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THE CRITICAL FRACTURE ENERGY erro using ABAQUS simulate fracturing

hanrrycn's picture

I've build a 2D dimensional model of hydraulic fracturing based on the example on Verification Manual. I use the same data from the example. I build the model in CAE and edit it in input file to add cohesive element and cflow. however, the simulation stoped after 10 minutes indicating that a erro:"THE CRITICAL FRACTURE ENERGY IS SMALLER THAN THE ELASTIC ENERGY PRIOR TO DAMAGE INITIATION. THE DATA MIGHT NOT BE SPECIFIED CORRECTLY FOR *DAMAGE INITIATION OR *DAMAGE EVOLUTION. 

I used the same data from the example, how can I be wrong while the example can run successfully. I increase the first data in *Damage Initiation and run the simulation again. the fracture continue propogate along the cohesive element but after fracture a few more element, the simulation stoped again with the same erro.

I checked every thing and compare my input file and the example file, the only thing difference is the mesh goemetry. later, I tried to increase the rate of change of flow rate, the same erro occured sooer, wich mean the fracturing will break donw less cohesive element before erro occurs.

I have no idea what is going wrong.  I don't think it's the problem of material propertiy. is this can be mesh problem? too coarse or too fine?

Need your helpCry 

 

PS: original example file(hydrfract-coh2d4p.inp) and my input file(frac2D.inp) attached 

AttachmentSize
Plain text icon frac2D.txt158.43 KB
Plain text icon hydrfract-coh2d4p.txt140.43 KB
hanrrycn's picture

since no one answered my question. I tried to build another model to prove my hypothesis. I use the same data but different mesh stiyle (the same size as before)around the cohesive element. and it works!

 

but I still don't know why the mesh around the cohesive element have such a big impact on the results since it has the same size as before  

Hello Hanrrycn,

My Ph.D. is very similar to this subject. I have some questions about how you solved this problem. First of all, I want to know how you applied initial stress condition ?I mean how did you calculate them?because they wrote subroutine SIGINI for that.

my second problem is that how to apply pore pressure Boundary condition and I see you have none. However, in the corresponding Abaqus manual, they defined pore pressure which is very confusing for me. here I copy and paste .

*Boundary,user
**_PickedSet5, 8, 8, 1
TOP, 8, 8, 1
BOT, 8, 8, 1

Hello Hanrrycn,

My Ph.D. is very similar to this subject. I have some questions about how you solved this problem. First of all, I want to know how you applied initial stress condition ?I mean how did you calculate them?because they wrote subroutine SIGINI for that.

my second problem is that how to apply pore pressure Boundary condition and I see you have none. However, in the corresponding Abaqus manual, they defined pore pressure which is very confusing for me. here I copy and paste .

*Boundary,user
**_PickedSet5, 8, 8, 1
TOP, 8, 8, 1
BOT, 8, 8, 1

Hello Hanrrycn,

My Ph.D. is very similar to this subject. I have some questions about how you solved this problem. First of all, I want to know how you applied initial stress condition ?I mean how did you calculate them?because they wrote subroutine SIGINI for that.

my second problem is that how to apply pore pressure Boundary condition and I see you have none. However, in the corresponding Abaqus manual, they defined pore pressure which is very confusing for me. here I copy and paste .

*Boundary,user
**_PickedSet5, 8, 8, 1
TOP, 8, 8, 1
BOT, 8, 8, 1

Regards,

Ellla

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