Fatigue properties of ceramic hollow sphere filled aluminium matrix syntactic foams

Metal matrix syntactic foams, consisting of two grades of aluminium alloys and a set of oxide ceramic hollow spheres, were investigated in the aspect of cyclic loading. The results of the compressive - compressive cyclic loading with the load asymmetry factor of R=0.1 ensured full reliability design data for the investigated material in the lifetime region, while the fatigue limits were determined by staircase method. Based on the measurements the Wöhler curves of the foams were constructed, including the median curves, their confidence boundaries and the fatigue strength. Regarding the matrix material, the softer matrix ensured higher load levels for the fatigue strength than the more rigid matrix. Considering the size of the reinforcing ceramic hollow spheres, larger spheres performed better than the more vulnerable smaller ones. One common failure mode was isolated for the investigated foams: the samples were broken along a shear band, similar to the case of quasi-static loading.