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Shock and Vibration
Volume 13 (2006), Issue 6, Pages 607-618
http://dx.doi.org/10.1155/2006/257170

Shock Analysis Method for Systematic Performance Evaluation of Component Embedded in Handheld Electronic Devices

C.S. Chin

Research Robotic Centre, Department of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore

Received 21 February 2005; Revised 20 June 2005

Copyright © 2006 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

It is important to identify the robustness of product (or embedded component inside the product) against shock due to free drop. With the increasing mobile and fast-paced lifestyle of the average consumer, much is required of the products; such as consumers expect mobile products to continue to operate after drop impact. Since free drop test is commonly used to evaluate the robustness of small component embedded in MP3 player, it is difficult to produce a repeatable shock reading due to highly uncontrolled orientation during the impact on ground. Hence attention has been focus on shock table testing, which produces a higher repeatable result. But it failed to demonstrate the actual shock with the presence of rotational movement due to free drop and also it suffers from a similar limitation of repeatability. From drop to drop, shock tables can vary about ± 5% in velocity change but suitable for making a consistent tracking the product improvement.

Although many test procedure (such as ASTM D3332 [5]) have been written around shock test machines, as a whole, the test perform on the shock tables have no direct correlation over the free-drop testing. Since both will have some velocity change variability. Some products react more to torsion forces than they do to orthogonal forces, fortunately, due to the size of the product, the exposure to this torsion force is less prominent. Since the intent of lab testing is to re-create real world events, a unique ways to establish a shock test that encompasses the features of the two tests are needed. Thus, establishing the robustness of the small component against shock due to topple drop at various tilt angle under different drop orientations and platform (such as on the office table), on a MP3 player is needed. This eventually enables a high repeatable and realistic shock testing for product performance evaluation in MP3 player.

There are few advantages of using tilt tester for shock testing. Firstly, close approximations to the actual free drops test with better repeatability. Secondly, it ensures that the shock level is reduced prior to performing a final free drop test (using actual product) and hence reduces the cost. Thirdly, it reduces the number of trials and cycle time needed for shock testing. Lastly, it provides a platform for shock absorber design for component (embedded in the MP3 player) as shown in the Section 3.