ZAMM 73, T423-T426, 1993


INFLUENCE OF DAMAGE ON THE MECHANICAL BEHAVIOR
OF SHORT FIBER REINFORCED MMCs
WITH STRONG AND WEAK INTERFACES

C.A. Abel, E. Weissenbek and F.G. Rammerstorfer

Institute of Lightweight Structures and Aerospace Engineering,
TU Wien, Vienna, Austria


Abstract - Two different types of damage - depending on the interface strengh - are investigated for a composite system consisting of an Al matrix (99.9%) reinforced with Al2O3.SiO2 (Sumitomo-ALTEX) short fibers. A finite element study is conducted using a two-dimensional axisymmetric unit cell model with special boundary conditions to investigate an aligned periodic array of staggered and unstaggered fiber arrangements embedded in a matrix. For strong interfaces (perfect interfaces), a damage indicator based upon a void nucleation and growth mechanism is used to represent the extent of matrix damage due to plastification. The damage parameter has been found to be a better indicator of the overall composite's strength than the global stress-strain behavior. The weak interface is represented as unbonded with frictional contact. A damage failure mechanism is postulated based upon the sequence of debonding along the fiber to account for the unexpected global behavior of a negative Poisson's ratio (a volume inrease) in response to an axial tensile loaded MMC with specific fiber arrangement.


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