Fault-tolerant elastic–plastic lattice material

Abstract

The paper describes a fault-tolerant design of a special two-dimensional beam lattice. The morphology of such lattices was suggested in the theoretical papers (Cherkaev and Ryvkin 2019 Arch. Appl. Mech. 89 , 485–501; Cherkaev and Ryvkin 2019 Arch. Appl. Mech. 89 , 503–519), where its superior properties were found numerically. The proposed design consists of beam elements with two different thicknesses; the lattice is macro-isotropic and stretch dominated. Here, we experimentally verify the fault-tolerant properties of these lattices. The specimens were three-dimensional-printed from the VeroWhite elastoplastic material. The lattice is subjected to uniaxial tensile loading. Due to its morphology, the failed beams are evenly distributed in the lattice at the initial stage of damage; at this stage, the material remains intact, preserves its bearing ability, and supports relatively high strains before the final failure. At the initial phase of damage, the thinner beams buckle; then another group of separated thin beams plastically yield and rupture. The fatal macro-crack propagates after the distributed damage reaches a critical level. This initial distributed damage stage allows for a better energy absorption rate before the catastrophic failure of the structure. The experimental results are supported by simulations which confirm that the proposed fault-tolerant material possesses excellent energy absorption properties thanks to the distributed damage stage phenomenon. This article is part of the theme issue ‘Modelling of dynamic phenomena and localization in structured media (part 2)’.

Architectured Lattice Materials with Tunable Anisotropy: Design and Analysis of the Material Property Space with the Aid of Machine Learning

“…The capabilities of the proposed archimats can be significantly expanded using beams with nonlinear elastic properties. [14,32] These can be pre-bent beams, which, therefore, have different stiffness in tension and compression, electrochemically activated beams, or temperature-sensitive beams. [33][34][35] Alternatively, non-linearity of the elastic response can be achieved by playing with the node construction (hinged/fixed).…”

“…[ 11,12 ] A further possibility of controlling the properties of lattice structures is using beams with two different values of stiffness. [ 13,14 ]…”

“…[11,12] A further possibility of controlling the properties of lattice structures is using beams with two different values of stiffness. [13,14] In this article, an alternative approach is proposed. It is based on varying the elastic properties of the beams in the unit cell while keeping the lattice geometry fixed.…”

Architecturing materials at mesoscale: some current trends

“…The crystallographic unit cell may contain atoms of more than one sort, and by analogy, rod lattice materials with more than one kind of rods can be generated. Lattice materials whose elementary unit cell contains different constituent entities offer further great possibilities to extend the material property space [44][45][46][47][48][49][50][51]. Examples of such architectured lattice materials are given in Figure 4.…”

The Emergence of Sequential Buckling in Reconfigurable Hexagonal Networks Embedded into Soft Matrix

“…Cellular lattice structures assembled from repeating cells are widely known for their superior combination of low weight and high mechanical properties [ 1 , 2 , 3 ]. In general, the mechanical performance of lattices is defined by the geometry of the unit cells [ 4 , 5 , 6 , 7 ], and rational design of the internal architecture enables the engineering of lattices with enhanced stiffness [ 8 , 9 ], controlled anisotropy of mechanical properties [ 10 , 11 ], or lattices that are tolerant to partial failure [ 12 , 13 ]. Unsurprisingly, many mechanical metamaterials can be considered as successors of cellular materials [ 14 , 15 ].…”