What is the difference between shock and vibration testing?

In manufacturing, developing high product quality is paramount. Implementing rigorous testing protocols during the product development phase is an investment in product consistency, reduced costs linked to quality issues, and customer loyalty, leading to the long-term success of your business.

Mechanical stress testing is an essential component of developing a high-quality product. This process involves subjecting a device to both shock testing and vibration testing in order to determine whether a device can remain functional when subjected to sudden, abrupt motion changes that are to be expected with service environments like product handling, shipping and transportation, aerospace, or weapon firing.

Simply put, shock is one hard impact, while vibration is shock repeated over and over again.

Testing products and systems for both shock and vibration is critical in order for engineers to design solutions to effectively mitigate both forces and ensure product longevity.

What is the difference between shock and vibration?

Although fundamentally different, vibration often accompanies shock.

When a hammer strikes a stationary object, it applies shock that disrupts the object's equilibrium. This impact also sends rapid, powerful vibration forces throughout the system, causing further disruption beyond the initial point of contact.

Engineers must test for both shock and vibration to ensure a product or system can endure real-world operating conditions.

How is mechanical shock testing done?

While vibration testing identifies issues from consistent vibration, mechanical shock testing assesses a product or system’s ability to withstand a short burst of energy, like a sudden impact, bump, collision, drop, or explosion.

Mechanical shock testing ensures that equipment continues to function within performance standards after exposure to shocks encountered during normal operations. It also verifies that equipment remains securely attached to its mountings and does not separate in a way that could be hazardous during crashes or collisions.

There are different types of mechanical shock tests, including:

• Pyro-shock: tests the resilience of systems for use in aerospace and military applications when weapons are being fired or ordinances are being detonated.
• Drop testing: tests the resilience of a system in the situation of common mishaps like being dropped
• Free-fall and variable force test techniques: tests how objects hold up in a free fall, solely under the influence of gravity
• Impact testing: tests the ability of a system to withstand an impact like an item being dropped on it
• Classical shock: using an electrodynamic shaker, engineers can test a system’s ability to withstand many classical pulse shapes
• Complex shocks: designed to re-create complex pulses with a frequency response comparable to the operational environment

How is vibration testing performed?

Vibration testing evaluates a product's ability to withstand mechanical vibrations that it may encounter in everyday use, like the vibrations from a ship’s engine or from driving a vehicle on a rugged terrain. If not considered during the design process, these vibrations can cause mechanical and electrical systems to fatigue and fail.

In order to determine a product’s durability, engineers use a machine called a vibration controller or mechanical shaker to measure how a device under test (DUT) reacts while it is being shaken at different frequencies.

Mechanical shakers enable engineers to set specific vibration settings like how fast and how strong the shaking should be, and adjust the parameters based on how the DUT responds.

How Nemko can help

Both shock and vibration testing are vital components of the product development and quality assurance process, allowing engineers to evaluate the durability, reliability, and performance of products exposed to sudden mechanical impacts.

By understanding the purpose, setup considerations, test profiles, and associated advantages and limitations, engineers can anticipate the shortcomings of a DUT and work to ensure product integrity and customer satisfaction.

Involving Nemko’s team of experts early in the design process can reduce your costs and accelerate the process of bringing your device to market. Contact us today to learn more about international standards for shock and vibration testing and how we can help you get certified.