An equivalent elastoplastic damage model based on micromechanics for hybrid fiber-reinforced composites under uniaxial tension

A micromechanics-based equivalent elastoplastic damage model for both notch-sensitive and multiple cracking hybrid fiber reinforced composite is proposed in this study. In this model, the elastic modulus, first cracking strength, and ultimate strength are estimated based on micromechanics. To quantify strain after matrix cracks, a novel characteristic length is defined based on the damage mechanics. The effects of the fiber length, diameter and modulus, and interfacial bond stress on the characteristic length of hybrid fiber reinforced composite are presented. In order to avoid the difficulty of determining the traditional damage and plastic potential function, this model is developed from the behavior of single fiber at mesolevel to the response of hybrid fiber reinforced composite at macrolevel. Then the calculated results are verified with several published experimental results of fiber reinforced composites and hybrid fiber reinforced composite, including notch-sensitive cracking fiber reinforced composite, multiple cracking fiber reinforced composite, and multiple cracking hybrid fiber reinforced composite reinforced with two types of fibers (steel fiber and polyethylene fiber). A parametric study has been performed to investigate the effects of the fiber properties, including the fiber volume fraction, length, diameter, and interfacial bond stress, on the tensile performance of hybrid fiber reinforced composite reinforced with steel fiber-like and polyethylene fiber-like fibers. The results indicate that enhancement of the tensile performance can be achieved more effectively by improving the polyethylene fiber-like fiber than steel fiber-like fiber.