Affiliations: Research Robotic Centre, Department of Mechanical and
Aerospace Engineering, Nanyang Technological University, Singapore 639798,
Singapore. E-mail: [email protected]
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.
