Sine, Random, Shock, and Beyond: What Your Vibration Controller Can Do

At Dongguan Precision Test Equipment Co., Ltd., the heart of our advanced vibration test systems lies in the vibration controller. This sophisticated device orchestrates the entire testing process, enabling the simulation of a wide array of dynamic environments. Understanding the diverse functionalities of a vibration controller is key to unlocking the full potential of your testing capabilities. Let's explore the fundamental test types that modern controllers empower you to perform:

1. Sine Vibration Testing: The Pure Tone Simulation

What is it? Sine vibration testing involves subjecting a test specimen to a single-frequency oscillation that varies over time. The relationship between time and frequency is one-to-one, and the motion (acceleration, velocity, or displacement) follows a periodic sinusoidal pattern.

Key Features:

• One-to-one time-frequency correspondence.
• Periodic variation of motion parameters.
• Characterized by peak values to describe vibration magnitude.
• Frequency-dependent dominance: Low frequency (displacement), Medium frequency (velocity), High frequency (acceleration), with transition points known as cross-over frequencies.
• Energy concentrated at a specific frequency point.

Applications:

• Testing with periodic excitation (fixed frequency, stepped frequency, or swept frequency).
• Identifying the resonant frequencies of a product.
• Packaging dither (jostling) tests.
• Superimposing with random excitation to create more realistic environmental simulations.

2. Random Vibration Testing: Embracing Real-World Complexity

What is it? Random vibration testing utilizes non-deterministic signals, often described using probabilistic and statistical methods. It provides a more accurate representation of many real-world vibration environments.

Key Features:

• Non-deterministic signal described statistically.
• Simultaneous excitation across all test frequencies with randomly varying amplitudes at each frequency.
• From a time perspective, it's a superposition of multiple instantaneous random vibrations.
• Response curves at measurement points differ at every instant in time.
• More representative of real-world excitation.

Applications:

• Simulating vibrations experienced by vehicles during actual driving conditions.
• Simulating air turbulence affecting aircraft in flight.
• Simulating vibrations induced by fluid turbulence.

3. Compound Vibration Testing: Mimicking Complex Excitation

Compound vibration testing involves combining different types of vibration to create more realistic and complex simulation scenarios. Common modes include:

• Sine on Random (SoR): Superimposing one or more sinusoidal tones onto a broadband random vibration signal.
• Random on Random (RoR): Superimposing one or more narrowband random vibration signals onto a broadband random vibration signal.
• Sine on Random on Random (SRoR): Combining broadband random, narrowband random, and sinusoidal vibrations simultaneously.

Key Features:

• Broadband random vibration typically has a lower overall magnitude, while narrowband random and sine vibrations have higher magnitudes.
• Random on Random mode can achieve significant vibration levels with relatively lower overall excitation force.

Applications:

• Simulating vibration tests under complex excitation conditions.
• Achieving high-level vibration tests in segments.

4. Shock Testing: Simulating Transient Events

Shock testing simulates sudden, transient mechanical events. Common shock environments include:

• Random bouncing shocks during transportation.
• Accidental impacts, jolts, and drops during operation.
• Controlled shock environments utilizing impact energy.
• Sudden releases of chemical or other forms of energy (e.g., explosions).

              Half sine wave                                                                     Trapezoidal wave

Forward sawtooth wave Back-peak sawtooth wave

5. Understanding the Shock Response Spectrum (SRS):

The Shock Response Spectrum is a crucial concept in shock testing. It represents the maximum response of a series of single-degree-of-freedom (SDOF) systems with the same damping characteristics when subjected to a given transient time-domain signal.

Time Domain Simulation:

Advanced controllers also enable time domain simulation for highly specific scenarios:

• Seismic Wave Simulation (Transient Time Domain Simulation): Recording and reproducing actual earthquake waveform data on the vibration table to simulate the vibrations experienced by test specimens during real seismic events, assessing their reliability and resilience.
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• Road Load Data Replication (Long-Duration Time Domain Simulation): Recording and reproducing long-duration road load data on the vibration table to simulate the vibrations experienced by test specimens during actual driving conditions, evaluating their performance and lifespan.
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Failure Types Induced by Shock:

Shock events can lead to various types of failures, including:

• Structural deformation.
• Loosening of mountings, leading to cracks or even fractures.
• Loosening of electrical connections and poor contact, causing unstable product performance.
• Changes in the relative positions of internal units within a product, leading to performance degradation or component breakage.

The Power of the Controller:

The vibration controller is the central command unit that allows you to define, execute, and analyze these diverse vibration and shock tests. Its sophisticated algorithms and signal processing capabilities ensure accurate reproduction of desired waveforms, precise control over test parameters, and comprehensive data acquisition for thorough analysis.

At Dongguan Precision, our controllers are designed with user-friendliness and advanced functionality in mind, empowering you to simulate a wide spectrum of real-world dynamic environments and gain critical insights into the durability and performance of your products. Contact us today to learn more about how our controller technology can enhance your testing capabilities.