Cyclic plasticity of additively manufactured Ti-6Al-4V bracket for aeroengine application

This work aims to establish the mechanical relationship between additive manufactured Titanium alloy and geometrically complex load-bearing aeroengine lightweight structure under cyclic loading. To achieve this, the constitutive behavior of Laser Powder Bed Fusion (LPBF) Ti-6Al-4V was characterized through a computational cyclic plasticity model derived based on the uniaxial strain-range controlled low cycle fatigue (LCF) test. An idealised three-dimensional (3D) finite element (FE) model was developed and experimentally validated to investigate the remote response and localised stress-strain nature in the bracket elements for risk evaluation and structural optimization. The predicted results indicated that the dominant cracking mode of the bracket under LCF test, was more dependent on the localised maximum principal stress rather than von Mises equivalent stress. Furthermore, the first failed region exhibited an opening crack (Mode-I failure), while the second and third failed regions showed a mixture of opening and shear crack (Mode-I and Mode-II failure). The microscopic observation further revealed that the three failed regions exhibited a ductile type of fracture at the cracking initiation and final fracture regions, and a brittle fracture at the propagation region.

Automated summary

This study aims to establish the mechanical relationship between additive manufactured Titanium alloy and geometrically complex load-bearing aeroengine lightweight structure under cyclic loading. The constitutive behavior of laser powder bed fusion (LPBF) Ti-6Al-4V was characterized through a computational cyclic plasticity model derived from the low cycle fatigue (LCF) test. A finite element (FE) model was developed and experimentally validated to investigate the stress-strain nature and optimize the structure. The results showed that the cracking mode of the bracket was dependent on the local maximum principal stress and exhibited a mixture of opening and shear cracks.