Low-velocity impact resistance of the Z-pin reinforced carbon fiber composite laminates

A voronoi user material subroutine (VUMAT) was developed using the three-dimensional Hashin damage criterion and exponential nonlinear damage evolution method. An interlayer damage model based on the quadratic nominal stress (QUADS) criterion and B-K fracture criterion was introduced, and a finite element model of Z-pin reinforced composite laminates under low-velocity impact was established. The low-velocity impact behavior of Z-pin reinforced composite laminates with different impact velocities (0.6 m/s, 0.4 m/s, and 0.3 m/s), different layup forms ([0 degrees/90 degrees](4) and [0 degrees/45 degrees/90 degrees/-45 degrees](2)), and different Z-pin spacing (4 mm, 8 mm, and 16 mm) was studied using ABAQUS. The results indicate that different layup forms have little effect on the low-velocity impact behavior of Z-pin reinforced composite laminates. The Z-pin spacing has a significant influence on the low-velocity impact behavior of Z-pin reinforced composite laminates. When the impact velocity is 0.4 m/s, the specific energy absorption of composite laminates with Z-pin spacing of 16 mm is 85.93% and 87.7% lower than that of composite laminates with Z-pin spacing of 4 mm and 8 mm. As the Z-pin spacing decreases (Z-pin density increases), the impact resistance of Z-pin reinforced composite laminates first increases and then decreases.