Fatigue behaviour of a C/C-composite under interlaminar shear loading conditions

The fatigue behaviour of a carbon fibre reinforced carbon under interlaminar shear loading conditions was investigated at room temperature. Two different testing procedures were applied: the conventional short-beam-bending test and a new compression-shear test. It can be shown that the new approach tests the interlaminar properties more sensitively and critically because it produces a predominant, nearly homogeneous shear stress between the laminates and, as a consequence, causes pure shear failure. The bending test, on the other side, is additionally influenced by the fibres. The Interlaminar Shear Strength values determined under compression-shear are remarkably smaller and their deterioration with increasing cycling number is more pronounced. This means that the new test describes better the influence of the matrix which dominates all interlaminar processes.