What Is a Vibration Tester?
A vibration tester is a testing machine that applies vibration to parts or products.
The main purpose is to check for damage or failure caused by vibration. It is also used to examine the vibration response characteristics of components.
Any product can be damaged due to fatigue caused by vibration over a long period. Therefore, vibration tester is often used for quality assurance purposes.
A vibration tester is mainly used to check vibration resistance performance by sinusoidal or random wave vibration. They are also used to measure mechanical impedance, which is the vibration response characteristic of a mechanical system, to determine resonance frequencies and vibration countermeasures.
Uses of Vibration Testers
Vibration testers are used to confirm the vibration resistance of parts and products and to determine the vibration response characteristics of components and structures.
Principle of Vibration Testers
Vibration testers are classified into mechanical, hydraulic, electrodynamic, servo motor, and other types depending on the drive system. The classifications are as follows.
1. Mechanical Vibration Testers
This method uses a motor as the driving force to mechanically convert rotational motion into reciprocating motion. Compared to hydraulic and electrokinetic types, mechanical vibration testers are relatively inexpensive. In recent years, mechanical vibration testers have been replaced by other methods due to their shortcomings in controllability.
2. Hydraulic Vibration Testers
This method uses hydraulic pressure from a hydraulic pump as the driving force. The servo valve switches the hydraulic circuit at high speed to generate vibration. This method is suitable when low vibration frequency, long stroke, and high power are required. The frequency range is 1 to 300 Hz. It is often used when large structures such as buildings are vibrated by seismic waves.
3. Electrokinetic Vibration Testers
This method utilizes the Lorentz force generated when an electric current is applied to a conductor in a magnetic field. By bypassing an alternating current through a drive coil installed in a magnetic field with an excitation coil, a reciprocating motion is generated in response to the current. The vibration of the shaker is detected by a pickup and fed back to the controller to keep the vibration at a set value. This method is characterized by a wide range of vibration frequencies and can be used up to particularly high vibration frequencies. The vibration frequency range is generally from 5 to 3,000 Hz, but some small shakers are capable of higher frequencies, up to 40,000 Hz.
4. Servo Motor Type Vibration Testers
This method uses a servomotor linear actuator that combines an AC servomotor and a ball screw to generate vibration. The load capacity is lower than that of the hydraulic type, and the frequency range is lower than that of the electrodynamic type. The operating range is intermediate between the hydraulic and electrodynamic types. The frequency range is 0.01 to 300 Hz.