ASTM D6068-10

Standard Test Method for Determining J-R Curves of Plastic Materials

SIGNIFICANCE AND USE
A J-R curve produced in accordance with this test method characterizes the crack growth resistances of a wide range of tough polymers and polymer blends (1-5) that cannot be obtained in sufficient size and thickness for valid characterization by linear elastic fracture mechanics in Test Methods D5045.
The  J-R  curve characterizes, within the limits set forth in this test method, the resistance of a polymeric material to slow stable crack growth after initiation from a preexisting sharp flaw.
A  J-R  curve can be used as an index of material toughness for blend or alloy design, material selection, materials processing, and quality assurance (6).
The  J-R  curves from bend specimens represent lower bound estimates of  J  capacity as a function of crack extension, and have been observed to be conservative relative to those obtained from specimen configurations under tensile loading.
The  J-R  curves for a given material of constant microstructure tend to exhibit lower slope (flatter) with increasing thickness. Thus, it is recommended that the largest possible specimen with representative microstructure be used.
The  J-R  curve can be used to assess the stability of cracks in structures in the presence of ductile tearing, with awareness of the differences that may exist between laboratory test and field conditions.
A  J-R  curve may depend on the orientation and propagation of the crack in relation to the anisotropy of the material which may be induced by specimen fabrication methods.
Because of the possibility of rate dependence of crack growth resistance,  J-R  curves can be determined at displacement rates other than that specified in this test method (7).
SCOPE
1.1 This test method covers the determination of the J-integral versus crack growth resistance (J-R) curves for polymeric materials.  
1.2 This test method is intended to characterize the slow, stable crack growth resistance of bend-type specimens in such a manner that it is geometry insensitive within limits set forth in this test method.
1.3 The recommended specimens are the three-point bend (SE (B)) and pin-loaded compact tension (C (T)) specimens. Both specimens have in-plane dimensions of constant proportionality for all sizes. Specimen configurations other than those recommended in this test method may require different procedures and validity requirements.
1.4 This test method describes a multiple specimen method that requires optical measurement of crack extension from fracture surfaces. It is not recommended for use with materials in which the crack front cannot be distinguished from additional deformation processes in advance of the crack tip.
1.5 The values stated in SI units are to be regarded as the standard.
1.6 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.
Note 1—There is no equivalent ISO standard.

General Information

• Status: Historical
• Publication Date: 30-Jun-2010
• ICS: 83.040.01 - Raw materials for rubber and plastics in general
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.10 - Mechanical Properties

Relations

• Replaces: ASTM D6068-96(2002)e1 - Standard Test Method for Determining J-R Curves of Plastic Materials
• Effective Date: 01-Jul-2010
• Replaced By: ASTM D6068-10(2018) - Standard Test Method for Determining <emph type="bdit">J-R </emph>Curves of Plastic Materials
• Effective Date: 01-Oct-2018

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:D6068 −10
Standard Test Method for
1
Determining J-R Curves of Plastic Materials
This standard is issued under the fixed designation D6068; 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 D5045 Test Methods for Plane-Strain Fracture Toughness
and Strain Energy Release Rate of Plastic Materials
1.1 This test method covers the determination of the
E399 Test Method for Linear-Elastic Plane-Strain Fracture
J-integral versus crack growth resistance (J-R) curves for
Toughness K of Metallic Materials
Ic
polymeric materials.
E616 Terminology Relating to Fracture Testing (Discontin-
3
1.2 This test method is intended to characterize the slow,
ued 1996) (Withdrawn 1996)
stable crack growth resistance of bend-type specimens in such
E1152 Test Method for Determining-J-R-Curves
a manner that it is geometry insensitive within limits set forth
E1737 Test Method forJ-Integral Characterization of Frac-
in this test method. 3
ture Toughness (Withdrawn 1998)
F1473 Test Method for Notch Tensile Test to Measure the
1.3 The recommended specimens are the three-point bend
(SE(B)) and pin-loaded compact tension (C(T)) specimens. Resistance to Slow Crack Growth of Polyethylene Pipes
and Resins
Both specimens have in-plane dimensions of constant propor-
tionality for all sizes. Specimen configurations other than those
3. Terminology
recommended in this test method may require different proce-
dures and validity requirements.
3.1 Definitions—Terminology related to fracture testing
contained in Terminology E616 is applicable to this test
1.4 This test method describes a multiple specimen method
that requires optical measurement of crack extension from method.
fracture surfaces. It is not recommended for use with materials
3.2 Definitions of Terms Specific to This Standard:
−1
in which the crack front cannot be distinguished from addi-
3.2.1 J-integral, J (FL )—a mathematical expression, a
tional deformation processes in advance of the crack tip.
line or surface integral over a path that encloses the crack front
1.5 The values stated in SI units are to be regarded as the from one crack surface to the other, used to characterize the
localstress-strainfieldaroundthecrackfront.SeeTerminology
standard.
E616 for additional discussion.
1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.2.2 J-Rcurve—aplotofresistancetostablephysicalcrack
extension, ∆a .
responsibility of the user of this standard to establish appro-
p
priate safety and health practices and determine the applica-
3.2.3 net thickness, B (L)—the distance between the roots
N
bility of regulatory limitations prior to use.
of the side grooves in side grooved specimens.
NOTE 1—There is no equivalent ISO standard.
3.2.4 original crack size, a (L)—the physical crack size at
0
the start of testing.
2. Referenced Documents
3.2.5 original uncracked ligament, b (L)—the distance
0
2
2.1 ASTM Standards:
from the original crack front to the back edge of the specimen
D618 Practice for Conditioning Plastics for Testing
(b =W−a' ).
0 0
D4066 Classification System for Nylon Injection and Extru-
3.2.6 physical crack extension, ∆a (L)—an increase in
p
sion Materials (PA)
physical crack size (∆a =a −a ).
p p 0
3.2.7 physical crack size, a (L)—the distance from a refer-
p
1
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
ence line to the observed crack front. The distance may be a
and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.
calculated average of several measurements along the crack
Current edition approved July 1, 2010. Published July 2010. Originally approved
ε1
front. The reference line depends on the specimen geometry
in 1996. Last previous edition approved in 2002 as D6068 - 96(2002) . DOI:
10.1520/D6068-10.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D6068−10
4. Summary of Test Method
4.1 This test method describes a multiple specimen tech-
nique for determining the J-R curve for polymeric materials.
The J-R curve consists of a plot of J versus crack extension in
the region of J-contr
...

This document is not anASTM standard and is intended only to provide the user of anASTM 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.
´1
Designation:D6068–96 (Reapproved 2002) Designation: D6068 – 10
Standard Test Method for
1
Determining J-R Curves of Plastic Materials
This standard is issued under the fixed designation D6068; 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
´ NOTE—Editorially corrected figure reference in paragraph 7.3 in November 2002.
1. Scope
1.1 This test method covers the determination of the J-integral versus crack growth resistance (J-R) curves for polymeric
materials.
1.2 This test method is intended to characterize the slow, stable crack growth resistance of bend-type specimens in such a
manner that it is geometry insensitive within limits set forth in this test method.
1.3 The recommended specimens are the three-point bend (SE (B)) and pin-loaded compact tension (C ( T)) specimens. Both
specimens have in-plane dimensions of constant proportionality for all sizes. Specimen configurations other than those
recommended in this test method may require different procedures and validity requirements.
1.4 This test method describes a multiple specimen method that requires optical measurement of crack extension from fracture
surfaces.Itisnotrecommendedforusewithmaterialsinwhichthecrackfrontcannotbedistinguishedfromadditionaldeformation
processes in advance of the crack tip.
1.5 The values stated in SI units are to be regarded as the standard.
1.6 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.
NOTE 1—There is no equivalent ISO standard.
2. Referenced Documents
2
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
D4066 Classification System for Nylon Injection and Extrusion Materials (PA)
D5045 Test Methods for Plane-Strain Fracture Toughness and Strain Energy Release Rate of Plastic Materials
E399 Test Method for Linear-Elastic Plane-Strain Fracture Toughness K of Metallic Materials
Ic
E616 Terminology Relating to Fracture Testing (Discontinued 1996)
E1152 Test Method for Determining-J-R-Curves
E1737 Test Method for J-Integral Characterization of Fracture Toughness (Discontinued 1998)
F1473 Test Method for Notch Tensile Test to Measure the Resistance to Slow Crack Growth of Polyethylene Pipes and Resins
3. Terminology
3.1 Definitions—Terminology related to fracture testing contained in Terminology E616 is applicable to this test method.
3.2 Definitions of Terms Specific to This Standard:
−1
3.2.1 J-integral,J(FL ) —a mathematical expression, a line or surface integral over a path that encloses the crack front from
one crack surface to the other, used to characterize the local stress-strain field around the crack front. See Terminology E616 for
additional discussion.
3.2.2 J-R curve—a plot of resistance to stable physical crack extension, Da .
p
3.2.3 net thickness, B (L)—the distance between the roots of the side grooves in side grooved specimens.
N
3.2.4 original crack size, a (L) —the physical crack size at the start of testing.
0
1
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.
Current edition approved November 10, 2002. Published January 2003. Originally approved in 1996. Last previous edition approved in 1996 as D6068-96. DOI:
10.1520/D6068-96R02E01.
´1
Current edition approved July 1, 2010. Published July 2010. Originally approved in 1996. Last previous edition approved in 2002 as D6068 - 96(2002) . DOI:
10.1520/D6068-10.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at [e-mail]. ForAnnualBookofASTMStandards
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 ----------------------
D6068 – 10
3.2.5 original uncracked ligament, b ( L)—the distance from the original crack front to the back edge of the specimen (b
0 0
=W−a8 ).
0
3.2.6 physical crack extension, Da (L)—an increase in physical crack size (Da =a −a ).
p p p 0
3.2.7 physic
...