Compression and interlaminar shear behavior of steered laminates manufactured by automated fiber placement

Abstract

Variable stiffness (VS) composite structures can significantly reduce weight by adjusting fiber orientation. However, in current designs, the directional properties of composites cannot be fully utilized due to the lack of comprehensive mechanical characterization of VS laminates. This paper aims to investigate the compressive and out‐of‐plane bending behavior of steered laminates. Firstly, the critical steering radius theory was studied and derived. Secondly, five steered laminates with different radii and one “baseline” laminate were designed, manufactured, and tested to examine the effects of fiber steering on compressive and interlaminar shear strength (ILSS). The results indicate that, compared to the “baseline” laminate, the steered laminates exhibit a decreasing trend in both compressive strength and ILSS, with the maximum reductions being 32.1% in compressive strength and 9% in shear strength. Meanwhile, the microstructure was observed to gain an in‐depth understanding of the changes in the mechanical properties of the steered laminates. This study comprehensively evaluates the mechanical performance of steered laminates and provides appropriate steering limits for the design and manufacture of VS structures.Highlights The critical steering radius theory was studied and derived. Five steered laminates with different radii and one “baseline” laminate were designed, manufactured, and tested to examine the effects of fiber steering on compressive and ILSS. The microstructure was observed to gain an in‐depth understanding of the changes in the mechanical properties of the steered laminates.