Failure Mechanism and Structural Analysis of Chain Slings with Non-Standard Connections

This study investigates the mechanical behavior and failure characteristics of chain slings under standard and non-standard fastening methods. Through dimensional inspections, fracture tests, and finite element analysis, we identified critical factors influencing chain failure. Chains exhibiting over 10% diameter reduction or increased pitch exceeded discard criteria and showed significant strength loss. Fracture loads in aged chains dropped by more than 35% compared to standards. Structural analysis revealed that standard fastening (using master links) ensures uniform stress distribution and higher load capacity, whereas non-standard fastening (direct wrapping on eyebolts) caused stress concentration, reduced tensile capacity by over 15%, and led to localized failure near contact areas. These results validate the structural soundness of international standards (DIN EN 818-4, ISO 3056) and highlight the risks of improper fastening. Practical recommendations include strict adherence to standard fastening methods, avoidance of direct wrapping, and implementation of regular inspections. The findings emphasize the need for design considerations regarding fastening geometry and suggest further research into fatigue life prediction and contact condition optimization.