I am trying to calibrate my sand using Excalibre. I tried some triaxial element tests using Abaqus. However the results are different between Excalibre and Abaqus.
Calibrate hypoplastic model
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Hi Sahar, please also check the initial void ratio for triaxial tests indicated by excalibre. This is the only issue I can think about, otherwise you have some error in Abaqus input.
Hi David, this is the input file for my abaqus model. This input file is for the sand example “lapProtocalTemplateSand” shared on Excalibre automatic calibration page. I got the hypoplastic parameters from Excalibre and input them into Abaqus. The peak of deviatoric stressstrain curve from Abaqus is much higher than the experimental curve and the Excalibre curve. I can’t find the mistake in my input.
*Heading
** Job name: CD50ExcalibreSampleSand Model name: CD50ExcalibreSampleSand
** Generated by: Abaqus/CAE 2016
*Preprint, echo=NO, model=NO, history=NO, contact=NO
**
** PARTS
**
*Part, name=Part1
*Node
1, 0., 0.
2, 0.100000001, 0.
3, 0., 0.100000001
4, 0.100000001, 0.100000001
5, 0.0500000007, 0.
6, 0.100000001, 0.0500000007
7, 0.0500000007, 0.100000001
8, 0., 0.0500000007
*Element, type=CAX8
1, 1, 2, 4, 3, 5, 6, 7, 8
*Nset, nset=Set1, generate
1, 8, 1
*Elset, elset=Set1
1,
*Nset, nset=topn
3, 4, 7
*Nset, nset=botn
1, 2, 5
*Nset, nset=axis
1, 3, 8
** Section: Section1
*Solid Section, elset=Set1, material=Material1
,
*End Part
**
**
** ASSEMBLY
**
*Assembly, name=Assembly
**
*Instance, name=Part11, part=Part1
*End Instance
**
*Elset, elset=EL, instance=Part11
1,
*Elset, elset=_Surf1_S2, internal, instance=Part11
1,
*Elset, elset=_Surf1_S3, internal, instance=Part11
1,
*Surface, type=ELEMENT, name=Surf1
_Surf1_S2, S2
_Surf1_S3, S3
*End Assembly
**
** MATERIALS
**
*Material, name=Material1
*Density
1.0927,
*Depvar
13,
*User Material, constants=16, unsymm
36.5, 1.,49846., 0.243, 0.572, 1.144, 1.372, 0.09
4.5, 0., 0., 0., 0., 0., 0., 0.51
**
** BOUNDARY CONDITIONS
**
** Name: axisbc Type: Displacement/Rotation
*Boundary
Part11.axis, 1, 1
** Name: botbc Type: Displacement/Rotation
*Boundary
Part11.botn, 2, 2
** Name: topbc Type: Displacement/Rotation
*Boundary
Part11.topn, 2, 2
**
** PREDEFINED FIELDS
**
** Name: Predefined Field1 Type: Geostatic stress
*Initial Conditions, type=STRESS, GEOSTATIC
Part11.Set1, 50., 0.1, 50., 0., 1., 1.
** Name: Predefined Field2 Type: Void ratio
*Initial Conditions, TYPE=RATIO
Part11.Set1, 0.51
** —————————————————————
**
** STEP: Step1
**
*Step, name=Step1, nlgeom=NO
*Geostatic
**
** LOADS
**
** Name: Load1 Type: Pressure
*Dsload
Surf1, P, 50.
**
** OUTPUT REQUESTS
**
*Restart, write, frequency=0
**
** FIELD OUTPUT: FOutput1
**
*Output, field
*Node Output
U,
*Element Output, directions=YES
E, S
**
** HISTORY OUTPUT: HOutput1
**
*Output, history, variable=PRESELECT
*End Step
** —————————————————————
**
** STEP: Step2
**
*Step, name=Step2, nlgeom=NO, inc=1000
*Static
0.001, 1., 1e15, 1.
**
** BOUNDARY CONDITIONS
**
** Name: topbc Type: Displacement/Rotation
*Boundary
Part11.topn, 2, 2, 0.05
**
** LOADS
**
** Name: Load1 Type: Pressure
*Dsload
Surf1, P, 50.
**
** OUTPUT REQUESTS
**
*Restart, write, frequency=0
**
** FIELD OUTPUT: FOutput1
**
*Output, field
*Node Output
U,
*Element Output, directions=YES
E, S
**
** HISTORY OUTPUT: HOutput1
**
*Output, history, variable=PRESELECT
*End Step