The Fabrication And In-plane Tensile And Shear Performance Of 3D Woven Composites

In this study,three 3D woven composite plates were manufactured by the Resin Film Infusion(RFI)method.The in-plane tensile and shear quasi-static performance were investigated by experimental and numerical methods.The tensile and shear moduli and strength were obtained.The experimentally determined moduli and strength fall in a reasonable range and exhibit a small scatter,implying a stable quality of the RFI fabricated 3D woven composites.An idealized geometric model was generated based on micro-CT images.A subsequent numerical simulation for in-plane tensile and in-plane shear performance was carried out.An RFI apparatus was designed and fabricated in chapter 2.After optimization for the ramp up speed,vacuum pressure and other aspects of RFI method,three composite plates were successfully manufactured.Compared with the widely used Resin Transfer Molding method,RFI has a lower capital investment and a simpler apparatus.However,such defects as visible voids and lack of resin exist in the composite plates,requiring a further improvement over the existing manufacturing process and equipment.The in-plane tensile and in-plane shear performance of RFI manufactured composites were experimentally studied in chapter 3.The Digital Image Correlation technology was used to extract full-field strain information.Due to the periodic internal structure of 3D woven composites,the strain fields of the tensile specimen were also manifest beautiful periodic patterns.The data of in-plane tensile and in-plane shear performance is stable.Optical microscopy was used to study the damage of specimens.All the specimens display typical acceptable failure modes.In chapter 4,yarn cross-section areas and unit cell dimensions were obtained from micro-CT images,from which an idealized geometric model was established.After the failure criteria were chosen,numerical simulation was conducted for the in-plane tension and in-plane shear performance of 3D woven composites.Compared with experimental data,the results of a numerical study are off by a reasonable amount.