Fatigue performance assessment of auxetic lattice structures

Lattice structures, widely utilised in aerospace and automotive applications, offer high strength-to-weight ratios, particularly when optimised through additive manufacturing. This study evaluates the fatigue performance of four auxetic lattice structures fabricated from Ti-6Al-4V alloy. The geometries were designed with consistent dimensions and analysed in single and 3x3 multi-cell configurations under fixed support and symmetric loading conditions. Structural simulations were conducted using Ansys Workbench, where tensile forces of 10 MPa and 20 MPa were applied to single and multi-cell models, respectively. Results reveal that Auxetic 3 exhibited the longest fatigue life (5.66 million cycles) due to smooth transitions and uniform stress distribution, while Auxetic 2 displayed the shortest fatigue life (233,040 cycles) owing to significant localised stress concentrations. A comparison of single and multi-cell models demonstrated that stress accumulation at cell connections in multi-cell structures reduces overall fatigue life. These findings provide a basis for finding better auxetic lattice structures for enhanced durability in loadbearing applications.