Plastic strain localization in Bouligand structures.

Area of Science:

• Materials Science
• Mechanics of Materials
• Biomaterials

Background:

• The Bouligand structure, characterized by helicoidal fiber stacking, is prevalent in natural composites.
• While its toughening mechanisms are studied, the inelastic deformation processes within Bouligand structures remain unclear.
• Understanding these mechanisms is crucial for designing advanced composite materials.

Purpose of the Study:

• To investigate and compare the plastic deformation mechanisms of Bouligand, crossed-lamellar, and single lamellar structures.
• To elucidate the influence of interfacial properties and lamellar thickness on the plastic behavior of Bouligand structures.
• To provide insights into the energy dissipation pathways in Bouligand structures.

Main Methods:

• Computational calculations were performed to simulate plastic deformation.
• Analysis focused on mechanisms such as necking, strain localization, fiber rotation, lamellar twisting, and delamination.
• Parametric studies were conducted to assess the effects of interfacial cohesive strength and lamellar thickness.

Main Results:

• Unlike single and crossed-lamellar structures that undergo necking, Bouligand structures exhibit plastic strain localization bands, fiber rotation, lamellar twisting, and delamination.
• Bouligand structures show lower initial plastic energy dissipation than crossed-lamellar structures but can achieve high damage energy dissipation through lamellar delamination.
• Plastic dissipation in Bouligand structures is sensitive to lamellar interface strength and lamellar thickness; thicker lamellae enhance plastic dissipation by suppressing strain localization.

Conclusions:

• The plastic deformation of Bouligand structures involves complex mechanisms including strain localization and delamination, differing significantly from simpler layered composites.
• Interfacial properties and lamellar thickness are critical parameters controlling the energy dissipation and deformation behavior of Bouligand structures.
• This research provides fundamental understanding for the development of novel bioinspired materials mimicking the Bouligand architecture.