alinole ansys upgrade

[AmrGmar]

Hello, everyone.
I have to perform the modal analysis of a tree with two cast discs using single-dimensional elements.

I shaped the tree with beam188 elements and disks as concentrated masses with mass21 elements inserting as real costants mass x y z and moments of inertia.

both the knots of the beam188 element and the mass21 element have 6 gdl.
to verify that I should find so many natural frequencies as the total gdl, for simplicity I shaped the tree with 4 knots two end and two with the characteristics given by the two disks inserted in the constant real. I should therefore have 24 frequencies (in a free analysis)

the problem is that I do not understand why the result provides a total number of 60 frequencies.

I don't understand why since there are only 4 knots with 6 glds per knot.

Thank you for letting me down.

 

[F_Ingrasciotta]

hi, the problem lies in the definition of the beam188 element, in fact if you set the keyoption(3) =3 the program autonomously creates two internal nodes to the element.
then get the following scheme:

♪
No...

at the end the number of knots become:

- 4 knots defined by you
-2 knots int x 3 elements = 6 additional nodes

the total knots then becomes 10 x 6 gdl = 60 gdl

also considers that the results of the analysis can be trusted only for the first n°gdl/2 modes of vibration since beyond this value the error increases considerably.

 

[AmrGmar]

hi, the problem lies in the definition of the beam188 element, in fact if you set the keyoption(3) =3 the program autonomously creates two internal nodes to the element.
then get the following scheme:

♪
No...

at the end the number of knots become:

- 4 knots defined by you
-2 knots int x 3 elements = 6 additional nodes

the total knots then becomes 10 x 6 gdl = 60 gdl

also considers that the results of the analysis can be trusted only for the first n°gdl/2 modes of vibration since beyond this value the error increases considerably.

Thank you so much