Modeling and experimental investigations of mechanical properties of hybrid composite rods with gradient composition

Abstract

The concept of creating a functionally gradient material characterized by a smooth change in composition was used in the fabrication of hybrid composite rods. A hybrid core structure with a glass fiber core and a carbon fiber shell was adopted as the basis. To reduce the risk of delamination at the core-shell interface, a gradual transition was implemented from the core of the rod, made based on high-modulus fiber, to the outer shell composed of low-modulus fiber. The strength and modulus of elasticity in bending for hybrid composite rods were modeled. Using the proposed model, an optimal scheme for distributing glass and carbon fibers across the cross-section of a composite rod was selected. Hybrid composite rods with a diameter of 25 mm, with the same matrix (31±0,1%) and fiber (69±0,1%) content, but with different distribution patterns of glass and carbon fibers along the cross-section, were manufactured via pultrusion technique. The bending strength and stiffness characteristics of composite rods were experimentally determined. Mechanical properties of rods with different reinforcement schemes were compared: homogeneous, core-shell, single, and double gradient. The results indicate that a hybrid rod with a gradient reinforcement scheme exhibits higher values of strength and modulus of elasticity during bending. The modulus of elasticity of the rod with the "double gradient" structure was 103 GPa, for comparison, the modulus of elasticity of the rod made by the "core-shell" scheme was 82 GPa. The simulation aligns well with the experimental data.