Internal 3D cracks evolution and the toughening mechanisms of the hierarchical structures in Strombus gigas shell

Abstract Strombus gigas shell is a lightweight, high-strength and high-toughness biocomposite material. In-depth exploration of its internal microstructure characteristics and the corresponding strengthening and toughening mechanism is of great significance to the design of high-performance composite materials. Here, the high-resolution synchrotron radiation X-ray computed tomography technology was adopted to carry out the in-situ three-dimensional investigation on the deformation and fracture evolution of the internal crossed-lamellar hierarchical structures of the Strombus gigas shell during the tensile process. In the experiment, some important three-dimensional crack initiation and propagation evolution phenomena were observed, such as the multi-point bursting, progressive propagation and spatial network arrangement of cracks and the reverse ‘C’-shaped cracks, which may have great contribution to the load-bearing capacity and toughness of the shell. According to the mechanical analysis of the visualized evolutionary information of the deformation and fracture of hierarchical microstructures, a strengthening and toughening regulation mechanisms that driven by the local stress concentration, and guided by the hierarchical structure and weak interface was proposed. This study may have a positive guiding significance for exploring and learning the toughening design strategy of lightweight composites.