To evaluate the residual fatigue life of components, the fatigue life prediction based on crack growth analysis has been presented, although it requires the specification of an initial fault. If there are always early imperfections on materials, serving as comparable starting cracks, Fracture Mechanics crack growth-based fatigue predictions may be utilized as an alternative to simulate the entire fatigue life of structural components. Very few researchers have addressed the issue of enhance fatigue life due to impact load also very less investigation has happened on effective and efficient assessment of Stress Intensity Factor (SIF) through numerical approach. This research mainly focuses on extracting Stress Intensity Factor for In-plane Mode I loading and efficient utilization of local coordinate system displacement to extract accurate Stress Intensity Factor (SIF) computational. Taking different (a/W) values to predict the critical crack length & extract stress intensity factor through computational and analytical & validated through experimental.