Research On Repair Performance Of T300/7901 Carbon Fiber Composite Laminate

T300/7901 carbon fiber composite laminates have advantages such as high specific stiffness,high specific strength,excellent heat resistance,and low cost,and are widely used in fields such as aircraft manufacturing,automotive manufacturing,and shipbuilding industry.However,in the working environment,the plywood will face various types of damage,such as oxidation,surface peeling,and low-speed impact damage.The proportion of low-speed impact damage in the service process of carbon fiber composite laminates is the highest.After being subjected to low-speed impact,composite laminates will cause fiber tearing,delamination,and other damage at a certain depth below the surface.There is currently no clear standard for the repair methods of similar damages and the evaluation methods of composite material performance after repair,which has attracted the attention of many researchers.Among the numerous research achievements,the evaluation of the repair performance of composite laminates mainly focuses on statics,and there are few dynamic evaluation methods for their working conditions.Therefore,it is necessary to evaluate the dynamic performance of carbon fiber composite laminates after impact repair based on modal analysis.The main research content of this article includes:(1)Conduct impact experiments on T300/7901 carbon fiber composite laminates with[45/0/-45/90] 3s layup and plain weave method,and repair the impacted laminates with adhesive patches and fastener connection patches;(2)Based on the cohesion model,modal analysis was conducted on the T300/7901 carbon fiber composite laminates repaired by two different repair methods:[45/0/-45/90] 3s ply and plain weave,adhesive patch repair,and fastener connection patch.The first six natural frequencies and vibration modes of the repaired T300/7901 carbon fiber composite laminates were extracted;(3)Conduct secondary impact tests on the laminated plate repair structure with two different repair methods: [45/0/-45/90] 3s ply and plain weave,adhesive patch repair,and fastener connection patch repair.Verify the finite element simulation results based on vibration experiments,and conduct modal analysis on the repaired structure;(4)Conduct vibration experiments on composite laminates after the first impact,first impact repair,and second impact to verify the accuracy of modal frequencies extracted from finite element simulation.Additionally,perform ultrasonic C-scans on composite laminates after the first impact,first impact repair,second impact,and vibration damage experiments,respectively,Based on the fatigue cycle and damage situation,a damage model of T300/7901 carbon fiber composite laminates in an environment close to natural frequency is obtained.Through modal analysis,two different repair performance evaluation methods,namely [45/0/-45/90] 3s ply and plain weave,adhesive patch repair,and fastener connection patch repair,are obtained.