| How to repair quickly helicopter structural components at room temperature has become a main focus in military and civilian industries as more and more composite were used in helicopter structural components.The epoxy resin adhesive was one of bonding repair method used in composite and its modification is still progressing.The development of domestic adhesives with high performance is imperative in order to ensure the safety of raw material and supply chain of helicopter bonding repair.In this paper,a new plasticizer with core-shell structure was used to toughen epoxy resin and modified epoxy resin was used as adhesive of components repairing,the main contents are briefly introduced following:1?Urea-formaldehyde deposited on ENR latex particles surface resulted in forming of a new core-shell particles(E-CSPs)by a poly-condensation reaction.The results showed that E-CSPs with 2:1 ratio of core-shell occurred as white powder and suit for engineering application.It has a spherical appearance with a mean thickness of 21 nm for the UF shell and the diameters of these particles varied from 82 nm to 1076 nm.The E-CSPs were incorporated into epoxy resin as toughening agent and the results showed that optimal component ratio of resin system including epoxy resin modified with silicone,E51,AFG90and 694 thinner was 25:10:50:15.In addition,the results showed that heat resistance and adhension performances were affected by the structure of the amino-terminated silicone prepolymer.The organic silicone modified epoxy resin had high shear strength and good heat resistance when the R/Si was 1.4,the Me/Ph was 1.5 and the dosage was 20.Mechanical test results showed that the impact strength was enhanced significantly.The viscosity of J-352was 4.4 Pa·s,which resulted in good infiltration into fiber.J-352 had good heat resistance,the initial decomposing temperature of the cured was around 342?,and the final carbon residue rate was 11.3%at 800?.2?The properties of J-352 and EA9396 adhesives infiltrating dry carbon cloth and dry glass cloth composite were studied.The results showed that J-352 adhesives infiltrating dry carbon cloth had higher resin quality and lower fiber volume fraction and pore rate than EA9396 adhesives.However,the resin quality,fiber volume fraction and pore rate of J-352and EA9396 adhesives infiltrating dry glass cloth were similar.DMA results showed that T_g of J-352 adhesives infiltrating dry carbon cloth and dry glass cloth composite was about 80?,which was higher than T_g of EA9396 adhesives infiltrating dry carbon cloth and dry glass cloth composite.In addition,postcure existed in EA9396 adhesives infiltrating composite.Mechanical test results showed that the composite infiltrated by J-352 had better tensile and compression properties compared to EA9396.Therefore,J-352 suited to be used in field of composite repairing.3?The feasibility study about J-352 adhesive used in repairing of scratch and internal delamination of composite laminates was done.A new finite element simulation method was presented.The simulation and experiment results showed that the repair effects of J-352 were better than that of EA9396,the residual strength of laminate repaired by J-352 were higher than 80%and met the repair requirements.The results obtained in the experiments are in good agreement with ones acquired in the simulation,which indicated the validity of repairing model.The fracture of the test samples were observed by SEM and failure mode and fracture mechanism was determinined.4?The model of intact and repaired typical T-beam was builted by the Patran/Nastran software.The result showed that the mechanical properties of T-beam repaired by J-352bonding repair could meet the requirement for use. |
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