This book dealing with applying mechanical vibration during solidification and its effect on fatigue life of alloy as cast. Vibration at different frequencies and amplitudes has been applied to the mold during solidification. Neural Networks method was used to simulate the conditions of the vibrating system in this work, also to extend the area of investigation for fatigue life modification. The Neural Networks was used to find S-N curves at virtual conditions; high frequencies 0f and amplitudes , which produced improvement in fatigue life.