Mechanical Shock Testing

Mechanical shock testing is the application of high levels of acceleration, for a very short period of time, to a component, product, system or structure in order to observe its response or degradation. Mechanical shock testing simulates the effects on a test sample of an acceleration pulse that may be caused by an impact, drop, explosion, or other high amplitude and short duration acceleration or deceleration.

Although there is overlap between the two definitions, vibration testing is distinguished from mechanical shock testing by being applied for a longer period of time, ranging from a few minutes to many weeks. Mechanical shock tests have typical durations of less than one second per shock, although multiple shocks over longer time periods are commonly performed.

Mechanical shock testing is also distinguished from thermal shock testing which is performed by very rapidly changing the temperature of the test sample.

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Mechanical Shock Testing Examples

Other than drop testing of packaged products, the most common mechanical shock test for typical electronic products is a classical half-sine (more precisely a haversine). Approximately triangular shaped (“sawtooth”) pulses are the next most common. Shock pulses with very high amplitudes are sometimes specified in the frequency domain as an SRS (Shock Response Spectrum) rather than the classical time domain pulse shape. The most common mechanical shock test for electronic products is a half-sine of 20 or 30 g peak amplitude and a duration of 11 msec.

Common Shock Tests:

Repetitive Shock Test
Half-Sine Shock Tests
Sawtooth Shock Tests
High Amplitude Shock
SRS (Shock Response Spectrum) Profiles
Pyroshock

Mechanical Shock Test Standards

Including, but not limited to:

ASTM D4169

EN/IEC 61373

EN/IEC 68-2

ISO 16750-3

ISTA

MIL-STD 810, MIL-STD-202, MIL-STD-883

RTCA/DO-160G

IEC 60068-2-31

IEC 60068-2-55

and more!

How is High Level Mechanical Shock Testing Performed

High Level mechanical shock testing utilizes a shock machine that accelerates a test sample to generate a controlled impact event. Unlike direct impact scenarios (e.g., a vehicle striking a barrier), the sample does not contact the barrier directly. Instead, it is mounted to a high-mass metal plate on the side opposite the impact surface. A compressible programmer material between impact surfaces defines the shock pulse shape based on its properties (e.g., thickness, hardness).

Shock amplitude is governed by the impact velocity of the platen/sample system. This may be achieved via free-fall or, more commonly, with compressed air to reach higher accelerations and reduce system height. Hydraulics are typically used to position the platen prior to release.

Accelerometers mounted to the platen enable closed-loop control, allowing the system to measure each shock pulse and adjust parameters such as drop height and air pressure to maintain accuracy and account for material changes over repeated impacts.

Testing is typically conducted in a single axis per drop, so samples are reoriented to evaluate all six directions (three axes, two directions). A common test profile includes three shocks per orientation, totaling eighteen shocks.

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Mechanical Shock Testing Using Shakers

Electrodynamic vibration systems (“shakers”) are commonly used to apply mechanical shock at lower amplitudes and durations. This equipment enables precise control over shock pulse shape and frequency content while allowing the test sample to remain in its normal vertical orientation (with a slip-table used for horizontal inputs). However, shaker displacement limits constrain the maximum achievable shock amplitude and duration.

Unlike impact-based methods, shakers generate shock through controlled acceleration and deceleration rather than physical impact. To achieve the required end velocity of zero, the system must first accelerate the test sample before rapidly decelerating it (or vice versa). This dual motion requires significant displacement – particularly for longer pulse durations – which can limit test capability even when sufficient force is available.