Information and insight from fracture mechanics experts

Annual AFGROW User Workshop

The 3rd Annual AFGROW User Workshop was held at the Davis Conference Center in Layton, UT on 11 - 12 Sep 2012. 54 representatives from different companies and government agencies were in attendance. We would like to thank all of our attendees and speakers who have made the AFGROW User Workshop 2012 such a success. As a result of this year,s Workshop, example plug-ins for a corner cracks at a countersunk hole and multiple straight shank holes will be demonstrated. These plug-ins will use StressCheck ® as the real-time K-solver. The 2012 AFGROW User Workshop proceedings are now available online. 

Removing Bonded Repair Capability

As we approach the first commercial release of AFGROW, it makes sense to do a little "code cleaning." Based on user input (or lack thereof), it appears that the bonded repair analysis capability is not being used. Therefore, we are planning to remove the capability from the new release. We are asking for input from anyone who would be adversly affected by this decision.  

New AFGROW Features

Spectrum Filtering Options: Tension and Compression Modification This will allow users to adjust spectrum tension and compression values independently. The primary purpose of this capability is to allow users to model interference fit pins as a pre-load which may be considered to be a function of crack length. The modifications will be in either equation or tabular form. The general capability will allow for a number of input parameters to be used in order to make the capability as flexible as possible. Compression Factors for Stress Intensity Solutions Stress intensity solutions for the crack opening mode are applicable under tensile loading conditions. Examples include a crack at an open hole, and a crack at a hole under bearing load. In the first case, the stress field in the assumed crack plane under remote tension, is quite different in magnitude under remote compression. In the second case, the crack will not see any compression due to the geometry. Although K is not defined under compression loading, the K-values calculated under compression use the same solution as the values calculated under tension loading. These values are then used to determine a crack growth rate for the resulting R-value. The ability to correct this situation may help improve crack growth life predictions for load spectra that includes significant amount of compression loading. Beta Correction for Advanced Through-the-Thickness Cracks AFGROW currently allows users to apply beta correction factors to classic models and corner cracked advanced models. The capability will be added to the advanced through crack cases. This will provide additional modeling flexibility for these cases. K-Solution for an Edge Notch in a Plate A new advanced solution for corner or through crack at an edge notch in a plate is being developed. This will permit users to continue life predictions for continuing damage cases in which a crack has grown from a hole to the near edge, and another crack was growing simultaneously on the opposite side of the hole. Some have reported using an edge crack to simulate this continuing damage condition, but the result will be extremely conservative since the hole radius will tend to reduce the actual K-value for this geometry. The availability of this new solution will provide better accuracy for these types of problems. Comments/suggestions are welcome