Dynamic Mechanical Properties Of 3D Woven Composites At High Strain Rates

Carbon fiber and its reinforced composite materials have many advantages such as light weight and impact resistance,and are gradually widely used in important application technology fields such as aerospace and bulletproof engineering.Three-dimensional woven carbon fiber composites have stronger impact damage resistance and delamination damage resistance compared with traditional laminated composites and braided composites.Gradually,the deformation damage characteristics and failure mechanism of three-dimensional woven carbon fiber composites under ultra-high speed impact have become a research hotspot.In this paper,theoretical analysis,experimental research and numerical simulation are combined to systematically study the dynamic test,dynamic constitutive model and damage characteristics of composite materials,which provides valuable theoretical basis and key technology for further revealing the failure mechanism and failure mode of composite materials under high strain rate.In this study,the Hopkinson compression bar test device is used to study and design the dynamic test of three-dimensional woven carbon fiber composites.Considering the test conditions of different loading modes and different strain rates,the test scheme is optimized,and a more suitable test scheme for the dynamic compression performance test of three-dimensional woven carbon fiber composites is proposed.The main research results are as follows:(1)With the help of Hopkinson compression bar(SHPB)test device and using the three wave method to process the experimental data,the compression and failure characteristics of three-dimensional woven carbon fiber composites(T700 / BMI)under three loading modes(warp,weft and Z direction)are obtained,and the effects of different loading modes and different strain rates on the compression and failure characteristics of three-dimensional woven carbon fiber composites are given.The experimental results show that the dynamic compressive strength of 3d woven carbon fiber composites in z direction is much greater than that in warp and weft direction.The mechanical properties in warp and weft direction are less sensitive to strain rate,while the mechanical properties in Z direction are more sensitive to strain rate,and the compressive strength increases with the increase of strain rate.(2)Based on the experiment,the stress-strain relationship of three-dimensional woven composites with different loading modes and different strain rates is obtained,and then its dynamic strength and stiffness are obtained.Then the damage mode is observed and the one-dimensional dynamic constitutive equation is established through Zhu Wang Tang(ZWT)constitutive equation.(3)The numerical simulation software LS-DYNA was used to comprehensively study the deformation characteristics and mechanical properties of 3d woven composites under different strain rates.The numerical simulation results were compared with the experimental results to verify the reliability of the simulation model.Through the in-depth analysis of the numerical simulation results,the internal failure mechanism and mechanical characteristics of the material studied in this paper are explored.The results show that different loading modes and different strain rates have a significant impact on the impact resistance of the material.Figure [44] table [11] reference [82]...