The accuracy of the GROWTH module, in charge of crack growth analyses, can be mainly validated comparing the calculated stress intensity factors from FEMs which reproduce models whose SIF solutions are available in literature (from handbooks or relevant papers like the one from Newman-Raju ‘Stress Intensity Factor Equations for Cracks in Three-Dimensional Finite Bodies Subjected to Tension and Bending Loads’, which is a commonly accepted reference).

It's to be noted that the reference solutions, equations, shall not be considered ‘precise’ solutions, as they have been derived in the past from calculations, in most of the cases from FEM, with the addition of ‘appropriate’ engineering judgement.

Therefore, when we see differences between our calculated solutions and the reference ones, we can argue whether our solution (on which we control the FEM level or refinement) is more ‘correct’ or the reference one. One argument we can bring in support of this: for example the Newman-Raju equations have been derived calculating SIFs from FEMs where conventional 2nd order elements were used at the crack front, not quarter point elements like LIFING does, and using the Crack Closure Integral method, which is less precise than the M-Integral used by LIFING. Moreover the equations have been derived on the basis of a small selection of c/a crack aspect ratios and a/W parameters.

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Having that said, we sow below three tests:

1. Edge crack in a finite 2D plate, subjected to constant tension load.

2. Edge crack in a finite 2D plate, subjected to in-plane bending.

3. Corner crack in a rectangular 3D plate subjected to constant tension load.

The LIFING calculated SIFs are compared to the available reference solutions.