Definition
Vibration testing machine is a kind of experimental equipment that simulates the vibration environment experienced by products during transportation, installation and use. It evaluates the structural integrity, functional reliability, and fatigue life of the specimen under specific vibration conditions by applying controlled mechanical vibration. This equipment is widely used in the reliability verification and quality evaluation of industrial products, and is one of the key instruments in the field of environmental and reliability testing.
Principle
The working principle of the vibration testing machine is based on electromagnetic or mechanical drive to generate periodic or random vibration excitation. Electromagnetic shakers are a common type, and their core works according to Ampere's law and Faraday's law of electromagnetic induction. When the alternating current passes through the moving coil, a Lorentz force is generated in a constant magnetic field, which drives the table and the specimen on which it is mounted to reciprocate. Its basic force formula can be expressed as:F = B * L * I, among themFAs a driving force,Bis the magnetic flux density,Lis the effective length of the conductor,Iis the current. The control system adjusts the waveform, frequency, and amplitude of the input current through a power amplifier to precisely control the vibration parameters.
Measurement method
In vibration testing, the measurement of key parameters relies on sensors and data acquisition systems. Accelerometers, such as piezoelectric accelerometers, are typically mounted on a table or specimen to convert mechanical vibrations into electrical signals. The measurement system conditions and collects the signal, and then analyzes the physical quantities such as acceleration, velocity, and displacement. The frequency characteristics are obtained by spectrum analysis, while the vibration magnitude is controlled and verified according to the test spectrum specified by relevant standards (e.g., IEC 60068-2 series, GB/T 2423 series). The measurement process requires ensuring that the sensor is securely mounted, the signal link is reliable, and that it is calibrated regularly to ensure data accuracy.
Influencing factors
The results of the vibration test are influenced by multiple factors. The quality, size, center of gravity position and stiffness of the installation fixture will affect the vibration transmission characteristics, which may cause uneven vibration on the table or local resonance of the specimen. The test parameter settings, such as frequency range, vibration magnitude, test duration, and vibration direction, directly determine the severity of the test and the authenticity of the environmental simulation. In addition, environmental conditions such as laboratory temperature, humidity, and the performance status of the equipment itself, such as the lateral motion ratio of the countertop, harmonic distortion, etc., will also affect the repeatability and comparability of the test.
Applications
The application of vibration testing machines covers many industrial fields. In the automotive industry, it is used to test the durability of parts and vehicles under simulated road vibrations. In the electronic and electrical industry, it is used to evaluate the vibration resistance of circuit boards, connectors and complete products during transportation and use. In the aerospace field, it is used to verify the functional reliability of airborne equipment in flight vibration environments. In addition, vibration testing plays an important role in the packaging, construction and defense industries, helping R&D and quality departments identify design defects and improve product robustness.
Equipment selection
Choosing the right vibration testing machine is a systematic project that requires a comprehensive evaluation of technical requirements and resource conditions. First, it is necessary to clarify the requirements of the test standards and determine the required key performance indicators such as thrust, frequency range, maximum displacement, velocity and acceleration. The thrust should be calculated according to the total mass of the specimen (including the fixture) and the target acceleration. Secondly, consider the direction of vibration (vertical, horizontal, or both) and the size of the countertop. The performance of the control system, such as the types of waveforms supported, random control capabilities, the number of data acquisition channels, and the ease of use of the software, are also important considerations. In addition, the infrastructure conditions of the laboratory, such as load-bearing, space and power supply, as well as the availability of maintenance costs and technical support after the equipment is operational, should also be factored into the decision-making process.