ON THE SIMULATION OF DUCTILE CRACK EXTENSION IN AN AL/SIC METAL MATRIX COMPOSITE USING DAMAGE MODELS

摘要

In a metal matrix composite made of aluminium A 6061 T6 and 20 vol% SiC particles, ductile crack extension only occurs in the ductile Al phase, whereas cracks of the rigid SiC inclusions and decohesion of the Al/SiC interfaces were not observed experimentally. The SiC particles lead to locally different constraints on the micro scale, resulting in a zig-zag shaped crack path. The failure process in the Al phase consists of the nucleation of voids resulting from rigid second-phase inclusions, the growth and coalescence of voids up to final failure. The ductile Al matrix is modelled by using Gurson's constitutive model, whereas the SiC particles are assumed to be elastic. The observed crack path is in good agreement with the numerically predicted crack path.