All Tests
Vibration and shock tests are experimental tests used to evaluate the resistance and reliability of components, devices, or structures subjected to mechanical stresses such as vibrations and impacts. These tests are fundamental in sectors such as aerospace, automotive, railway, electronics, and military to ensure products can operate in harsh environments without failure.
Vibration Tests
Vibration tests simulate the mechanical oscillations a product may undergo during transport, operation, or real-world use. They are divided into:
- Sine Vibrations: applied at a specific frequency to identify structural resonances.
- Random Vibrations: simulate real operating conditions with random variations in frequency and amplitude.
- Shock Vibrations: short high-acceleration pulses to simulate events such as impacts or explosions.
Shock Tests
Shock tests assess a product’s ability to withstand sudden impacts such as drops or collisions. Some types include:
- Classical Shock: simulates impacts with defined waveforms (e.g., sawtooth, trapezoidal).
- Drop Test: evaluates the resistance of electronic devices and packaging to free falls.
- Ballistic or Explosive Shock: used in military fields to simulate explosions or violent impacts.
These tests are carried out with instruments such as shaker tables, impact hammers, and drop systems, often according to international standards (ISO, MIL-STD, IEC).
Sine and Random vibration tests are two methodologies used to verify the resistance and reliability of components and systems subject to mechanical vibrations. They are widely used in aerospace, automotive, electronics, and military applications.
Sine Vibration Test
Sine vibration consists of a periodic signal at one or more well-defined frequencies, simulating predictable and repetitive vibrations.
Characteristics:
- The object is subjected to oscillations with a single frequency at a time, which can be varied continuously or step by step.
- The amplitude and frequency of the vibration can be precisely controlled.
- Often used to identify resonance frequencies, where vibrations amplify mechanical stresses on the component.
Types of Sine Tests:
- Sweep Sine: frequency progressively varies over a range (e.g., 10 Hz – 2000 Hz) to identify resonances.
- Dwell Sine: a specific frequency is maintained constant for a prolonged period, useful to check resistance at critical frequencies.
Applications:
- Identification of structural response.
- Material resistance tests to repetitive stresses.
- Mechanical fatigue analysis.
Random Vibration Test
Random vibration is a complex signal composed of many simultaneous frequencies with variable amplitude over time, simulating real-world operating conditions more realistically than sine vibration.
Characteristics:
- The signal consists of a set of random frequencies reproducing real operating environments (e.g., vibrations experienced by a satellite during launch or a car on a rough road).
- The vibration intensity is described in terms of PSD (Power Spectral Density), representing energy distributed across frequencies.
- Allows evaluation of product behavior in unpredictable, multi-frequency conditions.
Applications:
- Vibration tests on electronic, aerospace, and automotive components.
- Simulation of transport and environmental vibrations.
- Stress tests for structural fatigue resistance.
Differences between Sine and Random Vibration
| Characteristic | Sine Vibration | Random Vibration |
|---|---|---|
| Signal Type | Sinusoidal, one frequency at a time | Multiple simultaneous frequencies |
| Main Purpose | Identify resonances and analyze structural response | Simulate real conditions and assess fatigue resistance |
| Control | Precise and deterministic | Stochastic (random) with defined power density |
In many cases, both tests are combined for a more complete evaluation, for example in Sine-on-Random tests, where a sinusoidal signal is superimposed on a random signal to simulate vibrations with dominant periodic components.
Shock tests are mechanical tests used to evaluate the resistance of a component, device, or structure to sudden and violent impacts. These tests simulate real conditions such as drops, impacts, explosions, or accidental collisions, helping identify weaknesses in materials and mechanical or electronic connections.
Types of Shock Tests
Shock tests can be divided into several categories depending on the type of impact simulated.
1. Classical (Mechanical) Shock
Consists of a single or repeated impulse applied to the test object.
The signal has a predefined waveform, such as:
- Half-Sine Shock: simulates typical impacts such as drops or collisions.
- Trapezoidal: used for more severe tests on ductile materials.
- Rectangular Pulse: to simulate longer-duration shocks.
Applications: tests on electronic components, aerospace and automotive structures to verify impact resistance.
2. Drop Shock
The object is dropped from a defined height onto a rigid surface or a specific support.
The test evaluates:
- Resistance to transport shocks (e.g., a remote control falling).
- Structural integrity after accidental impacts.
Applications: smartphones, laptops, handheld controls, medical instruments, packaging.
Shock Test Parameters
During a shock test, several key parameters are measured:
- Acceleration (g): impact intensity, measured in multiples of gravitational acceleration.
- Pulse Duration (ms): the time the object is subjected to acceleration.
- Waveform: defines the type of energy transferred to the object.
Elettra has two test sites with shakers equipped with slip tables for 3-axis tests, allowing execution of:
- Sine Vibration according to IEC60068-2-6 international standards.
- Random Vibration according to IEC60068-2-64 international standards.
- Shock according to IEC60068-2-27 international standards.
These baseline standards are referenced by major railway sector standards as well as ETSI standards for telecommunications equipment.
Packaging validation tests are also performed according to ASTM 4169.
