Current Version

Introduction The crack growth life prediction program, AFGROW, (Air Force Grow) is the latest version of a program that was previously known as MODGRO. The executable for Windows 9x/NT/2k is available. Changes Version 4.0011.14 Released: Jun 29, 2006 Fixed a problem that was causing AFGROW to run significantly slower than earlier versions for many cases. This was a result of changes that had been made to accomodate crack IDs for the multiple crack models. Bug fix for FASTRAN retardation model. The FASTRAN model was not developed to be used for multiple crack (offset cracks) cases in which it is necessary to independently calculate crack growth for multiple crack tips. Expanded COM capabilities Additions and improvements to the on-line help Minor bug fixes and interface modifications Acknowledgement User input was instrumental in bringing about this release. It would be next to impossible to find all bugs, major or minor, without the user base giving us their comments and suggestions. We encourage all our users to send us their comments and suggestions. Previous Releases Version 4.0010.13 Released: Feb 03, 2006 Modified the K-Solutionn for the bearing load case for the Single/double corner & surface cracked classic models. The new solutions Were revised after much work had been done to compare the old through crack solutions to detailed FE analyses. The part-through cases were modified using the Newman-Raju equations along with a bearing load correction. Modified the K-Solutions for the Corner and Through-the-Thickness Classic lug models. These new solutions are based entirely on detailed lug FEMs. The resulting solutions are a combination of curve fit and table look-up using these data. Added a feature to the predict, preferences menu to allow users to select the pin loading boundary conditions used in the FEM for the Classic lug solutions. The default condition is to use the cosine load distribution for the corner crack until the crack reaches 70% of the thickness, then transition to the Spring boundary condition when the crack reaches 80% of the thickness. The through crack case default is the Spring boundary condition (see the help for more information. Added the ability for users to develop Plug-In K-Solutions and select them from the model menu, under the "Plug-In" option. Drawing tools have also been added to AFGROW so that the user-defined plug-in models may be animated in the annimation frame. Expanded COM capabilities Additions and improvements to the on-line help Minor bug fixes and interface modifications Version 4.0009e.12 Released: Sep 20, 2004 Bug fix for the NASGRO Equation (DKthreshold variable was being calculated as Kmax(threshold) when R < 0). For all rate models (except the Forman equation), AFGROW uses Kmax in place of Delta K. As a result, we were inadvertantly using Kmax(threshold) in the NASGRO equation when we should have converted back to Delta K for use in the NASGRO equation. This bug fix was included in version 4.0008.12.11, but was re-introduced in version 4.0009.12. We apologize for our error here. Bug fix for the CalculateBetas feature in the COM module. Bug fix for RunFrozPredict in the COM module Bug fix in the Forman equation when the Willenborg or Hsu model is used. The Willenborg and Hsu models update the effective stress ratio based on Kmax and Kmin. This happens after the Kmax and Kmin values are initially computed. The updated stress ratiois not being passed to the Forman equation. Additions and improvements to the on-line help Minor bug fixes and interface modifications Version 4.0009.12 Released: Jun 7, 2004 Added the FASTRAN retardation model Added the Hsu retardation model Expanded the table-lookup database for the classic oblique crack solution New Advanced Tabular Solution for double, unsymmetric corner cracks at a hole (tension, bending, and bearing loading) Bug fix for the classic single and double corner cracked hole model (bending load case) Changed the position and crack length definitions in the Advanced Models (Multiple Crack) Interface. The position of an object is now measured from the left edge of the plate to the center of the object. Crack lengths are now consistent with the Classic Model Interface. Interal crack lengths in the c-direction are half-lengths, a-dimensions are full lengths, cracks attached to holes are measured from the hole edge. XML Input/Output Ability to drag and drop input files to the AFGROW interface Allow the use of a single stress ratio in the table look-up growth rate model (required for the FASTRAN retardation model) Advanced (multiple crack) models now accessible through COM Added the ability for users to turn off the compression adjustment in the Willenborg retardation model Added the ability to enter an initial opening stress directly in the closure retardation model Bug fix in the user-defined beta and residual stress table interpolation Additions and improvements to the on-line help Minor bug fixes and interface modifications Version 4.0008.12.11 Released: Jun 20, 2003 Bug fix for the NASGRO Equation (DKthreshold variable was being calculated as Kmax(threshold) when R < 0). For all rate models (except the Forman equation), AFGROW uses Kmax in place of Delta K. As a result, we were inadvertantly using Kmax(threshold) in the NASGRO equation when we should have converted back to Delta K for use in the NASGRO equation. Bug fix for time dependent spectra (time for the last cycle in each sub-spectra file was added twice) Bug fix for part-through to through crack transition. AFGROW prints the part-through and through crack dimensions at transition for the same number of cycles (to show the starting point for the growth of the through crack. As a result, AFGROW was actually adding cycles twice for the stress level ocurring at the time of transition. The K-Solution for two, symmetric cracks at a hole (both classic and 2-crack models) was updated to solve a problem for short crack lengths where the solution was slightly less than the single crack case. The new curve fit being used was also refined using additional FEM and published data. The difference is not large, but will be noticeable in terms of the predicted life. Solved a minor bug in the 2-crack interface which caused the code to crash when the plate with was changed before any cracks or holes were added Corrected a bug in the status view (bending stress ratio was incorrectly displayed as the bearing stress ratio) Version 4.0007.12.11 Released: Feb 19, 2003 Fixed a bug in the double, symmetric, surface crack K-solution. A few years ago, the finite width correction for all cracked hole models was modified and the new factor was multiplied instead of divided as was previously done (since, the old correction was a secant function (1/cos())). The new factor had been inadvertently divided (copy and paste error). This was the only model affected by this error. Updated the new finite width correction for all cracked hole K-solutions. This is a VERY minor change and will not be noticeable for nearly all cases. It simply reflects the latest curve fit (which had been included in the manual, but not in the code). Version: 4.0006.12.11 Released: Feb 5, 2003 Added significant improvements and bug fixes to the closure model. Fixed a significant bug in the implementation of the NASGRO equation. When R > 0, the equation for Kop/Kmax was incorrectly implemented. Fixed an indexing bug in the interpolation routine used for beta correction as a function of crack length. Modified the COM interface to allow growth rate information to be extracted as a function of Delta K (or Kmax if R < 0). Minor typo/spelling fixes, updated Users Guide and Technical Manual, and updated the Dispatch Interface (COM) Manual. Version: 4.0005.12.10 Released: Jul 24, 2002 Included the ability to add holes to the Two Crack Model option to allow life prediction to first failure for one or two through cracks growing from or toward holes. Fixed a bug in the critical crack length routine that could cause AFGROW to hang (infinite loop) for some very limited cases. Releasing a new version of the cycle counting routine to force the program to do a better job of capturing overal maximum or minimum levels when they may only be counted as a partial cycle. Fixed a minor bug in the crack length vs. cycle plotting routine to allow users to change the legend. Minor typo/spelling fixes and updated Users Guide and Technical Manual. Version: 4.0004.12.10 Released: May 31, 2001 Added the ability to start a life analysis from any point in an input loading spectrum - only available using a COM client program. The function is: SetStartPredictFromCycle(double dCycleNumber) Added a COM function to obtain spectrum information. The function is: long GetSpectrumInfo (double* dCycles, double* dLevels, double* dSubspectra, double* dMaxValue, double* dMinValue) Added the ability to save an input file (*.da3) from a COM client program. The function is: SaveProblemDefFile(BSTR strFileName) Fixed a bug in the output interval option which could cause AFGROW to fail to print output for several intervals immediately after transition from a part-thru to a through-the-thickness crack. Minor typo/spelling fixes and updated the Dispatch Interface (COM) Manual. Version: 4.0003.12.9 Released: Feb 09, 2001 Added the ability to plot crack growth curves for multiple crack dimensions. Added the ability to generate a beta table for a matrix of user-defined crack lengths using the COM server. Added an option to output life in hours from the COM server. Corrected a minor bug in the beta solution for single and double corner cracked holes. This bug would appear in rare cases when a/c is <= 1. Minor typo/spelling fixes, updated the on-line help, and changed the overlay icon in the crack growth plot view. Version: 4.0002.12.8 Released: Sep 26, 2000 Added the ability to view spectrum exceedance plots. Fixed a bug in the crack growth plot in cases where there are a LARGE number of cycles. Fixed a bug in the animation frame when changing from English to Metric units. Fixed a bug in cases where an environment file was saved inside the AFGROW input file (the full path was not being read correctly when it contained spaces). Included a new version of the cycle counting tool with bug fixes and updated help infomation. AFGROW will now print out large numbers of cycles (up to 9,999,999,999,999) and/or small crack lengths as required without truncation or overflow problems. Corrected spelling errors in the status view. Version: 4.0001.11.8 Released: May 19, 2000 Changed the default angle for the corner cracked lug to be consistant with the angles used for the corner cracked hole in a plate. Corrected spelling errors in the status view, and updated the on-line help. Version: 4.00.11.8 Released: April 24, 2000 Added the capability to perform life prediction for 2 independent through cracks. A drag and drop capability has been created to aid in the design of the 2-crack model. A properties dialog has also been added to support this new capability. Added time dependent crack growth capability. Changed the default angle for the C-direction (corner cracked hole) from 0 to 5 degrees. Included an option to change the parametric angles used to determine K in the A and C direction for part through cracks (located in the registry). Added the capability to zoom in and out on the specimen view. New grid control is used in all dialogs which require tabular input. Updated the on-line help for the new two-crack capability. This version is the first version that has been built using Microsoft Visual C++ Version 6.