Basic principle and selection method of electric vibration test system
The selection of vibration test systems involves various parameters such as test specifications, test standards, test samples, test fixtures, vibration test systems, vibration controllers, and measurement sensors, which are cumbersome and important. Therefore, it is the result of repeated considerations and repeated exchanges with manufacturers. The following parameters must be considered when selecting a vibration test system.
Determine the required excitation force
The working principle of the electric vibration system is: the excitation force is generated by the interaction of a fixed magnetic field and a moving coil passing current in the magnetic field. When the moving coil passes the alternating current, the moving coil IP generates a corresponding alternating motion. The excitation force required for a vibration test is equal to the product of the mass of the moving part and the test acceleration.
F=mA
When the mass of the moving coil of the shaking table is m0, the mass of the additional table (or horizontal sliding table) and the fixture is mf, and the mass of the vibration test sample is mS
The required excitation force provided by the required vibration excitation system is:F= (m0+mf+mS) A
Manufacturers should provide the quality of the moving parts and the quality of the additional table or horizontal slide. Customers can choose the maximum excitation force corresponding to the vibration system according to the calculated excitation force.
For example: the customer test sample is 30kg, the weight of the additional table and fixture is 20kg, the maximum vibration acceleration is 15g, the weight of the moving part of the selected electric vibration system is 10kg, and the mass of the moving coil of the preselected DC-1000-15 vibration system is 10kg, the thrust of the system is:
F=(m0+mf+mS)A= （30+20+10）x15=900kg
Choose DC-1000-15 to meet the thrust needs of customers. (The rated excitation force of the DC-1000-15 vibration test system is 1000 kg.)Due to the frequency response characteristics of the vibration fixture and customer test samples, the customer should leave a margin of more than 10% when selecting the vibration thrust.
The relationship between maximum acceleration, maximum speed, large displacement and frequency
For sinusoidal vibration, the frequency Hz, displacement DmmO-P, velocity Vm / s and acceleration A have the following relations:
V=（2 π f / 1000）* D
A=（2 π f）* V=[（2 π f）quadratic / 1000] * D
Consideration of parameters such as acceleration, velocity, displacement and frequency range
Maximum no-load acceleration:
The maximum acceleration value that a vibration system can generate under no-load conditions. This value is generally the vibration system's excitation force divided by the mass of the moving part.
Maximum speed:
The maximum speed that a vibration test system can reach, which is usually limited by the length of the moving coil windings and the output voltage of the power amplifier.
Maximum displacement of the vibration system:
The maximum displacement that a vibration test system can produce. This value is usually limited by the displacement protection device. Expressed as single amplitude 0-p or peak-to-peak amplitude p-p.
Frequency Range:
The vibration test system corresponds to the frequency range in which certain variables can be applied. For example, maximum displacement, maximum speed, and maximum acceleration.
Rated excitation force of the vibration system:
Rated thrust generated by the vibration system. In sinusoidal vibration, this value refers to peak thrust; in random vibration, this value refers to rms. This value is limited by the maximum current that the moving coil can pass.
Maximum test load:
The maximum test load that the shaking table can carry. This value is limited by the supporting coil of the moving table of the moving table, but the bearing capacity of the shaking table can be enlarged by methods such as auxiliary support.
Choice of vibration controller
The choice of vibration controller mainly considers the type and function of the test, and determines the type of vibration test required according to the test specification or product test standard. There are several types of vibration tests:
Sine vibration test, random vibration test, classic shock test, waveform emergence, etc.
There are other considerations: you need several control points and several test points to determine several input channels and several output channels. The sensor used is IEPE or charge input type.
Optional spare parts
Su Shi provides a variety of options for customers to choose, in order to better and more conveniently complete the customer's vibration test. The basic options are: center holding device, additional table, horizontal slide, auxiliary support device, auxiliary guide device, vibrating table electric moving device, vibrating table electric steering device, remote control device.
