KIsi Discussion. Fall 2015 ASTM Meeting

Transcription

1 KIsi Discussion Fall 2015 ASTM Meeting 1

2 Introduction C E399 KIc Toughness defined by 95% secant Corresponds to 2% crack growth As specimen width increases, the crack growth at K Q increases, creating an R-curve effect for the K Q value Force, P O C VCMOD, VPProposed KIsi Size insensitive fracture toughness Alternate analysis method to K Ic (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: b o M K (K/ y ) 2, (b o = W-a) where M K = 2.5 for K Ic and M K W for K Isi Removes the P max /P Q requirement Secant Offset for C(T) SQ[%] = /(W-a) Width Offset W = 1 C = 10.6% W = 2 C = 5.3% W = 3 C = 4.1% W = 4 C = 2.7% W = 5 C = 2.2%

3 Example of Validity Criterion Approach from Doug Wells and Phillip Allen, Nov meeting They used FEA to investigate compliance change due to plasticity for a C(T) specimen Showed 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 criterion K Ic ligament requirement is: b o M K (K/ y ) 2, C (%) 12.0% 10.0% 8.0% 6.0% 4.0% 2.0% 0.0% T7351 C(T) Specimen W = 5 W/B 2 M K = b o ( 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 1.0 where M K = 2.5 for K Ic M K is variable for K Isi K Isi Ligament Requirement: (K/ y ) 2 < 12.5mm, or M K b o / 12.5 (mm/mm), M K = b o / (K/ y ) 2 Increasing load Analysis result is plasticity only For data, compliance change has both plasticity and crack growth 3

4 Key differences between K Ic and K Isi Crack growth K Ic fixed 2% crack growth (fixed secant) K Isi fixed a = 0.5mm crack growth (variable secant) P max /P Q K Ic has P max /P Q requirement, which in essence restricts the amount of stable tearing basically requiring minimal tearing before fast fracture K Isi no P max /P Q requirement; allows significant stable tearing Deformation limits K Ic fixed deformation limit (MK = 2.5) K Isi variable deformation limit (function of specimen size) 4

5 K Isi Subcommittee Ballot Closing Statistics (Spring 2014) Sent: 176 Returned: 115 % Returned: 65 Total Negatives: 5 Total Comments: 12 5

6 Outstanding Items to Resolve to Go Forward Affirmative with Comment 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 -K Isi 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

7 Outstanding Items to Resolve to Go Forward (cont) Negatives 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 size Shannon 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

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

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10 ASTM Committee Meeting E Surface Cracks E2899 Business November 17, 2015 Doug Wells & Phillip Allen NASA MSFC 1

11 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 C. New Business Review of E updates 2

12 Analytical Round Robin Phase II Preliminary results from the round robin were presented in November 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 3

13 Analytical Round Robin Phase II Round Robin Objectives: 1) Determine the consistency in the interpretation of the test evaluation requirements in E ) 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), 4

14 Analytical Round Robin Phase II RR Phase II based on 4142 steel SC(T) test 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 1.75 (44.45) (12.67) 5.00 (127.0) (63.60) (457.2) R2.23 (R56.6) 4.50 (114.3) 2.63 (66.8) 5.00 (127.0) 5

15 Analytical Round Robin Phase II 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 6

16 E740 Items ASTM E 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 7

17 E740 Items Work Item has been established: 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. 8

18 E2899 Ballot E 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. 9

19 E2899 Proposed Changes Clarification of precrack evaluation section 10

20 E2899 Proposed Changes Clarification of Fig 8 nomenclature 11

21 Analytical Round Robin Phase II Elastic-Plastic Regime Assessment, E Crack front conditions and deformation regime assessment J/(r* ys ) = 1/C r a =36.00 r b =36.00 r a = 90.0 r b = /C K 1/C Ja 1/C Jb Tearing Load 0.01 Two parameter, elastic-plastic regime T-Stress/ ys 12

22 E2899 Proposed Changes Modifications to A6.3 Force-CMOD Elastic Compliance Comparison 13

23 Analytical Round Robin Phase II Force-CMOD Comparison, E 2899 A6.3 and A Force (kn) Experiment Lab-1 Lab-1-T Lab-2 Lab-2-T Lab-3 Lab-4 Lab-5 Lab-6-T Lab-7 Lab-8 Lab-9-T Lab CMOD (mm) Note: Lab-9-T force at CMOD i exceeds the test P i by 5.25%, but the analysis results are still included in the following evaluations. 14

24 Analytical Round Robin Phase II Elastic Compliance Evaluation, E 2899 A6.3 Comparison for Lab-1 Experiment Elastic Slope Determined Using Linear Fit to 20-50% of Max Data Range Experiment Elastic Slope Determined Using SDAR Graham-Adler Fitting Algorithm Slope % diff. =0.06 Experiment slope = 8111 Slope % diff. =2.23 Experiment slope =

25 Analytical Round Robin Phase II Elastic Compliance Evaluation, E 2899 A6.3 Experiment Elastic Slope Determined Using Linear Fit to 20-50% of Max Data Range Lab Elastic Slope % Diff. Lab Lab 1 T 2.88 Lab Lab 2 T 5.55 Lab Lab Lab Lab 6 T 2.47 Lab Lab Lab 9 T 3.30 Lab Experiment Elastic Slope Determined Using SDAR Graham-Adler Fitting Algorithm Lab Elastic Slope % Diff. Lab Lab 1 T 0.66 Lab Lab 2 T 3.27 Lab Lab Lab Lab 6 T 0.25 Lab Lab Lab 9 T 5.39 Lab

26 Analytical Round Robin Phase II Elastic-Plastic Regime Assessment, E J-Integral (kj/m 2 ) Lab-1 Lab-1-T Lab-2 Lab-2-T Lab-3 Lab-4 Lab-5 Lab-6-T Lab-7 Lab-8 Lab-9-T Lab-10 final CMOD CMOD (mm) 17

27 Analytical Round Robin Phase II Elastic-Plastic Regime Assessment, E Range of J values at CMOD i Lab J at i Lab Lab 1 T Lab Max Lab 2 T Avg Lab Min Lab Std. Dev Lab Lab 6 T Lab Lab Lab 9 T Lab J-Integral (kj/m 2 ) Lab-1 Lab-1-T Lab-2 Lab-2-T Lab-3 Lab-4 Lab-5 Lab-6-T Lab-7 Lab-8 Lab-9-T Lab-10 final CMOD CMOD (mm) 18

28 Analytical Round Robin Phase II Elastic-Plastic Regime Assessment, E As reported values Lab J at i Lab Lab 1 T Lab Max Lab 2 T Avg Lab Min Lab Std. Dev Lab Lab 6 T Lab Lab Lab 9 T Lab Corrected Lab 8 value to CMOD i Lab J at i Lab Lab 1 T Lab Max Lab 2 T Avg Lab Min Lab Std. Dev Lab Lab 6 T Lab Lab Lab 9 T Lab

29 Analytical Round Robin Phase II Backup 20

30 Analytical Round Robin Phase II Objectives: 1) Determine the consistency in the interpretation of the test evaluation requirements in E ) 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 us: 21

31 Analytical Round Robin Phase II RR Phase II based on 4142 steel SC(T) test 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 1.75 (44.45) (12.67) 5.00 (127.0) (63.60) (457.2) R2.23 (R56.6) 4.50 (114.3) 2.63 (66.8) 5.00 (127.0) 22

32 Analytical Round Robin Phase II 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), 23

33 Analytical Round Robin Phase II Force-CMOD Comparison, E 2899 A6.3 and A Force (kn) Experiment Lab-1 Lab-1-T Lab-2 Lab-2-T Lab-3 Lab-4 Lab-5 Lab-6-T Lab-7 Lab-8 Lab-9-T Lab CMOD (mm) Note: Lab-9-T force at CMOD i exceeds the test P i by 5.25%, but the analysis results are still included in the following evaluations. 24

34 Analytical Round Robin Phase II Elastic Compliance Evaluation, E 2899 A6.3 Comparison for Lab-1 Experiment Elastic Slope Determined Using Linear Fit to 20-50% of Max Data Range Experiment Elastic Slope Determined Using SDAR Graham-Adler Fitting Algorithm Slope % diff. =0.06 Experiment slope = 8111 Slope % diff. =2.23 Experiment slope =

35 Analytical Round Robin Phase II Elastic Compliance Evaluation, E 2899 A6.3 Experiment Elastic Slope Determined Using Linear Fit to 20-50% of Max Data Range Lab Elastic Slope % Diff. Lab Lab 1 T 2.88 Lab Lab 2 T 5.55 Lab Lab Lab Lab 6 T 2.47 Lab Lab Lab 9 T 3.30 Lab Experiment Elastic Slope Determined Using SDAR Graham-Adler Fitting Algorithm Lab Elastic Slope % Diff. Lab Lab 1 T 0.66 Lab Lab 2 T 3.27 Lab Lab Lab Lab 6 T 0.25 Lab Lab Lab 9 T 5.39 Lab

36 Analytical Round Robin Phase II Critical Angle, i, Evaluation, E 2899 A J/J max *(T/Sys+1) or J/J max *(0.25*T/Sys+1) tear location at =36.00 Final Analysis Step 0.1 Final step predicted tear at =38.00 Analysis Tear Point 0.05 Tear point predicted tear at = % deviation from max (deg.) 27

37 Analytical Round Robin Phase II Critical Angle, i, Evaluation, E 2899 A i Lab Lab Lab 1 T 36.0 Lab Max Lab 2 T 36.0 Avg Lab Min Lab Std. Dev Lab Lab 6 T 38.0 Lab Lab Lab 9 T 30.0 Lab B (mm) B (mm) W (mm) W (mm) 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 =

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40 Analytical Round Robin Phase II Elastic-Plastic Regime Assessment, E Range of estimated i values 100 J-Integral (kj/m 2 ) Lab-1 Lab-1-T Lab-2 Lab-2-T Lab-3 Lab-4 Lab-5 Lab-6-T Lab-7 Lab-8 Lab-9-T Lab Parametric Angle, (deg) 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. 31

41 Analytical Round Robin Phase II Elastic-Plastic Regime Assessment, E J-Integral (kj/m 2 ) Lab-1 Lab-1-T Lab-2 Lab-2-T Lab-3 Lab-4 Lab-5 Lab-6-T Lab-7 Lab-8 Lab-9-T Lab-10 final CMOD CMOD (mm) 32

42 Analytical Round Robin Phase II Elastic-Plastic Regime Assessment, E Range of J values at CMOD i Lab J at i Lab Lab 1 T Lab Max Lab 2 T Avg Lab Min Lab Std. Dev Lab Lab 6 T Lab Lab Lab 9 T Lab J-Integral (kj/m 2 ) Lab-1 Lab-1-T Lab-2 Lab-2-T Lab-3 Lab-4 Lab-5 Lab-6-T Lab-7 Lab-8 Lab-9-T Lab-10 final CMOD CMOD (mm) 33

43 Analytical Round Robin Phase II Elastic-Plastic Regime Assessment, E As reported values Lab J at i Lab Lab 1 T Lab Max Lab 2 T Avg Lab Min Lab Std. Dev Lab Lab 6 T Lab Lab Lab 9 T Lab Corrected Lab 8 value to CMOD i Lab J at i Lab Lab 1 T Lab Max Lab 2 T Avg Lab Min Lab Std. Dev Lab Lab 6 T Lab Lab Lab 9 T Lab

44 Analytical Round Robin Phase II Elastic-Plastic Regime Assessment, E Crack front conditions and deformation regime assessment J/(r* ys ) = 1/C r a =36.00 r b =36.00 r a = 90.0 r b = /C K 1/C Ja 1/C Jb Tearing Load T-Stress/ ys Two parameter, elastic-plastic regime %J plastic r a =36.00 r b =36.00 r a = 90.0 r b = 90.0 LEFM Deform Limit, C K EPFM Deform Limit, C Ja EPFM Deform Limit, C Jb Tearing Load Point r*sys/j 35

45 TASC Update What is TASC? TASC (Tool for Analysis of Surface Cracks) is a computer program created by NASA MSFC that enables easy computation of threedimensional, nonlinear J-integral (fracture energy) solutions for surface cracked plates in tension. Test specimen fracture surface 36

46 TASC Accessibility A TASC project page is hosted on Sourceforge.net at: 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 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 Allen PA, Wells DN. Elastic-Plastic J-Integral Solutions for Surface Cracks in Tension Using an Interpolation Methodology. NASA MSFC; NASA/TM

47 Analytical Round Robin Phase II TASC Solution US Units Stress (ksi) 50 Force (kip) 50 J phi = LPPL Equation Data Table Strain Interpolated Result Test Record Test Tearing Point 5.0% Error Limits CMOD (in) Stress (ksi) Section Yield Net Section Yield J phi = J (in-lb/in 2 ) J el =36.00 J total =36.00 J el = 90.0 J total = 90.0 Tearing CMOD Interpolated Result 20 Test Record Test Tearing Point 5.0% Error Limits CMOD (in) CMOD (in) 38

48 Analytical Round Robin Phase II TASC Solution US Units T-Stress/ ys Final Step Tear Point tear location at =36.00 J (in-lb/in 2 ) J el Final Step J total Final Step J Tear Point J Tear Point tear location at = (deg.) (deg.) J/J max *(T/Sys+1) or J/J max *(0.25*T/Sys+1) tear location at =36.00 Final Analysis Step 0.1 Final step predicted tear at =38.00 Analysis Tear Point 0.05 Tear point predicted tear at = % deviation from max (deg.) K (ksi-in 0.5 ) K Jel Final Step K Jtotal Final Step K Tear Point K Tear Point tear location at =36.00 Newman-Raju Eq (deg.) 39

49 Analytical Round Robin Phase II TASC Solution US Units r a =36.00 r b =36.00 r a = 90.0 r b = %J plastic LEFM Deform Limit, C K EPFM Deform Limit, C Ja EPFM Deform Limit, C Jb Tearing Load Point length (in) r*sys/j length (in) J/(r* ys ) = 1/C r a =36.00 r b =36.00 r a = 90.0 r b = /C K 1/C Ja 1/C Jb Tearing Load T-Stress/ ys 40

50 Analytical Round Robin Phase II TASC Solution SI Units Stress (MPa) Force (kn) J phi = LPPL Equation Strain Interpolated Result 100 Test Record Test Tearing Point 5.0% Error Limits CMOD (mm) Stress (MPa) Section Yield Net Section Yield J phi = Interpolated Result Test Record 100 Test Tearing Point 5.0% Error Limits CMOD (mm) J (kj/m 2 ) J el =36.00 J total =36.00 J el = 90.0 J total = 90.0 Tearing CMOD CMOD (mm) 41

51 Analytical Round Robin Phase II TASC Solution SI Units T-Stress/ ys Final Step Tear Point tear location at =36.00 J (kj/m 2 ) J el Final Step J total Final Step J Tear Point J Tear Point tear location at = (deg.) (deg.) J/J max *(T/Sys+1) or J/J max *(0.25*T/Sys+1) tear location at =36.00 Final Analysis Step 0.1 Final step predicted tear at =38.00 Analysis Tear Point 0.05 Tear point predicted tear at = % deviation from max (deg.) K (MPa-m 0.5 ) K Jel Final Step K Jtotal Final Step K Tear Point K Tear Point tear location at =36.00 Newman-Raju Eq (deg.) 42

52 Analytical Round Robin Phase II TASC Solution SI Units r a =36.00 r b =36.00 r a = 90.0 r b = %J plastic LEFM Deform Limit, C K EPFM Deform Limit, C Ja EPFM Deform Limit, C Jb Tearing Load Point length (mm) r*sys/j length (mm) 43

53 E1921 Ballot Items & Results Mikhail Sokolov ORNL Rob Tregoning NRC ASTM Committee Week November 17, 2015

54 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 J c conversion Overview of changes Provide equation for E(T) in 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 o C Specifically defines the ASME Code data used to derive equation November 17, 2015 ASTM E08 Committee Week Meetings Page 2 of 5

55 E08 (15-03), Item 13: Balloted Revision Proposed changes to 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 o C. 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 -200 o C T 300 o C. November 17, 2015 ASTM E08 Committee Week Meetings Page 3 of 5

56 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%) Item Affirm. Neg. Comm. Abst. Per. E : E(T) Guidance E Comments Juan Donoso Jude Foulds Markus Heinimann Enrico Lucon Marc Scibetta November 17, 2015 ASTM E08 Committee Week Meetings Page 4 of 5

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

58 ASTM E08 meeting, Nov Proposal of mitigation in dimensional tolerance requirements in ASTM E1921 Proposal of change in mechanical notch requirement in ASTM E1921 Central Research Institute of Electric Power Industry Masato Yamamoto, CRIEPI Kim Wallin, VTT Naoki Miura, CRIEPI November 17,

59 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

60 Outline of proposal Mitigation in dimensional tolerance requirements for C(T) specimens Change in specification of mechanical notch shape and dimension requirement C(T) specimens It was agreed to proceed to ballot for the mitigation of notch height N for 0.16T (4mm T) C(T) specimens (May 2015) November 17,

61 MITIGATION OF TOLERANCE November 17,

62 Requirements of dimensional tolerances ASTM E1921 gives dimensional tolerances of C(T) specimens as relative values Those requirements were set assuming larger (1inch T) specimens, considering available machining and measurement preciseness. November 17,

63 PVP Miura et. al addressed the mitigation of tolerance requirement for 4mm T Mini C(T) specimens Change in K J 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 K J November 17,

64 Analysis Model Mini C(T) specimens Variable dimensions: B, a m, W, L, 2H, N, and GL Fixed dimensions: a f, L D, and D D D 1 D H N L D GL D 2 D 1 B a m L W a f 7

65 Analysis Matrix Base case Effect of notch height 0.1mm = W Effect of thickness Effect of crack length Effect of width Effect of length Effect of height Effect of GL 8

66 Effect of Dimensional Tolerances Comparison of two K J s K 0 : derived from J by finite element analysis index in which all dimensional factors are taken into account K c : 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

67 Effect of Dimensional Tolerances Both K 0 and K c normalized by values for standard dimension case Values of K 0 and K c where they approximately reach maximum fracture toughness capacity, K Jc(limit) Normalized K J Dimensional tolerance in ASTM E1921 K 0 K c Crack length, mm Effect of crack length on normalized K J Change of 10% ( 0.4 mm) in a causes approximate variation of 5% in K J Trend is similar both for K 0 and K c a is one of dominant factors to impact on K J, nevertheless, contribution of a must be properly considered in ASTM E

68 Effect of Dimensional Tolerances Normalized K J Dimensional tolerance in ASTM E1921 K 0 K c Normalized K J Dimensional tolerance in ASTM E1921 K 0 K c Specimen thickness, mm Effect of thickness on normalized K J Specimen width, mm Effect of width on normalized K J Situation is similar for contributions of B and W Changes of 0.1 mm in B or W induce variation of K J less than 1% 11

69 Effect of Dimensional Tolerances Normalized K J Dimensional tolerance in ASTM E K 0 K c 0.99 K 0 K c Specimen length, mm Normalized K J Dimensional tolerance in ASTM E1921 Specimen height, mm Effect of length on normalized K J Normalized K J Gauge length, mm K 0 K c Effect of height on normalized K J Normalized K J W Notch height, width, mm 0.063W K 0 K c Effect of GL on normalized K J Effect of notch height on normalized K J Effects of L, 2H, GL, and N implicitly considered in K 0, while they cannot be taken into account in K c These effects are still limited within assumed range of dimensions 12

70 Proposal on tolerances ( ) N D ( 2±0.04) 2H (9.6±0.08) Mitigation of the redmarked tolerances to W (or 0.013W) (0.1mm in Mini C(T)) B (4±0.08) 0.8 at side surface a 0 (4±0.4) W (8±0.04) L (10±0.08) E e1 Proposal W, am, D 0.005W W L, B, 2H 0.010W W November 17,

71 CHANGE IN MECHANICAL NOTCH SHAPE AND DIMENSION REQUIREMENT November 17,

72 Requirement of mechanical notch shape and dimension ASTM E1921 specify the acceptable envelope for mechanical notch and pre crack. 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 November 17,

73 Sensitivity of notch envelope angle on K K N : K for ideal crack (H=0) K C(T) : K for machining notch and precrack November 17, 2015 H, h+δa f, and angle of β are important to be included as the notch requirement 16

74 Notch Shape effect in PVP L D GL D 1 D 1 D 2 D 2 N D 90 2H Normalized K J N=0.001W Δa PC = 1.366N Δa PC = 1.2N K 0 K c a m L W N : 0 0.5mm Δa PC : 0.6 mm a f Notch height, width, mm Mitigation of maximum notch height does not significantly affect the evaluation of K J 17

75 Minimum Δa pc to keep the current requirement for notch and crack envelope Notch angle, α (deg) minimum Δa pc Remark N Rectangular notch with no sharpened zone N Similar to narrow notch with circular profile 60 N Maximum angle for wide notch < N Angle where 0.5N is sufficient to keep the envelope November 17,

76 Relationship between required minimum Δa pc and W Minimum Δa_pc, mm 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 Sepcimen width, W, mm Minimum Δa_pc, mm Δa_pc current (Narrow, N=0.01W) Grater of 0.5N or 0.6mm, Narrow, N=0.01W Sepcimen width, W, mm Wide notch with maximum notch height Narrow notch with maximum notch height Documented specification in Fig. 5 for both of Narrow and Wide notches not always suffice the envelope requirement November 17,

77 Proposal for notch height requirement (1) 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 20

78 Comparison of Δa pc between current and proposed requirements Minimum Δa_pc, mm 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) Sepcimen width, W, mm November 17,

79 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 E Task Group on Ductile-to-Brittle Transition Tampa FL, 17 th November 2015

80 Background A new Annex A1 to E1921 has been successfully balloted on Special Requirements for Determining the Reference Temperature, T o,x, at Elevated Loading Rates [E ]. It collects provisions previously scattered inside the main body of the Standard, plus references to Annex A17 of E (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 T o from impact-tested PCC specimens (IAEA CRP-8, conducted between ). Some of the lessons learned will be used to propose modifications of the current Section 12 (P & B) of ASTM E

81 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 17 th, 2015 at ASTM Workshop on Fracture Toughness Testing and Evaluation at Elevated Loading Rates

82 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 T 0 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 T 0 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.

83 Precision Statement Statistics were calculated using the standard deviation of participants individual T 0 (calculated using Eq. 30 or E1921). One participant was excluded after being statistically identified as an outlier. Repeatability Reproducibility Number of Parameter determinations Average Repeatability Reproducibility Standard Standard Limit, r Limit, R Deviation, s r Deviation, s R T 0, C A 7.40 B Since calculated s R < s r, it is set s R = s r in accordance with E691.

84 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 T 0. Rationale a) New analysis is simpler than current analysis. b) It corresponds to E691 for the special case where each lab supplies a single T 0 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 E ).

85 Modified Section 12 Single T CURRENT REVISED Multi T CURRENT REVISED