Numerical And Experimental Study On Scarf Repairment Properties Of Composite Material

CFRP(Carbon Fiber Reinforced Polymer)composites are widely used in aerospace field because of their excellent properties.However,composite structures will inevitably produce defects and damages in actual working conditions.Composite material repair methods can be divided into: mechanical connection repair,adhesive repair.Composite material bonding repair can be divided into patch repair and excavation repair.Excavation repair can provide higher strength recovery rate and smooth dynamic surface for the repaired structure.Therefore,digging and repairing has greater advantages.Composite material structure will be affected by static load and fatigue load during service,so it is of great significance to carry out fatigue performance analysis of composite material repaired structure.This paper studies the static tensile strength,fatigue residual strength,and fatigue life of the excavation repair structure.Firstly,in order to study the static tensile performance of the T300/7901 composite excavation repair structure,this paper creates a finite element model based on the three-dimensional progressive damage theory,and combines the UMAT subroutine to realize the damage criterion of the laminate.The simulation results are compared with the test results to verify the validity of the established model.Secondly,through the method of combining simulation and experiment,the influence of excavation angle,adhesive layer thickness,excavation depth,and patch rotation angle on the static tensile strength of the composite excavation structure is analyzed.Combining simulation software to analyze the damage initiation and expansion of the rubber layer under different excavation and repair parameters,and provide theoretical guidance for the selection of excavation and repair parameters.Through the establishment of a proxy model,the cut and repair parameters of the CFRP laminated board cut and repair structure are jointly optimized.Finally,the specimens with three stress levels are selected for tensile-tension fatigue test,and the S-N curve of the composite structure is obtained.The test method is used to analyze the residual strength of the excavation structure under single-stage load and the residual fatigue life and residual strength under two-stage load,and the fatigue damage and failure law of the damaged specimen is analyzed through the test.