PSI - Issue 79

Mays H. Udah et al. / Procedia Structural Integrity 79 (2026) 53–64

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3.3. Stress intensity factor The relationship between the SIF and crack length was plotted for different loads; 615 N, 400 N, and 300 N (see Fig. 11). The data reveal that the SIF value varies with crack length. At the 300 N load, the SIF increases slightly with crack length before decreasing at a faster rate. For the 400 N load, the SIF reaches its maximum value before beginning to decline. At the 615 N load, however, the SIF values remain relatively stable despite variations in crack length. These observations suggest that the SIF values are primarily influenced by the applied load; as the load increases, the SIF values also increase, as expected. Meanwhile, crack length has a moderate effect on the SIF. Ultimately, a higher SIF results in a lower number of fatigue cycles needed to achieve final failure.

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Fig. 11. Comparison of SIF-a curves under different load levels: (a) 615 N; (b) 400 N; (c) 300 N.