抄録
In the torsional vibration of a small vessel driveshaft system, ripple torque from engine excites the first mode vibration and causes rattle noise from the final gear. Employing soft shaft coupling may suppress this noise. However, this makes second mode resonant frequency lower and resonates driveshaft system in the nominal rotational speed range. In this study, hardening shaft coupling using permanent magnet is proposed. This coupling works as softer spring in idle rotation range and harder spring in nominal drive range by static torque, and this characteristic help avoidance of resonance. To verify dynamic characteristics of this hardening spring, scale model experiment was conducted, and compared numerical simulation with experiment. The analytical results agree well with the experimental results.
