WEB Propagating material instabilities in periodic architectured materialsWednesday (23.09.2020) 16:50 - 17:05 S: Structural Materials 2 Part of:
Under tension low carbon steels exhibit inhomogeneous plastic deformation. This instability called Piobert-Lüders banding creates fronts of localized strain that propagate in the structure.
To date, only simple geometries, sheets and tubes, have been studied. This paper focuses on architectured materials and specifically lattice structures which can be defined as a tessellation of unit-cells periodically distributed in space. This class of advanced materials draws new mechanical properties from its architecture.
We investigate the effect of the architecture on the global behavior of the entire structure. Especially, how bands interact with a lattice and how to control initiation and propagation of localized strain with the architecture. An elastoplastic material model [1,2] is used in this work to simulate the Piobert-Lüders band formation and propagation. The model also considers a large deformation framework for elasto-plasticity with periodic boundary conditions  in order to represent the architectured material. Initiation and propagation of material instabilities depend on the geometry and the relative orientation of the solicitation. Propagating and
non-propagating behaviors are identified for the Piobert-Lüders bands and related to the type of geometries. Material instabilities affect the mechanical behavior of the structure as far as they are governed by the architecture. Those conclusions have been compared to experimental testing on laser cut architectured specimen of ARMCO steel.
The choice of a specific architecture can be made with the objective of concentrating initiation of plasticity in specific region and even of avoiding plasticity from other region, hence paving the way to materials instability-based materials.