A time-dependent tensile constitutive model for long-fiber-reinforced unidirectional ceramic-matrix minicomposites considering interface and fiber oxidation

Abstract

<jats:p> In this paper, a time-dependent tensile constitutive model of long-fiber-reinforced unidirectional ceramic-matrix minicomposites is developed considering the interface and fiber oxidation. The relationship between the time-dependent tensile behavior and internal damage is established. The damage mechanisms of time-dependent matrix cracking, fiber/matrix interface debonding, fiber failure, and the oxidation of the interface and fiber are considered in the analysis of the time-dependent tensile stress–strain curve. The fracture mechanic approach, matrix statistical cracking model, and fiber statistical failure model are used to determine the time-dependent interface debonding length, matrix crack spacing, and the fiber failure probability considering the time-dependent interface and fiber oxidation. The effects of the fiber volume, fiber radius, matrix Weibull modulus, matrix cracking characteristic strength, matrix cracking saturation spacing, interface shear stress, interface debonding energy, fiber strength, fiber Weibull modulus, and oxidation time on the time-dependent tensile stress–strain curves, matrix cracking density, interface debonding, and fiber failure are discussed. The experimental time-dependent tensile stress–strain curves, matrix cracking, interface debonding, and fiber failure of four different unidirectional SiC/SiC minicomposites for different oxidation time are predicted. The composite tensile strength and failure strain increase with the fiber volume, fiber strength, and fiber Weibull modulus, and decrease with the oxidation time; the fiber/matrix interface debonding length increases with the fiber radius and oxidation time and decreases with the interfacial shear stress and interface debonding energy; the fiber/matrix interface oxidation ratio increases with the interfacial shear stress, interface debonding energy, and oxidation time and decreases with the saturation matrix crack spacing. </jats:p>

Elastic moduli prediction of a short fiber composite with interface debonding at fiber ends

“…The followings are interface-relevant developments on this formula. In case of the fiber lateral surface debonding, an equilibrium condition in terms of debonding length is available in (Gao et al, 1988;Longbiao, 2020). By considering the effect of surrounding fibers, Fu et al (Fu et al, 2000) derived a multi-fiber pull-out model based on the shear-lag formulism.…”

“…Nonetheless, stiffness prediction for an SFRC with debonded fiber end interface has attracted much less attention than that for a perfect bonding case, although the latter itself is not an easy job. The existing methods can be classified into Shear-Lag formula (Cox, 1952; Henry and Pimenta, 2018; Longbiao, 2020; Xiong et al., 2018), finite element approach (FEA) (Noda et al., 2020; Notta-Cuvier et al., 2015; Schneider et al., 2019; Shah et al., 2020; Tian et al., 2015), mean-field homogenization (Eshelby, 1957; Muller et al., 2016; Naili et al., 2020; Schemmann et al., 2018; Xu et al., 2022) and other models (Lancioni and Alessi, 2020; Lee, 2016).…”