New method to predict fatigue life of composite laminate with delaminating effect considered

The classic Tsai-Hill method did not consider delaminating effect; as a result, when delaminating effect can not be ignored, the deviation of its calculated fatigue life from test data becomes very large. We propose a new method, which takes delaminating effect into consideration, that can make the deviation of calculation life from test data much smaller. In the full paper, we explain our new method in much detail; here we give only a briefing. This edge delamination failure mode is caused by the high interlaminar stress concentrated near the free edges. In this paper, we present a simplified method for calculating the interlaminar stress near the free edge of composite laminate. Then the formula to calculate fatigue life of composite laminate is proposed. Finally we give a numeral example of a 16-layer laminate plate [-45/0/45/90/-45/0/45/0]_sym. The loading tensile stress cyclically varied from 10% to 100%. When the maximum (100%) loading stress was 711, 620, or 566 MPa respectively, we obtain the following results; the test fatigue life was 2 127, 27 612, or 91 327 cycles respectively; the life calculated by the classic Tsai-Hill method was 96046, 358543, or 1.29×10⁶ cycles respectively; the life calculated by our new method was 17955, 57450, or 131318 cycles respectively. These results show preliminarily that our new method can give calculated lives much closer to test fatigue lives.