13th International Conference on Fracture June 16–21, 2013, Beijing, China -5- Figure 4. Influence of inclusion size on the fatigue life Fig. 5 shows the results of the modified S-N curves of the VA-tests (FELIX) in comparison to the tests with constant amplitude loading using the approach by Murakami [8] with ( ) α σ ⎥⎦ ⎤ ⎢⎣ ⎡ − ⋅ ⋅ + = 2 120 1 143 1 6 inc V w R area ) . (H / (1), for inclusions near to the specimen’s surface and ( ) α σ ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ − ⋅ ⋅ + = 2 1 120 1 56 1 6 inc V w R area ) . (H / (2) for subsurface inclusions. Figure 5. Reconstructed load-time history tests (FELIX) in comparison to constant amplitude tests The S-N curves are shifted to higher lifetimes for variable amplitude loadings in comparison to constant amplitude loadings. However, the order of load amplitudes influences the lifetime. The reconstructed load time history FELIX 10 with decreasing load amplitudes and the load time history
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