Experimental Study On Mechanical Properties Of Adhesive-rivet Hybrid Repair Of Composite Materials

With the development of science and technology,composite materials are widely used in aircraft structures.The damage of composite materials is inevitable,so it is of great significance to further research on composite fuselage maintenance technology.At present,there are few researches on adhesive-rivet hybrid repair,and most of the existing researches are limited to the finite element simulation and theoretical analysis.The actual failure mode,damage location,repair effect,dangerous location and damage reason of adhesive-rivet hybrid repair are still unclear.Therefore,the uniaxial tensile test of the composite aircraft skin was designed,manufactured and completed in this paper.The three-dimensional finite element simulation models of the test specimens were established by using ANSYS finite element simulation software.The effects of different repair methods and damage sizes on the tensile properties of repaired structural parts were studied by means of combination of scientific experimental research and finite element simulation.The details are as follows:(1)Five groups of test specimens were designed and made,including no-damage specimens,adhesive repair specimens and adhesive-rivet hybrid repair specimens with 60 mm and 30 mm circular hole damage,and the test was completed under uniaxial tensile load.(2)The failure strength,failure mode and the damage form at fracture of no-damage specimens,adhesive repair specimens and adhesive-rivet hybrid repair specimens with 60 mm and 30 mm circular damage were compared.The results show that repair effect of adhesive-rivet hybrid repair is better than that of adhesive repair.The failure mode of adhesive repair is the fracture around rivet hole and that of adhesive repair is the fracture in the middle of the motherboard.The damage form at fracture of specimens are the same under different repair modes.The difference of the effect between 60 mm and 30 mm is not obvious to adhesive-rivet hybrid repair specimens.(3)Based on the five groups of test specimens,the three-dimensional finite element models were established and the simulation numerical calculation was completed.By comparing the stress distribution diagram and stress value of motherboard,patch and adhesive layer in the non-destructive model,adhesive repair model and adhesive-rivet hybridrepair model with 60 mm and 30 mm circular damage,the failure location of adhesive-rivet hybrid repair structure is concluded and the reason of failure is stress concentration.The stress distribution and the dangerous part of adhesive-rivet hybrid repair model with 60 mm circular damage is the same as that with 30 mm circular damage.The relationship between the size of damaged hole and the repair effect of adhesive-rivet hybrid repair is analyzed.The effect of damaged size on the repair effect is small.The influence of damage size can be ignored when the requirement is not strict.