Vibration analysis and simulation of composite fan blades with various laminate configurations

Composite blades, known for their exceptional specific strength, stiffness, and damping characteristics, are pivotal in addressing blade fatigue issues in aero-engines. This paper designs and manufactures eight composite fan blades with various lay sequences, examining the effects of ply ratio and lay sequence on the blades' vibration characteristics. A vibration test platform was constructed, subjecting the eight blades to varying levels of sinusoidal, random, and impact excitations. The vibration responses were measured using an accelerometer (A3), a displacement sensor (X1), and a strain gauge (S1). The measured blade vibration modes and natural frequencies were compared with finite element simulation results. The study reveals that blades without 90°plies exhibit significantly higher natural frequencies than those with 90° plies. The comparison shows that the error between simulation and experiment is less than 8% for the first five modes, demonstrating the finite element simulation model's effectiveness. Additionally, different stacking sequences at the same ply ratio influence the natural frequencies. The first vibration mode frequency decreases with increasing excitation magnitude, indicating a certain degree of nonlinearity in the blades.