Definition
An electromagnetic shaker is a device that uses the principle of electromagnetic induction to generate controllable mechanical vibrations. It is widely used in reliability verification and performance testing of industrial products by converting electrical energy into mechanical energy and simulating the vibration conditions of products or materials in an experimental environment.
How it works:
Its core is based on the physical principle of the force of current-carrying conductors in a magnetic field. The system is mainly composed of a vibrating table, a power amplifier, a control system and a measuring sensor. When the power amplifier amplifies the control signal and feeds it to the moving coil of the bench, the moving coil in a constant magnetic field generates an alternating Lorentz force due to the change of current, thereby driving the table to reciprocate. Its basic force formula can be expressed as:
F = B * L * I
where F is the driving force, B is the magnetic flux density in the magnetic gap, L is the effective length of the moving coil wire, and I is the current passing through the moving coil. By precisely controlling the waveform, frequency, and amplitude of the input current, the vibration parameters can be controlled.
Measurement method
The measurement of vibration parameters usually follows relevant international and national standards. Key measurement items include acceleration, frequency, and displacement. Acceleration is measured by piezoelectric accelerometer, and its output charge signal is converted into a voltage signal by a charge amplifier and analyzed. The frequency response is obtained by comparing the control signal with the sensor feedback signal. Displacement is often measured by laser displacement sensors in non-contact. Measurement data is collected and processed by a dynamic signal analyzer to generate graphs such as spectrum, transfer functions, and more.
Influencing factors
The accuracy and repeatability of shaking table test results are influenced by a variety of factors. Insufficient connection stiffness between the table and the specimen can lead to resonance frequency offset and waveform distortion. The mass and centroid distribution of the specimen can affect the load characteristics of the table and may limit the output of maximum acceleration or displacement. The linearity and distortion of a power amplifier directly affect the waveform fidelity of the output vibration. In addition, changes in ambient temperature may affect magnet performance and sensor sensitivity, and the accuracy of control algorithms is the key to achieving complex vibration spectral reproduction.
Applications:
The equipment serves quality assurance in many industrial fields. In the electronic and electrical industry, it is used to test the vibration resistance of circuit boards, connectors and the whole machine in the transportation and use environment. In the field of automotive parts, it is used to simulate the fatigue effects of engine vibration or road bumps on components. In the study of packaging materials, it is used to evaluate the protective capacity of packaging structures during logistics. In the aerospace sector, tests are used to verify the functional integrity of components in vibration environments during takeoff and flight. In basic materials science, it is also used to study the mechanical properties of materials under cyclic loads.
Selection considerations
Selecting a suitable electromagnetic shaker requires systematic technical matching. First, it is necessary to clarify the frequency range, maximum acceleration, velocity, and displacement parameters required by the test standard to ensure that the equipment thrust and stroke meet the requirements. Secondly, it is necessary to evaluate the size of the table and the installation interface to adapt to different sizes of test samples. Consider the waveform distortion of the device, lateral motion ratio, and other indicators, which are related to the accuracy of the test. For complex tests, it is necessary to confirm whether the control system supports functions such as random vibration, sine sweep, and impact spectrum synthesis. Reliability of long-term operation, ease of maintenance, and energy consumption levels are also factors that need to be balanced in comprehensive decision-making.