How to confirm that Abaqus is incorporating the prescribed geometric imperfections?
How to confirm that Abaqus is incorporating the prescribed geometric imperfections?
(OP)
Dear All,
I created a certain shell-element based model of a frame structure using Abaqus 6.10.3 software.
The approach that I adopted to incorporate initial geometric imperfections was via the scaling of the first buckling modes.
Thus, I:
(i) Performed a buckling analysis of the model recording the nodal displacements of each buckling mode (Command: *NODE FILE, Global=Yes / U)
(ii) Created a second analysis with two steps named Equilibrium and Riks:
(ii.i) Previous to the following steps, geometric imperfections were incorporated based on the scaling of the first buckling mode (Command: *IMPERFECTION, FILE=, STEP=1 / 1,1.32)
(ii.ii) On the first step - Equilibrium, a negligible load (1N) was applied and a static non-linear analysis was carried on. This step was created with the sole purpose of incorporating geometric imperfections and residual stresses (RS not included yet) to allow the structure to find a new equilibrium (situation where an uneven residual stresses distribution is considered)
(ii.iii) On the second step - Riks, a non-linear failure analysis based on the Riks methodology was carried on.
Since my model was built in [mm], I reckon I am considering an imperfect shape equal to the first buckling mode w/a maximum value of displacement of 1.32 mm.
MY QUESTION IS: How can I confirm if that was in fact the imperfect shape adopted in the analysis? When I check the displacement values after the first iteration of the step 1, the maximum displacement of the model has a magnitude of 10^-2 mms (instead of the expected 1.32 mms).... So I am concerned about what Abaqus is in fact assuming...
Thankful in advance.
/sc
I created a certain shell-element based model of a frame structure using Abaqus 6.10.3 software.
The approach that I adopted to incorporate initial geometric imperfections was via the scaling of the first buckling modes.
Thus, I:
(i) Performed a buckling analysis of the model recording the nodal displacements of each buckling mode (Command: *NODE FILE, Global=Yes / U)
(ii) Created a second analysis with two steps named Equilibrium and Riks:
(ii.i) Previous to the following steps, geometric imperfections were incorporated based on the scaling of the first buckling mode (Command: *IMPERFECTION, FILE=
(ii.ii) On the first step - Equilibrium, a negligible load (1N) was applied and a static non-linear analysis was carried on. This step was created with the sole purpose of incorporating geometric imperfections and residual stresses (RS not included yet) to allow the structure to find a new equilibrium (situation where an uneven residual stresses distribution is considered)
(ii.iii) On the second step - Riks, a non-linear failure analysis based on the Riks methodology was carried on.
Since my model was built in [mm], I reckon I am considering an imperfect shape equal to the first buckling mode w/a maximum value of displacement of 1.32 mm.
MY QUESTION IS: How can I confirm if that was in fact the imperfect shape adopted in the analysis? When I check the displacement values after the first iteration of the step 1, the maximum displacement of the model has a magnitude of 10^-2 mms (instead of the expected 1.32 mms).... So I am concerned about what Abaqus is in fact assuming...
Thankful in advance.
/sc





RE: How to confirm that Abaqus is incorporating the prescribed geometric imperfections?
RE: How to confirm that Abaqus is incorporating the prescribed geometric imperfections?
Using a high scale factor I was finally able to see the deformed shape. I was surprised to realise that geometric imperfections were already incorporated on step 0 of the analysis.
Btw, did you ever have problems obtaining the descendent part of the force-displacement curve while performing a Riks analysis (and be aware that no warning messages were issues)?
Anyway, I appreciated your help a lot.
/sc