the remaining ones are to be dried and tested. To afford matching, the 4-ft sticksof one bolt shall be interchanged with the 4-ft sticks of the next adjacent bolt from the same tree to form two c
45、omposite bolts, eachbeing complete and being made of equal portions of the adjacent 4-ft bolts. The sticks from one of these composite bolts shall betested green and those from the other shall be tested after drying. Thus, the sticks of each composite bolt shall be regarded as ifthey were from the s
46、ame bolt. Paragraph X2.5 illustrates a method of forming composite bolts.5.10.4 The traditional procedure provides for end-to-end matching (end matching) of sticks to be tested dry with those to betested green, which is to be preferred when practicable. If, because of the nature of the material, end
47、 matching is not practicable,side matching may be used.6. Cruciform SamplingSecondary Method6.1 The cruciform secondary method is intended for use in evaluating the properties of wood only when relatively small trees,generally less than 12 in. (300 mm) in diameter, (30 cm) in diameter when measured
48、approximately 412 -ft (1.37-m), diameterbreast height, are available to provide the test specimens and only when 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 cannot reasonably beo
49、btained. Whenever possible, the procedure for the primary method shall be used regardless of the size of trees. Since theprocedure for the secondary method for many features, such as in selection and care of material, is identical with the primarymethod, the secondary method presented herewith are referenced to the primary method, and procedure is given only where itdiffers therefrom. For convenience the section numbers in the secondary method corresponds in the last two digits with thenumbering of the primary method. Thus, Section 6 for the secondary method c
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