of length in an infinite sheet as shown in the figure 2, we have and is independent of the crack length. Also, can be considered to be independent of the crack length. By assuming the above integral simplifies to by integrating the above expression for and cases, the total number of load cycles are given by Now, for and critical crack size to be very large in comparison to the initial crack size will give The above analytical expressions for the total number of load cycles to fracture are obtained by assuming . For the cases, where is dependent on the crack size such as the Single Edge Notch Tension (SENT), Center Cracked Tension (CCT) geometries, numerical integration can be used to compute . Case II For crack closure phenomenon has an effect on the crack growth rate and we can invoke Walker equation to compute the fatigue life of a specimen before it reaches the critical crack size as Numerical calculation This scheme is useful when is dependent on the crack size . The initial crack size is considered to be . The stress intensity factor at the current crack size is computed using the maximum applied stress as If is less than the fracture toughness , the crack has not reached its critical size and the simulation is continued with the current crack size to calculate the alternating stress intensity as Now, by substituting the stress intensity factor in Paris–Erdogan equation, the increment in the crack size is computed as where is cycle step size. The new crack size becomes where index refers to the current iteration step. The new crack size is used to calculate the stress intensity at maximum applied stress for the next iteration. This iterative process is continued until Once this failure criterion is met, the simulation is stopped. The schematic representation of the fatigue life prediction process is shown in figure 3. Example The stress intensity factor in a SENT specimen (see, figure 4) under fatigue crack growth is given by The following parameters are considered for the calculation mm, mm, mm, , , MPa,, . The critical crack length, , can be computed when as By solving the above equation, the critical crack length is obtained as . Now, invoking the Paris–Erdogan equation gives By numerical integration of the above expression, the total number of load cycles to failure is obtained as