Fracture behaviors of nacre-like composites via phase-field fracture modeling

Nacre-inspired composites, composed of hard and soft phases, exhibit exceptional combinations of stiffness, strength, and fracture toughness. However, the fracture behaviors of these composites are significantly influenced by the geometric factors and material properties of their constituents. In this study, we systematically investigate the fracture behaviors of nacre-like composites by employing a phase-field fracture model considering the effects of oblique angle between loading and platelet directions, a critical factor often overlooked in previous studies, coupled with the effect of other geometric and material parameters, such as the aspect ratio, Young's modulus and fracture toughness ratio between hard and soft phase. Our findings highlight the significant influence of the oblique angle on the mechanical properties and fracture behaviors of these composites. Particularly, it is found the maximum Young's modulus and strength are obtained when the direction of hard platelet is aligned with the tension direction, while the maximum toughness is achieved at a moderate oblique angle, especially in cases of large aspect ratios, small Young's modulus and fracture toughness ratios between the hard and soft phases. Besides, the maximum fracture toughness is more likely to be obtained at a small aspect ratio and large Young's modulus ratio between hard and soft phases. The insights gained from our study would offer valuable guidance for the design and practical application of nacre-mimetic composites.