Aerospace Engineering Tutorial👨🏫Deterministic InstrumentsFor Vibrational Analytics &Aero-Elasticity
0IVIBROMETERS – SEE VIBRATION MEASURING INSTRUMENTS AVAILABLE FROM TME
2020-10-01


Preventing faults before they occur is a very important factor influencing the cost and time of replacement and maintenance of machines or their components. It is much easier to plan such actions than to react to sudden failures. A vibrometer is a useful device for precise measurements that facilitate diagnostics and the inspection of wear and tear of components. In this article, we will discuss how vibrometers work and present several popular models.
VIBROMETER – WHAT DO YOU NEED TO KNOW ABOUT IT?
Vibration diagnostics, i.e. vibration and oscillation testing, is one of the fundamentals of the mechanical diagnostics of machines. It is indispensable when evaluating the balance of a machine and its individual components, including especially the assessment of bearings and concentricity. Moreover, it allows detecting any changes in the state of the machine foundation. Mechanical vibrations are a very fast oscillatory motion of a specific mechanical system around the axis of its equilibrium and they are caused by the inertia of individual elements (reciprocating motion) or unbalance of rotating parts.The measurement of vibrations and oscillations is usually performed at the place where the machine is installed, with the use of various types of meters and sensors. Detailed tests reveal the displacements, velocities and accelerations of vibrations, while the frequency analysis of vibrations enables signal distribution into components. These data, together with the machine's operating parameters and its design, enable maintenance engineers to assign specific machine elements to individual spectrum components or to determine the machine’s states at a specific moment.
Such data is obtained by maintenance engineers thanks to the most modern generation of vibrometers, which constitute an important part of the TME product portfolio. The diversity in this group of meters is large and the devices themselves are so interesting that they deserve to be discussed and presented in more detail.
WHAT ARE VIBRATION SENSORS (VIBROMETERS), WHAT TYPES ARE AVAILABLE ON THE MARKET?
Vibration sensors, meters and analysers, usually called vibrometers, are portable devices which, thanks to various vibration detection methods – based on accelerometers or laser technology – measure the vibration level of a machine or its components. It is a reflection of the technical condition, and its thorough analysis makes it possible to diagnose the defects or wear of bearings, determine possible misalignment or asymmetry, and detect plays or throws. Constant or regularly repeated monitoring of vibration levels also makes it possible to predict failures before they occur.
Currently produced mobile vibrometers often resemble typical meters of electrical parameters: they have a similar body and are equipped with similar multi-line LCD displays. The most modern vibrometers combine the functions of a meter and vibration analyser, tachometer and balancer. They allow the maintenance engineers to perform general vibration measurements, assess the condition of the machine according to specific standards, check the wear of rolling bearings, determine the temperature and speed of the rotating element, as well as balance the rotor. During these processes, a modern vibrometer saves all the data in its memory and then sends it to a PC or a mobile device equipped with dedicated analysis and archiving software.
Vibrometers based on accelerometers
The most common vibrometers on the market belong to one of two types: vibrometers based on accelerometers or laser vibrometers. The former measure both displacement and acceleration, allowing the sensor to be mounted directly on the machine and indicate the magnitude of the vibration with high accuracy. The sensor can be an integral part of a vibrometer – or it can be a small accessory connected to the meter with a special connector and then fixed with a magnet on the machine, which works in tight spaces. Their key element – the accelerometer, or rather the transducer used in it – may belong to one of three different types: piezoelectric, piezoresistive or capacitive. In piezoelectric transducers, the crystals generate an electrical charge under mechanical load, in piezoelectric transducers the electrical resistance is measured, while it !