NASGRO v6.2 Release Notes
Contents
1. be input have been increased e For 1 D tables the maximum number of rows was increased from 25 to 50 For 2 D tables the maximum number of rows in the da dN table with different da dN set for each stress ratio was increased from 25 to 50 and the number of rows in the da dN table with same da dN set for all stress ratios from 25 to 450 Additional changes to the tabular data capability include A different approach to consolidate user supplied da dN tables with different da dN set into a uniform 2 D table The consolidated uniform 2 D table on which crack growth calculation is based retains all the user specified da dN entries in the original da dN tables and shares the same da dN set for all the stress ratios Capabilities to check if user supplied da dN curves for different stress ratios cross or not The characteristic parameters of the Walker interpolation logic the Walker exponents are calculated before crack growth analysis for better computational efficiency Implemented a methodology to adjust computational error from interpolation for stress ratio eliminating negative slope of da dN vs AK curve Changed and extended the rules of access to tabular da dN capabilities The 2 D table of da dN vs AK and R option has been extended to work with Willenborg retardation models It is now accessible by the non load interaction model the Boeing constant closure model the generalized Willenborg model and the modified generaliz2. constants Interpolation type M NASGRO Linea C Hermite Plot P Fastran Previously the 2 D da dN data tables consisted of two different data formats one using the same da dN values for all R and the other using a different set of da dN values for each R In v6 2 there is now only one high level choice of a 2 D table in the data format pull down menu however the same different da dNdata types are now sub options once the 2 D data format is chosen This is illustrated in the screen shot of the NASFLA material GUI shown below This figure also shows the new interpolation schemes that have been implemented for 2 D tabular data for NASGRO v6 2 Interpolation for R has three options piece wise linear new default option cubic spline the previous default option and Walker Walker interpolation logic is used to extrapolate if a cycle goes beyond the bounds of the user supplied R values regardless of which R interpolation scheme is selected Interpolation for AK has two options piece wise linear default and Hermite polynomial Appendix A of the User s Manual provides extensive detail describing the implementation of the interpolation schemes as well as an overview of how NASGRO expands the user specified table into a uniform 2 D table for use in the crack growth analysis EZI NASFLA Crack Growth Analysis SEs File Options Tools Help Hp Geometry epom i Material ym Eoad Blocks BuildSchedule FYOut
3. input that it is the new value that will apply to the calculation and not the original material file value Changed the label of the Material Tab radio box from Cth value option to Cth value used in analysis to make clear that this setting is used for the analysis only and is not used in the View curvefit button s plots The ability to allow the user to change Cthm the fanning factor for negative stress ratios has been restored in v6 2f after temporarily suspending this ability in v6 2 beta The Cth value option 0 Initially has been removed from use for 3D and 4D crack cases For crack cases CC08 CC11 EC02 EC05 SC17 SC18 TC11 TC12 TC13 TC17 TC18 and TC19 the output echo of user supplied stress pairs when using the OPS option with univariant stress input tables has been improved All original user supplied stress pairs are now echoed in the output display Previously a reduced number of stress input pairs was shown Also in NASSIF For crack cases CC02 CC03 CC04 CC07 SC11 SC12 TC03 TC04 TC05 TCO9 and TC10 the net section stress check for S3 vs YS or flow stress was removed for pin loading bearing stress Also in NASSIF amp NASCCS For crack cases SC11 SC12 and SC18 the geometry limits displayed in the GUI were updated and some redundancies were eliminated Also in NASSIF NASCCS amp NASGLS For crack cases TC13 and TC18 the correction factor applied for converting from a one crack so
4. point limit on alternate stress format arrays by raising it to 2500 and rewrote the OPS routines to fix an error encountered when very small numbers are compared Also in NASSIF e Corrected internal library support issues within the OPS routines which prevented some intermediate plot files to be produced resulting in a GUI crash during plotting Also in NASSIF The following NASFLA fixes also pertain to NASSIF and NASCCS e Crack case SC04 external crack fails right away no matter what initial crack size is specified e Lay out at least one interpolation point between any two raw data points when plotting user specified beta factors for crack case DTO1 e Interpolation outside the parameter limits of the tabulated data was terminated with an error The fix ensures the computation will not be terminated when such an out of bound scenario is encountered e Crack case TC18 o Corrected bitmap image regarding the definition of crack length c The correct measurement begins at the notch tip not from the center of the root radius as previously depicted o The SIF solutions were under predicted for cracks at the notch tips of elliptical holes with e2 gt e This problem has been resolved by interpolating between the crack at hole solution and the crack in plate solution e For crack cases TC17 and TC18 a description line was added to the NASGRO output files to indicate which notch shape angular straight edge or elliptical wa
5. provided in the naSsfla excel_templates subfolder that accept input for a number of NASGRO crack cases These worksheets write NASFLA GUI input files call the NASFLA GUI to read these input files run crack growth calculations in the background and finally pipe the computed results back to Excel in the same format used when a user selects saving ALL calc d data to csv file after a normal interactive GUI session The objective of enabling access to NASFLA in this mode is to provide a means whereby NASFLA can be run quickly from within Excel for simple geometries material options and load sequences These worksheets operate on a reduced set of input options and are not intended to reproduce a complete input interface within Excel Details about how to run NASFLA interactively from within Excel are provided in Appendix Z of the User s Manual The following list shows the input options and parameters that are currently available e Geometry o Applicable to models TCO1 TC03 TCOS and SCO1 o input for basic parameters crack size thickness width hole diameter etc o crack size input restricted to User entry only no NASA std NDE method specification e Material non interaction model only o NASGRO equation constants from the NASGRO material file only o material input via NASGRO material ID only no manual editing of constants e Load blocks o load block type Input cycles and stresses manually only o upto
6. the out2 file This has been corrected Also in NASGLS Crack cases CC08 SC18 If either crack case CC08 or SC18 is selected followed by selecting crack case TC13 then reselecting either CCO8 or SC18 again the initial crack plane stress definition choice of Remote tension remained as TC13 s choice Tension bend This problem has been corrected and now upon reselection of the original crack case CCO8 or SC18 this choice will be correctly relabeled back to Remote tension Also in NASGLS Crack case CC08 o Fixed an error which in the presence of an out of bounds crack resulted in an attempted de allocation of unallocated memory Also in NASGLS o Fixed an improper out of bounds validity check which prevented normal functioning of this crack case when a c 0 5 Also in NASGLS Crack case TC11 Fixed an initialization error which prevented normal functioning of this crack case when run as a symmetric crack with symmetric stressing Also in NASGLS Crack cases CC04 CC07 Adjusted bitmap images to properly convey to the user that these solutions assume that the stresses applied to the lower surface are remote from the crack Also in NASGLS Fixed a stress gradient reversal error in ECO5 which result in reversals of applied and residual stress in the output although the calculations themselves were correctly done Crack case PSO1 o Removed the Stress label radiobox from Geometry tab This was previously used
7. these three d L ratios and enables the user to input any d L value that he wishes as long as 1 12 lt d L lt 1 3 This capability was implemented by performing two successive Hermite polynomial 1 D interpolations first on the stiffness ratio and then on the rivet spacing ratio No extrapolation is allowed and an error message is displayed if the input d L value is outside the 1 12 or 1 3 bounds New Options for Treatment of Negative Pin Load Bearing Stress S3 For crack cases in which pin loads bearing stresses are present the treatment of negative pin loads was modified to allow the user to specify the option for computing K These options appear on the Geometry page of the NASFLA GUI as shown below and pertain only to bearing stresses S3 Negative pin load bearing stress assumption Compression clipping if Kmin lt 0 set Kmin 0 Full range use actual values of Kmin and Kmax Two sign independent cycles 0 to Kmin and 0 to Kmax This change pertains to the pin load crack cases TC03 TC04 TCO5 TC10 CC02 CC03 CC04 CC07 SC11 and SC12 The first option compression clipping uses only the positive side of the cycle setting negative Ks equal to zero This is a new option and is now the default it is deemed more realistic than the second option The second more conservative option is to use the full range of K from a negative minimum to a positive maximum K and it is still available The third option which split
8. 10 blocks of up to 10 steps each e Print options o no restrictions 10 Options not listed above are considered advanced options and as such are not available for user modification from their default values The figure below shows the input worksheet for crack case TCO1 as an example initial crack size aa A1ACSOABI Load block count Block number Block type for each block aae fet et a sae eel ff e e Step count for each block Step 1 cles SOmin SOmax Simin Simax 10 0 100 20 020 30 0 30 40 0 100 Step 2 cles SOmin SOmax S1min S1max 10 0 101 20021 400101 Step 3 cles SOmin SOmax Simin S1max 10 0 102 400102 Step 4 cles SOmin SOmax Simin Simax T 033 Step 5 cles SOmin SOmax S1min S1max 6 cles SOmin SOmax S1min S1max T cles SOmin SOmax Simin S1max a cles SOmin SOmax S1min Simax Step 9 cles SOmin SOmax Simin Simax Step 10 cles SOmin SOmax S1min 1max Scale factors for each block TERTRE Project name nasfla tc01 Save data to folder D Documents and Settings jbeek Desktop testbuffer Run NASFLA Other New or Changed NASFLA Items e When batch processing a list of input files a single message window will now be presented giving the user the option to save all older format input files in the new format This allows a long list of input files to be run without any user intervention Previously a window wo
9. AC1 2524 T3 sheet in L T amp T L orientations M2KN13AC1 2050 T84 plate in T L amp L T orientations M2SA13AC1 2050 T84 plate in S L orientation M2SAIS5AC1 6156 T6 sheet in T L amp L T orientations M6GB13AB1 oOoo0o0o0o NASGRO equation curve fit was added for 2014 T6 aluminum forging M2AD23AB1 NASGRO equation curve fit was added for ZE41A T5 magnesium casting T2NAS1AC1 Changes were made in the materials files using M2KN in the material ID for 2524 T3 and retaining M2LA exclusively for 2618 T6 A typographical error in the value of Bx in the material database files NASMFC amp NASMEM was corrected for 2524 T3 ID M2KN11AC1 Corrected the curve fit constants for two Titanium alloys material IDs PBEA13AB1 and P3EC13AB1 NASFLA Fixes Crack case EC04 o Inconsistent results fixed for remote bending and user defined bending o Inconsistent results fixed with crack case ECOS5 for univariant stressing Modified the transfer of NASA standard NDE flaw size information from the GUI to the DLL now passing the actual initial flaw sizes in lieu of the descriptive information transferred earlier This change together with corrections made to the DLL ensures that calculations performed using the NASA standard NDE option are based on crack sizes that correspond to MSFC STD 5009 the current standard NASFLA GUI would crash when attempting to load user material fits that had been created in NASMAT due to NA
10. SMAT adding blank values for Kle Klc AK Bk when choosing Enter Kc or Kle directly NASMAT will no longer add blank values for these constants Loading incomplete input files with no material data at times disabled the GUI 14 Crack cases SC01 SC05 SC11 SC12 SC15 SC17 SC19 NDE depth radiobox was not being removed from screen when Initial flaw option was reset to User entry or when NDE Type choice was reset to Click to display choices Crack cases SCO7 SC08 SC13 SC14 If Initial flaw option is set to NASA std NDE changing the Crack Tip Input radiobox would not update the Geometry Grid to contain the correct NDE flaw sizes for the selected crack tip Crack case CC11 a bug encountered when computing the limit load was fixed Crack case EC02 when running multiple aspect ratios the results except the first one were incorrect This resulted from one of crack sizes exceeding the solution limits The scenario triggered a transition flag and as a result provided SIF solutions based on incorrect crack model After an analysis when exclusively viewing any Input choices on the Computations tab many extra blank lines were added to the display window in error Crack cases SSO1 SS12 Removed Initial flaw option radiobox since the NASA standard NDE choice for initial flaw size should not be offered for these cases Corrected the screen layout for the Material tab selections of the Strip Yield crack gro
11. September 29 2011 NASGRO v6 2 Release Notes NASFLA Additions and Changes New Stress Intensity Factor Models also in NASSIF and NASCCS e TC17 Through Crack at Edge Notch in Plate Univariant WF o This stress intensity factor SIF solution is valid for a crack at the tip of an edge notch of arbitrary shape Two common types of notch shape are supported in the GUI an angular straight edge notch and an elliptical notch for a very wide range of geometry parameters Stresses can be applied as remote tension in plane bending or un cracked crack plane stresses s Tee ss 2 oo d i 0 1 2 3 So 0s s24 F l i o lt Sat lt 0 76 A 29 cC lt 09 3 W d r Slee eye t 058575 a eae i 0 1 2 3 TC17 Elliptical Notch e TC18 Through Crack s at Offset Embedded Slot or Elliptical Hole in Plate Univariant WF o This SIF solution is for a through thickness crack or two symmetrical through thickness cracks at the notch tip s of an offset embedded slot or elliptical hole in a plate A wide range of geometry parameters is allowed Stresses can be applied as remote tension in plane bending or un cracked crack plane stresses TC18 Embedded Slot ees Sttttttttt 2e 2e4 W Sof prr B ei 0 99 wW lt i aS 2 Brey i 0 1 2 3 TC18 Elliptical Hole TC19 Through Crack at Offset Hole in Plate with Broken Ligament Univariant WF o This SIF solution is for a through thickness crack a
12. an internal error handling issue which prevented analysis results from being produced e Crack cases EC04 ECOS5 Corrected a batchfile format error when writing crack size data preventing analyses from being run NASCCS Fixes e Crack case CC11 Stress grid input was missing from the batch file preventing an analysis to be run 20 NASMAT Additions Added crack growth data for the following materials Steel C4DF21AB01 4340 190 UTS Aluminum Alloys M2AD23ACOI1A 2014 T6 forging M2KN11ACO1 2524 T3 sheet M2KN12ACO1 2524 T3 sheet M2SA11AC01 2050 T84 plate M2SA12ACO01 2050 T84 plate M2SAI5ACO01 2050 T84 plate M6GB11AB01 6156 T6 sheet M6GB11AC01 6156 T6 sheet M6GB12AB01 6156 T6 sheet M6GB12AC01 6156 T6 sheet M7GJ11ACO1C 7050 T7451 plate M7GJ12ACO1D 7050 T7451 plate Magnesium Alloys T2NA51ACO1 ZE41A T5 casting T2NA52ACO1 ZE41A T5 casting T2NA54ACO1 ZE41A T5 casting T2NA55ACO1 ZE41A T5 casting NASMAT Changes Removed certain errant data points from the following two Aluminum material IDs M2AD23AB01A 2014 T6 forging and M7PF11ABO01B 7150 T7751 plate Removed the data for the following Aluminum material ID M2AD23AB01B 2014 T6 forging Changes were made in the materials files using M2KN in the material ID for 2524 T3 and retaining M2LA exclusively for 2618 T6 The material ID for data added in v6 2a for 7050 T7451 Aluminum alloy ha
13. d For crack case ECO05 the crack tip designations in the failure message for this model were misleading when the FAD analysis option was used The output has been modified to be consistent with the crack tip designations shown in the GUI bitmap FAD output files out4 outS and Newman TPFC output file out6 are now all saved back to the input file directory after computations have completed and are renamed with the project input file name similar to out1 and out2 On the Computations tab if any items in the Select Details to Show listbox were highlighted prior to re running an analysis those selections were erroneously cleared requiring the user to unnecessarily re select them for repeated viewing Choosing Shakedown correctly forces OPS on but did not automatically increase the size of the user input stress grids Default values for Schedule and Block interval for controlling output frequency were missing after some input files were loaded User material IDs longer than 15 digits caused intermittent GUI problems When plotting material IDs comparison plots containing more than six IDs caused plotting problems Material file values were reloaded in error whenever Options Units was selected to change units in the GUI For crack case TCO3 an error was corrected in the conversion of pin load bearing stress S3 during transition from TCO3 to TC02 The material plots for Basic and Comparison fits were modified to use th
14. d material properties However FASTRAN uses a unique modified Dugdale strip yield model to simulate plasticity induced crack closure in the vicinity of the fatigue crack tip for improved accuracy in the prediction of load ratio load history and crack size effects The existing strip yield module in NASGRO which is called STRIPY has similar functionality to FASTRAN but many small differences in the details The most recent version of FASTRAN 5 3 has been interfaced with the current version of NASGRO and is now included in NASGRO v6 2 in a semi independent form FASTRAN cannot currently be executed in NASGRO through the NASGRO GUI In order to execute FASTRAN through NASGRO the input deck must be manually generated directly from available NASGRO NASFLA and FASTRAN input decks and the program must be executed interactively in the MS Windows system command windows so called batch mode The description of these two steps generating input decks and program execution is described in the new Appendix Y of the NASGRO Reference Manual A complete User s Manual for FASTRAN 5 3 including a complete description of the input file structure is also included The NASGRO development team plans to integrate FASTRAN into the NASFLA GUI and to enable many NASGRO features to be used with FASTRAN and vice versa in future years subject to available funding Linking Excel to NASFLA Beginning with NASGRO v6 2 several customized Excel worksheets are
15. e screen value for Threshold Alpha Previously the default value of 2 0 was used regardless of what was typed on screen Corrected errors in calculation of stress intensity factors and crack growth rates for embedded 4 D cracks EC02 EC04 and ECO5 subjected to load steps with large number of cycles Changes were made to the closure function forcing it to remain non negative everywhere in its domain of definition avoiding possible discontinuities in Keff The only 16 calculations that this change can potentially affect are those involving load steps with highly negative lt 2 stress ratios Corrected calculation of the under load ratio for the 2D modified generalized Willenborg model Some crack sizes were not set properly for the calculation of stress intensity factors and crack growth rate during crack growth analysis for 3D cracks Fixed an output error in SCO1 wherein crack tip stress intensity factors in excess of Keac did not apparently trigger failure despite the calculated life being consistent with earlier v4 22 correct versions Removed previous file size limit of 2000 lines for Alternative 2D stress input files Crack case TC11 corrected the calculation of compounding factors when using the symmetric crack option The correct values for fatigue crack growth threshold will now be properly written to the out2 file for 2D tabular da dN capabilities When changing units using Main Menu Options Units
16. ed Willenborg model New Temperature Interpolation Scheme for Fatigue Crack Growth Data The optional temperature interpolation algorithm which predicts the FCG behavior at intermediate service temperatures bounded by discrete temperatures where the user has specified material properties has been completely revised in NASGRO 6 2a The new interpolation scheme is based on common da dN values instead of common AK values as used previously This new approach resolves some potentially serious unstable interpolative problems that could occur near the threshold and instability regimes in the previous versions In the Paris regime the new approach will give similar but not always identical results to the previous approach Illustration of FCG Curves Interpolated between User defined Curves at T1 and T2 da dN Efficiency Improvement for Large Long Block Spectrum Files The internal algorithms for reading and storing data from long block spectrum files have been revised The new algorithms can substantially reduce total computation time for NASFLA analyses using very large spectrum files Improvements to Calculation Modes for Computing Initial Crack Size or Scale Factor A new solution algorithm was implemented for the two inverse calculation modes that allow the user to compute an initial flaw size given a target life and to compute a scale factor multiplier on the spectrum given a target life These alternate calculation modes are a
17. esaved e Upon completion of an analysis the GUI will now automatically display the Output Summary information in the display window on the Computations tab Previously the user was required to manually click the View Output Summary button for this information to be displayed e Enhanced 2 D tabular da dN plotting capabilities to plot user provided da dN vs dK curves even if the curves intersect e Improved compounding capabilities issuing error messages to the outl file if user specified crack sizes are outside the bounds of the compounding tables Also in NASSIF Changes and Additions to NASFLA Materials Curve Fits e Altered the descriptive text for each material in each of the user multi temperature template files in US customary and in metric units to be in both systems of units allowing the user when making choices to view the textual part in both systems simultaneously e Changed the NASGRO equation curve fits constants for 7050 T7451 aluminum in L T and T L orientations based on newly acquired data Material IDs M7GJ11AC1 and M7GJ12AC1 e NASGRO equation curve fit was added for AerMet 100 steel EINB18AC1 e The materials file ID ELNB23AB1 AerMet 100 was changed to ELINB18AB1 to make it consistent with the data upon which the fit was based 13 NASGRO equation curve fits were added for the following aluminum alloys o 2524 T3 sheet in L T orientation M2KN11AC1 2524 T3 sheet in T L orientation M2 KN12
18. lution to a two crack symmetric solution was updated to include an additional boundary correction factor The results have been validated against FE results Also in NASSIF Crack cases TC17 TC18 TC19 Revised Appendix B to include net section yield NSY analysis Also in NASSIF NASCCS amp NASGLS 12 e Crack case SC13 Added a warning message indicating solution inaccuracy if the ratio of fillet radius r to bolt major diameter D 1 D is outside the numerical range of 0 005 1 0 Also in NASSIF NASCCS amp NASGLS e Removed the View curvefit button from the Material tab for non NASGRO material selections This button provided no functionality for these choices and only displayed the message Material plots still under development for this combination of material source and format when clicked This button remains active to provide plotting functionality for NASGRO material files both temperature and non temperature using the NASGRO equation constants Data format e For 3D and 4D crack cases SC17 non symmetric SC18 non symmetric SC19 EC02 EC04 EC05 the selection of O initially for the Cth value option radiobox on the Material tab is no longer allowed In these cases this option will be grayed out and the radiobox choice will default to 0 throughout Any previously created input files for these cases containing this setting will be loaded with O throughout instead and the input file will be r
19. n schemes is available piece wise linear or Hermite polynomial When using the 1 D table AKeff option with strip yield an additional option is now available that allows the user to represent the behavior in the threshold and instability regions in the form of the NASGRO or FASTRAN equations with the default being neither i e just using the tabular data A view of the NASFLA material tab GUI for the 1 D table and AKeff option is shown below ZA NASELA Crack Growth Analysis B6 H Geometry A Geom Tables i Material an Load Blocks Build Schedule EF outputoptions SF Computations Load interaction model Material properties Nor Interaction Data source New data Save input to User material file after computations C Constant Closure syenee ETETE Generalized Willenborg alias gt table da dN vs Ke Chang Willenborg Show materials list Strip Yield a 2 character alloy code description constraint model ye Constant NASA 4 char heat treat code description gF I da dN multiplicative factor Through crack toughness computed from Ke value entered directly C K1c k Bk equation Ke v thickness table Material properties ID code M7 UTS Yield Kle Crack growth parameters 1D table da dN dKeff A Alpha Initial defect choice User set pl stress strain constraint transition Closed fatigue crack Open saweut v lt E gt Threshold and instability
20. of this recommendation 22 NASGRO 6 20 data files Install Program Choose a folder on your local PC to install NASGRO 6 20 data files Click the button to the right to browse folders C Users jcardinal D ocuments nasgro620f Disk space needed 88 Mb Available disk space 389175 IMPORTANT NOTES 1 For NASGRO to be able to access these data files later the installation process requires appropriate read write privileges for the configuration file nasgro ini in the C WwINDOW S folder This folder may be called C WinNT in some Windows versions 2 Some Windows versions are known to impose severe restrictions on programs abilitiy to write to data files located in the Program Files folder or its subfolders Users are strongly urged to choose a folder under My Documents as the installation location for the NASGRO data files Click Nest to continue lt Back Exit
21. putOptions ZF Computations Load interaction model Material properties Nor Interaction Data source New data ma Save input to User material file after computations C Constant Closure neoc p z PiGeremiced Wiebo ata format 2 D table da dN vs dK and Ra Chang Willenborg Show materials list Strip Yield 2 character alloy code description 4 char heat treat code description I da dN multiplicative factor Through crack toughness computed from Ke value entered directly C K1c k Bk equation Ke v thickness table Material properties ID code M7 UTS Yield Kle Crack growth parameters 2D table da dN data type Diff da dN set for each R Same da dN set for all A R gt R R gt dad K __ da dN E ee ws lt gt Interpolation type for R Interpolation type for dK Linear Cubic spline C Walkerlogic Linear C Hermite Set options and plot I Save expanded table to separate text file Plotting capabilities were added to NASGRO v6 2 to display user supplied tabular da dN AKdata These capabilities allow the user to plot da dN vs AK data including the original data points the interpolation curves for the table stress ratios and the interpolation curves for additional user specified stress ratios The GUI also allows the user to plot the interpolation curves of AK vs R at each of the specified da dN levels The number of tabular data points that can
22. ression Full Two Sign Independent Type Cases Crack Case NASGRO v6 1 amp Earlier Clipping Range Cycles Plate TC03 TCO2 a Two Sign Indep Cycles X X Lug TC04 none Compression Clipped xX Plate TCOS none Two Sign Indep Cycles x X Plate TC09 none Two Sign Indep Cycles Tube TC10 none Full Range X Plate cco2 TCO3 Mixed c X Lug cco3 TC04 Compression Clipped X Plate CC04 b TCO3 Mixed c X Plate CC07 b TC03 Mixed c X Plate SCi11 TCO3 Mixed c X Lug SC12 TC04 Full Range X Notes a Pin load converted to equivalent Tension Bending after transition to TCO2 b GUI graphic revised to show wavy bottom of plate to remove impression that these models could be lugs c These confusing mixed approaches details omitted will no longer be used Default option x Option available Option not available Improved Tabular Fatigue Crack Growth Rate Data Capabilities The capability to input fatigue crack growth rate data in the form of tabular da dN AK data sets was completely revised and improved in NASFLA for v6 2 NASGRO v6 2 provides three kinds of tabular da dN approaches 1 1 D table of da dN vs AK 2 1 D table of da dN vs AKeff 3 2 D table of da dN vs AK and R The 7 D table of da dN vs AK option is for a single R ratio and is available only for the non interaction crack growth model The I D table of da dN vs AKeff option applies to only the strip yield model For each of these 1 D formats a choice of two interpolatio
23. s been changed to M2GJ12ACOI1D 21 NASMAT Fixes e Fixed crash when attempting to save da dN DK data to the user file that had been converted from a vs N data e Corrected problems that occurred when adding material fits to user material files Existing IDs weren t being updated new entries and IDs were not added in proper order and GUI would issue debug alert messages and crash e When entering da dN DK data or a vs N data via a text file the use of a T or t in the Text File Information dialog to represent a Tab delimiter has been fixed and now functions properly NASFORM Fixes e The NASFORM GUI would not display the NASGRO user manual if the programs were installed to any location other than the default location suggested by the installer This has been fixed Installation of NASGRO Data Files It is now highly recommended for Windows Vista and Windows 7 users to NOT install the NASGRO data files in the C Program Files location These two operating systems impose severe restrictions on programs ability to write to data files located in the Program Files folder or its subfolders Therefore My Documents or Documents is now suggested as the default installation path for the NASGRO data files installer as shown in the data files install screen on the right Appendix I the installation instructions has been revised accordingly and the data files installer s dialog box notifies the user
24. s specified e For crack case TC12 the incorrect handling of internal stress quantity indicators had prevented plotting of stress grid data This has been fixed e For crack cases SC11 SC12 and SC18 when loading an input file containing SIF compounding data the number of SIF compounding grids was not being properly assigned from the saved values due to the c then a display configuration used for these geometries This has been fixed 18 When loading an input file containing SIF compounding tables a warning message would sometimes be displayed in error stating the table currently displayed was outside the new range This has been corrected For crack cases TC17 and TC19 an error was corrected in the net section stress calculation for remote tension and bending For crack case DTO3 an error in the batch file was corrected that prevented an analysis to be run if the number of columns contained in any geometry table was greater than 13 and a multiple of 7 Also in NASGLS The input modified flag was being erroneously set by using the Show tables for radio box on the GeomTables tab for crack case DTO3 and all crack cases that use SIF Compounding This radio box enables data or SIF Compounding tables for a specific crack tip to be shown and does not alter data As such this flag should not be set Also in NASGLS For crack case CC08 an incorrect geometric check in the code caused erroneous NAN FO values to be printed in
25. s the full range into two independent cycles one from zero to Kminl and the other from zero to Kmax is available only for TCO3 TCO5 and TCO9 with TCO9 having only this option available In NASGRO v6 1 and earlier some models the lugs TC04 and CC03 used compression clipping others used the full range approach CC04 CC07 SC11 and SC12 and still others used the two sign independent cycles approach TC03 TC05 while TC10 and CC02 used a mixed approach This caused inconsistencies when comparing results and was confusing In NASGRO v6 2 the compression clipping option is now the default however the full range approach is also available The capability to use the third option was retained in v6 2 for those models that previously had it TCO3 and TC05 The calculation for TC09 however remains unchanged from v6 1 and only has the third option available See the summary table below for additional details Note that previously existing input files nasfla in created with earlier NASGRO versions will be loaded into the v6 2 NASFLA GUI retaining the previously run option if available Otherwise the NASGRO v6 2 default option will be used Pin Load Options by Crack Case for NASGRO v6 2 Compared with Previous Approaches Pin Loaded Transitions to Previous Options Implemented for NASGRO v6 2 Part Crack Pin Loaded Approach Comp
26. t a hole in a plate with one of the net sections completely broken through o This crack case can be used to describe a continuing damage scenario after the short ligament in the TC13 crack case is broken through and a through thickness crack initiates at the opposite side of the hole The broken ligament is represented by two parallel edge surfaces with an infinitesimal gap Stresses can be applied as remote tension in plane bending or un cracked crack plane stresses Wey Sttttttttt i 0 1 2 3 Sitti a D ar Seg Sz TC19 Broken Ligament e TC13 Through Crack s at Offset Hole in Plate Addition of In Plane Remote Bending Capability Previously stresses could be applied to crack case TC13 only as local crack plane stresses or as remote uniform tension Based on the algorithm used for new crack case TC 18 it is also now possible to apply remote in plane bending stresses to TC13 S TC13 now accepts a remote in plane bending stress S2 Sotttt tt ttf ad B D cm ft e TC16 Through Crack In Thin Curved Stiffened Panel with Bulging Addition of Capability to Interpolate for Rivet Spacing Previously when choosing to use the Rooke amp Cartwright correction in crack case TC16 the user was restricted to a choice of three rivet spacing ratios d L 1 3 1 6 and 1 12 Now in NASGRO v6 2 the radio button choices for these three d L ratios have been replaced by a text input box that removes the restriction of using only
27. the following Kc fields shown on the Material tab for New Data for each selection of the radiobox Through crack toughness computed from were not being converted Kc Klc and the Ke vs thickness table After a material has been selected if the Material Selection dialog is re run it was possible to undo the previous Material Category Alloy and Heat Treat selections then return to the Material tab by clicking OK with no selection for any or all of these three choices This enabled an input file to be saved without a chosen material category alloy heat treat which would then load incorrectly due to this missing data For multi temperature analyses only the NASGRO format long block file type may now be selected since this is the only format that allows for temperature data After changing temperature based material selections on the Material tab it was possible that the stress values in the Load Blocks grid displaying the BLOCKT file data could be manually changed Improved the capabilities of crack size limits to include intra load step checking of crack size in addition to the inter load step checking already performed Elapsed execution time is now properly calculated for very small durations 17 e User entered tension and compression stress data files grids can now be visualized in the GUI both with and without the OPS option by using the Geometry tab s Plot Stresses button Also in NASSIF e Overcame a 2000
28. to assign a stress label for display in various outputs but was confusing This 19 output display will now be hardcoded to SO conforming to the existing stress labels throughout the GUI which are also SO The Geometry Grid field Stress description will continue to be used to describe the stress Also in NASGLS o The expression shown in the crack case s bitmap has been revised to use superscripts instead of two asterisks to more clearly depict exponents Also in NASGLS e Removed crack case DT04 Also in NASGLS NASSIF Fixes e Crack case SS12 Stress was not properly computed was zero when Load input was set to Pin load P e Crack case TC11 o Errant Stress file does not exist message displayed and program crash occurred o Crack lengths were displayed incorrectly in the output showing only the final crack length when computing correction factors e Crack cases TC13 TC17 TC18 TC19 Output Options tab showed incorrect stress quantity labels for the crack plane stress definition of Tension bend e Crack case TC15 Screen layout error for SIF Compounding checkbox e Crack case Corrected an error in the OPS internal routines which prevented analysis results from being produced e Crack cases CC09 CC10 EC04 SC19 For bivariant analyses with user provided stress input files abnormal behavior in calculations was observed for a c values near 1 0 This has been corrected e Crack case CC11 Corrected
29. uld be presented for each old format input file encountered which slowed down this automation significantly Additionally if the user opts to save old formats a list of those saved files will now be presented at the end of processing in the output window Also in NASSIF NASCCS amp NASGLS e Whenever a material file parameter value is changed manually by the user a note will now be displayed at the top of the material tab to indicate this change This note makes clear that at least one value is no longer a file value which is needed since the data source field will still show material file Additionally when a material plot is performed on changed values the plot title will show as NASGRO EQN curve Previously the title was Basic Fit to indicate the NASGRO equation curve generated 11 used the material file constants and was fitted to the data both of which are no longer true once any parameter value has been altered Labels on the Output Options tab Block interval for printing steps in a block and if a non zero choice is made the labels for the boxes below it have been changed to make clear that quantities like maxima when printed are not for individual step maxima but rather the running block maximum to the end of the step being printed The text displayed under the Cth value option on the Material tab was altered to be the input cell value throughout to inform the user that if the value in this cell is changed during
30. vailable via the Options item on the NASFLA toolbar 121 NASFLA Crack Growth Analysis TCO1 NASFLA in File efi Tools Help fp Unts gt epee f Material Load Blocks BS Elasticity type Tr Calculation mode gt I v Calculate crack growth given initial Flaw size y Tooltips Calculate initial flaw size given target life Calculate scale factor multiplier given target life Set user tool E GUI Thickness t Initial flaw size c Save options now Save options on exit In making the inverse solution algorithm more robust there were a series of improvements and bug fixes made including e Anew more accurate convergence criterion was implemented such that the relative error between the actual calculated fatigue life in cycles and the target life is less than one percent In previous versions of NASGRO the convergence criterion was based on schedules and could be very inaccurate depending on the content of the schedule e Capability was added to perform these two types of inverse calculations for 3 dof and 4 dof crack cases e Revised output formats in the out1 file Implementation of FASTRAN Crack Growth Program The FASTRAN computer program is a specialized fatigue crack growth analysis tool developed by J C Newman Jr FASTRAN performs the same basic function as NASGRO evaluate fatigue crack growth in metallic structures as a function of cyclic applied loads crack and component geometry an
31. wth model and the NASGRO equation constants to avoid overlap of controls for Strip Yield transition grid and Threshold Alpha Changing the Crack Growth Model selection on the Material Tab did not always correctly repopulate the Data Format dropdown box with all possible selections Crack case CC09 A bug that caused the long block feature to malfunction with this model has been fixed When loading tabular 2 D material data using different da dN sets for each R from file some rows were not loaded into the grid correctly if they contained leading blanks The FAD failure criterion option has been fixed to work with 1D FCG table 2D FCG table and Walker equation constants data formats GUI sometimes incorrectly displayed the NASGRO equation materials for selection instead of the correct Walker equation materials when Chang Willenborg was chosen as the Crack Growth Model User was not prompted to resave input file when Crack Growth Model selection was changed Additionally the default material parameter values for Willenborg models Shutoff Overload Ratio 3 0 and PhiO 0 4 were incorrectly erased when a new project was chosen or an existing GUI input file was loaded 15 Corrected column position of a over c data in output viewing window Output data column headers initially missing when selecting all details to show on the Computations tab Proper headers for out2 and csv files were missing when FAD analysis option was use
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