ASTM D143-94

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 143 – 94
Standard Methods of Testing
Small Clear Specimens of Timber
This standard is issued under the fixed designation D 143; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The need to classify wood species by evaluating the physical and mechanical properties of small
clear 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 comparing
variables, the need will undoubtedly continue to exist.
In the preparation of these methods for testing small clear specimens, consideration was given both
to the desirability of adopting methods that would yield results comparable to those already available
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. Forest Service,
the former Forest Products Laboratories of Canada (now Forintek Canada Corp.), and other similar
organizations, the methods naturally conform closely to the methods used by these institutions. These
methods are the outgrowth of a study of both American and European experience and methods. The
general adoption of these methods will tend toward a world-wide unification of results, permitting an
interchange and correlation of data, and establishing the basis for a cumulative body of fundamental
information on the timber species of the world.
Descriptions of some of the strength tests refer to primary methods and secondary methods. Primary
methods provide for specimens of 2 by 2-in. (50 by 50-mm) cross-section. This size of specimen has
been extensively used for the evaluation of various mechanical and physical properties of different
species of wood, and a large number of data based on this primary method have been obtained and
published.
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 large
enough to represent a considerable portion of the sampled material. It is advisable to use primary
method specimens wherever possible. There are circumstances, however, when it is difficult or
impossible 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 the
desirability in certain situations to evaluate a material which is too small to provide a 2 by 2-in.
cross-section, a secondary method which utilizesa1by 1-in. (25 by 25-mm) cross section has been
included. 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 grain. Toughness and tension
parallel 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 necessarily
directly comparable. Guidance on the effect of specimen size on a property being evaluated is beyond
the scope of these methods, and should be sought elsewhere.
Where the application, measurement, or recording of load and deflection can be accomplished using
electronic equipment and computerized apparatus, such devices are encouraged, providing they do not
lower the standard of accuracy and reliability available with basic mechanical equipment.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 143
1. Scope D 5536 Practice for Sampling the Forest Trees for Determi-
nation of Clear Wood Properties
1.1 These methods cover the determination of various
E 4 Practices for Force Verification of Testing Machines
strength and related properties of wood by testing small clear
specimens.
3. Summary of Methods
1.1.1 These methods represent procedures for evaluating the
3.1 The mechanical tests are static bending, compression
different mechanical and physical properties, controlling fac-
parallel to grain, impact bending toughness, compression
tors such as specimen size, moisture content, temperature, and
perpendicular to grain, hardness, shear parallel to grain (Note
rate of loading.
1), cleavage, tension parallel to grain, tension-perpendicular-
1.1.2 Sampling and collection of material is discussed in
to-grain, and nail-withdrawal tests. These tests may be made on
Practice D 5536. Sample data, computation sheets, and cards
both green and air-dry material as specified in these methods.
have been incorporated, which were of assistance to the
In addition, methods for evaluating such physical properties as
investigator in systematizing records.
specific gravity, shrinkage in volume, radial shrinkage, and
1.1.3 The values stated in inch-pound units are to be
tangential shrinkage are presented.
regarded as the standard. The SI values are given in parenthe-
ses and are provided for information only. When a weight is NOTE 1—The test for shearing strength perpendicular to the grain
(sometimes termed “vertical shear”) is not included as one of the principal
prescribed, the basic inch-pound unit of weight (lbf) and the
mechanical tests since in such a test the strength is limited by the shearing
basic SI unit of mass (Kg) are cited.
resistance parallel to the grain.
1.2 The procedures for the various tests appear in the
following order:
4. Significance and Use
Sections
4.1 These methods cover tests on small clear specimens of
Photographs of Specimens 5
wood that are made to provide the following:
Control of Moisture Content and Temperature 6
Record of Heartwood and Sapwood 7
4.1.1 Data for comparing the mechanical properties of
Static Bending 8
various species,
Compression Parallel to Grain 9
4.1.2 Data for the establishment of correct strength func-
Impact Bending 10
Toughness 11
tions, which in conjunction with results of tests of timbers in
Compression Perpendicular to Grain 12
structural sizes (see Methods D 198 and Test Method D 4761),
Hardness 13
Shear Parallel to Grain 14 afford a basis for establishing allowable stresses, and
Cleavage 15
4.1.3 Data to determine the influence on the mechanical
Tension Parallel to Grain 16
properties of such factors as density, locality of growth,
Tension Perpendicular to Grain 17
Nail Withdrawal 18 position in cross section, height of timber in the tree, change of
Specific Gravity and Shrinkage in Volume 19
properties with seasoning or treatment with chemicals, and
Radial and Tangential Shrinkage 20
change from sapwood to heartwood.
Moisture Determination 21
Permissible Variations 22
5. Photographs of Specimens
Calibration 23
5.1 Four of the static bending specimens from each species
1.3 This standard does not purport to address all of the
shall be selected for photographing, as follows: two average
safety concerns, if any, associated with its use. It is the
growth, one fast growth, and one slow growth. These speci-
responsibility of the user of this standard to establish appro-
mens shall be photographed in cross section and on the radial
priate safety and health practices and determine the applica-
and tangential surfaces. Fig. 1 is a typical photograph of a cross
bility of regulatory limitations prior to use.
section of 2 by 2-in. (50 by 50-mm) test specimens, and Fig. 2
2. Referenced Documents
is the tangential surface of such specimens.
2.1 ASTM Standards:
6. Control of Moisture Content and Temperature
D 198 Methods for Static Tests of Timbers in Structural
6.1 In recognition of the significant influence of temperature
Sizes
and moisture content on the strength of wood, it is highly
D 2395 Test Methods for Specific Gravity of Wood and
desirable that these factors be controlled to ensure comparable
Wood-Base Materials
test results.
D 3043 Methods of Testing Structural Panels in Flexure
6.2 Control of Moisture Content—Specimens for the test in
D 3500 Test Method for Structural Panels in Tension
the air-dry condition shall be dried to approximately constant
D 4442 Test Methods for Direct Moisture Content Measure-
weight before test. Should any changes in moisture content
ment of Wood and Wood-Base Materials
occur during final preparation of specimens, the specimens
D 4761 Test Method for Mechanical Properties of Lumber
shall be reconditioned to constant weight before test. Tests
and Wood-Base Structural Material
shall be carried out in such manner that large changes in
moisture content will not occur. To prevent such changes, it is
These methods are under the jurisdiction of ASTM Committee D-7 on Wood
desirable that the testing room and rooms for preparation of test
and are the direct responsibility of Subcommittee D07.01 on Fundamental Test
Methods and Properties. specimens have some means of humidity control.
Current edition approved May 15, 1994. Published July 1994. Originally
published as D 143 – 22 T. Last previous edition D 143 – 83.
2 3
Annual Book of ASTM Standards, Vol 04.10. Annual Book of ASTM Standards, Vol 03.01.
D 143
FIG. 1 Cross Sections of Bending Specimens Showing Different Rates of Growth of Longleaf Pine (2 by 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)
Specimens
6.3 Control of Temperature—Temperature and relative hu- secondary method specimens. The actual height and width at
midity together affect wood strength by fixing its equilibrium the center and the length shall be measured (see 22.2).
moisture content. The mechanical properties of wood are also
8.2 Loading Span and Supports—Use center loading and a
affected by temperature alone. When tested, the specimens
span length of 28 in. (710 mm) for the primary method and 14
shall be at a temperature of 68 + 6°F (20 + 3°C). The tempera-
in. (360 mm) for the secondary method. These spans were
ture at the time of test shall in all instances be recorded as a
established in order to maintain a minimum span-to-depth ratio
specific part of the test record.
of 14. Both supporting knife edges shall be provided with
bearing plates and rollers of such thickness that the distance
7. Record of Heartwood and Sapwood
from the point of support to the central plane is not greater than
7.1 Proportion of Sapwood—The estimated proportion of
the depth of the specimen (Fig. 3). The knife edges shall be
sapwood present should be recorded for each test specimen.
adjustable laterally to permit adjustment for slight twist in the
specimen (Note 2).
8. Static Bending
NOTE 2—Details of laterally adjustable supports may be found in Fig.
8.1 Size of Specimens—The static bending tests shall be
1 of Methods D 3043.
made on 2 by 2 by 30 in. (50 by 50 by 760 mm) primary
method specimens or 1 by 1 by 16 in. (25 by 25 by 410 mm) 8.3 Bearing Block—A bearing block of the form and size of
D 143
FIG. 3 Static Bending Test Assembly Showing Method of Load Application, Specimen Supported on Rollers and Laterally Adjustable
Knife Edges, and Method of Measuring Deflection at Neutral Axis by Means of Yoke and Dial Attachment (Adjustable scale mounted on
loading head is used to measure increments of deformation beyond the dial capacity.)
that shown in Fig. 4 shall be used for applying the load for crosshead of 0.10 in. (2.5 mm)/min (see 22.3), for primary
primary method specimens. A block having a radius of 1 ⁄2 in. method specimens, and at a rate of 0.05 in. (1.3 mm)/min for
(38 mm) for a chord length of not less than 2 in. (50 mm) shall
secondary method specimens.
be used for secondary method specimens.
8.6 Load-Deflection Curves:
8.4 Placement of Growth Rings—The specimen shall be
8.6.1 Load-deflection curves shall be recorded to or beyond
placed so that the load will be applied through the bearing
the maximum load for all static bending tests. The curves shall
block to the tangential surface nearest the pith.
be continued to a 6 in. (150 mm) deflection, or until the
8.5 Speed of Testing—The load shall be applied continu-
specimen fails to support a load of 200 lbf (890 N) for primary
ously throughout the test at a rate of motion of the movable
method specimens and to a 3 in. (76 mm) deflection or until the
specimen fails to support a load of 50 lbf (220 N) for secondary
method specimens.
8.6.2 Deflections of the neutral plane at the center of the
length shall be taken with respect to points in the neutral plane
above the supports. Alternatively, deflection may be taken
relative to the tension surface at midspan. However, take care
to ensure that vertical 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). After the proportional limit is
reached, 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, normally approxi-
mately 1 in. (25 mm). Where deflections beyond 1 in. are
encountered, the deflections may be measured by means of the
scale mounted on the loading head (Fig. 3) and a wire mounted
at the neutral axis of the specimen of the side opposite the
yoke. Deflections are read to the nearest 0.01 in. (0.2 mm) at
0.10 in. (2.5 mm) intervals and also after abrupt changes in
load.
8.6.4 The load and deflection of first failure, the maximum
load, and points of sudden change shall be read and shown on
FIG. 4 Details of Bearing Block for Static Bending Tests the curve sheet (Note 3) although they may not occur at one of
D 143
the regular load or deflection increments. weighed immediately before test, and after the test a moisture
section approximately 1 in. (25 mm) in length shall be cut from
NOTE 3—See Fig. 5 for a sample static bending data sheet form.
FIG. 5 Sample Data Sheet for Static Bending Test
8.7 Description of Static Bending Failures—Static bending the specimen near the point of failure. (see 21.1 and 22.1).
(flexural) failures shall be classified in accordance with the
9. Compression Parallel to Grain
appearance of the fractured surface and the manner in which
the failure develops (Fig. 6). The fractured surfaces may b
...