Causes of edge cracks and natural frequency reduction in composite material outlet guide vanes

During the vibration fatigue test, the edge of the composite material outlet guide blade cracked, and the natural frequency of the blade decreased by more than 15%. The causes of blade edge cracks and the decrease in natural frequency were analyzed using methods such as macroscopic observation, metallographic examination and scanning electron microscopy analysis. The results shows that fatigue cracking occurred on the edge of the blade, which was due to uneven stress and deformation in the local area of the blade. The arc shaped scratches on the surface of the edge promoted the initiation and propagation of cracks. The bonding strength between the blade and resin fiber interface was low, leading to interlayer cracking in the R zone of the blade root, resulting in a decrease in the natural frequency of the blade.