Damping refers to the physical phenomenon in which an oscillating or vibrating system is retarded to dissipate energy over time. When a ship or a floating marine structure is swaying in waves, the damping is mainly external damping such as viscous damping and wave-making damping.

• 1. Classification of damping
• 2. Measurement method of damping
• 3. The role of damping

## 1. Classification of damping

There are two types of damping: linear and torsional. Linear damping is the force of two components moving a distance in a specific direction. The position of the damping on both parts can be specified, from which COSMOSMmotion calculates the damping force.

## 2. Measurement method of damping

In general, there are three damping measurement methods: ① logarithmic decay method; ② sine sweep method; ③ random response method.
The logarithmic decay method is to give the structure an initial excitation, record the free decay response time history of the structure, and obtain the structural damping.

The sine sweep or random response method is to apply excitation to the structure, record the vibration response time history of the structure, and perform spectrum analysis on the response time history, and use the half-power bandwidth method to obtain the structural damping. The difference between these two methods lies in the different excitations applied, one is sinusoidal excitation and the other is random excitation.

## 3. The role of damping

1. Damping helps to reduce the resonance amplitude of the mechanical structure, so as to avoid the structural damage caused by the dynamic stress reaching the limit.

2. Damping helps the mechanical system to quickly return to a stable state after being subjected to an instantaneous impact.

3. Damping helps to reduce sound radiation caused by mechanical vibration and reduce mechanical noise. The noise of many mechanical components, such as the housing of the transportation tool and the saw blade, is mainly caused by vibration. The use of damping can effectively suppress the resonance, thereby reducing the noise.

4. It can improve the machining accuracy, measurement accuracy and working accuracy of various machine tools and instruments. All kinds of machines, especially precision machine tools, need to have high shock resistance and dynamic stability when working in a dynamic environment, and their dynamic performance can be greatly improved through various damping treatments.

5. Damping helps reduce the ability of the structure to transmit vibration.In the design of vibration isolation structure of mechanical system, reasonable use of damping technology can significantly improve the effect of vibration isolation and vibration reduction.