Safe zones for shock-protection of fragile components during impact-induced clatter

Article type: Research Article

Authors: Goyal, Suresh | Papadopoulos, James M.

Affiliations: Network Hardware Integration Research, Lucent Technologies, Bell Laboratories, 600 Mountain Avenue, Rm. 1B-212, Murray Hill, NJ 07974. Tel.: +1 908 582 5959; Fax: +1 908 582 6228; E-mail: [email protected] | Paper Converting Machine Company, 2300 South Ashland Avenue, Green Bay, WI 54307. Tel.: +1 920 491 6763; E-mail: [email protected]

Abstract: Clattering motion that occurs when flat objects strike the ground at an oblique angle is studied through a simple, tractable, model of a rigid bar with arbitrary, but symmetric, mass distribution and coefficient of restitution. The maximum velocity changes, or velocity shocks, that occur at various locations of the bar as it clatters to rest, are presented. It is shown that different parts of the bar can be subjected to sequences of velocity changes that are both higher, and lower, than those encountered in a single clatter-free impact. The implication that the drop-tolerance of an electronic product can be increased by configuring it to have 'safe zones' -- where the velocity shocks are lower -- for the placement of fragile components, is analysed. It is shown, through example, that a significant safe zone can be created in the center of the product by configuring it to have a low moment of inertia and by minimizing coefficient of restitution.

Journal: Shock and Vibration, vol. 9, no. 6, pp. 265-276, 2002