Breakage of packaged cookies due to fatigue failure from repetitive shock

The commercial value of cookies is easily lost when they break due to mechanical stress, such as shock, during distribution. Therefore, it is important to prevent shock by incorporating a cushioning design into cookie packaging. To optimize packaging, we must first understand the type of breakage caused by shock. During distribution, fatigue failure due to repetitive shocks might be the main factor involved in breakage of cookies because events related to shock stress usually occur more than once. Accordingly, we investigated the relationships between acceleration, shock frequency, and the occurrence of breakage in two types of packaged cookies (soft and hard). A drop test was performed at heights of 0.15–0.45 m. The results suggest that both types of cookies are broken by repetitive shocks, and the relationship between the number of shocks, acceleration (related to drop height), and the occurrence of breakage can be expressed as power approximation curves. Generally, the breakage of cookies due to mechanical stress is known to be a result of brittle fractures. However, our results suggest that the visible breakage of packaged cookies due to repetitive shock may be the result of fatigue failure. In addition, we propose a simple method that uses a small accelerometer to simulate breakage during transportation. The results of this study contribute to the development of new cushioning packaging designs to reduce the breakage of cookies during transportation. Graphical Abstract: (Figure presented.)