How can you determine the amplitude and frequency of a vibration signal?

1 What is a vibration signal?

A vibration signal is a representation of the displacement, velocity, or acceleration of a point or a region in a structure over time. It can be measured by sensors, such as accelerometers, strain gauges, or displacement transducers, that convert the physical motion into electrical signals. A vibration signal can be either periodic or non-periodic, depending on whether it repeats itself in a regular pattern or not. A periodic signal can be characterized by its amplitude and frequency, which are two important parameters for vibration analysis.

2 What is amplitude?

Amplitude is the maximum value or peak of a vibration signal, measured from the equilibrium or mean position. It indicates the intensity or magnitude of the vibration. Amplitude can be expressed in different units, depending on the type of signal. For example, displacement amplitude can be in meters, millimeters, or micrometers, while acceleration amplitude can be in meters per second squared, g-forces, or decibels. Amplitude can be affected by factors such as damping, resonance, loading, and boundary conditions.

3 What is frequency?

Frequency is the number of cycles or oscillations of a vibration signal per unit time. It indicates the rate or speed of the vibration. Frequency can be expressed in different units, such as hertz (Hz), which means cycles per second, or radians per second (rad/s), which means angular displacement per second. Frequency can be affected by factors such as stiffness, mass, geometry, and material properties.

4 How to measure amplitude and frequency?

There are different methods to measure the amplitude and frequency of a vibration signal, depending on the type and quality of the data. One of the simplest methods is to use a time-domain analysis, which involves plotting the signal versus time and visually inspecting the waveform. You can measure the amplitude by finding the peak value or the peak-to-peak value (the difference between the maximum and minimum values) of the signal. You can measure the frequency by finding the period (the time for one cycle) of the signal and taking its reciprocal. For example, if the period is 0.01 seconds, the frequency is 1/0.01 = 100 Hz.