Design, Preparation, Characterization And Evaluation Of New Non-web Needle-punched Composite Material

Based on the research background of low-cost,high-performance,and low-damage needling technology for high-speed aircraft radomes,this paper proposed a novel none-felt needled preforms and composite.Through experiments and numerical simulation methods,the structure and performance of none-felt needled preforms and composite were systematically studied.The concepts of half-cut cloth and none-felt needled preforms were proposed,and then half-cut fabric and novel none-felt needled preforms were designed and prepared.The structure of none-felt needled preform was characterized by 3D profiler and Micro-CT.It was found that compared with the traditional felt needled preform,the fiber volume fraction of none-felt needled preform increased by 22.8%.Besides,the diameter and length of the needled fiber bundles in the none-felt needled preform increased by 195.2%and 132.3%respectively.Through the double cantilever beam（DCB）experiment and the double notch shear（DNS）experiment,the ModeⅠfracture toughness(G_IC)and ModeⅡinterlaminar shear properties of none-felt needled composites were studied.The study found that the interlayer performance of none-felt needled composite was significantly enhanced than that of traditional felt needled composite.The ModeⅡinterlaminar shear strength of none-felt needled composite was up to 108.6%higher than that of traditional felt needled composite.The maximum failure load of the DCB experiment increased by 107%,and the G_ICincreased by 129%.The double cohesive zone model was used to establish the ModeⅡinterlaminar shear model and ModeⅠDCB model of the none-felt needled composite.DNS and DCB displacement load curve,ModeⅡinterlaminar shear strength and DNS experiment strain cloud graph in the FEM all were very close to these in the experiments,and the error range was less than 11.6%.The in-plane tensile and bending properties of novel none-felt needled composite were studied through tensile test and bending test.The study found that the tensile properties and bending properties of novel none-felt needled composite were much better than that of the traditional felt needled composite,and the tensile strength and tensile modulus increased by up to 31.5%and 32.8%;bending strength and bending modulus increased by 13.1%and 26.7%respectively.The impact resistance of novel none-felt needled composite with different half-cut clothes was studied.It was found that novel none-felt needled composite had better impact resistance than the traditional felt needled composite.The depth of the front pit,the height of the back protrusion,and the area of damaged area after failure of sample were reduced by up to 23.9%,63.2%,and 47.3%,respectively.In addition,the novel none-felt needled composite had better impact damage tolerance,and its compressive strength after impact was up to 8.7%higher than that of the traditional felt needled composite.