Hoang Minh Company has enough equipment and human resources to measure shaft torsional vibrations during long-distance testing as required in Chapter 8, Part 3 of QCVN 21:2015/BGTVT

Vibrations of ship propulsion systems, including torsional vibrations, longitudinal vibrations and transverse vibrations, in which torsional vibrations are often of interest. Calculating vibrations of the ship's dynamic system is carried out thanks to conversion models from the real dynamic system to the equivalent system. Here, the finite element method is the throughout calculation method applied to all the problems mentioned above.

 MODELING THE SHIP AXLE SYSTEM
Torsional vibrations
To calculate torsional vibrations, the real shaft system must be replaced with a simple elastic system consisting of a cylindrical shaft and many circular discs attached to this shaft. This reference system must ensure the following conditions:
For any frequency, the helix angle of the real shaft must coincide with the helix angle of the equivalent shaft.
The moment of inertia of the equivalent mass must be equal to the moment of inertia of the actual mass.
So the converted real axis system is a system consisting of an ideal elastic axis that is weightless but has stiffness equivalent to the real axis and masses placed at certain positions (Figure 2).