Residual Stresses In and Around a Short Fiber in Metal Matrix Composites Due To Temperature Change

Mechanical properties and damage evolution of short-fiber-reinforced metal matrix composites (MMC) are studied under a micromechanics model accounting for the history of cooling and thermal cycling. A cohesive interface is formulated in conjunction with the Gurson-Tvergaard matrix damage model. Attention is focused on the residual stresses and damages by the thermal mismatch. Substantial stress drop in the uniaxial tensile response is found for a computational cell that experienced a cooling process. The stress drop is caused by debonding along the fiber ends. Subsequent thermal cycling lowers the debonding stress and the debonding strain. Micromechanics analysis reveals three failure modes. When the thermal histories are ignored, the cell fails by matrix damage outside the fiber ends. With the incorporation of cooling, the cell fails by fiber end debonding and the subsequent transverse matrix damage. When thermal cycling is also included, the cell fails by jagged debonding around the fiber tops followed by necking instability of matrix ligaments. [S0094-4289(00)01202-0]

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Effect of Short Fiber Reinforcement on the Fracture Toughness of Metal Matrix Composites

Advanced Composite Materials ◽

10.1163/156855109x434801 ◽

2010 ◽

Vol 19 (1) ◽

pp. 41-53 ◽

Cited By ~ 6

Author(s):

I. T. Lee ◽

Y. Q. Wang ◽

Y. Ochi ◽

S. I. Bae ◽

K. S. Han ◽

...

Keyword(s):

Fracture Toughness ◽

Metal Matrix Composites ◽

Metal Matrix ◽

Fiber Reinforcement ◽

Short Fiber ◽

Matrix Composites

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Finite Element Modeling for Prediction of Residual Stresses in Fiber Reinforced Metal Matrix Composites

13th Computers in Engineering Conference ◽

10.1115/cie1993-0058 ◽

1993 ◽

Author(s):

Partha Rangaswamy ◽

N. Jayaraman

Keyword(s):

Residual Stress ◽

Finite Element ◽

Residual Stresses ◽

Metal Matrix Composites ◽

Metal Matrix ◽

Matrix Material ◽

Unit Cell ◽

Experimental Results ◽

Matrix Composites ◽

Layer Removal

Abstract In metal matrix composites 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 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 have 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 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 simulated 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 an eight-ply unidirectional composite with Ti-24Al-11 Nb as matrix material reinforced with SCS-6 fibers.

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