Modeling Dynamic Crack Propagation in Heterogeneous Variable Stiffness Composites Using the Phase-Field Method

Composites are widely used in the building sector for high-rise building load-bearing components, bridge decks, prefabricated structural panels, and seismic-resistant members, where excellent mechanical performance and structural durability are critical. As specialized advanced composites, variable stiffness composites (VSCs) have gained increasing engineering applications due to their excellent overall performance. Nevertheless, exploring the fracture characteristics of composite materials, especially VSCs, remains a significant challenge. In particular, cracks in composite components can adversely affect structural integrity and durability. In this study, a dynamic fracture phase-field model for VSCs is developed within the framework of elastic dynamics to investigate crack propagation behavior of VSCs under dynamic loads. The proposed model is first validated by experimental results of fracture behavior of single-edge cracked FRC laminae. Then, the proposed model is employed to systematically study the effects of three fiber orientation design variables and internal defects on the fracture behavior of VSCs. Additionally, fiber trajectories are optimized for different pore distribution configurations. The results demonstrate that the model effectively captures the fracture behavior of VSCs and that optimizing these three design parameters enables the fabrication of high-performance VSCs with enhanced crack propagation resistance. This work provides fundamental insights for the design of curvilinearly fiber-reinforced composites and lays a solid theoretical foundation for the practical application of VSCs in building engineering.