Could you please stop deleting previous threads once you get the reply and then creating new ones with basically the same question ?
As I've already said in your first thread, there's no output variable for crack length or its change in Abaqus (only crack propagation direction in form of an angle is available). Thus, you have to measure it manually and you can enter it using XY Data --> From keyboard if you want to create a plot. Maybe you could also create a Python script for this but it won't be easy.
I once used the Meazure software (small open-source software for Windows) to do this for the results of the XFEM crack propagation analysis. After calibrating, you can measure anything on your screen, including cracks visualized in Abaqus.
I am not sure that I can do this. even if I measure the crack length, I have to measure ıt for each step size. What about this way: if I choose crack tip as a set in history output and choose U2 direction to see displacement versus time. It will show the displacement of crack tip. Because crack length = current crack tip-initial crack tip.
To make it clear - exactly what kind of analysis did you perform ? Is it a simulation in which the crack actually propagates through the mesh or contour integral evaluation with stationary crack ?
I see, then the manual method with Meazure software won't work. I think that I would run an additional analysis with crack propagation enabled and then measure the actual length of the crack. Because with the stationary crack model you can get only the crack opening displacement and you would have to apply some analytical formulas to obtain the crack length.
I've seen some formulas for crack length in the Wikipedia article "Compact tension specimen". Maybe you could find more information about this in books about fracture mechanics (like those by D. Broek, E.E. Gdoutos, J.F. Knott, B. Lawn, T.L. Anderson, A.T. Zehnder or other authors) and in research papers. CT specimen is very common and basic so it should be described in detail in literature.
The main question here is what is your crack growth mechanism? Then you need to establish a crack growth model, which you can then determine crack growth rates in terms of time (or cycles).
