Hello,

I have defined a hydraulic fracturing process in a rock based on the Abaqus sample example "hydrfract_xfem_c3d8rp" in which initial geostatic stress is defined through "load> predefined field> stress". In theory geostatic stress has an effect on breakdown pressure as " breakdown pressure= 3 * (minimum horizontal stress) - (maximum horizontal stress) + (rock tensile strength) " but when I change the minimum or maximum horizontal stress in my model, breakdown pressure doesn't change at all. what may cause this and how can I fix this? Any help is appreciated

Thank you

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