The Effect of Internal Delamination Damage on the Tensile Strength of Aeronautical Composites

For aeronautical composite materials,the appearance of internal delamination has a fatal impact on their mechanical properties and may even seriously threaten aircraft flight safety.In this study,the effect of internal delamination damage with different sizes and depths on the tensile strength of aeronautical composites was investigated.Firstly,based on carbon-fiber-reinforced composites commonly used in aircraft,laminate specimens with internal delamination damages of different depths and diameters were fabricated,and tensile tests of composite materials were carried out.Then,the finite element model for the carbon-fiber-reinforced laminate specimens was established,and the validity of the model was verified by comparing its simulation results with the experimental data.Furthermore,by changing the geometric parameters of the internal delamination damage model,the influence of delamination damage on the tensile strength of carbon-fiber-reinforced composites was analyzed and summarized.The results show that,on the one hand,for the internal delamination damages of the same area,the closer is the delamination damage to the surface layer,the lower is the tensile strength.In particular,the closer is the delamination damage to the surface layer,the greater is the decrease in tensile strength,which exhibits an obvious nonlinear relationship.On the other hand,for the internal delamination defects of the same depth,the difference in delamination area has little effect on the tensile strength.This law provides a reference for the damage detection and maintenance focus of aeronautical composite structures,which is of great significance to ensure the safe use of aeronautical composites.