Fiber push-out study of a copper matrix composite with an engineered interface: Experiments and cohesive element simulation

The fiber push-out test is a basic method to probe the mechanical properties of the fiber/matrix interface of fiber-reinforced metal matrix composites. In order to estimate the interfacial properties, parameters should be calibrated using the measured load-displacement data and theoretical models. In the case of a soft matrix composite, the possible plastic yield of the matrix has to be considered for the calibration. Since the conventional shear lag models are based on elastic behavior, a detailed assessment of the plastic effect is needed for accurate calibration. In this paper, experimental and simulation studies are presented regarding the effect of matrix plasticity on the push-out behavior of a copper matrix composite with strong interface bonding. Microscopic images exhibited significant local plastic deformation near the fibers leading to salient nonlinear response in the global load-displacement curve. For comparison, uncoated interface with no chemical bonding was also examined where the nonlinearity was not observed. A progressive FEM simulation was conducted for a complete push-out process using the cohesive zone model and inverse fitting. Excellent coincidence was achieved with the measured push-out curve. The predicted results confirmed the experimental observations.