Effect of Difference in Acceleration and Velocity Change on Product Damage Due to Repetitive Shock

To investigate the influence of different combinations of peak acceleration and velocity change on repetitive-shock-induced damages leading to cumulative fatigue in products, we performed drop tests of products packaged similar to those in actual transportation, from several different drop heights and with two kinds of cushioning materials. The damage boundary curves (DBCs), corresponding to the degree of damage per shock, were prepared to investigate the possibility of DBC application for the evaluation of repetitive-shock-induced damage. The drop test showed erroneous results, when predicting repetitive-shock-induced damage, if based only on the relationship between peak acceleration and the degree of damage per shock, as have been carried out in previously reported studies. In our study, the DBCs for a specific degree of damage per shock were prepared, although the ranges of the peak acceleration and velocity change were limited. Preparation of DBC corresponding to the degree of damage per shock, as determined from the peak acceleration and velocity change beforehand, may increase the accuracy of predicting repetitive-shock-induced damage to products from cumulative fatigue. Copyright © 2013 John Wiley & Sons, Ltd.