Bending performance after impact and progressive failure behavior of hard-soft hybrid composites based on bionic double helicoidal

Bionic design concepts are widely used in the design and development of composite materials to significantly improve the comprehensive performance of the material. In this study, inspired by the double helicoidal structure of collagen fibers of coelacanth scales and the hard-soft hybrid structure of deep-sea sponges, this study designed and prepared carbon/basalt fiber hybrid composites with linear, sinusoidal and exponential helical angles. The residual bending performance of Bionic Double Helicoidal-Hybrid Fiber Reinforced Polymer (BDH-HFRP) after impact was studied through drop hammer impact tests and three-point bending tests. The Variable Mechanics Analysis User Material Subroutine (VUMAT) user subroutine suitable for fiber hybrid composites was written and the progressive failure process of BDH-HFRP was simulated by using ABAQUS software. The test results were compared with the simulation results. The results show that the established simulation model can accurately predict the bending after impact performance of BDH-HFRP laminates. Under the impact conditions, the peak load, peak displacement and energy absorption of the laminates increase with the increase of the impact energy, but there are significant differences due to the different angles of the helicoidal layup. After being impacted, the bending performance of the laminates is weakened, and the greater the impact energy, the lower the residual bending strength of the laminates. Compared with the pure bending condition, the bending strength of the sinusoidal laminate decrease the most after being impacted by an energy of 30 J, which is 22.98%. However, under the 40 J impact energy, the sinusoidal laminate exhibits a higher residual bending strength, which is 13.28% and 14.13% higher than that of the linear and exponential double-helicoidal laminates respectively. Furthermore, under pure bending while matrix tensile damage is the main inducement of early stiffness degradation. Under bending conditions after impact, matrix damage is the main impact damage. Under low impact energy conditions, fiber compression damage dominates in the subsequent bending load, while under high impact energy conditions, the damage of both fibers and matrix expands simultaneously, and the matrix damage expands more severely. Finally, a comparison is made with cross-ply laminate, and it is found that BDH-HFRP had obvious advantages in bending load-bearing capacity and energy dissipation after impact. And a comparative analysis of the bending after impact properties of laminates with different carbon fiber volume fractions reveals that 50% carbon fiber volume fraction laminates have good load carrying capacity and damage tolerance. The research results can provide a reference for the design of high-performance composite structures in the field of oil and gas pipeline repair.