Mechanical Performances of CFRP Rods Under Tension‐Bending Load: Experimental and Theoretical Analysis

ABSTRACT

Carbon fiber‐reinforced polymer (CFRP) rods with the advantages of lightweight, high strength, corrosion, and fatigue resistant have a promising application prospect in the field of engineering structures. Due to the lack of mechanical performances and theoretical prediction method under complex loading conditions, which limits the application scenarios of CFRP rods. In the present paper, the effect of rod diameter and bending radius on the failure mode and ultimate load capacity of CFRP rods was obtained through mechanical tests, the influence mechanism of the initial bending strain on the tensile performance was revealed, and the theoretical prediction method for the ultimate load capacity of tension‐bending test was established based on plane‐section assumption and the superposition principle. The research results show that the initial bending strain significantly changes the tensile failure behavior of CFRP rods, the failure behavior changes from brittle fracture failure to step‐like fracture failure with the increases of bending strain. The initial bending strain leads to the uneven stress distribution on the cross‐section of CFRP rods, which reduces the ultimate load capacity of tension‐bending test for CFRP rods, while the effect of initial bending strain on stress–strain constitutive relationship of CFRP rods is ignorable. The bending deformation of CFRP rods satisfies the plane‐section assumption, and the strain development of CFRP rods under tension‐bending load conforms to the principle of linear superposition. The established theoretical prediction method can accurately obtain the ultimate load capacity of CFRP rod under tension‐bending load, and the error between the predicted results and the experimental results is less than 8.8%.