Evaluating the Impact of Multiaxial Fatigue on the Integrity of Automated Storage System Rails

Abstract

As automated warehouses become more central to supply chains, the durability and safety of rack structures—especially shuttle rails—are increasingly critical. These components face repeated loading cycles, making them vulnerable to fatigue failures. Traditional rack design often overlooks fatigue, focusing on static loads. When fatigue is considered, it typically centers on Mode I failure (normal stress-induced cracking), neglecting complex triaxial stress states and Mode II-III shear fatigue— especially in rail joints where stress concentrations occur.

This study examines the capabilities of traditional and multiaxial fatigue approaches to capture these effects. Using a real-world case with observed rail joint failures, numerical analysis reveals that conventional methods fail to predict these failures, while multiaxial approaches succeed due to their consideration of combined Mode I, II and III loading. The results show that relying solely on conventional fatigue models can overestimate fatigue life, risking system integrity. Incorporating multiaxial fatigue evaluations is therefore essential for reliable design and long-term performance of rack structures in automated warehouses.