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Fracture mechanics of nacre-like materials using discrete-element models: Effects of microstructure, interfaces and randomness

2018; Elsevier BV; Volume: 124; Linguagem: Inglês

10.1016/j.jmps.2018.10.012

1873-4782

Najmul Abid, J. William Pro, François Barthelat,

Paleontology and Stratigraphy of Fossils

Biological materials such as nacre, bone and spider silk boast unusual combinations of stiffness, strength and toughness. Behind this performance is the staggered arrangement of stiff and elongated inclusions embedded in a softer and more deformable matrix. In this study, we use the discrete element method (DEM) to simulate large fracture models of staggered composites (up to 450,000 tablets). The models explore the combined effects of tablet arrangement, interface properties and statistical variations on fracture mechanics: crack deflection, crack bridging, volumetric process zones of different size and shapes, transient and steady-state crack propagation regimes, full crack resistance curves. We find that moderate statistical variations in the microstructure increases toughness because the crack gets pinned into tougher regions. However, higher statistical variations generate very weak regions which can be activated far from the main crack, leading to discontinuous cohesive zones, sparse process zones, and an overall decrease in toughness. These results suggest an important rule for the design of nacre-like materials: microstructural randomness should be minimized to achieve the highest combinations of properties.