This thesis is focused on the comparison between Numerical Calculation and FEM Analysis by ANSYS by software for Impeller Shafting System of Low Noise Large Cavitation Tunnel. The impeller shafting system are considered buoyancy effect to influence driving shaft in the water that reason why the shaft diameter 800mm above. The shafting are arranged two solid shafts at forward end, three hallow shafts in the water and one hallow shaft on the tail. The bearings are arranged one self aligned journal bearing on the tail shaft and one axial thrust with two journal bearings on the motor shaft. The strength calculation was done by MathCAD.
The structural analysis was done by ANSYS. The reaction forces for bearings which are located motor shaft bearing, intermediate shaft bearing and tail shaft bearing are measured by hydraulic jack.
The final results are as follows :
(1) The structural analysis which compared design calculation was much higher values because the software supplier need to reduce risk for the structural damages. Therefore most of softwares are consisted strong boundary conditions for more safety designing.
(2) The actual reaction forces for bearings which compared design calculation values was very much close to calculation data it with the table 3a for comparison data of reaction forces.
Therefore, the design calculation is based on real values for structural designing but the software is focused on the safety designing more than 30% of design calculation and some of critical designing is much higher safety margin to improve risk of structural damages.