Hello,
I am trying to write down a kinematic hardening umat for Abaqus. For this reason i need to reate a cyclic loading in my input file. I try the solution suggested in the internet however could not solve my problem.
My model has a total time of 1000, i want it to start with 1mm displacement (tension) and go to -1mm dipslacement(compression) and come back to 1mm again at the 1000th second. I tried to write down the amplitude function below, however i did not work. Can you please suggest me a solution for my problem. Thank you in advance!
Related part of the input file:
*********************************************************************
** INITIAL CONDITIONS, MODEL DATA
*********************************************************************
*Initial Conditions, Type=Temperature
nall,
*********************************************************************
** BOUNDARY CONDITIONS, MODEL DATA
*********************************************************************
**
*Nset,nset=BOT
1,2
*Nset,nset=TOP
3,4
*Nset,nset=xx
1
*Boundary
BOT,2
xx,1
*Nset,nset=REF
1
*Amplitude, name=Amp-1, time=TOTAL TIME
0., 1., 500., 0., 1000., 1.
********************************************************************
** ANALYSIS STEP, STANDARD
****************************************************************
*STEP, Name=Load, nlgeom=yes,inc=20000
*Static
1.0,1000,1.d-10,25.0
*CONTROLS, PARAMETERS=LINE SEARCH
10,1.0,0.0001,0.25,1.0
*CONTROLS, PARAMETERS=TIME INCREMENTATION
,,,,,,,10,,,,,,
**
*Boundary, type=displacement
TOP,2,2,1.0
I could be wrong, but shouldn't your amplitude be 0.,1.,500.,-1., 1000.,1. if you want to model the compression?
Hi Çağatay Kasar ,
you can easily accomplish it using Python scripting.
You can write something like that:
def generate_cyclic_model(length, strain, number_of_cycles, model='Model-1'):
…..m=mdb.models[model]
…..p=m.parts['Part-1']
…..a=m.rootAssembly
…..i=a.instances['Part-1-1']
…..initial_inc=0.01
…..maxInc=0.15
…..point=p.ReferencePoint(point=(1.0, 0.0, 0.0))
…..a.Set(name='point', referencePoints=(i.referencePoints[point.id], ))
…..m.StaticStep(name='Step-1', previous='Initial', maxNumInc=1000000000, initialInc=initial_inc, minInc=1e-27, maxInc=0.15, nlgeom=ON)
…..displacement = length * strain
…..m.DisplacementBC(amplitude=UNSET, createStepName='Step-1',distributionType=UNIFORM, fieldName='', fixed=OFF, localCsys=None, name='BC-4', region=a.sets['point'], u2=displacement)
…..i = 2
…..bc=m.boundaryConditions['BC-4']
…..while i < number_of_cycles:
…..…..m.StaticStep(name='Step-{}'.format(i), previous='Step-{}'.format(i-1))
…..…..m.steps['Step-{}'.format(i)].setValues(initialInc=initial_inc, maxInc=maxInc,
…..…..maxNumInc=10000)
…..…..if i % 2 == 0:
…..…..…..bc.setValuesInStep(stepName='Step-{}'.format(i), u2=-displacement)
…..…..else:
…..…..…..bc.setValuesInStep(stepName='Step-{}'.format(i), u2=displacement)
…..…..i += 1
You can also find the code in the attached py.
Cheers,
Claus
You may use amplitude with PERIODIC definition. You can choose between Sin or Cos and have to provide angular frequency (omega)(rad/s) and the duration of the step shall decide the number of cycles.
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