Investigation Of Low Velocity Impact On CF/BMI Composite Laminates

Due to good mechanical property and design tailorability,high-performance composite materials have been widely used in the aerospace field,particularly CF/BMI.CF/BMI composite laminates structures are very sensitive to low-velocity impact,which can easily induce interlaminar cracks.Obviously,studying this weakness of composites is of great importance to improve their performance.Based on this fact,a finite element model was built to simulate low-velocity impact of CF/BMI,a kind of typical composite laminates.The effect of different boundary condition on impact damage was studied.Besides,the damage conditions of composites under quasi-static and impact load were compared.The main conclusions are listed as follows.(1)The damage mechanism of the laminates under the low-velocity impact are basically the same as those of the laminates under the pure bending load,which are due to the delamination damage caused by the stress concentration at the interface.(2)Under low-velocity impact,the damage area in the composites was found to be proportional to the square of velocity.(3)According to the simulation results,as the thickness of the laminate increases,the area of the delamination damage increases in the beginning and decreases afterwards.reaching an maximum at a certain impact velocity.Obvious size effect was observed in the impact tests.as the size of the laminate increases,the damage area decreases.(4)The ABAQUS/Explicit solver was used to simulate the quasi-static indentation test of composite laminates.The delamination area of the laminate under quasi-static load was compared with that under impact load.