Nonlinear mechanics of two-dimensional carbon-carbon composite structures and materials

Abstract

The inelastic mechanics of isotropic materials are usually modeled by scalar functions of the material stress or strain state. Simple effective stress-strain models work well because of the material symmetry and homogeneity usually found in structural materials, and because a single deformation mechanism accounts for inelastic strain behavior. In contrast, laminated carbon-carbon composites are anisotropic with a weak matrix phase and exhibit at least two inelastic deformation mechanisms in coupon tests. The motivation for the present work was the bimodular nonlinear strain response found in testing involute cylinders of a low modulus carbon-carbon material typical of a composite used in nozzle components for several years and now used in several industrial products to replace asbestos. These experimental results raised basic questions about nonlinear material modeling and characterization for this class of composites. The present paper describes results from a program that developed and demonstrated a nonlinear model for two-dimensional carbon-carbon composites based directly on coupon stress-strain data. A low modulus bidirectional material, K-KARB, was used to validate the model in room temperature tests.

Mechanical Behavior and High‐Temperature Performance of a Woven Nicalon™/Si‐N‐C Ceramic‐Matrix Composite

“…This phenomenon could, in turn, lead to scatter in the fiber-to-fiber pullout (push-in) response. The local stress field around the fibers may be further complicated by the woven fiber architecture, [24][25][26][27][28][29][30] which may also have a strong influence on the fiber pull-out length. 30…”

Finite Element Micromechanics and Minimechanics Modeling of a Three- Dimensional Carbon-Carbon Composite Material

“…Stanton and Kipp used a similar approach in their models of two-dimensional woven carbon-carbon involute structures [30,31]. In their work, the material model of Batdorf [32] was incorporated into a finite element analysis of involute cones.…”

“…Stress-strain curves for room temperature, 1093°C, 1649*C and 2204°C are plotted in Figure 24. The three Richard-Blacklock parameters, ER, n and ., used to represent stress-strain plot shown in Figure 24 It has been argued that energy methods based constitutive models do not work well for modeling carbon or carbon-carbon composites [30][31][32]. Yet the work of Pollock [33] appears to model carbon-carbon mechanical behavior quite well using principles based on energy methods.…”

Micro-Deformations in C3000/PMR15 Woven Composite

“…Stiffness and stress distributions were calculated for an undamaged and a damaged composite under thermal-mechanical loading. Other researchers such as Kimpara et al [6], Jortner [7], and Stanton et al [8] have also used FEM to investigate woven composites. In a literature review, Walrath and Adams [9] investigated the use of finite elements on composite materials.…”