ICME Modeling In Aircraft Tie-Down Design for Production Improvement

Aircraft tie-downs have been widely used to secure aircrafts to a ship's deck. Tie-downs are heat treated by a quenching, tempering, and carburizing process to achieve the strength and surface hardness. The high surface hardness could result in low ductility and lead to cracking with the weld-induced residual stress and compounded when external loads are applied. This is a major concern because the tie-downs are subject to cyclic, dynamic loading which could induce cracking during services under sea-state loading conditions. ICME models including thermo-mechanical models were used to optimize the welding sequence and geometry designs to reduce weld residual stress. It was found that the corners of tie-downs have the highest weld residual stress and slightly increasing the corner radius can then significantly reduce the possibility of cracking or crack initiation points. Experiments were conducted to validate the modeling predictions on the current baseline and the improved designs.