SHOCK-EXCITED VIBRATIONS OF A CONSERVATIVE DUFFING OSCILLATOR WITH APPLICATION TO SHOCK PROTECTION IN PORTABLE ELECTRONICS

Shock-excited vibrations of a conservative puffing oscillator are exam ined in application to shock protection of a vulnerable product during accidental drop. We show that a hard characteristic of the oscillator might be advisable for a product which is able to withstand high acce lerations (decelerations), while the maximum displacement has to be ma de small by any means. On the other hand, application of a spring with a soft characteristic can result in appreciably lower maximum acceler ations (decelerations) than in a linear system and therefore can be re commended in the case when the requirement for the lowest displacement possible is not very stringent. However, if the drop height is not kn own with certainty (which is typically the case) the advantages of a s oft spring cannot be utilized to the full extent, because of the possi bility of a ''rigid impact''. In such a case a probabilistic approach can be effectively used to design a soft spring with a low enough prob ability of a rigid impact. The obtained results can be helpful, partic ularly, when designing spring protectors in portable electronics. The author believes that these results can be useful for a rather broad cl ass of nonlinear springs, not necessarily with cubic restoring forces. Copyright (C) 1996 Published by Elsevier Science Ltd.