ASTM E855-21

Standard Test Methods for Bend Testing of Metallic Flat Materials for Spring Applications Involving Static Loading

SIGNIFICANCE AND USE
4.1 Measurements of bending proof strength, offset yield strength in bending, and modulus of elasticity in bending should be made for materials whose principal stressing mode is bending. For many materials, the tensile and compressive moduli are somewhat different. Since the modulus of elasticity in bending is a combination of the tensile and compressive moduli, it is often different from each of them.  
4.2 Precise measurements of the modulus of elasticity in bending offset yield strength in bending, and bending proof strength require due regard for numerous variables that can affect their determination. These include (1) material characteristics such as specimen orientation with respect to the rolling direction, grain size, residual stresses, previous strain history, dimensions and specimen preparation, orientation of deformed grains relative to the direction of the normal stress; and (2) test conditions, such as temperature, temperature variations, condition of the test equipment, and adherence to the test procedure.  
4.3 Fundamental Assumptions:  
4.3.1 The test section of the specimen is subjected to uniform bending moment, which produces a uniform strain at the outer fiber throughout the gauge length of the specimen (applies to Test Method C only).  
4.3.2 The neutral axis is located at the centerline of the thickness of the test specimen.  
4.3.3 Transverse cross sections of the beam remain plane and normal to the longitudinal fiber of the beam during bending.  
4.3.4 The effect of shear stresses is negligible.
SCOPE
1.1 This standard describes three test methods2 for determining the modulus of elasticity in bending, the bending proof strength, and the offset yield strength in bending of metallic strips or sheets intended for the use in flat springs:  
1.1.1 Test Method A—a cantilever beam test,  
1.1.2 Test Method B—a three-point beam test (that is, a beam resting on two supports and centrally loaded), and  
1.1.3 Test Method C—a four-point beam test (that is, a beam resting on two supports and loaded at two points equally spaced from each support).  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Jan-2021
• ICS: 21.160 - Springs
• Technical Committee: E28 - Mechanical Testing
• Drafting Committee: E28.02 - Ductility and Formability

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E855 − 21
Standard Test Methods for
Bend Testing of Metallic Flat Materials for Spring
1
Applications Involving Static Loading
This standard is issued under the fixed designation E855; 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.
3
1. Scope 2.2 ASTM Standards:
E4 Practices for Force Verification of Testing Machines
2
1.1 This standard describes three test methods for deter-
E6 Terminology Relating to Methods of Mechanical Testing
mining the modulus of elasticity in bending, the bending proof
E177 Practice for Use of the Terms Precision and Bias in
strength, and the offset yield strength in bending of metallic
ASTM Test Methods
strips or sheets intended for the use in flat springs:
E691 Practice for Conducting an Interlaboratory Study to
1.1.1 Test Method A—a cantilever beam test,
Determine the Precision of a Test Method
1.1.2 Test Method B—a three-point beam test (that is, a
beam resting on two supports and centrally loaded), and 3. Terminology
1.1.3 Test Method C—a four-point beam test (that is, a beam
3.1 Definitions of terms common to mechanical testing:
resting on two supports and loaded at two points equally
3.1.1 The terms bend test, chord modulus, gauge length,
spaced from each support).
modulus of elasticity, proportional limit, springback, stress-
strain curve, tangent modulus, testing machine, yield strength,
1.2 The values stated in inch-pound units are to be regarded
and Young’s modulus are used as defined in Terminology E6.
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
3.2 Definitions of Terms Specific to This Standard:
and are not considered standard. 3.2.1 In addition to the terms in Terminology E6, the
following descriptions of terms apply in connection with these
1.3 This standard does not purport to address all of the
test methods for determining bend properties:
safety concerns, if any, associated with its use. It is the
−2
3.2.2 bending stress at the outer fiber, σ [FL ]—the nomi-
b
responsibility of the user of this standard to establish appro-
nalstressintheouterfiberofabeamresultingfromapplication
priate safety, health, and environmental practices and deter-
of a bending moment.
mine the applicability of regulatory limitations prior to use.
−2
3.2.3 elastic limit in bending [FL ]—the greatest bending
1.4 This international standard was developed in accor-
stress that a material is capable of sustaining without perma-
dance with internationally recognized principles on standard-
nent strain remaining after complete release of the bending
ization established in the Decision on Principles for the
moment.
Development of International Standards, Guides and Recom-
−2
3.2.4 modulus of elasticity in bending, E [FL ]—the ratio
mendations issued by the World Trade Organization Technical
b
of bending stress at the outer fiber to corresponding strain
Barriers to Trade (TBT) Committee.
below the elastic limit in bending.
2. Referenced Documents
3.2.5 span length, L [L]—the distance between supports.
−2
3.2.6 bending proof strength, σ [FL ]—the nominal bend-
2.1 The following documents of the issue in effect on date
p
ing stress at the outer fiber of a beam that results in a specific
of use of these test methods form a part of these test methods
permanent strain in the outer fibers upon unloading.
to the extent referenced herein:
−2
3.2.7 cyclic bending yield strength [FL ]—the maximum
nominalstressinuniformcyclicbendingresultingfromagiven
plastic deformation in the outer fibers of a beam.
1
These test methods are under the jurisdiction of ASTM Committee E28 on
Mechanical Testing and are the direct responsibility of Subcommittee E28.02 on
Ductility and Formability.
Current edition approved Feb. 1, 2021. Published March 2021. Originally
3
approvedin1981.Lastpreviouseditionapprovedin2013asE855 – 08(2013).DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/E0855-21. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
2
Method D, which appeared in the last previous edition, was dropped because of Standards volume information, refer to the standard’s Document Summary page on
the unavailability of commercial testing equipment. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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...

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. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E855 − 08 (Reapproved 2013) E855 − 21
Standard Test Methods for
Bend Testing of Metallic Flat Materials for Spring
1
Applications Involving Static Loading
This standard is issued under the fixed designation E855; 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.
1. Scope
2
1.1 This standard describes three test methods for determining the modulus of elasticity in bending bending, the bending proof
strength, and the bending strength offset yield strength in bending of metallic strips or sheets intended for the use in flat springs:
1.1.1 Test Method A—a cantilever beam,beam test,
1.1.2 Test Method B—a three-point loaded beam test (that is, a beam resting on two supports and centrally loaded), and
1.1.3 Test Method C—a four-point loaded beam test (that is, a beam resting on two supports and loaded at two points equally
spaced from each support).
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 The following documents of the issue in effect on date of use of these test methods form a part of these test methods to the
extent referenced herein:
3
2.2 ASTM Standards:
E4 Practices for Force Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E111 Test Method for Young’s Modulus, Tangent Modulus, and Chord Modulus
1
These test methods are under the jurisdiction of ASTM Committee E28 on Mechanical Testing and are the direct responsibility of Subcommittee E28.02 on Ductility
and Formability.
Current edition approved April 1, 2013Feb. 1, 2021. Published April 2013March 2021. Originally approved in 1981. Last previous edition approved in 20082013 as
E855 – 08.E855 – 08(2013). DOI: 10.1520/E0855-08R13.10.1520/E0855-21.
2
Method D, which appeared in the last previous edition, was dropped because of the unavailability of commercial testing equipment.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E855 − 21
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions of terms common to mechanical testing:
3.1.1 The terms bend test, chord modulus, gauge length, modulus of elasticity, proportional limit, springback, stress-strain curve,
tangent modulus, testing machine, yield strength, and Young’s modulus are used as defined in Terminology E6.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 In addition to the terms in Terminology E6, the following descriptions of terms apply in connection with these test methods
for determining bend properties:
3.1.2 bend properties—those properties of a material that are associated with elastic and inelastic behavior when a bending force
is applied, or that involve the relationship between bending stress and strain.
− −22
3.2.2 bending stress at the outer fiber, (FLσ [FL )—]—the nominal stress in the outer fibersfiber of a beam resulting from
b
application of a bending load.moment.
− −22
3.2.3 elastic limit in bending (FL[FL )—]—the greatest bending stress that a material is capable of sustaining without
permanent strain remaining a
...