How to Choose the Right Vibration Testing Equipment?

Vibration testing is a crucial aspect of mechanical environmental testing. It subjects products and materials to controlled oscillations, simulating the vibrations they might encounter during their lifecycle – from manufacturing and transportation to end-use. The core of this testing lies in the vibration test system, a specialized piece of mechanical environmental testing equipment.

At Dongguan Precision Test Equipment Co., Ltd., we offer a comprehensive range of vibration test systems tailored to diverse industry needs. Understanding the different types of vibration tables and their characteristics is paramount when selecting the right equipment for your specific application. Let's delve into the classification, principles, and features of various vibration test systems to guide your decision.

II. Classification, Principles, and Characteristics of Vibration Test Systems

Vibration test systems can be broadly categorized into three main types based on their working principles: Electrodynamic Vibration Systems, Mechanical Vibration Systems, and Hydraulic Vibration Systems.

1. Electrodynamic Vibration Systems:

• Primary Specification: Output excitation force (measured in Newtons or pounds-force).
• Frequency Range: Widest range, typically 5-3000 Hz.
• Maximum Displacement: Generally ±12-25 mm.
• Maximum Acceleration: Typically up to 100g.
• Horizontal Vibration: Achieved with the addition of a horizontal slip table.
• Control Capabilities: Excellent control accuracy for sine, random, and shock vibration profiles using a vibration controller.
• Advantages: Wide frequency range, high acceleration capability, precise control, suitable for complex test profiles.
• Disadvantages: Smaller table size (often requiring auxiliary tables), higher running costs and purchase price.
• Typical Applications: High-frequency, high-acceleration vibration testing of electrical and electronic components, small assemblies, etc.

(1) Excitation System (Shaker): The core of the electrodynamic system, consisting of: * Magnetic Circuit System: Composed of permanent magnets, a magnetic base, a magnetic top cover, a center magnetic pole, and an excitation coil, generating a constant magnetic field. * Moving Coil System (Armature): Includes the table, drive coil (voice coil), and table mounting screws. Inputting an alternating current into the drive coil, which is within the magnetic field, generates the excitation force along the coil's axis, transmitted to the test specimen via the table. Adjusting the frequency and amplitude of the input current controls the output vibration frequency and amplitude. * Lower Guidance and Suspension System: Utilizes guide wheels, bearings, guide rods, and air springs for stable vertical movement. * Upper Guidance System: Employs guide wheels, guide wheel seats, and rocker arms for additional stability. * Table Suspension System: Consists of columns, trunnions, slide rods, linear bearings, and springs to support the moving assembly.

(2) Cooling Blower: Essential for dissipating heat generated by the moving coil and excitation coil during operation, ensuring long-term system reliability. Typically includes a high-pressure centrifugal fan, silencer, and ductwork.

(3) Vibration Controller: Generates and controls the vibration signal (e.g., sine sweep, fixed frequency, dwell, random). When used with an accelerometer mounted on the vibration table, it forms a closed-loop control system, accurately measuring and adjusting the frequency and amplitude of the vibration. Key components include a signal generator, signal control circuits, charge amplifier, measurement circuits, and power supply.

(4) Power Amplifier: Amplifies the low-level signal from the vibration controller to the power levels required to drive the electrodynamic shaker and provides the excitation power for the magnetic field. Comprises a preamplifier, intermediate amplifier, power output stage, protection circuits, excitation power supply, and main power supply.

2. Mechanical Vibration Systems:

• Primary Specification: Maximum payload capacity.
• Frequency Range: Generally 5-80 Hz.
• Maximum Displacement: Typically ±3-5 mm.
• Maximum Acceleration: Generally up to 10g.
• Horizontal Vibration: Often achievable without an additional slip table for certain designs.
• Control Capabilities: Primarily for fixed frequency and swept sine vibration. Random vibration is not typically supported.
• Advantages: Large table size, high payload capacity, low power consumption, relatively low purchase price.
• Disadvantages: Narrow frequency range, high noise levels, inability to perform random vibration tests.
• Typical Applications: Whole unit vibration testing of electrical, electronic, and optical instruments.

3. Hydraulic Vibration Systems:

• Primary Specification: Output excitation force.
• Frequency Range: Generally 1-200 Hz.
• Maximum Displacement: Typically ±100-200 mm.
• Maximum Acceleration: Generally up to 10g.
• Horizontal Vibration: Achieved with the addition of a horizontal slip table.
• Control Capabilities: Capable of random vibration with a suitable random vibration controller.
• Advantages: Low frequency capability, large displacement.
• Disadvantages: High noise levels, high running costs and purchase price.
• Typical Applications: Full vehicle vibration testing for the automotive industry, seismic simulation for civil engineering and hydraulic structures.

4. Vibrator (Shakers Based on Electromagnetic Principles):

• Displacement Amplitude: Typically ±1-3 mm.
• Application: Often used for vibration testing within industrial processes.
• Limitations: Do not typically meet the accuracy requirements for formal environmental vibration testing in terms of distortion, transverse vibration, and uniformity.

III. Product Selection Guide: How to Choose the Right Vibration Test System

Selecting the appropriate vibration test system requires careful consideration of your specific testing requirements:

1. Frequency:

• For vibration tests below 80 Hz with a fixed displacement, a mechanical vibration system may be suitable.
• For frequencies in the range of 1-200 Hz, consider a hydraulic vibration system.
• For applications requiring a wider frequency range (0-3000 Hz), an electrodynamic vibration system is the necessary choice.

2. Amplitude (Displacement):

• For displacement amplitudes below ±5 mm, a mechanical vibration system might be sufficient.
• For displacement amplitudes up to ±12 mm, an electrodynamic vibration system is generally considered.
• For large displacement requirements reaching ±100-200 mm, a hydraulic vibration system is essential.

3. Payload:

• Ensure the weight of your test specimen falls within the rated payload capacity of the vibration table.
• Payload directly impacts the achievable vibration amplitude, especially the acceleration capability of electrodynamic vibration systems.

4. Direction of Vibration:

• For horizontal vibration testing of larger payloads, both electrodynamic and hydraulic vibration systems typically require the addition of a horizontal slip table.

By carefully evaluating these factors in relation to your specific testing needs and industry standards, you can make an informed decision and select the vibration test system that best meets your requirements. At Dongguan Precision Test Equipment Co., Ltd., our experienced team is ready to assist you in navigating these considerations and providing the optimal vibration testing solution for your products. Contact us today to discuss your application!