Abstract:

In this chapter, the results obtained in the experiments and simulations are discussed in a concise manner. The single fibre push-out-tests were performed in the past as an investigation method for a quantitative evaluation of the wire-matrix debonding shear strength as well as for receiving a qualitative impression of the interface regarding the fibre-reinforced metal matrix composites. The debonding shear strength for the stainless steel wire-reinforced aluminium matrix composite was found to be 52 ± 4 MPa. An axisymmetric cylindrical finite element model was presented with the objective of evaluating the interfacial properties of stainless steel wire-reinforced aluminium matrix composites. It comprised of a wire of stainless spring steel 1.4310 (X10CrNi18-8), a matrix of aluminium alloy AA6060 and the interface. The interface was modelled using the cohesive layer concept where, in addition to the elastic parameters, a damage criterion based on the maximum nominal stress was also defined for the interface. The maximum nominal stress criterion defined the damage initiation and fracture energy concept was used for damage evolution. The interface parameters were varied to adopt the model according to the experimental results reported in the past. The simulation results were in good qualitative agreement with experimental results regarding the load-displacement-graph. The shear stress value at which damage initiated was determined to be 53 MPa which was nearly equal to the debonding shear strength found in the experimental investigation. Furthermore, the value of fracture energy required to define the damage evolution law for the interface was determined to be 0.04 J/mm³. More sophisticated implementation of interface behaviour is required concerning the stepwise debonding, failure evolution and the friction between the wire and the matrix once the complete debonding takes place. The shear stresses were found to be positive at the top of the specimen near the indenter. Moving away from this region towards the bottom of the specimen, the shear stresses became more and more negative. The shear stresses along the interface were observed to be almost constant and nearly equal to 53 MPa which is the maximum shear stress permitted by the failure initiation criterion for the interface. The simulation results showed the presence of compressive radial stresses at the top and tensile radial stresses at the bottom of the interface caused by the bending of the specimen. It indicated that, during single fibre push-out-test of wire-reinforced metal matrix composites where thin-slice geometries are used, interface failure initiation favoured by the tensile stress field, probably occurs at the bottom of the specimen even in the absence of thermally induced shear stresses.