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Shipping and handling, as well as everyday use, can expose products to shock vibrations that may pose a risk to their structural integrity. To simulate these conditions and ensure that devices can withstand such shocks, vibration test engineers employ drop shock testing in the lab. Let’s dive deeper into this fascinating process.
Understanding Drop Shock Testing
Drop shock testing focuses on non-repetitive shocks, such as accidental drops. During these tests, engineers employ classical shock pulses to deliver a sharp transfer of energy to the device. These pulses generate a unipolar acceleration shape and a predefined change in velocity. Test standards dictate the pulse shape, severity, duration, and tolerances.
Various types of drop tests exist, including free fall, rotational edge drop, and incline/horizontal impact. The primary characteristic shared by all these tests is the controlled setting in which they take place. Engineers can reproduce the tests, with predefined parameters like severity and orientation. If the test requires motion across all three axes, the product is unmounted, reoriented, and retested using the same profile.
The Importance of Standards
Drop shock testing plays a crucial role in determining product durability and packaging performance. Consequently, numerous industries mandate its implementation. For instance, the International Electrotechnical Commission (IEC) manages well-known drop-shock standards for electrical and electronic-related technologies, such as IEC 60068-2-27, IEC 60068-2-29, and IEC 60068-2-31. These standards define pulse shapes, peak acceleration, and duration, aiming to recreate the operational environment or meet design requirements.
Moreover, packaging standards required by Amazon for vendors using Fulfillment By Amazon (FBA) also incorporate drop shock testing. ISTA 6-Amazon-Over Box defines a general simulation test for e-commerce fulfillment, while ISTA 6-Amazon-SIOC establishes guidelines for Ships in Own Container (SIOC) packaged products shipped through Amazon’s distribution system.
Additional standards include SAE J1455 for automotive shock and drop testing, MIL-STD-810 for military systems, DO-106, and EN 60068-2-27.
Drop Shock Machinery: Crafting the Perfect Pulse
The selection of drop shock machinery depends on several factors: the product’s mass, desired amplitude, pulse duration, and pulse shape. Machines designed for drop shock testing utilize a product’s rapid deceleration to generate user-defined pulses. These machines consist of a table mounted on two parallel columns. The columns are raised to a pre-calculated height and then dropped onto a reaction mass that absorbs some of the shock to prevent direct contact with the ground.
Test Set-Up
During a free-fall drop shock test, the product is secured to a test table. The acceleration amplitude and pulse shape are determined by the height from which the product is dropped and the impact surface material. The higher the drop height, the greater the acceleration when the product strikes the reaction mass.
To generate various classical shock pulses, drop shock machines incorporate components called programmers. These programmers determine the pulse shape as the table drops onto the seismic mass. Additionally, when a machine’s height is insufficient to generate the desired acceleration, elastic bands or pneumatic cylinders can be added to increase the impact velocity. The dynamic response of the programmer defines the shape of the pulse.
Electrodynamic Shakers
While drop shock machines utilize mechanical methods to arrest movement, electrodynamic shakers work differently. They require pre- and post-pulse compensation to achieve zero acceleration, velocity, and displacement parameters. Although shakers are reliable and efficient for routine shock testing, classical shock tests require the integration of pre-/post-pulse compensation pulses to reset the shaker to zero parameters.
Building Test Profiles Using Recorded Data
Whenever possible, it is essential to ensure that test severity and pulse shape mirror the operational environment. Engineers have the option to record field data and use it to build a shock pulse or compare a test profile to the recorded information. Transient Capture software, provided by Vibration Research (VR), offers an intuitive interface for recording transient events. Typically used with drop shock machines, this software aids in package testing, product life testing, and pass/fail product testing. Engineers can compare the captured waveform(s) with acquired data or analyze them using the shock response spectrum (SRS).
Drop Shock Vibration Test Software
Performing drop shock tests is made easy and efficient with the Shock software from VR. This software includes the standard classical shock pulses, and engineers can customize pre-/post-pulse compensation amplitudes and shapes. Furthermore, engineers can use the user-defined transient option to create a pulse from a recorded waveform.
For a more comprehensive range of shock test standards, VibrationVIEW software provides pre-defined test profiles. Engineers can also save new test profiles for quick repeatability.
To learn more about the Shock module or to download a free demo of the software, visit Ratingperson.
Experience the reliability and effectiveness of drop shock testing with the innovative software from VR. Ensure your products and packaging can withstand the shocks of the real world.
