How do you measure and analyze ship vibration and noise levels?

1 Vibration Measurement

Vibration is the oscillatory motion of a body or a system of bodies around a fixed or equilibrium position. Vibration measurement involves the use of sensors, such as accelerometers, strain gauges, and displacement transducers to capture the vibration signals in different directions and locations on the ship. These signals are then converted into electrical signals and recorded by a data acquisition system. The data can be displayed in different formats, such as time domain, frequency domain, or spectral density, to show the amplitude, frequency, and phase of the vibration.

2 Noise Measurement

Noise is the unwanted sound that interferes with the desired sound. Noise measurement involves using microphones, sound level meters, and sound analyzers to capture the sound pressure level and frequency spectrum in different locations on the ship. The noise level can be expressed in decibels (dB), which is a logarithmic scale that compares the sound pressure to a reference level. The noise spectrum can be divided into different frequency bands, such as octave bands or one-third octave bands, to show the distribution of noise energy across the frequency range.

3 Vibration Analysis

Vibration analysis is the process of identifying the causes and effects of vibration on the ship structure and machinery. Analytical methods involve the use of mathematical models and equations to describe the vibration behavior of the ship system. Numerical methods consist of computer software and simulations to solve complex vibration scenarios. Experimental methods include field and laboratory tests to measure and validate the vibration response and performance of the ship system.

4 Noise Analysis

On the other hand, noise analysis identifies the causes and effects of noise on the ship environment and occupants. Noise analysis employs analytical methods like mathematical models and equations to depict the sound propagation and radiation from the noise sources. Similar to vibration analysis, noise analysis uses computer software and simulations to solve challenges. Field and laboratory tests can measure and validate the noise level and spectrum of the ship environment.

5 Vibration Control

After identifying the roots of excessive vibration, it's time to control the vibration level and impact on the ship system. Vibration control can be achieved by modifying the source, path, or receiver of the vibration. Source modification involves changing the design or maintenance of the vibration-generating equipment. Path modification involves altering the stiffness, damping, or isolation of the ship structure or components. Receiver modification entails shifting the sensitivity, location, or orientation of the vibration-affected machinery or equipment.

6 Noise Control

Noise control seeks to alleviate the impact of noise level on the ship environment and occupants. Source, path, and receiver modifications can accomplish noise control. Source modification requires adjusting the design or maintenance of the noise-generating equipment. Change the absorption, reflection, or transmission of the sound waves by the ship structure to conduct path modification. Receiver modification involves altering the sensitivity, location, or orientation of the noise-affected microphones, sound level meters, or sound analyzers.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?