burningliquid
Mechanical
Dear Friends,
I am currently trying to model the buckling behaviour of a monolithic spherical shell under uniform compressive pressure in ABAQUS. Whenever I try to run a buckling analysis I get one of the following errors:
NOTE: I have provided all my steps at the end of this message.
- “Error in job Job-1: TOO MANY ITERATIONS NEEDED TO SOLVE THE EIGENVALUE PROBLEM”
- “THE EIGENVALUES CANNOT BE FOUND. THIS COULD BE CAUSED BY INSTABILITIES IN THE BASE STATE (CHECK FOR NEGATIVE EIGENVALUES IN THE MOST RECENT GENERAL ANALYSIS STEP)”
Sometimes I also get the following:
- “NODE SET ASSEMBLY__PICKEDSET4 HAS NOT BEEN DEFINED” & “A BOUNDARY CONDITION HAS BEEN SPECIFIED ON NODE SET ASSEMBLY__PICKEDSET4 BUT THIS NODE SET IS NOT ACTIVE IN THE MODEL”
Have I constrained the structure correctly? Or have I missed out something fundamental?
I would greatly appreciate your help or if you could simply point me in the correct direction.
Burningliquid
Steps:
- Created a Revolved Shell (R=1m)
- Specified Material Properties (E=62GPa, Poisson=0.3)
- Made a Section (Shell, Homogenous and assigned created Material)
- Assigned Section to the Part (Middle Surface)
- Created a datum point on the surface of the sphere (0.0,-1.0,0.0) [Assuming (0,0,0) at centroid of sphere]
- Added the part to the Assembly
- Steps
o Initial: I have constrained the single datum point on the surface against all translation directions (i.e. u1=u2=u3=0)
o Buckling Step (linear perturbation, buckling, 30 eigenavlues, Maximum Iterations to 100) applied a uniform pressure of magnitude 1.
- Finally I meshed the part (Seed = 0.1, Quad-Dominated Sweep)
- Submitted the job
I am currently trying to model the buckling behaviour of a monolithic spherical shell under uniform compressive pressure in ABAQUS. Whenever I try to run a buckling analysis I get one of the following errors:
NOTE: I have provided all my steps at the end of this message.
- “Error in job Job-1: TOO MANY ITERATIONS NEEDED TO SOLVE THE EIGENVALUE PROBLEM”
- “THE EIGENVALUES CANNOT BE FOUND. THIS COULD BE CAUSED BY INSTABILITIES IN THE BASE STATE (CHECK FOR NEGATIVE EIGENVALUES IN THE MOST RECENT GENERAL ANALYSIS STEP)”
Sometimes I also get the following:
- “NODE SET ASSEMBLY__PICKEDSET4 HAS NOT BEEN DEFINED” & “A BOUNDARY CONDITION HAS BEEN SPECIFIED ON NODE SET ASSEMBLY__PICKEDSET4 BUT THIS NODE SET IS NOT ACTIVE IN THE MODEL”
Have I constrained the structure correctly? Or have I missed out something fundamental?
I would greatly appreciate your help or if you could simply point me in the correct direction.
Burningliquid
Steps:
- Created a Revolved Shell (R=1m)
- Specified Material Properties (E=62GPa, Poisson=0.3)
- Made a Section (Shell, Homogenous and assigned created Material)
- Assigned Section to the Part (Middle Surface)
- Created a datum point on the surface of the sphere (0.0,-1.0,0.0) [Assuming (0,0,0) at centroid of sphere]
- Added the part to the Assembly
- Steps
o Initial: I have constrained the single datum point on the surface against all translation directions (i.e. u1=u2=u3=0)
o Buckling Step (linear perturbation, buckling, 30 eigenavlues, Maximum Iterations to 100) applied a uniform pressure of magnitude 1.
- Finally I meshed the part (Seed = 0.1, Quad-Dominated Sweep)
- Submitted the job