In the physical world, vibration is a very common phenomenon. From the universe itself to atomic particles, it is present in everything. Nowadays, the capacity to measure, monitor, and analyze vibration has become essential in industries like research and development. Unfortunately, due to the lack of clarity in vibration analysis and test equipment selection, researchers are not always able to create a precise and reproducible vibration measuring system. There are a few difficulties in measuring vibration, such as choosing the right component, system design, signal conditioning, waveform analysis, and setup. The definition, operation, types, and uses of vibration sensors are covered in this article.
What is Vibration Sensor?
Working Principle of Vibration Sensor
The method by which a vibration sensor detects system vibrations consists of the use of various optical or mechanical principles. These sensors' typical sensitivity ranges are 10 mV/g to 100 mV/g, while they can potentially have lower and greater sensitivity levels.
Depending on the application, the sensor's sensitivity can be selected. Therefore, it is critical to understand the range of vibration amplitude levels to which the sensor will be subjected during measurements.
There are various techniques for vibration sensors to measure vibration, but in general, the following three principles are most commonly employed.
Electrical measurement: The fluctuation in engineering vibration is transformed into electrical signals, which are shown and recorded after amplification. It first converts mechanical vibration to an electric quantity and then measures it. This is the most popular vibration measurement method.
Optical measurement: The change in engineering vibration is turned into an optical signal, which is amplified by the optical system and then shown and recorded. This approach is also used in devices such as laser vibrometers.
Mechanical measurement: Engineering vibrations are turned into mechanical signals, which are then amplified by the mechanical system before being measured and recorded. The most common instruments are lever-type vibration meters and Geiger vibration meters. This method has a relatively low measurement frequency and accuracy, but it is simple to use.
Different Methods for Measuring Vibration
There are three techniques to measure vibration: displacement, velocity, and acceleration.
1. Displacement is the distance an object travels from a reference point. It is ideal for measuring low frequencies.
2. Velocity is the rate at which displacement changes over time. which covers a broad range of frequencies. It works well for identifying the fatigue forces that lead to failure and wear.
3. The rate at which velocity changes over time is called acceleration. For measuring extremely high frequencies, it works best. Because they are durable and simple to transform from acceleration to velocity, accelerometers are among the most widely used vibration sensors.
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Classification of vibration sensor
In general, based on their many functions, vibration sensors can be classified as follows:
The mechanical reception concept divides it into two types: relative and inertia type.
Based on mechanical and electrical transformation principles, It can be classified as electric, piezoelectric, eddy current, inductance, capacitance, resistance, or photoelectric.
Based on the mechanical quantity measured, it is classified into three types: displacement sensor, speed sensor, and accelerometer.
According to the final output signal it can be classified into two types: Digital output sensor which is vibration switch and analog output vibration sensor provides the continuous equipment vibration value.
Study more: RPM Sensor working principle, types and applications.
Different Types of Vibration Sensors
Piezoelectric Vibration Sensor:
The vibration sensor in which piezoelectric material is used is called a piezoelectric vibration sensor. The piezoelectric force sensor works by utilizing the piezoelectric effect of a piezoelectric crystal, which means that its output signal is proportional to an external force.
- Use piezoelectric materials like quartz or ceramics.
- Ideal for high-frequency applications
Eddy Current Vibration Sensor:
Eddy current vibration sensors are non-contact sensors. It monitors the vibration displacement or amplitude of an object by changing the distance between the sensor's end and the object being monitored.
Inductive Vibration Sensor:
An inductive vibration sensor is a type of vibration sensor constructed using the idea of electromagnetic induction.
Capacitive Vibration Sensor:
- Measure changes in capacitance due to motion.
- Suitable for low-frequency applications.
Electrodynamic Vibration Sensor:
The relative type of electric sensor operates on the concept of electromagnetic induction. That means, when a moving conductor cuts the magnetic field line in a fixed magnetic field, the two ends of the conductor generate an electromotive force, hence the sensor created using this concept is known as an electrodynamic sensor.
Resistance Strain Type Vibration Sensor:
The resistance strain vibration sensor transforms the recorded mechanical vibration amount into a change in the resistance of the sensing element. To perform this electromechanical conversion, a variety of sensing devices are used, the most common of which is the resistance strain gauge.
Fiber Optic Vibration Sensor:
Fiber-optic vibration sensors, which detect vibration signals, have been around for over 30 years. The original optical fiber vibration sensor uses an interferometric construction. Vibration-induced optical fiber strain leads to the phase change of the interferometer's signal arm. However, this type of sensor arrangement is more complex and not suitable for repeated use.
Applications
Several industries use vibration sensors to measure vibrations in their daily equipment operations. Sensor properties will be determined by unique industrial features.
For instance, the sensors used in industries like wind power and mining for slow rotation of turbines have 1 Hz or less frequency response.
In contrast, these sensors are used by the gas and oil sectors, which require high frequency ranges between 10 Hz and 10 kHz for managing the rotation speed of gears and turbines.
The food and beverage, mining, metallurgy, gas and oil, paper, wind power, power generation, and other industries are the primary users of vibration sensors.
- Industrial Equipment Monitoring: Predictive maintenance in motors, pumps, and turbines.
- Construction: Monitoring structural integrity in bridges, dams, and buildings.
- Healthcare: measuring vibrations in medical devices or even human body functions.
- Automotive: Tracking engine and suspension vibrations.
- Aerospace: Ensuring the safety and performance of aircraft components.
Why It's Important to Use Vibration Sensors
Vibration sensors have become essential tools for industrial maintenance and dependability applications. Costs might be significant when a machine breaks down without warning. For example, coupling damage from a shaft unbalance may necessitate the replacement of the complete motor.
Wireless vibration Monitoring system
A wireless vibration sensor transmits readings to software on a continual basis over a network connection such as WiFi, LTE, or Ethernet. For example, a wireless sensor may transmit data to computerized maintenance management system (CMMS) software, where it can be stored and examined. These vibration sensors are more cost-effective and easy to install than wired sensors. The remote condition monitoring data can be accessed from practically anywhere. It allows for screening or data analysis, depending on the sensor and software. Collects and monitors data to detect defects early and prevent asset failure.
