A novel design strategy to enhance buckling resistance of thin-walled single-cell lattice structures via topology optimisation

Abstract

Lattice structures with thin walls or members are susceptible to instability due to their limited buckling strength. We propose a design methodology that utilises topology optimisation techniques to create lattice structure members with improved buckling resistance, demonstrated here on a single cell of a thin-walled square honeycomb lattice. We utilise the buckling mode of the single cell as a reference to inform the design of modified lattice structure members via optimisation, while ensuring the weight and stiffness of the structure remain unchanged. We apply a 2D topology optimisation method with the objective of maximising buckling load factors, while simultaneously enforcing constraints on stiffness and volume fraction within the optimisation domain. A family of designs is created via a parametric study, considering optimisation parameters like the thickness of the buckling member and the active domain. Designing and fabricating these structures also consider additive manufacturing constraints, such as minimal feature size and overhang. Experimental analysis of fabricated structures reveals a remarkable 70% increase in buckling strength without altering stiffness or weight. Numerical simulations corroborate these findings, with a discrepancy of less than 10%. This methodology shows the potential to enhance buckling resistance of thin-walled lattices in various lattice types while maintaining base cell stiffness.