Hey Everyone,
i’m facing a problem with solving a static analasys when the geometry was meshed with second order elements. I was using the basic meshing option of pre pro max.
When solving the job with linear elements, everything works fine.
Maybe i’m doing smth. wrong in meshing.
Thanks in advance
Eric
Hard to say without knowing the details. Are there any error messages ? Can you show the model setup ?
Shure,
so i have an centrifugal impeller.
To demonstrate the problem with second order elements, it is as simple as possible.
The numbers below are estimated upper bounds
number of:
nodes: 1479192
elements: 881096
one-dimensional elements: 0
two-dimensional elements: 0
integration points per element: 4
degrees of freedom per node: 3
layers per element: 1
distributed facial loads: 0
distributed volumetric loads: 1
concentrated loads: 0
single point constraints: 11748
multiple point constraints: 1
terms in all multiple point constraints: 1
tie constraints: 0
dependent nodes tied by cyclic constraints: 0
dependent nodes in pre-tension constraints: 0
sets: 4
terms in all sets: 3526342
materials: 1
constants per material and temperature: 2
temperature points per material: 3
plastic data points per material: 0
orientations: 0
amplitudes: 5
data points in all amplitudes: 5
print requests: 0
transformations: 0
property cards: 0
STEP 1
Static analysis was selected
Decascading the MPC’s
Determining the structure of the matrix:
Using up to 12 cpu(s) for setting up the structure of the matrix.
number of equations
4431702
number of nonzero lower triangular matrix elements
164843643
Using up to 12 cpu(s) for the stress calculation.
Using up to 12 cpu(s) for the symmetric stiffness/mass contributions.
Not reusing csc.
±------------------------------------------------+
PaStiX : Parallel Sparse matriX package +
±------------------------------------------------+
Version: 6.0.1
Schedulers:
sequential: Enabled
thread static: Started
thread dynamic: Disabled
PaRSEC: Disabled
StarPU: Disabled
Number of MPI processes: 1
Number of threads per process: 12
Number of GPUs: 0
MPI communication support: Disabled
Distribution level: 2D( 128)
Blocking size (min/max): 1024 / 2048
Matrix type: General
Arithmetic: Float
Format: CSC
N: 4431702
nnz: 334118988
Job failed - no results exist.
Process elapsed time: 94.497 s
When i change the meshsetting to linear element order, the monitor is showing this message:
The numbers below are estimated upper bounds
number of:
nodes: 225597
elements: 881096
one-dimensional elements: 0
two-dimensional elements: 0
integration points per element: 1
degrees of freedom per node: 3
layers per element: 1
distributed facial loads: 0
distributed volumetric loads: 1
concentrated loads: 0
single point constraints: 3312
multiple point constraints: 1
terms in all multiple point constraints: 1
tie constraints: 0
dependent nodes tied by cyclic constraints: 0
dependent nodes in pre-tension constraints: 0
sets: 4
terms in all sets: 3524936
materials: 1
constants per material and temperature: 2
temperature points per material: 3
plastic data points per material: 0
orientations: 0
amplitudes: 5
data points in all amplitudes: 5
print requests: 0
transformations: 0
property cards: 0
STEP 1
Static analysis was selected
Decascading the MPC’s
Determining the structure of the matrix:
Using up to 12 cpu(s) for setting up the structure of the matrix.
number of equations
675135
number of nonzero lower triangular matrix elements
11920437
Using up to 12 cpu(s) for the stress calculation.
Using up to 12 cpu(s) for the symmetric stiffness/mass contributions.
Not reusing csc.
±------------------------------------------------+
PaStiX : Parallel Sparse matriX package +
±------------------------------------------------+
Version: 6.0.1
Schedulers:
sequential: Enabled
thread static: Started
thread dynamic: Disabled
PaRSEC: Disabled
StarPU: Disabled
Number of MPI processes: 1
Number of threads per process: 12
Number of GPUs: 0
MPI communication support: Disabled
Distribution level: 2D( 128)
Blocking size (min/max): 1024 / 2048
Matrix type: General
Arithmetic: Float
Format: CSC
N: 675135
nnz: 24516009
±------------------------------------------------+
Ordering step :
Ordering method is: Scotch
Time to compute ordering: 0.6300
±------------------------------------------------+
Symbolic factorization step:
Symbol factorization using: Fax Direct
Number of nonzeroes in L structure: 218993472
Fill-in of L: 8.932672
Time to compute symbol matrix: 0.1129
±------------------------------------------------+
Reordering step:
Split level: 0
Stoping criteria: -1
Time for reordering: 0.2282
±------------------------------------------------+
Analyse step:
Number of non-zeroes in blocked L: 437986944
Fill-in: 17.865344
Number of operations in full-rank LU : 498.27 GFlops
Prediction:
Model: AMD 6180 MKL
Time to factorize: 18.8646
Time for analyze: 0.0414
±------------------------------------------------+
Factorization step:
Factorization used: LU
Time to initialize internal csc: 2.7794
Time to initialize coeftab: 0.1206
Time to factorize: 11.1591 (44.65 GFlop/s)
Number of operations: 498.27 GFlops
Number of static pivots: 0
Time to solve: 0.0927
- iteration 1 :
total iteration time 0.0986
error 1.8785e-07
- iteration 2 :
total iteration time 0.101
error 3.0834e-11
- iteration 3 :
total iteration time 0.108
error 1.0337e-14
Time for refinement: 0.3722
- iteration 1 :
total iteration time 0.102
error 7.5287e-17
Time for refinement: 0.1628
Sum: 15.879494
Total PaStiX Time: 15.879494
CCX without PaStiX Time: 11.506344
Share of PaStiX Time: 0.579843
Total Time: 27.385838
Reusability: 0 : 1
Using up to 12 cpu(s) for the stress calculation.
Job finished
Total CalculiX Time: 31.601422
Process elapsed time: 31.727 s
Larger meshes often cause problems in CalculiX and then it’s best to try with a different solver. Here you could use Pardiso instead of PaStiX. It can be selected in the step settings.