Mechanical properties and damage mechanisms of novel variable stiffness laminates

Laminated composite panels, widely employed in aerospace, aviation and transportation, face challenges in terms of load-bearing capacity and stability in practical applications. To address these issues, this study adopts an automated variable stiffness layup approach and investigates the mechanical properties and failure mechanisms of the resulting laminated composite panels. Firstly, a novel periodic linear extrapolation algorithm was proposed based on a linear variable angle function to optimize the fiber placement paths, achieving more detailed and precise variations in fiber trajectories. Subsequently, a finite element model for the new variable stiffness laminated panel was constructed using Python/Abaqus. Finally, the damage mechanisms under three-point bending for both constant and variable stiffness laminated panels were analyzed, revealing the impact of different fiber orientation angles on the mechanical properties, stress distribution and damage scenarios. The research findings indicate that the orientation angle of the central fiber significantly influences bending performance under three-point conditions, with 0° favoring performance enhancement and 90° leading to a decline in performance. Compared to the baseline with a central fiber orientation angle of 5°, employing a variable angle design effectively suppresses further extension of bending damage, ensures a uniform stress distribution within the laminated panel, and further enhances the ultimate bending stress, with a maximum improvement of 28.31%. This study provides crucial insights and a systematic approach for the subsequent design and optimization of laminated composite panels, contributing to advancements in bending resistance design for composite materials.