Today, monitoring, measuring, and analyzing vibrations are all critical to industries like research and development. Despite the different available types of test instruments and vibration analysis, researchers often struggle to discern the appropriate techniques for creating accurate and repeatable vibration measurement systems. As part of measuring vibration, some challenges must be addressed, including selecting an appropriate component, system layout, signal processing, waveform analysis, and setup. Throughout this article, we will explore vibration measurement in more detail.
What is vibration?
Vibration is the movement or mechanical oscillation of a machine or component about an equilibrium position. It might be periodic, like a pendulum, or random, like the movement of a tire on a gravel road. An item can vibrate in two ways: freely and forcefully.
When an object or structure is displaced or impacted and then allowed to oscillate naturally, it is called free vibration. The natural frequency is the frequency at which a structure would oscillate if it had not been impacted or displaced.
A resonance occurs when a system oscillates more violently at some frequencies than others. When vibrations are forced at or near an object's natural frequency, energy will be built inside the structure. Even though the input forced vibration is very small, the vibration can become quite large over time. If a structure vibrates at a frequency that matches the normal environmental vibration, the structure will vibrate more violently and fail prematurely.
When a structure vibrates as a result of a changing force, this is referred to as forced vibration. An object may be made to vibrate at unusual frequencies by rotating or alternating it. Vibration measurements are used in condition monitoring to determine the health of spinning machinery such as compressors, turbines, or pumps. These devices are made up of several pieces, each of which generates a distinct vibration pattern or signature.
What is vibration measurement?
The concept of vibration can be defined as a time-based (periodic/cyclic) movement of an item around a fixed axis. The following contributing factors influence vibration magnitude and rate:
- Natural frequencies and rigidity of the item
- The amplitude and frequency of any external energy source(s) that are causing the vibration.
- The method of connection between the vibration energy source and the item of interest.
Vibration measurement is complex due to its many components, including displacement, velocity, acceleration, and frequency. In addition, each of these components can be measured in different ways - peak-to-peak, peak, average, and RMS; each of which can be measured in the time domain (real-time, instantaneous measurements using an oscilloscope or data acquisition system), or frequency domain (vibration magnitude across a frequency spectrum), or just one number for "total vibration."
Sometimes vibration measurements are used as indirect measures of some other value. The approach to measuring vibration depends on the final measurement goal. Conditions such as wear, fatigue, and failure are often monitored or predicted by vibration measurements. These measurements are meant to determine the kinetic energy and forces acting upon an object. This is sometimes referred to as inertial vibration. One example is monitoring industrial motors in critical applications. In many circumstances, measuring acceleration allows for simple conversion to units of force if the object's mass is known.
How is vibration measurement done?
There are several vibration analysis and monitoring equipment available for vibration measurement.
Most commonly, vibrations are measured using a ceramic piezoelectric sensor or accelerometer. In a physical device, an accelerometer measures the dynamic acceleration as a voltage. An accelerometer consists of full-contact transducers mounted directly on elements that move rapidly, such as bearings, gearboxes, or blades. In addition to shock measurements, these sensors can also be used to measure low-frequency vibration and to measure explosions. One of the advantages of an accelerometer is its linearity over a wide frequency range and its high dynamic range.
The proximity probe is another sensor that may be used to monitor vibrations. Proximity probes, which measure acceleration to determine vibrations as opposed to accelerometers, are noncontact transducers that detect the distance to a target. These sensors are nearly always employed in rotating machines to monitor shaft vibration. Machine monitoring and protection measures for mechanical systems such as turbo machinery are an example of popular use. Because vibrations do not pass effectively to the exterior casing due to the flexible fluid film bearings and hefty housing, we can use proximity probes instead of accelerometers to monitor shaft motion directly.
What is the importance of vibration measurement?
Vibration can have an impact on the durability and dependability of mechanical systems or buildings, resulting in issues like damage, abnormal stopping, and disaster. Vibration measurement is a key preventative strategy for these issues. Let's look at the importance of vibration measurement.
Development and Research:
When building more reliable products, vibration and shock measurements are used to test samples or completed items.
Increasing Product Quality:
To solve vibration problems and improve product quality, vibration measurement is carried out on a sample, a mass-produced item, or all the completed products to eliminate inferior components and produce better ones.
Factory Safety Management:
As a preventative measure against breakdowns and difficulties in machinery, vibration is monitored on a regular basis and compared to the vibration at the start of construction or in normal condition after maintenance to set the equipment's status.
Production system maintenance:
The measurement of vibration is used not only when a problem arises but also during routine maintenance. The manufacturing system is maintained running by detecting defects or potential failures in parts through undesirable vibration patterns.
Pollution Inspection:
Vibration measurements are performed to determine that vibration levels are within the allowable range at a specified factory, construction site, or through road traffic and trains.
Conclusion:
Vibrations during construction are a known nuisance that can damage existing structures when they are not properly controlled and accounted for. Vibrations conveyed to a building, or other designed structure can cause varying degrees of damage. They can be of natural origins, such as during an earthquake, or mechanical (human or machine-created) origin. For that, engineers make accurate measurements to avoid fatigue and failure in buildings.
