Research On New Core-die Auxiliary Hot Pressing Co-curing Technology For CFRP Hat-stiffened Panels

As a new type of material with excellent performance,carbon fiber reinforced composite(CFRP)has high specific modulus,high specific strength,corrosion resistance,high temperature resistance,fatigue resistance,good damping and shock absorption,good damage safety,designability and A series of advantages such as multi-functional integration,CFRP hat-shaped reinforced structure has a large number of applications in the curved structure of new aircraft due to its structural stability,relatively high transmission circumferential load efficiency and high buckling strength.In the autoclave forming process of the hat-shaped reinforced wall panel,the co-curing molding process has a small number of cans,which greatly reduces the cost;and the co-curing does not require a glue adhesive,and the interface mechanical properties are good.The light weight and small amount of deformation have considerable advantages for the weight-bearing structure of a large passenger aircraft that requires a large weight and a precise size.In the past co-cure scheme of the hat-shaped stiffened wall panel,the vacuum bag core mold is easy to be damaged during the forming process,and the surface quality is not good due to the wrinkles;the metal core mold often appears to be demolded in the curved shell molding application.Difficult problem;the water-soluble core mold itself is easy to break during the experiment;the silicone core mold with pre-formed hole can not guarantee the pressure uniformity during the pressure transmission process.In this paper,a new process for forming a carbon fiber reinforced resin matrix composite hat-stiffened panel based on thin-walled silica gel airbag core mold assisted autoclave is proposed.The paper establishes a mathematical model of thermo-force-flow multi-field coupling of CFRP hat-stiffened panel siding by co-curing the autoclave,and based on the COMSOL Multiphysics finite element software,the hat-shaped reinforced siding is assisted by the thin-walled silicone airbag core mold.The autoclave co-cure process was modeled.According to the material characteristics and curing degree,the hot pressing process curve was established.The effects of different frame molds on the pressure and wall thickness of theshell were studied by finite element simulation.The pressure and wall thickness of the parts in the new process manufacturing process are relatively uniform,and the forming effect of the silicone rubber and the hat-shaped frame with a wall thickness of 1 mm is relatively good.The correctness of the finite element model was verified by testing the autoclave experimental molded parts.Combined with the mechanical tensile test results of the interface of the workpiece,the effects of different wall thickness silicone airbag core molds and different frame molds on the mechanical properties between the hat-shaped long raft and the skin were studied.The results show that the interface strength of the silicone rubber of 1 mm wall thickness and the hat frame is very good.In summary,the research on the molding quality of the hat-stiffened panel plate parts shows that the new process of co-curing of the autoclave based on the silicone air bag core mold assisted CFRP hat-stiffened panel plate is feasible.