The Bending Fatigue Comparison between 3D Braided Rectangular Composites and T-beam Composites

This paper reports the experimental comparison of quasi-static three-point bending and bending fatigue damage behavior between 3D braided rectangular composites (3DBRC) and 3D braided T-beam composites (3DBTC). The stress-deflection curves and failure modes were presented to compare the mechanical properties under quasi-static bending load condition. It was found that the load-carrying capacity of the 3DBTC was much better than that of-the 3DBRC, up more than 19 percent. In addition, the S-N curves were employed to illustrate the comparison of fatigue life. The fatigue resistance performance of the 3DBRC was much better than that of 3DBTC at the same stress levels. The increase of of cycle numbers to failure under stress levels of 80 %, 70 %, 60 % and 50 % were 789.6 %, 395.7 %, 48.5 % and 132 %, respectively. The curves of damage indices vs. % of life (n/Nx100 %) were given to characterize the three-stage accumulative fatigue failure process for both types of composites. Furthermore, the ultimate failure morphologies were presented to indicate the structural damage modes of the composites under the three-point bending cyclic loading condition.