ASTM D6874-03

Standard Test Methods for Nondestructive Evaluation of Wood-Based Flexural Members Using Transverse Vibration

SIGNIFICANCE AND USE
The dynamic modulus of elasticity provided by these test methods is a fundamental property for the configuration tested. This value can be related to static and other dynamic moduli of elasticity as measured on the same configuration.
5.1.1 The rapidity and ease of application of these test methods facilitate its use as a substitute for static measurements.
5.1.2 Dynamic modulus of elasticity is often used for surveys, for segregation of lumber for test purposes, and to provide indication of environmental or processing effect.
The modulus of elasticity, whether measured statically or dynamically, is often a useful predictor variable to suggest or explain property relationships.
SCOPE
1.1 These test methods cover the determination of the flexural stiffness and modulus of elasticity properties of wood-based materials by nondestructive testing using transverse vibration in the vertical direction.
1.2 The test methods are limited to specimens having solid, rectangular sections.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Apr-2003
• ICS: 19.100 - Non-destructive testing
• Technical Committee: D07 - Wood
• Drafting Committee: D07.01 - Fundamental Test Methods and Properties

Relations

• Replaced By: ASTM D6874-03(2009)e1 - Standard Test Methods for Nondestructive Evaluation of Wood-Based Flexural Members Using Transverse Vibration
• Effective Date: 01-Dec-2009

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:D6874–03
Standard Test Methods for
Nondestructive Evaluation of Wood-Based Flexural
Members Using Transverse Vibration
This standard is issued under the fixed designation D6874; 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 (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Nondestructive testing methods are used to determine the physical and mechanical properties of
wood-based materials. These test methods help ensure structural performance of products manufac-
turedfromavarietyofwoodspeciesandqualitylevelsofrawmaterials.Thesetestmethodsalsoassist
in evaluating the influence of environmental conditions on product performance.
These test methods for transverse vibration nondestructive testing of wood-based materials adopt
methods used by various testing and research organizations. These test methods will yield results
comparable to traditional methods, permitting standardization of results, interchange and correlation
of data, and establishment of a cumulative body of information on wood species and products of the
world.
1. Scope D4442 Test Methods for Direct Moisture Content Measure-
ment of Wood and Wood-Base Materials
1.1 These test methods cover the determination of the
D4444 Test Method for Laboratory Standardization and
flexural stiffness and modulus of elasticity properties of wood-
Calibration of Hand-Held Moisture Meters
based materials by nondestructive testing using transverse
D4761 Test Methods for Mechanical Properties of Lumber
vibration in the vertical direction.
and Wood-Base Structural Material
1.2 The test methods are limited to specimens having solid,
E4 Practices for Force Verification of Testing Machines
rectangular sections.
E1267 Guide for ASTM Standard Specification Quality
1.3 This standard does not purport to address all of the
Statements
safety concerns, if any, associated with its use. It is the
2.2 Other Standard:
responsibility of the user of this standard to establish appro-
ISO 7626/1 Vibration and Shock-Experimental Determina-
priate safety and health practices and determine the applica-
tion of Mechanical Mobility—Part 1: Basic Definitions
bility of regulatory limitations prior to use.
and Transducers
2. Referenced Documents
3. Terminology
2.1 ASTM Standards:
3.1 Definitions—See Terminology D9 and Test Methods
D9 Terminology Relating to Wood and Wood-Based Prod-
D198.
ucts
3.2 Definitions of Terms Specific to This Standard:
D198 Test Methods of Static Tests of Lumber in Structural
3.2.1 calibration—the determination of the relationship be-
Sizes
tween the response of standardized instrumentation to proper-
D1990 Practice for Establishing Allowable Properties for
ties of reference material, determined by a standard method.
Visually-Graded Dimension Lumber from In-Grade Tests
2 3.2.2 fundamental mode of vibration—the simplest mode of
of Full-Size Specimens
vibration for a simply supported beam is the vertical motion
D2915 Practice for Evaluating Allowable Properties for
2 produced from a slight vertical displacement of the member at
Grades of Structural Lumber
its mid-span. This is termed its fundamental mode of vibration
(Fig. 1) and is the mode to which this standard applies.
These test methods are under the jurisdiction of ASTM Committee D07 on
Wood and is the direct responsibility of Subcommittee D07.01 on FundamentalTest
Methods and Properties. Annual Book of ASTM Standards, Vol 03.01.
Current edition approved April 10, 2003. Published June 2003. DOI: 10.1520/ Discontinued 1996, see 1995 Annual Book of ASTM Standards, Vol 14.02.
D6874-03. Available from American National Standards Institute, 25 W. 43rd St., 4th
Annual Book of ASTM Standards, Vol 04.10. Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6874–03
parallel to the span to provide adequate bearing across the
width of the specimen.
6.2.3 Lateral Support—No lateral support shall be applied.
Specimens unstable in this mode shall not be tested using this
method.
6.2.4 Lengthwise Positioning and Overhang of the
Specimen—The specimen shall be positioned such that an
equal portion of the length overhangs each support. Excessive
overhang may alter results obtained. If basic equation (Eq 1) is
FIG. 1 Transverse Vibration in the Fundamental Mode
used, then the span(s) to length (L) ratio shall exceed 0.98. If
other s/Lratios are used, more exacting analysis and equations
shall be used; see Ref (1).
3.2.3 standardization—the determination of the response of
the instrumentation to a reference material.
NOTE 1—Intestingofdimensionlumber,anoverhangofapproximately
3.2.4 transverse vibration—the oscillation of a simply sup-
1in.oneachendisoftenused.Theamountofoverhangmaybeinfluenced
ported bending member that results from an initial displace-
by the convenience of handling and positioning but should be kept
uniform from specimen to specimen.
ment of the member at its mid-span or other means of exciting
its fundamental mode of vibration.
6.3 Excitation System—The member shall be excited so as
toproduceaverticaloscillationinareproduciblemannerinthe
4. Summary of Test Method
fundamental mode. The method of analysis is based on
4.1 The structural member is deflected at its mid-span and oscillation in this mode (Fig. 1).
allowed to oscillate in a transverse bending mode. Observa- 6.3.1 Manual Method—A manual deflection of the speci-
tions of frequency of oscillation are used to calculate modulus men will provide sufficient impetus for oscillation for many
of elasticity. products. The deflection shall be vertical with an effort to
exclude lateral components; neither excessive impact nor
5. Significance and Use prolonged contact with the specimen are recommended.
5.1 The dynamic modulus of elasticity provided by these
NOTE 2—For example, a manual tap on a 16-foot 2 by 12, supported
test methods is a fundamental property for the configuration flat-wisehavingaMOEof2.0 310 psiwillresultinaverticaloscillation
of between 3 and 4 Hz.
tested. This value can be related to static and other dynamic
moduli of elasticity as measured on the same configuration.
6.3.2 Mechanical Methods—The guidelines of 6.3.1 shall
5.1.1 The rapidity and ease of application of these test
be duplicated with mechanical systems. Specimens with very
methods facilitate its use as a substitute for static measure-
high stiffness require mechanical excitation by a high force or
ments.
carefully regulated impact/release.
5.1.2 Dynamic modulus of elasticity is often used for
6.4 Measurement System—Measurement of the frequency
surveys, for segregation of lumber for test purposes, and to
of oscillation shall be obtained by either a force or displace-
provide indication of environmental or processing effect.
ment measuring device calibrated to ensure accuracy in accor-
5.2 The modulus of elasticity, whether measured statically
dance with Practices E4 and ISO 7626/1.
or dynamically, is often a useful predictor variable to suggest
6.4.1 Force Measuring System—Changes in the force in
or explain property relationships.
response to the vibration at one or both of the supports are
methods used to obtain frequency of oscillation.
6. Apparatus
6.4.2 Deflection Measuring System—Measurement of the
6.1 The testing equipment shall consist of three essential mid-span displacement in response to the initial displacement
elements: is an alternative method to determine frequency of oscillation.
6.1.1 A support apparatus, 6.4.3 Measurement of the Fundamental Mode—In these test
6.1.2 An excitation system, and methods, it is critical that only the frequency associated with
6.1.3 A measurement system. the fundamental vertical oscillation mode be used. Use a short
6.2 Support Apparatus—The support shall provide vertical delay before acquiring the data to ensure the data acquired is
support to the ends of the specimen yet permit rotation. only related to the fundamental vertical mode.
6.2.1 Reactions—The specimen shall be supported in a
7. Test Specimen
manner to prevent damage to the specimen at the point of
contact between it and the reaction support.The reactions shall
7.1 Specimens shall be solid and rectangular. Deviations in
be such that change in length of the specimen longitudinal
shape and uniformity in dimension from end-to-end and
movement and rotation of the specimen about the reaction due
side-to-side incidental to sampling, such as wane included in a
to deflection will be unrestricted.
lumber grade description, shall be noted as part of the sample
6.2.2 Reaction Alignment—Provision shall be made at the
or specimen description.
reactionstoallowforinitialtwistinthelengthofthespecimen.
If the bearing surfaces of the specimen at its reaction are not
parallel to the bearing surface of the reactions, the specimen
The boldface numbers in parentheses refer to the list of references at the end of
shall be shimmed or the bearing surfaces rotated about an axis this standard.
D6874–03
7.2 Span to Depth Ratio—The span-to-depth ratio used 8.3.2.1 Thepresentationofresultsshallindicatewhetherthe
shall be greater than 20 unless special precautions are taken to calculations of E are based on the actual, individual piece cross
permit higher frequency measurements. section dimensions at the time of test or on standard (design
base) dimensions.
7.3 Moisture Content—Moisture content of specimens shall
8.3.2.2 Environmental Conditions—Sensitivity of the test
be measured in accordance with Test Methods D4442 or
specimens to changes in the test environment shall be consid-
D4444D4442D4444, or both. Specific reference to the current
eredincalculatingapparentmodulusofelasticityvalues.If,for
moisture status of the specimens shall be made; for example,
equilibrated, recently kiln dried containing gradients, air dried, example, the temperature varies during the test and affects the
properties of the test material, this shall be considered in
packaged specimens of unknown drying history, and so forth.
Use of Test Methods D4444 procedures to identify gradients presentation of test results.Appropriate adjustments for lumber
are included in Practice D1990 and in Ref (2).
caused by drying or surface wetting is recommended. MC
gradients within a piece may affect the dynamic E (see 8.3.2.3 Adjustments to dynamic E values for moisture
content of specimens above 22 % MC shall be documented
X1.1.17).
(see X1.1.21).
8. Procedure
9. Report
8.1 Standardization and Calibration—The testing system
9.1 The report shall be sufficiently complete to permit
shall be standardized and calibrated using standard reference
reproduction of the test, including the calibration process.
materials. The procedures ofAnnexA1 shall be followed. The
Inadequateexplanationofthebasisofthemodulusofelasticity
results of this test method are conditional upon proper stan-
measurement results in data of unknown comparability.
dardization and appropriate choice of calibration method.
9.2 Particular attention shall be given to comprehensive
NOTE 3—It has been a practice to use aluminum bars as well as lumber reporting of the traceability of transducer calibrations to
specimens as standardization materials and, often, also for calibration
nationally acceptable references.
against a standard static test results.
9.3 The report shall contain at least the following elements:
9.3.1 Equipment—Description of the apparatus, including
8.2 Excitation—The procedures of excitation listed under
the manufacturer of the device, the model, and the calibration
Section 6 shall be followed. Repetitions are recommended to
system if incorporated in the manufactured device. If mechani-
reduce the chance of bias caused by improper excitation.
cal excitation is employed, the mechanism shall be described
8.2.1 To quantify measurement uncertainty for precision
along with the method of assuring adequate excitation.
and bias estimates, specific data sets shall be taken during the
9.3.2 Test Setup—Description of the specimen supports, if
test sequence to allow calculation of this contribution to
not reported as part of 9.3.1; the support surfaces; and the
measurement tolerances.
provisions employed for support of twisted or irregular sur-
8.3 Calculation of Modulus of Elasticity:
faces.
8.3.1 Basic Equation—The following formula shall be used
9.3.3 Environment—Describe the temperatures during cali-
tocalculatemodulusofelasticityfromthemeasuredoscillation
bration and data collection and other factors in the operating
in the fundamental mode (Fig. 1):
environment that may affect measurement. Note changes in
2 3
~f ! w~s!
r these factors over the data collection period.
E 5 (1)
tv
K Ig
d 9.3.4 Calibration—Identify whether the E was calculated
using the fundamental formula (Eq 1) or the adjusted formula
where:
(see A1.2.4). If the latter was used, describe the source of the
E = transverse vibration modulus of elasticity, psi (MPa),
tv
factors k and z. A comprehensive description of the materials
s
s = span, in. (mm),
used for standardization and for calibration shall be provided.
w = weight of specimen, lbf (N),
9.3.5 Test Data—Present the test data in the units compa-
f = frequency of oscillation, Hz,
r
rable to those employed in 7.1. The data presentation shall
I = specimen moment of inertia, bh /12,
b = breadth (width), in. (mm), include an estimate of the precision and bias of the data and
h = height, in. (mm), method of estimation.
2 2
g = acceleration due to gravity, 386 in./s (9807 mm/s ),
9.3.6 Data Adjustments—All adjustments made to test data
and
shall be fully explained, including actions taken to meet the
K = constant for free vibration of a simply supported
d reporting requirements of Practice D2915.
beam, 2.47.
10. Precision and Bias
8.3.2 Analysis and Presentation of Results—Analysis of
data collected from samples and the presentations of results 10.1 The precision and bias are dependent upon equipment
shall be consistent with the appropriate methods of Practice used (see Section 6) and the Standardization and Calibration
D2915, Section 4. practices applied.
D6874–03
ANNEX
(Mandatory Information)
A1. STANDARDIZATION AND CALIBRATION
A1.1 Standardization where E is a predicted static modulus of elasticity, k is a
s s
calibration coefficient established by test with the calibrating
A1.1.1 Standardization shall be performed on the dynamic
material and z is a calibration offset factor.
test apparatus to verify t
...