Effect of Initial Pre-compression of Corrugated Paperboard Cushions on Shock Attenuation Characteristics in Repetitive Impacts

摘要

The use of paper as a cushioning material is motivated by its environmental advantage over polymeric materials such as expanded polystyrene. Various studies have been conducted to investigate the capability of corrugated paperboard (CPB) to act as cushioning materials for protective packaging. The studies have normally focused on performance of cushions and effects of climatic conditions on the shock attenuation in the first drop. However, no information is available to show that CPB can be engineered to produce a cushioning element with good shock attenuation in repetitive impacts. This study investigates the deterioration of the shock attenuation characteristics of CPB cushions in consecutive impacts. A series of cushion-test style experiments on multilayer cushion pads made entirely from CPB were conducted. Each cushion was first subjected to 20 impacts, followed by simulated warehousing in a climatic chamber, and then the additional 15 impacts. The effect of initial pre-compression strain introduced in the process of making cushion pads is discussed and demonstrated. The performance of cushions was judged not only by the maximum acceleration of shocks. Entire recorded shock pulses and calculated corresponding shock response spectra were analysed and are presented as 3D maps in order to reveal trends that occur when a cushion is subjected to multiple drops. The paper shows that the level of pre-compression has an important effect on the degree of deterioration of cushion performance after multiple drops. As an example, the maximum acceleration for a pad pre-compressed to 95% strain increased by less than 20% between the 1st and the 35th drop. In contrast, for 80% pre-compression, the increase was 300%. It was found that the selection of optimum static stress should be made in conjunction with the expected number of impacts in order to optimize the cushion performance.