Experimental and Numerical Investigations About Hydraulic Top Bracings and Its Influence on Engine and Vessels Superstructure Vibrations

Top bracings are widely used to control vibration of main engines onboard ships. Currently two types of top bracings are used: hydraulic top bracings and mechanical top bracings with a friction connection. Main advantages of hydraulic top bracing are their improved ability to compensate relative deflections between the engine and the ship and that their dynamic characteristic can be controlled by different settings. Compared to conventional mechanical top bracings MAN-ES hydraulic top bracings have two basic settings that can be controlled by engine speed: the standard active setting and the passive setting. While in the active setting the hydraulic top bracing acts like a spring with a certain amount of stiffness, similar in its behavior to the mechanical type, in the passive setting it acts like a weak damper.