Development of Design Analysis Methods for Carbon Silicon Carbide Composite Structures

Abstract

The stress—strain behavior at room temperature and at 1100° C (2000°F) is measured for two carbon fiber-reinforced silicon carbide (C/SiC) composite materials: a two dimensional (2D) plain-weave quasi-isotropic laminate and a 3D angle interlock woven composite. Previously developed micromechanics-based material models are calibrated by correlating the predicted material property values with the measured values. Four-point beam-bending subelement specimens are fabricated with these two fiber architectures and four-point bending tests are performed at room temperature and at 1100°C. Displacements and strains are measured at the mid-span of the beam and recorded as a function of load magnitude. The calibrated material models are used in concert with a nonlinear finite-element solution using ABAQUS to simulate the structural response of the two materials in the four-point beam bending tests. The structural response predicted by the nonlinear analysis method compared favorably with the measured response for both materials and both test temperatures. Results show that the material models scale-up fairly well from coupons to subcomponent level.

Multiscale Modeling of Advanced Materials for Damage Prediction and Structural Health Monitoring

“…Optical micrographs, such as those presented in Sullivan et al (2006) and Murthy, Gyekenyesi, and Mital (2004) demonstrate the variation in void shape, size, and distribution as a function of location within the composite. Typically, the intertow matrix surrounding the regions in which a tow is undulating has a higher volume fraction of voids compared with those away from the regions of undulation.…”

“…Since the carbon fibers are susceptible to corrosion at elevated temperatures, the PyC interphase offers increased corrosion resistance while also serving as a toughening mechanism through crack deflection, fiber/matrix debonding, and fiber pullout (Lamouroux et al, 1993). Due to the manufacturing process and insufficient infiltration (i.e., canning) of the matrix material, voids are distributed in the composite nonuniformly (Sullivan et al, 2006).…”

“…In addition, the presence of nonuniform void shape and size affects the global moduli and damage behavior of the composite. The presence of severe matrix microcracking in the as-produced C/SiC composite (Sullivan et al, 2006) results in the material system exhibiting nonlinearity in its mechanical behavior, even at very low stress levels. Therefore, in addition to stimulating thermally induced damage, the multiscale model developed in this chapter will also be able to predict the nonlinear behavior of the composite when subsequent mechanical loading is applied.…”

“…In CMCs manufactured via the CVI process, the concentration of voids in the weave tends to be nonuniform due to insufficient and uneven infiltration of the matrix material into the carbon fiber preform (Sullivan et al, 2006). Optical micrographs, such as those presented in Sullivan et al (2006) and Murthy, Gyekenyesi, and Mital (2004) demonstrate the variation in void shape, size, and distribution as a function of location within the composite.…”

“…Therefore, the model accounts for this variation in intertow matrix void distribution, size, and shape as a mesoscale input parameter. Voids also exist within the intratow matrix cells and micrographs indicate that these voids are evenly dispersed and uniform in size (Camus, Guillaumat, and Baste, 1996;El Bouazzaoui, Baste, and Camus, 1996;Murthy, Gyekenyesi, and Mital, 2004;Sullivan et al, 2006). The meso-and microscale voids are accounted for at a length scale below that at which the matrix constituent (either at the meso-or microscale) is examined by analyzing a separate RUC and homogenizing the properties to provide higher length scale effective properties (Liu and Arnold, 2011).…”