Fatigue life prediction of topologically optimized torque link adjusted for additive manufacturing

The torque link is part of the nose landing gear of aircraft. It prevents the piston from turning inside the cylinder of the shock absorber, enabling its up and down motion during the landing and take-off. As such, its structural integrity and life are crucial for aircraft safe operation, but because of complex geometry and variable loading conditions, its fatigue life estimation represents a real challenge. In this paper, fatigue lives of two different designs of the torque links of the light aircraft are evaluated by a numerical approach based on the improved FEM. Firstly, the fatigue life of the damaged torque link was assessed for actual load conditions. Then, improved torque links, obtained through topological optimization, were analyzed and their fatigue life was calculated. Finally, the numerical simulations of the additive manufacturing (AM) process of optimized torque links were carried out, and the fatigue life of these torque links, including residual stresses from AM, were estimated too. The obtained numbers of cycles in all cases were compared and discussed for all torque links cases. This is an advanced approach to fatigue life assessment of optimized printed 3D parts based on numerical simulations of both crack growth and AM process.