Differences between ASE and DYNA for calculation of eigenmodes


In the Teddy example files I’ve come across scripts in which the eigenmodes and eigenfrequencies of a structure are calculated in ASE, and in others it is done with DYNA. The record ‘EIGE’ seems to require the same input in both programs. I’ve done some tests myself and noticed that the resulting eigenfrequencies of both programs are almost the same, but not entirely. However, I also noticed that defining lumped masses with the ‘MASS’ record has no effect in the DYNA calculation, whereas it does in ASE. In this MASS record, I included a load case (#lc_dl) which I defined in another ASE program and which contains two dead loads (but not the selfweight).

MASS LC #lc_dl
EIGE NEIG #nr_of_eigenmodes LC #lc_eigen_first

So my question is what the difference(s) actually is/are, and which program is recommended. It wasn’t entirely clear to me from the descriptions in the manual.

Thank you for reading.

Hey, have you seen this post? Maybe it helps somehow.

Thank you, I hadn’t noticed it before posting this topic because I don’t speak German that well, but with the help of Google Translate it is indeed a useful post.

I see that the main difference is that DYNA is more suited for linear calculations. Does linear in this context mean that deformations are considered to vary linearly with stresses, or does it indicate another linear relationship between two quantities?

I think there used to be separate static and dynamic solvers. Nowadays, they have merged into ASE, which can also solve non-linear problems. I think you should just use modern ASE for any task.
Maybe someone will correct me