Abstract
In metal matrix composites (MMCs) residual stresses developing during the cool-down process after consolidation due to mismatch in thermal expansion coefficients between the ceramic fibers and metal matrix have been predicted using finite element analysis. Conventionally, unit cell models (UCMs) consisting of a quarter fiber surrounded by the matrix material have been developed for analyzing this problem. Such models have successfully predicted the stresses at the fiber-matrix interface. However, experimental work to measure residual stresses has always been on surfaces far away from the interface region. In this paper, models based on the conventional unit cell (one quarter fiber), one fiber, two fibers, four-plys, and eight-plys have been analyzed. In addition, using the element birth/death options available in the FEM code, the surface layer removal process that is conventionally used in the residual stress measuring technique has been stimulated in the model. Such layer removal technique allows us to determine the average surface residual stress after each layer is removed and a direct comparison with experimental results are therefore possible. The predictions are compared with experimental results of a unidirectional composite with Ti-24AI-11Nb as matrix material reinforced with SCS-6 fibers.
Keywords:
coefficient of thermal expansion (CTE) mismatch, composites, finite element modeling (FEM), material removal effects, residual stress, titanium matrix, X-ray stress measurements
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Author Rangaswamy P, Jayaraman N
Title Residual Stresses in SCS-6/Ti-24AI-11Nb Composite: Part II—Finite Element Modeling
Symposium ,
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