KIsi Discussion - ASTM International Nov 2015.pdf · Kang – Keep KIc in the title if KIsi in appendix ... • Analytical round robin phase II update • E740 future plans - Work

KIsi Discussion

1

Fall 2015 ASTM Meeting

C

O

Forc

e, P

E399 KIc• Toughness defined by 95% secant• Corresponds to 2% crack growth• As specimen width increases, the crack growth at KQ

increases, creating an R-curve effect for the KQ value

Proposed KIsi• Size insensitive fracture toughness• Alternate analysis method to KIc (not a replacement)• Toughness defined at fixed crack extension (a = 0.5mm)• Secant offset is specimen size and type dependent• Possible toughness increase for small specimens (W<50mm)• Possible toughness decrease for large specimens• Deformation limit is now variable with specimen size:

• bo MK (K/y)2, (bo = W-a)• where MK = 2.5 for KIc and MK ≈ W for KIsi

• Removes the Pmax/PQ requirement

Width OffsetW = 1 C = 10.6%W = 2 C = 5.3%W = 3 C = 4.1%W = 4 C = 2.7%W = 5 C = 2.2%

• Secant Offset for C(T)• SQ[%] = 100 - 135/(W-a)

Introduction

CMOD, V

PVC

Example of Validity Criterion

Approach from Doug Wells and Phillip Allen, Nov. 2012 meetingThey used FEA to investigate compliance change due to plasticity for a C(T) specimenShowed that: Results normalized very well using the compliance

change approach Results relatively insensitive to material Effect of plasticity on K was mostly less than 5%

for W/B = 2, but may be a larger factor for W/B = 4 and for the smallest specimens

Lead to current proposed deformation criterionKIc ligament requirement is: bo MK (K/y)2, where MK = 2.5 for KIc

MK is variable for KIsi

KIsi Ligament Requirement: (K/y)2 < 12.5mm, or MK bo / 12.5 (mm/mm), MK = bo / (K/y)2

3

Increasing load

0.0%

2.0%

4.0%

6.0%

8.0%

10.0%

12.0%

1.010.0C (%

)MK = bo (y/K)2

#28, W = 5.0, B = 2.2

#26, W = 5.0, B = 2.2

KIsi W = 1

KIsi W = 5

KIc Bounds

W&A Plasticity W/B=2

7475‐T7351C(T) SpecimenW = 5”W/B ≈ 2

• Analysis result is plasticity only• For data, compliance change has both plasticity and crack growth

Key differences between KIc and KIsi

Crack growth KIc – fixed 2% crack growth (fixed secant) KIsi – fixed a = 0.5mm crack growth (variable secant)

Pmax/PQ KIc – has Pmax/PQ requirement, which in essence restricts the amount of

stable tearing – basically requiring minimal tearing before fast fracture KIsi – no Pmax/PQ requirement; allows significant stable tearing

Deformation limits KIc – fixed deformation limit (MK = 2.5) KIsi – variable deformation limit (function of specimen size)

4

KIsi Subcommittee Ballot – Closing Statistics (Spring 2014)

5

Sent: 176Returned: 115% Returned: 65

Total Negatives: 5Total Comments: 12

Outstanding Items to Resolve to Go Forward

Documentation in the literature Scibetta - Referenced information for the C(T) and SE(B) secant offset

equations is different from what is in the appendix, and Secant Offset equations and for DC(T), A(T), A(B) are not documented in literature

Confusion about K’s and mandatory versus non-mandatory Lucon - KIsi is called “plane strain fracture toughness” in the terminology

and called “size-insensitive plane strain fracture toughness” in both the title and the body of the appendix

Hartman - Some confusion over what the K’s mean Ruggieri - Which K value should be used? …the toughness parameter

should have a clear and preferably unique definition to characterize the material's fracture resistance irrespective of the user's knowledge.

Link - For KIsi calculation, the validity requirement on mandatory specimen size is given in X1.6.1." Given that this Appendix is non-mandatory, I don't think you can have a mandatory size. I suggest you change the word from mandatory to minimum.

Kang – Keep KIc in the title if KIsi in appendix (e.g. non-mandatory). Change of the title implies an expansion of the concept of the linear-elastic plane strain fracture toughness (Negative).

6

Affirmative with Comment

Outstanding Items to Resolve to Go Forward (cont)

Tregoning – Concern about excluding KIsi from beryllium and high loading rate annexes. Is KIc required, but KIsi optional?

Allen – Deformation limit needs to be a function of specimen sizeShannon – Summary/History of KIc development (~ 4 pgs). Need to validate the method with significant data before standardizing. Concerned about fundamentally different direction.

James – Deformation limit needs published, compliance offset equations need published, validity criteria need validated.

7

Negatives

Way Forward

Agreement on various details of the standard Ballot only at the subcommittee level until documentation and initial data available to support wider

distributionDocument the equations as well as current understanding from analysis about partitioning plasticity and crack growth based deformation Need volunteer(s) to help with the effort Envision this as a natural extension to Kim Wallin’s 2004 paper

Complete initial testing to evaluate both SE(B) and C(T) for W/B and size dependencies, and side grooves (preferably for more than one material) Alcoa has donated material Would like to leverage Doug Wells test matrix Need volunteer(s) Is there existing data available from E1820 tests that can be used?

Document the test results as an experimental basis for the method ASTM report as a minimum, but JTE or similar would be best

Ballot KIsi at the Main committee assuming technical basis is strong

Long term possible goals: Larger round robin with detailed comparison of KIc and KIsi (assuming standardized) Revise to deprecate the graphical method and formalize the computer analysis method Add example data sets

8

9

Damage Tolerance Assessment BranchMSFC Engineering Directorate

1

ASTM Committee MeetingE08.07.03 Surface Cracks

E2899 Business

November 17, 2015

Doug Wells & Phillip AllenNASA MSFC

Damage Tolerance Assessment Branch


2

Agenda

A. Approval of the minutes from May 2015 meeting in Anaheim, CA

B. Old Business• Analytical round robin phase II update• E740 future plans - Work Item 50037

C. New Business• Review of E2899-15 updates


3

Analytical Round Robin Phase II

• Preliminary results from the round robin were presented in November 2014.

• Full analysis and reporting of the result set is in process (still……).

• Plan to publish the RR results in a NASA TM (public release)

• Round robin result overview included in back-up


4

Round Robin Objectives:

1) Determine the consistency in the interpretation of the test evaluation requirements in E2899.

2) Provide guidance/feedback for E2899 A6 - METHODOLOGY FOR PERFORMING ELASTIC-PLASTIC FINITE ELEMENT ANALYSIS AND COMPARISON TO TEST RECORD

3) Provide additional information on the analytical consistency of finite element (FE) methods as prescribed in the standard for future revision of the precision and bias statements.

4) Evaluate use of interpolated nonlinear FE solutions as an alternative to traditional FE analysis through use of TASC*.


* Tool for Analysis of Surface Cracks (TASC), https://sourceforge.net/projects/tascnasa/


5

RR Phase II based on 4142 steel SC(T) test


1.75(44.45)

18.00(457.2)

5.00 (127.0)

2.504(63.60)

R2.23(R56.6)

4.50 (114.3)

0.499(12.67)

5.00(127.0)

2.63 (66.8)

• Participants given specimen dimensions, fracture surface photo, material tensile test data, and SC(T) force-CMOD data.

• Asked to follow E 2899 and evaluate the test


6

RR Phase II participants in random order• Enrico Lucon – NIST• Greg Thorwald – Quest Integrity Group• Igor Varfolomeev - IWM• Jason Bely – Alcoa• Steven Altstadt – Stress Engineering Services• Michael Windisch – MT Aerospace• Ryan Sherman – Purdue University• Francisco Martin – Purdue University• Dawn Phillips – NASA MSFC• Phillip Allen (Lab 1) – NASA MSFC


• Participants evaluated the test results using elastic-plastic finite element analysis per E 2899 A6 and/or using TASC


7

ASTM E740-10 Status

E740 is a surface crack residual strength test method. No crack front parameters are evaluated as a part of this method, with exception of the stress intensity during precracking.

Standard renewed in 2010 now ready for customary 5 year review.

Forward plan:• Keep E740 active• Established work item for E2899 to accommodate residual strength

evaluations as an Annex.• Annex to be used directly or in support of field collapse test

evaluation• Once approved into E2899, Ballot E740 for withdrawal

E740 Items


8

Summary:ASTM E2899 provides an updated framework for the evaluation of initiation fracture toughness in surface cracks. The long-standing surface crack standard, ASTM E740, is in need of update. In contrast to the initiation toughness measure provided by E2899, E740 provides only a measure of the residual strength in the presence of a surface crack. The residual strength assessment in E740 is currently very limited. There is a desire to develop a more robust residual strength evaluation for the surface crack geometry in the E2899 standard, particularly to handle tests which fall into E2899s field collapse regime, meaning the deformation state in the specimen has exceeded the currently specified limits of validity for determination of the J-Integral fracture toughness parameter. The intent is to develop an annex for E2899 to handle the residual strength surface crack test. Once developed and integrated into E2899, the proposed plan is to ballot E740 for withdrawal. In the meantime, E740 will remain active.

E740 Items

Work Item 50037 has been established:


9

E2899 Ballot

E2899-15 Release• Three previous ballot items were incorporated in the -15

revision along with some editorial comments and corrections.

• Review updated items by looking at the -15 version.


10

E2899 Proposed Changes

Clarification of precrack evaluation section


11


Clarification of Fig 8 nomenclature


12

Elastic-Plastic Regime Assessment, E 2899 9.22


Crack front conditions and deformation regime assessment

Two parameter, elastic-plastic regime

-1 -0.5 0 0.50

0.01

0.02

0.03

0.04

0.05

0.06

0.07

T-Stress/ys

J/(r

*ys

) =

1/C

ra =36.00

rb =36.00

ra = 90.0

rb = 90.0

1/CK1/CJa1/CJbTearing Load


13


Modifications to A6.3 Force-CMOD Elastic Compliance Comparison


14

Force-CMOD Comparison, E 2899 A6.3 and A6.4


0 0.05 0.1 0.15 0.2 0.25 0.30

100

200

300

400

500

600

700

CMOD (mm)

Forc

e (k

N)

ExperimentLab-1Lab-1-TLab-2Lab-2-TLab-3Lab-4Lab-5Lab-6-TLab-7Lab-8Lab-9-TLab-10

Note: Lab-9-T force at CMODi exceeds the test Pi by 5.25%, but the analysis results are still included in the following evaluations.


15

Elastic Compliance Evaluation, E 2899 A6.3


Experiment Elastic Slope Determined Using Linear Fit to 20-50% of Max Data Range

Experiment Elastic Slope Determined Using SDAR

Graham-Adler Fitting Algorithm

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.080

100

200

300

400

500

600

Slope % diff. =0.06

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.080

100

200

300

400

500

600

Slope % diff. =2.23

Comparison for Lab-1

Experiment slope = 8111 Experiment slope = 8291


16



Lab Elastic Slope % Diff.Lab‐1 0.06Lab‐1‐T ‐2.88Lab‐2 ‐0.69Lab‐2‐T ‐5.55Lab‐3 2.16Lab‐4 9.27Lab‐5 2.33Lab‐6‐T ‐2.47Lab‐7 1.49Lab‐8 ‐0.63Lab‐9‐T 3.30Lab‐10 ‐1.07

Lab Elastic Slope % Diff.Lab‐1 2.23Lab‐1‐T ‐0.66Lab‐2 1.49Lab‐2‐T ‐3.27Lab‐3 4.28Lab‐4 11.23Lab‐5 4.44Lab‐6‐T ‐0.25Lab‐7 3.62Lab‐8 1.55Lab‐9‐T 5.39Lab‐10 1.11





17



0 0.05 0.1 0.15 0.2 0.25 0.30

20

40

60

80

100

120

140

160

CMOD (mm)

J-In

tegr

al (k

J/m2 )

Lab-1Lab-1-TLab-2Lab-2-TLab-3Lab-4Lab-5Lab-6-TLab-7Lab-8Lab-9-TLab-10final CMOD


18



0.15 0.16 0.17 0.18 0.19 0.2 0.21 0.22 0.23 0.24 0.2580

85

90

95

100

105

110

115

120

CMOD (mm)

J-In

tegr

al (k

J/m2 )


Range of J values at CMODi

Lab J at i

Lab‐1 101.19Lab‐1‐T 96.80Lab‐2 100.17 Max. 102.97Lab‐2‐T 96.67 Avg. 98.26Lab‐3 99.50 Min. 91.24Lab‐4 94.31 Std. Dev. 3.17Lab‐5 91.24Lab‐6‐T 98.04Lab‐7 102.97Lab‐8 98.52Lab‐9‐T 99.49Lab‐10 100.17


19



As reported values Corrected Lab 8 value to CMODi

Lab J at i


Lab J at i



20

Backup



21

Objectives:1) Determine the consistency in the interpretation of the test

evaluation requirements in E2899. 2) Provide additional information on the analytical

consistency of finite element (FE) methods as prescribed in the standard for future revision of the precision and bias statements. An evaluation of interpolated solutions as an alternative to FE will also be requested through use of the recently developed TASC.


To Participate or Ask Questions:Please email us:

[email protected]@nasa.gov


22

RR Phase II based on 4142 steel SC(T) test


1.75(44.45)

18.00(457.2)

5.00 (127.0)

2.504(63.60)

R2.23(R56.6)

4.50 (114.3)

0.499(12.67)

5.00(127.0)

2.63 (66.8)

• Participants given specimen dimensions, fracture surface photo, material tensile test data, and SC(T) force-CMOD data.

• Asked to follow E 2899 and evaluate the test


23

RR Phase II participants in random order• Enrico Lucon – NIST• Greg Thorwald – Quest Integrity Group• Igor Varfolomeev - IWM• Jason Bely – Alcoa• Steven Altstadt – Stress Engineering Services• Michael Windisch – MT Aerospace• Ryan Sherman – Purdue University• Francisco Martin – Purdue University• Dawn Phillips – NASA MSFC• Phillip Allen (Lab 1) – NASA MSFC


• Participants evaluated the test results using elastic-plastic finite element analysis per E 2899 A6 and/or using TASC*

* Tool for Analysis of Surface Cracks (TASC), https://sourceforge.net/projects/tascnasa/


24

Force-CMOD Comparison, E 2899 A6.3 and A6.4


0 0.05 0.1 0.15 0.2 0.25 0.30

100

200

300

400

500

600

700

CMOD (mm)

Forc

e (k

N)

ExperimentLab-1Lab-1-TLab-2Lab-2-TLab-3Lab-4Lab-5Lab-6-TLab-7Lab-8Lab-9-TLab-10

Note: Lab-9-T force at CMODi exceeds the test Pi by 5.25%, but the analysis results are still included in the following evaluations.


25






0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.080

100

200

300

400

500

600

Slope % diff. =0.06

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.080

100

200

300

400

500

600

Slope % diff. =2.23

Comparison for Lab-1

Experiment slope = 8111 Experiment slope = 8291


26



Lab Elastic Slope % Diff.Lab‐1 0.06Lab‐1‐T ‐2.88Lab‐2 ‐0.69Lab‐2‐T ‐5.55Lab‐3 2.16Lab‐4 9.27Lab‐5 2.33Lab‐6‐T ‐2.47Lab‐7 1.49Lab‐8 ‐0.63Lab‐9‐T 3.30Lab‐10 ‐1.07

Lab Elastic Slope % Diff.Lab‐1 2.23Lab‐1‐T ‐0.66Lab‐2 1.49Lab‐2‐T ‐3.27Lab‐3 4.28Lab‐4 11.23Lab‐5 4.44Lab‐6‐T ‐0.25Lab‐7 3.62Lab‐8 1.55Lab‐9‐T 5.39Lab‐10 1.11





27

Critical Angle, i, Evaluation, E 2899 A5.2


0 10 20 30 40 50 60 70 80 900

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

J/J m

ax*(

T/S

ys+1

) or

J/J m

ax*(

0.25

*T/S

ys+1

)

(deg.)

tear location at =36.00Final Analysis StepFinal step predicted tear at =38.00Analysis Tear PointTear point predicted tear at =36.005% deviation from max.


28

Critical Angle, i, Evaluation, E 2899 A5.2


-30 -20 -10 0 10 20 30

-20

-15

-10

-5

0

5

10

15

20

25

30

W (mm)

B (m

m)

-10 -5 0 5 10

-4

-2

0

2

4

6

8

10

12

14

W (mm)

B (m

m)

Lab i


Note: Lab-10 had a error in their T-stress calculation which resulted in a incorrect calculation of i. The Lab-10 corrected value is i = 35°.




31



0 15 30 45 60 75 900

20

40

60

80

100

120

Parametric Angle, (deg)

J-In

tegr

al (k

J/m2 )

Lab-1Lab-1-TLab-2Lab-2-TLab-3Lab-4Lab-5Lab-6-TLab-7Lab-8Lab-9-TLab-10

Note: Lab-8 reported J values were approx. ½ of the actual values likely due to a symmetry plane accounting error in the domain integral calculation. Therefore all Lab-8 values were multiplied by 2 for inclusion in the study.

Range of estimated i values


32



0 0.05 0.1 0.15 0.2 0.25 0.30

20

40

60

80

100

120

140

160

CMOD (mm)

J-In

tegr

al (k

J/m2 )



33



0.15 0.16 0.17 0.18 0.19 0.2 0.21 0.22 0.23 0.24 0.2580

85

90

95

100

105

110

115

120

CMOD (mm)

J-In

tegr

al (k

J/m2 )


Range of J values at CMODi

Lab J at i



34



As reported values Corrected Lab 8 value to CMODi

Lab J at i


Lab J at i



35



Crack front conditions and deformation regime assessment

-1 -0.5 0 0.50

0.01

0.02

0.03

0.04

0.05

0.06

0.07

T-Stress/ys

J/(r

*ys

) = 1

/C

ra =36.00

rb =36.00

ra = 90.0

rb = 90.0


101 102 103 104 1050

10

20

30

40

50

60

70

80

%J pl

astic

r*Sys/J

ra =36.00

rb =36.00

ra = 90.0

rb = 90.0

LEFM Deform Limit, C KEPFM Deform Limit, C JaEPFM Deform Limit, C JbTearing Load Point

Two parameter, elastic-plastic regime


36

TASC Update

• TASC (Tool for Analysis of Surface Cracks) is a computer program created by NASA MSFC that enables easy computation of three-dimensional, nonlinear J-integral (fracture energy) solutions for surface cracked plates in tension.

36

What is TASC?

Test specimen fracture surface


TASC Accessibility

• A TASC project page is hosted on Sourceforge.net at: https://sourceforge.net/projects/tascnasa/

• TASC can be freely downloaded in Windows® 64-bit standalone executable, Mac OS X® 64-bit standalone application, and MATLAB source file formats.

• No MATLAB license is required for the standalone executable versions license due to the royalty-free MATLAB Complier Runtime distribution provided with the program installation package, and no MATLAB experience is needed due to the simple GUI.

• TASC is released under the NASA Open Source Agreement Version 1.3.

• TASC was posted on Sourceforge on Jan. 28, 2014 and to date has had over 900 downloads

• TASC’s background documentation: Allen, P.A. and Wells, D.N., Interpolation Methodology for Elastic-Plastic J-Integral Solutions for

Surface Cracked Plates in Tension, Engineering Fracture Mechanics 119, 2014, pp 173-201. Allen, P.A. and Wells, D.N., Applications of Automation Methods for Nonlinear Fracture Test

Analysis, ASTM STP1571 on Sixth Symposium on Application of Automation Technology in Fatigue and Fracture Testing and Analysis, Accepted for publication Nov. 2013.

Allen PA, Wells DN. Elastic-Plastic J-Integral Solutions for Surface Cracks in Tension Using an Interpolation Methodology. NASA MSFC; 2013. NASA/TM-2013-217480.


38

TASC Solution – US Units


0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10

50

100

150

Strain

Stre

ss (

ksi)

LPPL EquationData Table

0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.010

50

100

150

Forc

e (k

ip)

CMOD (in)

Jphi

=552.72

Interpolated ResultTest RecordTest Tearing Point5.0% Error Limits

0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.010

100

200

300

400

500

600

700

800

J (in

-lb/in

2 )

CMOD (in)

Jel =36.00

Jtotal =36.00

Jel = 90.0

Jtotal = 90.0

Tearing CMOD

0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.010

20

40

60

80

100

120

Stre

ss (

ksi)

CMOD (in)

Jphi

=552.72

Section YieldNet Section Yield



39



0 10 20 30 40 50 60 70 80 90-1.05

-1

-0.95

-0.9

-0.85

-0.8

-0.75

-0.7

-0.65

-0.6

-0.55

T-S

tres

s/ys

(deg.)

Final StepTear Pointtear location at =36.00

0 10 20 30 40 50 60 70 80 900

50

100

150

K (

ksi-i

n0.5 )

(deg.)

KJel Final Step

KJtotal Final Step

KJel @ Tear Point

KJtotal @ Tear Point

tear location at =36.00Newman-Raju Eq.

0 10 20 30 40 50 60 70 80 900

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

J/J m

ax*(

T/Sy

s+1)

or

J/J m

ax*(

0.25

*T/S

ys+1

)

(deg.)


0 10 20 30 40 50 60 70 80 900

100

200

300

400

500

600

700

J (in

-lb/in

2 )

(deg.)

Jel Final Step

Jtotal Final Step

Jel @ Tear Point

Jtotal @ Tear Point

tear location at =36.00


40



-1 -0.5 0 0.50

0.01

0.02

0.03

0.04

0.05

0.06

0.07

T-Stress/ys

J/(r

*ys

) = 1

/C

ra =36.00

rb =36.00

ra = 90.0

rb = 90.0


-1 -0.5 0 0.5 1-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

length (in)

leng

th (

in)

101 102 103 104 1050

10

20

30

40

50

60

70

80

%J pl

astic

r*Sys/J

ra =36.00

rb =36.00

ra = 90.0

rb = 90.0



41

TASC Solution – SI Units


0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10

200

400

600

800

1000

1200

Strain

Stre

ss (

MPa

)

LPPL Equation

0 0.05 0.1 0.15 0.2 0.250

100

200

300

400

500

600

700

800

Str

ess

(MP

a)

CMOD (mm)

Jphi

=96.65

Section YieldNet Section Yield


0 0.05 0.1 0.15 0.2 0.250

100

200

300

400

500

600

700

Forc

e (k

N)

CMOD (mm)

Jphi

=96.65


0 0.05 0.1 0.15 0.2 0.250

20

40

60

80

100

120

140

J (k

J/m

2 )

CMOD (mm)

Jel =36.00

Jtotal =36.00

Jel = 90.0

Jtotal = 90.0

Tearing CMOD


42



0 10 20 30 40 50 60 70 80 90-1.05

-1

-0.95

-0.9

-0.85

-0.8

-0.75

-0.7

-0.65

-0.6

-0.55

T-S

tres

s/ys

(deg.)

Final StepTear Pointtear location at =36.00

0 10 20 30 40 50 60 70 80 900

20

40

60

80

100

120

J (k

J/m

2 )

(deg.)

Jel Final Step

Jtotal Final Step

Jel @ Tear Point

Jtotal @ Tear Point

tear location at =36.00

0 10 20 30 40 50 60 70 80 900

20

40

60

80

100

120

140

160K

(M

Pa-

m0.

5 )

(deg.)

KJel Final Step

KJtotal Final Step

KJel @ Tear Point

KJtotal @ Tear Point

tear location at =36.00Newman-Raju Eq.

0 10 20 30 40 50 60 70 80 900

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

J/J m

ax*(

T/Sy

s+1)

or

J/J m

ax*(

0.25

*T/S

ys+1

)

(deg.)



43



101 102 103 104 1050

10

20

30

40

50

60

70

80

%J pl

astic

r*Sys/J

ra =36.00

rb =36.00

ra = 90.0

rb = 90.0


-30 -20 -10 0 10 20 30-20

-15

-10

-5

0

5

10

15

20

25

30

length (mm)

leng

th (

mm

)

E1921 Ballot Items & Results

Mikhail SokolovORNL

Rob TregoningNRC

ASTM Committee WeekNovember 17, 2015

November 17, 2015 ASTM E08 Committee Week Meetings Page 2 of 5

E08 (15-03), Item 13: Guidance for E(T)

Objective Provide guidance on value of E(T) for use in pretest compliance

check, post-test crack length verification, and Jc conversion

Overview of changes Provide equation for E(T) in 8.6.2 Linear equation is accurate within 0.5% of ferritic steel values in

ASME, Section II, Part D between -200C to 300C

Initial Ballot E08 (14-03), Item 4 Several persuasive negatives and comments received

E08 (15-03) ballot revision Rectifies error in applicable temperature range for equation for E Clarifies temperature units in equation are oC Specifically defines the ASME Code data used to derive equation


E08 (15-03), Item 13: Balloted Revision

Proposed changes to 8.6.2 – unanimous concurrence from task group members during November 2014 meeting “…The nominal value of E shall come from either handbook values or

dedicated modulus testing per ASTM E111 or equivalent. Separate tensile test results do not provide accurate elastic modulus values. Alternatively, the following equation can be used to determine the nominal value of E:E = 204 – T/16 GPa, where T is the test temperature in oC.This equation was derived by a fitting the tabular values for ferritic steels contained in ASME Section II, Park D. The fit is valid for -200oC ≤ T ≤ 300oC.


E08 (15-03), Item 13 Results

Ballot closed on 9/29/15 Ballot statistics:

E08: 252 sent 191 returned (76%) E08.07: 167 sent 104 returned (62%)

Comments Juan Donoso Jude Foulds Markus Heinimann Enrico Lucon Marc Scibetta

Item Affirm. Neg. Comm. Abst. Per.

4: E(T) Guidance E08 98 0 5 93 100 E08.07 63 0 3 41 100


E08 (15-03), Item 13: Comments

Lucon, Scibetta, Heinimann caught additional “a” in “…equation was derived by a fitting the tabular values for ferritic…” This will be deleted in final version.

Donoso, Foulds correctly indicated that ASME reference should be “Part D” and not “Park D”. This will be corrected in the final version.

Foulds suggested more complete reference to ASME Boiler and Pressure Vessel Code. This will be adopted in the final version.

Enrico Lucon: Other comments Suggested editorial corrections on spacing, use of italics, and adding an

equation number will be handled by ASTM editor using conventional ASTM practice.

Not clear what term “separate” tensile test means (in sentence above ballot). Maybe use “non-dedicated”

Discuss this concern

Central Research Institute of Electric Power Industry

Proposal of mitigation in dimensional tolerance requirements in ASTM E1921

Proposal of change in mechanical notch requirement in ASTM E1921

1

ASTM E08 meeting, Nov. 2015

November 17, 2015

Masato Yamamoto, CRIEPIKim Wallin, VTT

Naoki Miura, CRIEPI

Background

Master Curve approach using Mini‐C(T)specimens (4 mm‐thickness) is promising method

Can be taken from broken halves of Charpy specimens used for surveillance program

Some of current dimensional requirements are severer for smaller specimens

2

Outline of proposal

Mitigation in dimensional tolerance requirements for C(T) specimens

Change in specification of mechanical notchshape and dimension requirement C(T)specimensIt was agreed to proceed to ballot for the mitigation of notch height N for 0.16T (4mm‐T) C(T) specimens (May 2015)

3November 17, 2015

MITIGATION OF TOLERANCE

4November 17, 2015

Requirements of dimensional tolerances ASTM E1921 gives dimensional tolerances of C(T) specimens as relative valuesThose requirements were set assuming larger (1inch‐T) specimens,considering available machining and measurement preciseness.

5November 17, 2015

PVP 2015‐45505

6

Miura et. al addressed themitigation of tolerance requirement for 4mm‐T Mini‐ C(T) specimensChange in KJ in various tolerance values was determined by 3‐D finite element analyses

Mitigation of tolerances of B, W, L, 2H and GL to ±0.1mm (0.0125W) gives negligibly small change in KJ

November 17, 2015

2H

Wam af

90N

D

GLL D

LB

D2

D2

D1

D1

Analysis Model

Mini‐ C(T) specimens Variable dimensions: B, am, W, L, 2H, N, and GL Fixed dimensions: af, LD, and D

7

Analysis Matrix

8

Effect ofnotch height

Effect of thickness

Effect of crack length

Effect of width

Effect of length

Effect of height

Effect of GL

Base case

0.1mm = 0.0125W

Effect of Dimensional Tolerances

Comparison of two KJs

K0 : derived from J by finite element analysis index in which all dimensional factors are taken into account

Kc : derived from J by ASTM E1921 for load vs. load‐line displacement relation obtained from finite element analysis can be considered as the index to judge whether dominant

dimensional factors are properly considered in ASTM E1921

9


Both K0 and Kc normalized by values for standard dimension case Values of K0 and Kc where they approximately reach maximum

fracture toughness capacity, KJc(limit)

10

0.90

0.95

1.00

1.05

1.10

3.4 3.6 3.8 4.0 4.2 4.4 4.6

Normalized

KJ

Crack length, mm

Dimensional tolerancein ASTM E1921

K0Kc

Change of 10% (0.4 mm) in a causes approximate variation of 5% in KJTrend is similar both for K0 and Kca is one of dominant factors to impact on KJ, nevertheless, contribution of amust be properly considered in ASTM E1921

Effect of crack length on normalized KJ


11

Situation is similar for contributions of B and WChanges of 0.1 mm in B or W induce variation of KJ less than 1%

0.98

0.99

1.00

1.01

1.02

3.85 3.90 3.95 4.00 4.05 4.10 4.15

Normalized

KJ

Specimen thickness, mm

Dimensional tolerancein ASTM E1921 K0

Kc

0.98

0.99

1.00

1.01

1.02

7.85 7.90 7.95 8.00 8.05 8.10 8.15

Normalized

KJ

Specimen width, mm

Dimensional tolerancein ASTM E1921 K0

Kc

Effect of thickness on normalized KJ Effect of width on normalized KJ


12

Effects of L, 2H, GL, and N implicitly considered in K0, while they cannot be taken into account in KcThese effects are still limited within assumed range of dimensions

0.98

0.99

1.00

1.01

1.02

9.85 9.90 9.95 10.00 10.05 10.10 10.15

Normalized

KJ

Specimen length, mm


K0Kc

0.98

0.99

1.00

1.01

1.02

9.45 9.50 9.55 9.60 9.65 9.70 9.75

Normalized

KJ

Specimen height, mm


K0Kc

0.98

0.99

1.00

1.01

1.02

2.55 2.70 2.85 3.00 3.15 3.30 3.45

Normalized

KJ

Gauge length, mm

K0Kc

0.90

0.95

1.00

1.05

1.10

0.0 0.1 0.2 0.3 0.4 0.5 0.6

Normalized

KJ

Notch width, mm

K0Kc

Effect of length on normalized KJ Effect of height on normalized KJ

Effect of GL on normalized KJ Effect of notch height on normalized KJ

0.01

W

0.06

3W

Notch height, mm

Proposal on tolerances

Mitigation of the red‐marked tolerances to 0.0125W (or 0.013W)(0.1mm in Mini‐C(T))

13

2.2

0.04

2.2

0.04

( )

3

a0 (4±0.4)W (8±0.04)

L (10±0.08)

D (2±0.04)

2H (9

.6±0

.08)

B (4±0.08)

0.8 at side surface

N

E1921‐14e1 ProposalW, am, D 0.005W 0.0125WL, B, 2H 0.010W 0.0125WNovember 17, 2015

CHANGE IN MECHANICAL NOTCH SHAPE AND DIMENSION REQUIREMENT

14November 17, 2015

Requirement of mechanical notch shape anddimension

Maximum height of narrow groove, N, is 0.01W, which gives too narrow (0.08mm) for Mini‐ C(T) specimens.

Minimum crack requirement Minimum crack length for streight notch is 1.3mm, which is too large for the Mini‐C(T) speicmen

15

ASTM E1921 specify the acceptable envelope for mechanical notch and pre‐crack.

November 17, 2015

Sensitivity of notch envelope angle on K

16November 17, 2015

KN : K for ideal crack (H=0)KC(T) : K for machining notch and precrack

H, h+Δaf , and angle of β are important to be included as the notch requirement

0.90

0.95

1.00

1.05

1.10

0.0 0.1 0.2 0.3 0.4 0.5 0.6

Normalized

KJ

Notch width, mm

K0Kc

Notch height, mm

Notch Shape effect in PVP2015‐45505

Mitigation of maximum notch height does not significantly affect the evaluation of KJ

17

2H

Wam af

90N

D

GLL D

L

D2

D2

D1

D1

N : 0 – 0.5mmΔaPC : 0.6 mm

ΔaPC= 1.2N

ΔaPC= 1.36

6N

N=0.001

W

Minimum Δapc to keep the current requirementfor notch and crack envelope

Notch angle,α (deg)

minimumΔapc

Remark

180 1.866N Rectangular notch with no sharpened zone

90 1.366N Similar to narrow notch with circular profile

60 N Maximum angle for wide notch

< 20.1 0.5N Angle where 0.5N is sufficient to keep the envelope

18November 17, 2015

Relationship between required minimum Δapc and W

Documented specification in Fig. 5 for both of Narrow and Wide notches not always suffice the envelope requirement

19November 17, 2015

0

0.5

1

1.5

2

2.5

3

0 50 100 150 200 250

Minim

um Δa_pc, m

m

Sepcimen width, W, mm

Δa_pc current (Narrow, N=0.01W)

Grater of 0.5N or 0.6mm, Narrow, N=0.01W

Narrow notch with maximum notch height

0

1

2

3

4

5

6

7

0 50 100 150 200 250

Minim

umΔa

_pc, m

m


Δa_pc current (α<40.2, N=0.063W or 6.25)

Δa_pc current (α=60, N=0.063W or 6.25)

Grater of 0.5N or 1.3mm, Wide, N=0.063W

Wide notch with maximum notch height

Proposal for notch height requirement (1)

20

Eliminating the specific requirement for “Narrow” and “Wide” notch

Any of notch shapes are acceptable if the requirement for maximum N (relative to W) Sum of precrack length and

sharpened notch length (relative to N)are satisfied.

Proposal for requirement

Maximum Notch Height 0.063W

Sum of precrack length and sharpened notch length 2.0N

Minimum Precrack Length 0.5N

Comparison of Δapcbetween current and proposed requirements

21November 17, 2015

0

5

10

15

20

25

30

0 50 100 150 200 250

Minim

um Δa_pc, m

m


Δa_pc proposal (α<40.2, N=0.063W) Δa_pc proposal (α= 60, N=0.063W) Δa_pc proposal (α=90, N=0.063W) Δa_pc proposal (α=180, N=0.063W) Δa_pc current (α<40.2, N=0.063W or 6.25) Δa_pc current (α=60, N=0.063W or 6.25)

Development of a Precision & Bias Statement for E1921 High Rate Annex

and proposed modifications to Section 12

E. Lucon & J. Splett - NIST, Boulder CO (USA)

ASTM E08.07.06 Task Group on Ductile-to-Brittle TransitionTampa FL, 17th November 2015

Background

A new Annex A1 to E1921 has been successfully balloted on “Special Requirements for Determining the Reference Temperature, To,X, at Elevated Loading Rates” [E1921-15].

It collects provisions previously scattered inside the main body of the Standard, plus references to Annex A17 of E1820-13 (Fracture Toughness Tests at Impact Loading Rates using Precracked Charpy-Type Specimens).

A new P & B statement for Annex A1 is proposed. It was developed from the statistical analysis of an interlaboratory study on the measurement of To from impact-tested PCC specimens (IAEA CRP-8, conducted between 2006-2009).

Some of the lessons learned will be used to propose modifications of the current Section 12 (P & B) of ASTM E1921-15.

Interlaboratory Study considered

IAEA CRP-8, “Master Curve Approach to Monitor Fracture Toughness of Reactor Pressure Vessels in Nuclear Power Plants,” Topic Area 2: Loading Rate Effects and Qualification of Impact Fracture Toughness

Round-Robin Exercise on Impact Fracture Toughness (Dynamic Master Curve analysis) using Charpy-type precracked (PCC) specimens• 10 participants

• 10 PCC specimens tested by each participant between -30 °C and 10 °C

• JRQ steel (A533B cl. 1)

• Loading rate/impact speed: 1.2 m/s.

Presentation given on May 17th, 2015 at ASTM Workshop on Fracture Toughness Testing and Evaluation at Elevated Loading Rates

Justification and Theoretical Background

Data do not conform to the requirements of E691 (Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method) because T0 and its σ do not represent typical means and σ is based on repeated measurements.

However, the definition of repeatability and reproducibility from E691 can be used.

Each T0 is considered to be based on a sample size of 1 for analysis purposes.

Calculated standard deviations are similar, so estimates were “pooled” to obtain the repeatability standard deviation.

Precision Statement

Statistics were calculated using the standard deviation of participants’ individual T0 (calculated using Eq. 30 or E1921).

One participant was excluded after being statistically identified as an outlier.

Since calculated sR < sr, it is set sR = sr in accordance with E691.

Parameter Number of determinations Average

Repeatability Standard

Deviation, sr

Reproducibility Standard

Deviation, sR

Repeatability Limit, r

Reproducibility Limit, R

T0, °C 9 -0.1 7.40A 7.40B 20.7 20.7

Proposed modification of current E1921 Section 12 (Precision and Bias)

• Proposal: simplify, improve, and correct the estimates of repeatability and reproducibility for both single-T and multi-T methods of estimating T0.

• Rationalea) New analysis is simpler than current analysis.

b) It corresponds to E691 for the special case where each lab supplies a single T0 and its associated uncertainty (eq. 30).

c) Paule-Mandel method is no longer needed.

d) Will be consistent with the P & B analysis of elevated loading rate data (Annex A1 in E1921-15).

Modified Section 12

Single T

Multi T

CURRENT

CURRENT

REVISED

REVISED

Documents

KIsi Discussion - ASTM International Nov 2015.pdf · Kang – Keep KIc in the title if KIsi in appendix ... • Analytical round robin phase II update • E740 future plans - Work