A Clamped Three-point Bending Setup for Fatigue of Thin Composite Laminates

Usually, fatigue tests on fibre-reinforced composites are performed in uni-axial tension/tension or tension/compression fatigue [1], providing the S-N data. Although bending fatigue tests are not widely accepted as a standard, they are used a lot for research purposes [2] and they do have some important advantages [3]. In case of three-point bending fatigue, the history of bending force versus midspan displacement is recorded. In [3], the authors examined a standard three-point bending set-up for fatigue testing of thin composite laminates. It was concluded that this set-up was not suited because (i) the large midspan displacement, caused by the specimen’s low bending stiffness, limited the test frequency in the fatigue test; (ii) the apparent hysteresis in the force-displacement curves was entirely due to friction between specimen and supports, and (iii) the computational demand for the finite element simulations was very large, because modelling of friction at the supports had to be taken into account.