At present, the attention to the speed is not paid any more for a good yacht, but there are more requirements to high comfort and low noise. The ship noise not only affects the work, lift and physical health of crew themselves but also affects the life of residents along the coast. The vibration source generating noise is one of the roots causing the fatigue damage of the ship structure to impact the service life and safety of the ship.
Ship noise is irregularly formed by different frequency and different intensity sounds made when the equipment runs and made by the outside stormy waves clapping the hull, and includes airborne noise existing at the compartment part, structure-borne noise existing in the hull structure (namely, vibration) and water noise existing in the water medium around the hull. The progress of science and technology requires us to develop the study in noise and noise control theory and method to improve human life and working conditions and create the comfortable acoustic environment.
The vibration damping and noise reduction technology are one of the methods for effectively controlling structural vibration and noise, namely, the vibratory mechanical energy is converted into the heat energy to be dissipated by utilising the viscoelasticity of material, thereby achieving the purposes of vibration damping and noise reduction.
The damping and noise reduction material play an indispensable important role in ship vibration damping and noise reduction engineering application, particularly in compartment noise reduction, the satisfactory effect can be achieved by laying the damping and noise reduction material and combining other noise reduction measures.
The vibration damping and noise reduction technology is that a structure layer including the damping material is directly adhered to the surface of the structural component to increase the damping performance of the structural component and improve the structural damping loss factor, the structural vibration energy is dissipated by the cyclic tensile strain or shearing stress of the viscous-elastic material to exert the damping capability in vibration damping and noise elimination to improve the vibration resistance of the mechanical structure, reduce the noise of the mechanical equipment and enhance the dynamic stability of the structural and mechanical systems. The Damping treatment technology is particularly suitable for the vibration damping and noise reduction of ribs, boards, casings and other components.
Noise control is to control the generation, transmission and receipt of noise source by taking the corresponding technical measures to obtain the acoustic environment required by people. In the ship, the engine room, the deck and the passenger compartment should be treated in noise control. In the yacht, vibration and noise are the two sides of one entity.
Besides the airborne sound radiated by the sound source, the structural vibration caused by the sound source will be propagated outside through the hull structures (such as deck, engine base, hull longitudinal material, partition plate, etc.), and the many mechanism noises are caused between the cabins, so that it is necessary to reduce the noise from the noise source and reduce the vibration of hull structure to reduce the noise of cabin.