ASTM D4812-19e1
(Test Method)Standard Test Method for Unnotched Cantilever Beam Impact Resistance of Plastics
Standard Test Method for Unnotched Cantilever Beam Impact Resistance of Plastics
SIGNIFICANCE AND USE
5.1 The pendulum-impact test indicates the energy to break standard test specimens of specified size under stipulated conditions of specimen mounting and pendulum velocity at impact.
5.2 The energy lost by the pendulum during the breakage of the specimen is the sum of the energies required to produce the following results:
5.2.1 To initiate fracture of the specimen,
5.2.2 To propagate the fracture across the specimen,
5.2.3 To throw the free end (or pieces) of the broken specimen (toss correction),
5.2.4 To bend the specimen,
5.2.5 To produce vibration in the pendulum arm,
5.2.6 To produce vibration or horizontal movement of the machine frame or base,
5.2.7 To overcome friction in the pendulum bearing and in the indicating mechanism, and to overcome windage (pendulum air drag),
5.2.8 To indent or deform plastically the specimen at the line of impact, and
5.2.9 To overcome the friction caused by the rubbing of the striking nose (or other part of the pendulum) over the face of the bent specimen.
5.3 For relatively brittle materials for which fracture propagation energy is small in comparison with the fracture initiation energy, the indicated impact energy absorbed is, for all practical purposes, the sum of items given in 5.2.1 and 5.2.3. The toss correction (5.2.3) may represent a very large fraction of the total energy absorbed when testing relatively dense and brittle materials.
5.4 For materials for which the fracture propagation energy (5.2.2) may be large compared to the fracture initiation energy (5.2.1), factors (5.2.2, 5.2.5, and 5.2.9) can become quite significant, even when the specimen is accurately machined and positioned and the machine is in good condition with adequate capacity (Note 3). Bending (5.2.4) and indentation losses (5.2.8) may be appreciable when testing soft materials.
Note 3: Although the frame and base of the machine should be sufficiently rigid and massive to handle the energies of tough specimens wit...
SCOPE
1.1 This test method covers the determination of the resistance of plastics to breakage by flexural shock, as indicated by the energy extracted from standardized pendulum-type hammers, mounted in standardized machines, in breaking standard specimens with one pendulum swing. The result of this test method is reported as energy absorbed per unit of specimen width.
Note 1: The pendulum-type test instruments have been standardized in that they must comply with certain requirements, including a fixed height of hammer fall that results in a substantially fixed velocity of the hammer at the moment of impact. Pendulums of different initial energies (produced by varying their effective weights) are recommended for use with specimens of different impact strengths. Moreover, manufacturers of the equipment are permitted to use different lengths and constructions of pendulums (with resulting possible differences in pendulum rigidities (see Section 5), and other differences in machine design).
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
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.
Note 2: This standard and ISO 180, Method U address the same subject matter, but differ in technical content.
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
Relations
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.
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Designation: D4812 − 19
Standard Test Method for
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Unnotched Cantilever Beam Impact Resistance of Plastics
This standard is issued under the fixed designation D4812; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
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ε NOTE—Editorial changes were made in April 2022.
1. Scope* 2. Referenced Documents
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2.1 ASTM Standards:
1.1 This test method covers the determination of the resis-
D256Test Methods for Determining the Izod Pendulum
tance of plastics to breakage by flexural shock, as indicated by
Impact Resistance of Plastics
the energy extracted from standardized pendulum-type
D618Practice for Conditioning Plastics for Testing
hammers, mounted in standardized machines, in breaking
D883Terminology Relating to Plastics
standard specimens with one pendulum swing. The result of
D5947Test Methods for Physical Dimensions of Solid
this test method is reported as energy absorbed per unit of
Plastics Specimens
specimen width.
E456Terminology Relating to Quality and Statistics
NOTE 1—The pendulum-type test instruments have been standardized
E691Practice for Conducting an Interlaboratory Study to
in that they must comply with certain requirements, including a fixed
Determine the Precision of a Test Method
height of hammer fall that results in a substantially fixed velocity of the
E2935Practice for Evaluating Equivalence of Two Testing
hammer at the moment of impact. Pendulums of different initial energies
(produced by varying their effective weights) are recommended for use
Processes
with specimens of different impact strengths. Moreover, manufacturers of
the equipment are permitted to use different lengths and constructions of 3. Terminology
pendulums(withresultingpossibledifferencesinpendulumrigidities(see
3.1 Definitions—Definitions used in this test method are in
Section 5), and other differences in machine design).
accordance with Terminology D883. For terms relating to
1.2 The values stated in SI units are to be regarded as
precision and bias and associated issues, the terms used in this
standard. The values given in parentheses are for information
standard are defined in accordance with Terminology E456.
only.
4. Summary of Test Method
1.3 This standard does not purport to address all of the
4.1 This test method differs from others of similar character
safety concerns, if any, associated with its use. It is the
in that unnotched test specimens are used (see Test Methods
responsibility of the user of this standard to establish appro-
D256 for procedures using notched test specimens). The lack
priate safety, health, and environmental practices and deter-
of a notch makes this test method especially useful for
mine the applicability of regulatory limitations prior to use.
reinforced materials where a notch may mask the effects of
NOTE 2—This standard and ISO 180, Method U address the same
orientation. It may also be used with other filled or unrein-
subject matter, but differ in technical content.
forced materials where a stress-concentrating notch is not
1.4 This international standard was developed in accor-
desired. It is not valid for materials that twist when subjected
dance with internationally recognized principles on standard-
to this test.
ization established in the Decision on Principles for the
5. Significance and Use
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
5.1 The pendulum-impact test indicates the energy to break
Barriers to Trade (TBT) Committee.
standard test specimens of specified size under stipulated
conditions of specimen mounting and pendulum velocity at
impact.
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ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics
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and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2019. Published October 2019. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1988. Last previous edition approved in 2011 as D4812-11. DOI:
Standards volume information, refer to the standard’s Document Summary page on
10.1520/D4812-19E01.
the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D4812 − 19
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