Numerical simulation of the fracture behavior of Ti/SiC composites between 20 °C and 400 °C

The fracture behavior of a Ti-6A14V matrix uniaxially reinforced with SiC fibers was analyzed between 20 degrees C and 400 degrees C using a multi scale approach that involved the finite element simulation of a three-point bend test on a notched beam of the composite. The material in front of the notch tip was discretized taking into account the actual fiber-matrix topology in the composite panels, while the rest of the beam was assumed to be homogeneous. The numerical simulations took into account the actual deformation and damage mechanisms experimentally observed (matrix plastic deformation, stochastic fiber fracture, and frictional sliding at the fiber/ matrix interface) using the appropriate finite element tools, and the corresponding fiber, matrix, and interfacial properties were independently obtained. The results of the numerical simulations were in good agreement with the experimental load-crack mouth opening displacement (CMOD) curves and reproduced accurately the actual deformation and fracture micromechanisms around the notch tip. Moreover, the apparent fracture toughness of the composite (computed from the maximum load and the initial notch length) was also very close to the experimental values, showing the potential of this multiscale approach to carry out "virtual" fracture tests in the computer once the physical mechanisms of deformation and fracture are included in the model and the corresponding micromechanical parameters are carefully measured.