Rsearch On Damage Repair Technology Of Composite Laminates Structure For Civil Aircraft

Advanced composite materials are widely utilized in military and civil aviation for their high specific stiffness,high specific strength,fatigue resistance and flexibility in design.With the increasing utilization of composite structures in aircraft,it is inevitable that it will be damaged in the process of production,manufacture and service period,which will affect their performance.Therefore,it is very necessary and important to study the damage repair technology of composite structures.Firstly,the tensile tests of the six kinds of composite laminates with different ply structures were prepared from an airline maintenance base and were carried out in this paper,and the tensile strength of composite laminates with different ply structures was obtained.At the same time,based on ABAQUS finite element software,three-dimensional finite element models of undamaged laminates,damaged laminates with central holes and composite laminates scarf repair with different layers are established by using non-linear simulation method,combining three-dimensional Hashin failure criterion and non-linear progressive degradation stiffness model.The validity of the model is verified by comparing the experimental data and numerical simulation results of undamaged laminates.Secondly,based on the established three-dimensional progressive damage model,the numerical simulation analysis of undamaged laminates,damaged laminates with central holes and composite laminates repaired by patches with different layers are carried out,and the ultimate tensile strength of laminates is obtained.The results show that the scheme is consistent with the original undamaged motherboard ply structure strength recovery rate which is the best,reaching 87.68%,while the residual strength of damaged laminates with central holes is only 58.75% of undamaged laminates.Finally,based on the three-dimensional progressive damage model,the damage evolution process of composite laminates under tension load is studied,and the stress distribution of composite laminates under different tension loads is obtained.The key parts of composite laminates that are prone to failure after scarf repaired and the failure mechanism is analyzed.Conclusions obtained in this article can provide some references for analysis and practical engineering of scarf repair in the future.