Dynamic failure of biomimetic dual-phase materials: Effects of microstructures on fracture modes and energy dissipation

Dual-phase structures in biological systems provide an efficient strategy for designing materials with superior mechanical performance. While the quasi-static mechanical properties of biomimetic dual-phase materials have been extensively investigated, their dynamic failure behaviors are significantly more complex. This complexity mainly arises from the interaction between the rate-dependent properties of constituent materials and the effects of microstructures, which remain less understood. In this work, we comprehensively investigate the dynamic failure processes of biomimetic dual-phase materials with various microstructures. Specimens incorporating soft and hard phases are additively manufactured, with variations in aspect ratio, volume fraction, and the shape of the hard phase. The fracture modes and energy dissipation of these structures at different impact velocities are studied with quasi-static and dynamic three-point bending tests. By combining experimental results with a rate-dependent tension-shear chain model, the dynamic failure mechanisms of dual-phase materials and the influence of their microstructures are revealed. As impact velocity increases, a fracture-mode transition from soft-phase fracture to both-phase fracture, and ultimately to hard-phase fracture is observed. Correspondingly, the energy dissipation exhibits an N-shaped curve (“increase-decrease-increase”) with respect to the impact velocity, achieving maximum dissipation when the fracture of both phases is balanced. Generally, larger aspect ratios, higher volume fractions, and triangular or circular shapes of the hard phase lead to fracture mode transitions at smaller impact velocities. This study highlights the potential for customizing microstructures of dual-phase materials to optimize energy dissipation in different impact environments.