Lattice materials have been studied extensively for their advantageous mechanical properties like high stiffness-to-weight and strength-to-weight ratios. These properties make them suitable for a multitude of applications like load-bearing structures, energy absorption and impact
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Lattice materials have been studied extensively for their advantageous mechanical properties like high stiffness-to-weight and strength-to-weight ratios. These properties make them suitable for a multitude of applications like load-bearing structures, energy absorption and impact attenuation. Amongst several planar microarchitectures, the Kagome topology is found to be optimal for effective mechanical properties like macroscopic elastic modulus. However, it has been shown that lattice defects such as nodal misalignments are detrimental to the macroscopic stiffness of the Kagome lattice. From a realistic standpoint, any manufactured lattice is expected to inevitably have these defects, which naturally makes the favorable stiffness properties of the Kagome inaccessible.
This work takes a step towards designing planar lattices with defect insensitive macroscopic stiffness. A novel design strategy is proposed for generating stiff, lightweight and robust lattice materials. The Kagome lattice is chosen as base architecture for the developed designs due to its excellent stiffness-to-weight property and extreme sensitivity towards defects. The generated designs involve appending the Kagome bulk with two unique and carefully designed microarchitectures. The first is a lattice developed using combinatorial design strategies, which demonstrates properties like perturbation-dependent switching between mechanism-states and load-bearing states. The second is a polarised lattice that enables localisation of mechanisms at specific sites of the lattice. This arrangement forms a "composite" lattice which when appropriately designed demonstrates robustness against manufacturing defects.
Development of such an architecture is carried out through an iterative design and analysis process which is based on reformulated matrix methods. A mass-spring model is used in contrast to regular pin-jointed models and a dynamical matrix method is developed as an alternative to traditional matrix analysis. Suitable designs formed out of this iterative process are verified for their stiffness properties using Finite Element models. Robustness against nodal defects is observed in well-designed lattice models. Satisfactory performance of such designs indicates the efficacy of the adopted design strategy which could potentially be applied to any lattice microarchitecture other than Kagome for robustness.