According to the different principles of vibration generation and mechanical structures, the main types of vibration machine include mechanical vibration tester, electro-dynamic vibration test system, hydraulic vibration test system, piezoelectric vibration machine, and magnetostrictive vibration machine. In environmental and reliability tests, mechanical vibration tester, electro-dynamic vibration test system and hydraulic vibration test system are often used, especially electro-dynamic vibration test system are the most widely used.
Whether it is a mechanical vibration tester, an electro-dynamic vibration test system or a hydraulic vibration test system, a complete vibration test system includes the following 4 modules:
1) Shaker
The shaker is a vibration actuator. Due to different implementation principles, they are subdivided into mechanical vibration tester, electro-dynamic shaker, hydraulic vibration test machine, various types of vibration exciters (such as electromagnetic vibration exciters, hydraulic actuators), etc. According to the different ways of excitation, it can be divided into a single vertical vibration machine, a combined vertical and horizontal slip table vibration machine, a biaxial or triaxial vibration machine, and a six-free vibration machine.
2) Power amplifier
It is the component that performs power conversion. Mechanical shakers are driven directly by an electric motor or indirectly through a gearbox without power conversion.
The signal output by the electro-dynamic shaker control system is a low-voltage, low-current signal, which is converted into a medium-voltage and high-current power output by a power amplifier to drive the winding coil to achieve high-power mechanical vibration. Depending on the excitation force of the electro-dynamic shaker, the electrical power output by the power amplifier ranges from several kilowatts to hundreds of kilowatts. The power amplifier of the early electric vibrating table was a tube power amplifier, and later developed into a high-power transistor amplifier. Now most of them use switching tube power amplifiers.
The output signal of the hydraulic vibration test system control system is also a low-voltage, micro-current signal. After being amplified by a small power circuit, it drives the electro-hydraulic servo valve to convert the electrical signal into a high-power hydraulic power signal output, so the power conversion device of the hydraulic table It is an electro-hydraulic servo valve.
3) The vibration control system is the control center of the vibration test.
Whether it is sinusoidal vibration, random vibration, vibration with multiple complex waveforms superimposed, or more complex multi-dimensional synchronous vibration, the vibration motion state and the accuracy of vibration simulation all rely on the vibration control system for modulation and real-time “equalization” “. In the early days of vibration control, analog control systems dominated, but now digital control systems dominate.
4) Vibration detection device
It is the basis for judging the values of various “vibration state parameters” in vibration tests. The real-time detection (or monitoring) data of the vibration detection device is fed back to the vibration control system, providing exact information for the control system to judge the current vibration state of the “vibration table + fixture + test piece, and make corrections to the next output signal accordingly” Decision-making and magnitude Therefore, the authenticity and validity of the detection results of the vibration detection device are the basis and prerequisite for the credibility of the entire vibration test results.
