Abaqus CDPM error - "THE INDEPENDENT VARIABLES MUST BE ARRANGED IN ASCENDING ORDER"? 1

[drennon236]

I am trying to get the correct grout behavior for high strength concrete 90 MPa using concrete damaged plasticity model. I got the data to work for 45 MPa strenght concrete but cannot get the 90 MPa to work. I have tried arranging the variables in ascending and descending order but still cant get it to work - is there something I am not seeing? I know its kind of a big question but at this point im slightly desperate, and need all the help I can get. I can send the CAE file and excel sheet if anyone has the time.

The compressive yield stress goes up from 45 MPa to 90 MPa then down again to 27 MPa, so its not all in ascending order. But its the same way for 45 MPa, it goes up then down and it works for that data. Does anyone know what im doing wrong?

 

[FEA way]

Could you attach the input file from this analysis that shows error ? And the one from the analysis that works properly, if possible.

 

[drennon236]

This is the one that does not work (for 90 MPa). I am not sure if I can upload two files in one post, but the next post is the one that works.

 

[drennon236]

This is the input file that works.

 

[FEA way]

The problem is caused by initial lines of compression hardening and compression damage definitions. For each of them leave only one line with 0 inelastic strain.

 

[drennon236]

Thank you FEA way, Ive been stuck on this for a while now, did not realize it was that simple. Could I ask you a follow up question; when I leave only one line with 0 inelastic strain, either by deleting what is marked in red, or starting the tabular values from a value of 55,81 MPa I get a response line that is a straigh curve, but the response should be similar to what is in the second picture - how should I apply the data Ive been given? - do I simply need to ask for other data? The tensile behavior is correct.

 

[FEA way]

Was the analysis completed ? I've noticed that when this issue with material definition is fixed the analysis runs but fails at about 10% due to convergence issues. Thus you will only get small part of the response curve from such uncompleted analysis. I think that you should use different boundary conditions, like those from Abaqus Verification Guide (Material Verification --> Mechanical properties --> Concrete damaged plasticity).

 

[drennon236]

It does fail at 45 MPa, which is the first value in the tabular data for compressive behavior. Seems it cannot move from elastic to plastic behavior when I just put some interpolated artificial values there to go from 0 to 1 e-6. Think it has to do with boundary conditions or still material definition problem?

 

[FEA way]

You should correct the boundary conditions (use those from Verification Guide example) but in this case it won't solve the convergence issue. Thus the problem is caused by incorrect material data.