SEDL / STP / STP1186-EB / STP24249S

Analysis of Thermomechanical Cyclic behavior of Unidirectional Metal Matrix Composites

Coker, D
Assistant research engineer and senior research engineer, University of Dayton, Research Institute, Dayton, OH

Ashbaugh, NE
Assistant research engineer and senior research engineer, University of Dayton, Research Institute, Dayton, OH

Nicholas, T
Senior scientist, Materials Directorate, Wright Laboratory, Wright-Patterson AFB, OH

Pages: 20    Published: Jan 1993

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Abstract

An analytical tool is developed to determine the three-dimensional stress state in a unidirectional composite subjected to axial loading and changes in temperature. A finite difference method is used to analyze a representative volume element of the composite which consists of concentric cylinders. The constituents are assumed to be elastic-plastic materials having temperature dependent properties. An iterative technique using the Prandtl-Reuss flow rule to determine incremental plastic strains is implemented in a computer code capable of predicting the axisymmetric triaxial stresses in a composite under thermomechanical fatigue (TMF) loading conditions. The model is verified with finite element method calculations for the problem of thermal residual stresses resulting from cool-down from the processing temperature. Results for several TMF loading conditions are compared with experimental data and 1-D predictions for a SCS-6 silicon carbide fiber and Ti-24Al-11Nb matrix composite. Significant differences are noted between results based on 1-D and 3-D approximations to the stress state in a composite and are discussed in detail.