Information and insight from fracture mechanics experts

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

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