528
I. Cr⸠stiu et al.
Table 1 Sizes of mesh elements and four natural frequencies of rotor–shaft
No. mode
Plane motion
Element size
2 mm
Element size
3 mm
Element size
4 mm
Element size
5 mm
Nodes 62119 Nodes 26179 Nodes 14103 Nodes 8074
Elements
35116
Elements
14454
Elements 7548 Elements 4133
Frequency
[Hz]
Frequency
[Hz]
Frequency
[Hz]
Frequency
[Hz]
1
OXY
577.34
579.83
581.85
583.4
1
OXZ
577.42
580.43
582.22
584.24
2
OXY
1128.7
1136.6
1140.1
1146.0
2
OXZ
1129.2
1137.6
1141.4
1147.5
3
OXY
2524.2
2530.3
2534.4
2540.7
3
OXZ
2524.2
2530.7
2535.6
2541.5
4
OXY
3652.7
3673.2
3688.3
3703.4
4
OXZ
3653.4
3676.2
3691.4
3708.6
Fig. 4 Fourth mode shape in OXZ plane for a simple supported disk
By analyzing the frequencies of the first vibration mode for the largest number
of nodes, i.e., for 2 mm elements, the deviation between the natural frequencies
corresponding to the motion in the two planes, OXY and OXZ, is less than 0.014%.
By doing the same, if the largest dimension of the element was chosen at 5 mm, the