Abstract:
To investigate the low-velocity impact mechanical properties of typical layups in helicopter composite rotor blades, low-velocity impact tests were conducted on a typical hybrid layup EW250F(0/90)/CF3052(45/−45)3/CF3052(0/90) laminate using a drop-weight apparatus. The low-velocity impact response curves were measured, and the damage characteristics were analyzed through dent depth, damage area, damage modes, and failure mechanisms. Quasi-static tensile tests and tension-tension fatigue tests were subsequently performed on the impacted laminates to determine their post-impact tensile residual strength, residual modulus, and fatigue limit strength. The experimental results revealed that: (1) At impact energies of 2.9 J and 3.6 J, the primary damage modes were delamination and matrix cracking. Residual deflection remained nearly negligible, with minimal variation in energy absorption capacity. However, the tensile residual strength exhibited a significant reduction, while the residual modulus showed only a slight decrease. (2) At impact energies of 7.2 J and 9.0 J, fiber breakage became the dominant damage mode. A pronounced increase in residual deflection and energy absorption capacity was observed. The tensile residual strength decreased marginally, whereas the tensile residual modulus declined substantially. (3) The primary failure modes during post-impact tension-tension fatigue were delamination and fiber breakage. The fatigue limit decreased significantly with increasing impact energy. The interfacial performance disparity between glass fiber and carbon fiber layers was identified as the primary cause of delamination damage.