NUMERICAL MODELING OF FIBER PUSH-OUT TEST IN METALLIC AND INTERMETALLIC MATRIX COMPOSITES - MECHANICS OF THE FAILURE PROCESS

The application of push-our test to characterize the mechanical behavior of interfaces in Metallic and Intermetallic Matrix Composites (MMCs and IMCs) is studied using Finite Element Method. A stress based criterion for debonding, and frictional resistance based criterion for interfacial sliding are used in the proposed model to predict the interfacial behavior during the push-out test. The complexities involved in modeling the process, and interpretation of the experimental results in the case of MMCs and IMCs, as compared with Ceramic Matrix Composites (CMCs) are addressed. The mechanics of interface failure is analyzed and an attempt is made to capture the debonding sequence during a thin-slice push-out test. The effect of different material and testing variables on the experimental observations are studied. The influence of processing induced residual stresses on interface behavior during the push-out test is examined in detail, with the main focus on the role of residual shear stresses in a thin-slice push-out test. The elastic-plastic behavior of the matrix and the temperature dependency of the constitutive properties are included in the analysis. The push-out behavior at elevated temperatures is also studied. The effect of temperature on the peak load in push-out tests, predicted using the proposed model, qualitatively agrees with the experimental observations.