Definition
A vibrometer is an instrument used to measure the vibration parameters of an object, often used to quantify physical quantities such as displacement, velocity, or acceleration generated by machinery or structures during motion. It captures vibration signals through sensors and converts them into readable data for engineering analysis and condition monitoring.
Principle
The working principle of the vibrometer is based on the electromechanical conversion effect of the vibration sensor. Common sensor types include piezoelectric, capacitive, and inductive. Taking piezoelectric sensor as an example, the internal piezoelectric material will generate an electric charge when subjected to mechanical stress, and the amount of charge is directly proportional to the acceleration received. The relationship between vibration parameters can be expressed by the following formula:
Velocity v = ∫ a dt
Displacement s = ∫ v dt
where a is acceleration, v is velocity, s is displacement, and t is time. The instrument enables the conversion between these parameters through integral or differential circuits.
Measurement method
Vibration measurement is usually divided into two methods: contact and non-contact. Contact measurement mounts the sensor directly on the surface of the measured object, which is suitable for vibration monitoring of most fixed equipment. Non-contact measurement uses a laser or eddy current probe to obtain vibration data without touching the object, often used in rotating components or high-temperature environments. The measurement should be based on standards such as ISO 10816 or GB/T 6075 to determine the measurement point location, orientation and sampling frequency to ensure data representativeness.
Influencing factors
The accuracy of vibration measurement results is influenced by a variety of factors. Sensor mounting (e.g., bolted, magnetic, or handheld) can introduce additional mass or contact resonance that alters the vibration characteristics of the system under test. Environmental conditions such as temperature, humidity, and electromagnetic interference can affect the sensor output signal. In addition, the frequency response range of the measurement system needs to cover the main frequency components of the vibration being measured, otherwise it will cause data distortion. Cable length and grounding can also introduce noise, which requires system calibration and verification before measurement.
Application:
Vibrometers are widely used in industrial and scientific research. In mechanical manufacturing, it is used for machine tool dynamic characteristics testing and rotor dynamic balance correction; In construction engineering, it can be used to monitor the vibration response of bridges or high-rise buildings under wind load or traffic excitation. In the power industry, it is commonly used for fault warning and health management of rotating equipment such as generators and fans. In addition, vibrometers are also used for environmental vibration assessment, such as monitoring of surrounding ground vibration caused by rail transit.
Selection
When choosing a vibrator, consider both measurement needs and environmental conditions. First, the type of parameter to be measured (acceleration, velocity or displacement) and the range of measurement should be clarified to ensure that the instrument covers the expected vibration amplitude. The frequency range needs to match the vibration characteristic frequency of the test object, and the upper limit of the common frequency for mechanical vibration monitoring is 1kHz to 10kHz. For long-term online monitoring, attention should be paid to the environmental adaptability of the instrument, such as protection level and temperature range. Portable instruments are suitable for on-site inspections, while multi-channel systems are better suited for laboratory modal analysis. Finally, instrument calibration and data interface compatibility are also aspects to consider in selection.