What are the dampening arrangements for tie rod vibrations?

flowchart LR
    A[Engine firing\npulses] -->|Exciting force| B[Tie rod\nnatural frequency]
    B --> C[Antinodal points\nmax amplitude]
    C --> D[Viscous shear\n damper]
    C --> E[Hydraulic\n damper]
    C --> F[Friction\n damper]
    C --> G[Rubber\n damper]
    D & E & F & G --> H[Energy\n dissipated as heat]

• Definition: Tie rod vibrations are longitudinal oscillations in the long tie rods of large 2-stroke engines, with maximum amplitude at antinodal points
• Cause: Exciting forces from engine firing and inertia at natural frequencies of the rod
• Dampening arrangements: Viscous shear dampers, hydraulic dampers, friction dampers, rubber dampers fitted at antinodal points; tuned to the rod’s natural frequency
• Purpose: Reduce stress, prevent fatigue failure, limit noise and structural transmission
• As Second Engineer: Verify damper condition during maintenance, check for wear/leakage, ensure correct tuning, record in PMS