Research On The Impact Damage And The Mechanism Of The Fatigue Fracture Of The Aerospace Composites Material

Due to the outstanding performance of the composite materials, it is widely used in civil aviation; however, its main failure modes are impact damage and fatigue fracture, so it is necessary to do the research on its impact resistance and fatigue properties.In the article, firstly, using the finite element simulation method to simulate the whole process of the impact of the civil aircraft skin by the hail, output the displacement cloud, the stress cloud at different time by calculating, and the maximum force of the impact for different impact energies, damaged area; the critical value of the impact energy 60 J, which means the beginning of the impact damage, the linear relationship of the impact energy and the impact damage area.Complete the butt of the impact model and the fatigue model in using the maximum impact force under different impact energies, which was obtained in the previous text, predict the fatigue life under different impact energies, obtain the critical value of the impact energy110 J, which means the beginning of the fatigue damage, the linear relationship of the impact energy and the fatigue damage area. But based on the comparative results, the critical value of the fatigue is smaller than the critical of the impact, the fatigue damaged areas are far more larger than the impact damaged areas, which shows that when the composite material is impacted, although no obvious damage on the surface, within a certain range, its fatigue properties have dropped significantly. Analyzing its fatigue failure area, it was a dumbbell-shaped, which was the same with the result of many impact tests. The result proved the damage of the impact on the fatigue properties of the composite materials, and the correctness of the butt of the impact model and the fatigue model.In this paper, combining the impact model and the fatigue model together to do the research on the impact resistance and fatigue properties of the composite materials, is an extremely innovative idea; the result of the research provide a strong basis for the maintenance and repairation of the composite materials on the civil aircraft.