There are several methods to consider the imperfection of the structure like the eigenvalue buckling mode, nonlinear buckling mode and weld depressions. But how to define imperfection as an equation in Abaqus software?
use python script :
A=[]
A=[
[1.1158,-0.0276,0.1377,0.0025,-0.0123,-0.0009,-0.0043,0.0008,0.0039,-0.0002,-0.0011],
[1.1421,-0.0457,0.2284,0.0065,0.0326,-0.0022,-0.0109,0.001,-0.0049,-0.0005,0.0027],
[1.1458,-0.0616,0.3079,0.0229,0.1146,-0.0065,0.0327,0,0,-0.0015,-0.0074],
[1.1439,-0.0677,0.3385,0.0316,0.1579,-0.0149,0.0743,0.0059,0.0293,-0.0012,0.0062],
[1.1271,-0.0697,0.3483,0.0375,0.1787,-0.0199,0.0995,0.0107,0.0537,-0.0051,0.0256]]
lnd=[1,sqrt(2),sqrt(6),sqrt(12),sqrt(20),sqrt(30),sqrt(42),sqrt(56)]
impF=0
APT=[]
for impF in range(len(lnd)-1):
if alpa>=lnd[impF] and alpa0 :
x1=i.coordinates[0]+wg*sin(pi*z1/(a))
mdb.models['Model-1'].parts['Splate'].editNode(nodes=i,coordinate1=x1,coordinate2=y1,coordinate3=z1)
rep=rep+1
rep=0
wp=0.05*beta*beta*PT
# global plate Imperfection
for i in mdb.models['Model-1'].parts['Splate'].nodes:
x1=i.coordinates[0]
y1=i.coordinates[1]
z1=i.coordinates[2]
for j in range(len(AimpCo)):
y1=y1+wp*sin(j*pi*z1/a)*sin(pi*x1/b)*AimpCo[j]
mdb.models['Model-1'].parts['Splate'].editNode(nodes=i,coordinate1=x1,coordinate2=y1,coordinate3=z1)
In Abaqus software, imperfections can be defined using the "perturbation" feature. The perturbation feature allows you to introduce small geometric imperfections into your model and to analyze their effect on the structural response. The perturbation can be defined as a displacement or a rotation in one or more directions at a specific location on the model.
To define imperfections as an equation in Abaqus, you can use the expression language in the perturbation feature. The expression language allows you to specify the magnitude and direction of the perturbation using mathematical expressions. For example, to introduce a sinusoidal imperfection in the z-direction, you can use the following equation in the perturbation feature:
AMPLITUDE*sin(2*pi*x/WAVELENGTH)
Where AMPLITUDE is the magnitude of the imperfection, WAVELENGTH is the wavelength of the sinusoidal imperfection, and x is the coordinate along the direction of the imperfection.
You can also use other mathematical functions and operators in the expression language to define imperfections, such as exponential functions, trigonometric functions, and logical operators.
It is important to note that the definition of imperfections in Abaqus should be based on the specific imperfection that is relevant to your analysis and should be validated against experimental or analytical data if possible. Additionally, it is recommended to perform sensitivity analyses to investigate the effect of different imperfection magnitudes and locations on the structural response.
Hi,
you can find an example on my GitHub (github.com/materialsguy/Buckling_Analysis_Laminated_Samples). We used an Eigenvalue analysis followed by a Static Step. The evaluation of the model is shown in our paper (researchgate.net/publication/370162701_Fatigue_life_assessment_of_metal_foils_in_multifunctional_composites_via_combined_experiments_and_simulations).
Cheers,
Claus
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