Study On Interlaminar Fracture Toughness Of Two-dimensional Braided Composite

At present,composite materials have been widely used in aerospace,automotive,wind power blades,and highway bridges.However,due to the invisible interlayer delamination during preparation and use,the use of composite materials is severely limited.Therefore,how to improve the performance of composite materials.Delamination-resistant properties have always been the focus of research.At present,the research on the interlaminar fracture toughness of composite materials mostly focuses on the unidirectional,multiaxial and other layered fabrics,while the interlaminar fracture toughness of the two-dimensional braided composites with better overall performance in structure is less related.Therefore,on the basis of previous studies,this paper adopts the method of interleaved toughening to study the interlaminar fracture toughness of two-dimensional braided composites.In this paper,polyurethane(TPU)nanofiber veils were prepared by electrospinning,and the effect of nanofiber veils thickness on the fracture toughness of two-dimensional laminated unidirectional glass fibers(UD-G)interlaminar was studied,and the best toughening effect was selected.For the nanofiber veils,it was found that the Mode I energy release rate of TPU with a thickness of 112.50μm reached2.587k J/m~2,which was 255.36%higher than that of the untoughened sample,Mode II energy release rate reaching 3.846 k J/m~2,which was 47.19%higher than that of the untoughened sample.The effect of TPU interleaved on the interlaminar fracture toughness of 2D-layered multiaxial glass fiber(NCF-G),unidirectional carbon fiber(UD-C)and satin carbon fiber(8H-C)composites was then investigated.It shows that TPU has a good toughening effect on the above fabrics,but due to the rigidity of unidirectional carbon fiber itself,it cannot resist the continuous increase of tensile displacement,resulting in a lower energy release rate than unidirectional glass fiber composites;unidirectional fiber composites with more fibers in the tensile direction,the energy release rate is stronger than that of multi-axial glass fibers.The satin carbon fiber composites have long float lines in the weft direction,resulting in composite samples with better performance than unidirectional carbon fibers.Toughness,resists prolonged Mode I tensile and therefore has a higher energy release rate than unidirectional carbon fiber composites,but lower than unidirectional glass fiber composites.Afterwards,unidirectional glass fibers and multiaxial glass fibers were prepared by lamination needle punching to prepare composites,and the effects of TPU interleaved and glass fiber mat needle punching on the interlaminar fracture toughness of composites were compared.The Mode I energy release rate of the fiber composite material is the highest,reaching 2.026 k J/m~2,and the Mode II energy release rate of the acupuncture unidirectional glass fiber composite material is the highest,reaching 3.854k J/m~2.Finally,the TPU interlayer interleaved toughening method was selected to study its effect on the interlaminar fracture toughness of the two-dimensional braided composites.TPU nanofiber veils can significantly improve the interlayer fracture toughness of the two-dimensional braided composites.Compared with TPU-toughened2D biaxial glass fiber braided composites and TPU nanofiber veils/glass fiber mat co-intercalated toughened composites,triaxial hybrid composites have the highest Mode I and Mode II interlaminar fractures Toughness,it can be seen that the two-dimensional triaxial hybrid composite material with carbon fiber axial yarn added in the axial direction has stronger anti-delamination performance;TPU nanofiber veils/glass fiber surface felt synergistic effect,in which needle punching has a strong effect on two-dimensional braided composite the interlaminar fracture toughness of the material has the greatest improvement effect.