6 Facts About Vibration Testing Systems

Vibration problem exists widely in the popular life and production, buildings, machines or the outside world will produce vibration under the incentive. And mechanical vibration often damages the normal work of machinery, and even reduces the service life of machinery and causes irreversible damage to the machine. Most of the mechanical vibration is harmful. Therefore, the study of vibration is not only conducive to improving the living environment and living standards, but also helpful to improve the service life of mechanical equipment. Mechanical vibration testing technology plays a very important role in industrial production, manufacturing efficient mechanical vibration testing system has become an important content of testing technology.

What is mechanical vibration?

Mechanical vibration refers to the process in which the displacement of an observation point on the mechanical equipment or structure changes with time around its mean value or relative datum when the mechanical equipment is in motion. Mechanical vibration is double-sided, beneficial and harmful.

There are two types of vibration, one is steady state vibration and the other is random vibration.

The three elements of vibration (signal three elements) : amplitude, frequency and phase

• Amplitude: Indicator of vibration intensity. Representation method: single peak value, effective value, average value, etc.
• Frequency: the reciprocal of the period. Through spectrum analysis, the main frequency components and their amplitude can be determined, so that the source of vibration can be found and some measures can be taken.
• Phase: The phase information of vibration signal is very important.

Types of vibration tests

1、measure the vibration of the working machinery or structure in the working state, such as: the displacement, speed, acceleration, frequency and phase of vibration, etc.

• Understand the vibration state of the tested object
• Rating
• Find the root cause
• Perform monitoring, analysis, diagnosis and prediction

2、Add some excitation to mechanical equipment or structure to test its forced vibration.

Obtain the vibration mechanical parameters or dynamic properties of the tested object, such as natural frequency, damping, response, mode, etc.

Composition of vibration test system

Vibration testing system is mainly composed of sensor, signal adjustment part, digital to analog converter, signal processing part, data recording part, feedback part and so on.

The sensor is the component that will be measured into some kind of electrical signal, is the most important part of the whole test system. The signal regulation part converts the output signal of the sensor into a form suitable for further transmission and processing. After processing, the original signal is more convenient to analyze and process, and most of the signal conversion is direct conversion of electrical signals. Signal processing part is the signal from the signal regulation link to carry out various operations and analysis, which is also the core meaning of the test. The digital-to-analog converter is the link of the conversion between analog signal and digital signal when the computer is used to test and control the system.

The main function of the test system is to convert the initial test signal into some signal for extraction and analysis more easily and easily. So the most important thing is that the signal is not distorted, that there is no disturbance. This puts forward more strict request to the test system.

Reasons, processes and results of vibration testing of products

First of all, in any product in the design, development stage, it is necessary to carry out vibration test, first, can analyze the vibration mode of the test product in different vibration state, test the ultimate strength of the product and set the relevant characteristic specifications; Secondly, failure analysis and improvement are carried out on the vibration test results of the sample. Full ESS testing is performed while the sample is in production to screen for potential defects in large numbers. (according to the features of the product and scale of vibration in ESS test effectively screen out the potential bad thing, and for electronic or institutions and processing when the residual thermal stress and stress can effectively eliminate them the effect of residual stress and can effectively eliminate the multilayer circuit board between discrete capacitance effect, will provide considerable help to product quality.) The second is to the product quality management (QC) and quality assurance (QA), can effectively ensure and manage the quality of the product level, certification production of the product its use function, specifications and reliability and the same as the label.

Generally speaking, vibration tests can screen out the following defects: Fixed a loose, electronic contact in bad place, screen out the potential of bad parts, filter out any defect in the solder joints, adjust the position of vibration, accuracy of distortion, components of the broken, damaged, abnormal circuit breaking short circuit, the power cord or the signal line of abnormal wear or wire break or loose fall off, specimen vibration noise, contact function failure, etc.

Vibration testing of products can provide the basis and reference for engineering development, process control, quality improvement and promotion, provide the interrelation conditions related to vibration, guarantee the quality of products, reduce maintenance expenses and increase the profit rate, improve the overall image, etc

Standard test requirements related to vibration testing

• IEC62133-2012
• UL1642
• 3
• GB31241-2014

Matters needing attention when using vibration test system

• Temperature and humidity

Do not operate vibration test system equipment outside the temperature and humidity limits; Refer to the relevant user manual.

• high altitude

At higher altitudes, vibrator cooling will be affected by reduced air density. If such problems are likely to arise, it is advisable to consult a professional engineering team for advice.

• cleanliness

The vibration test system and other related equipment shall not be operated in a humid, greasy, dirty or dusty environment. Dirt and dust may cause the central positioning system (if installed) to fail to function properly. Water from wet conditions can corrode the vibrator and may cause a short circuit. Oil on or around the vibrator can make the surface smooth and pose a danger to operators. Therefore, making sure the surrounding area is tidy is an important part of daily maintenance activities.

• condensation

If the operating temperature and humidity (e.g., working in a temperature chamber) bring the temperature of the vibrator moving coil below the dew point, moisture will condense on the moving coil. This can corrode the frame and cause a short circuit. These problems can be avoided by:

• Use heat shield
• Install heating elements around the moving coil/temperature box interface
• Direct the hot air discharged by the fan to the bottom of the temperature box

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