Visualizing shear and tension cracks in a UCS test - UDEC 7

Using UDEC 7, I am performing a uniaxial compressive test on a rock sample. I have written a fish code to calculate the number and length of shear and tension cracks. My previous post provides the details (Dividing by zero- About contact length). I would like to have suggestions on how can I visualize the cracks in UDEC. Given below is a figure for the reference. Is there any fish function I can use? Kindly provide your suggestions. Thank you.

Just a quick reply, since nobody else is answering:

  • In your example figure the crack paths are obviously drawn by hand in post-production. And only for a selected subset of fractures. If you want it like that, you’d have to go a similar route

  • If I am not mistaken, in UDEC7 you can plot Joints - Color by Label and then choose “State” as you coloring variable. Then just adjust coloring as necessary, but I haven’t tried that.

  • You can also plot any joint-property, so you could e.g. write a fish function that (temporarily for evaluation) overwrites some property with a damage indicator (e.g. set the normal-stiffness to 0 for undamaged contacts and 1 for shear damage etc.). With some clever use of the color scheme (transparent for 0) you could get the desired effect


Thank you. For point 2 and 3, I will start working and see how it goes. For point 1, if the cracks paths are marked “shear” and “tension” cracks manually, then how can one know for sure which cracks are because of shear and which ones are due to tension? Is it drawn using common sense like cracks which pass along the center are more likely to be shear cracks while those near the edges are tensile?

I can’t speak for the author, but it is possible that he/she either marked those open joints by inclination (vertically aligned tensile fracture, inclined shear fractures) or maybe it was done based on looking at one of the methods I proposed, but then “simplified” for the publication.

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Thank you for the guidance. This much explanation is enough to move forward . :slight_smile:

I found the answer and I am putting it here for the benefit of the community. @MariamJ
Instead of using GIIC interface, the other UDEC interface UDEC GUI has the ability to visualize the fracture states. Check the figure below.

Thus, one does not need to create a separate fish program. :slight_smile:

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