High-temperature constitutive model for three-dimensional needled C/C-SiC composite under tensile loading

Abstract

Tensile experiments of three-dimensional needled C/C-SiC composite from room temperature to 1800℃ were performed to investigate tensile behavior. The damage characteristics and macroscopic mechanical behavior of the composite are relevant to the testing temperature and off-axis angles of the tensile loading. The tensile strength increased while the modulus decreased with the increase of temperature. A high-temperature nonlinear constitutive model was established to analyze the nonlinear stress–strain relationship of the composite. Plastic strain accumulation and stiffness degeneration were described by the plasticity and damage theories. The effect of temperature on the tensile behavior of the composite was particularly considered in this model by introducing a thermal damage variable. The proposed constitutive model can predict the stress–strain behavior of the material subjected to different off-axis tensile load, and at different temperatures. Fairly good agreement was achieved between the predicted and experimental results.

In situ observation of compression damage in a 3D needled-punched carbon fiber-silicon carbide ceramic matrix composite

“…Peng et al [8] studied the monotonic tensile response, damage development and acoustic emission activity of 3D needle-punched C/SiC composite, observing a beneficial effect of interfacial PyC and pores in the matrix on microcracking damage that initiated at low fractions of the strength. Xie et al [9] conducted room temperature and high temperature (800°C, 1200°C, 1500°C and 1800°C) tensile tests of a 3D needled C/C-SiC composite and established a nonlinear constitutive model to describe the stress-strain relationships. Chen et al [10] conducted in-plane tensile experiments of 3D needle-punched C/C-SiC composites from room temperature to 2000°C to study the microscopic failure mechanisms, finding that relaxation of thermal residual stresses tended to counteract the effects of decreasing the interfacial strength, but increasing SiC crystallization degraded the strength of the matrix at higher temperature.…”

“…fiber cloth, short-cut web and needle). The available analyses of the fracture mechanism and damage patterns [6,7,9,11] were all post-mortem investigations, and as such provided limited information on the sequence of damage development and the microstructure components from which it initiated. X-ray computed tomography (XCT) is a nondestructive imaging technique that can provide in situ observations and both qualitative and quantitative information of structure within materials [12].…”