Hello,
I have calculated the modal frequencies of a part with Sfepy. The
results have been compared to Ansys. Unfortunately, the results
are different.
I have repeated the calculation by changing the next parameters trying to
find stable results.
-Solver: eig.scipy/eigsh
-Solver:eig.scipy_lobpcg -
-i_max(iterations)
-Mesh size. I have tested different mesh from 12k cells to 22k cells.
-Order
I am not able to get results in a reasonable time by using eig.scipy/eigsh .
(as reference for 13k cell, time is around 10 min)
The calculation runs with the solver eig.scipy_lobpcg. In all the tests, I
am not able to reach good tolerance. So, the results are quite dependent on
the number of elements, i_max parameter, and order. On the other hand, if I
try to make it more accurate, the time processing is too long.
Could you give any hint or recommendation?
The simulation condition is free, without boundary conditions.The first
modes from Ansys are 4746 Hz, 5118 Hz, 5426 Hz, 6906 Hz. The six first
modes corresponding to rigid motion have been discarded.
The modes with Sfepy are 8710 Hz, 12954 Hz, 13138 Hz , 15213 Hz
Ansys use tetrahedrons with quadratic formulation (midside nodes) and fine
mesh.
You can find attached code and commands to run it.
To run the model write in the terminal:
python modal_analysis.py Dummy_Modal_4_1.mesh
--solver="eig.scipy_lobpcg,i_max:1000,largest:False" --young 74854
--density 2.7e-9 --poisson 0.3 --order 1
Units: mm, N, MPa, Tn/mm3
Thanks,
Jesus S.