Research Of The Out-of-plane Shear Properties Of Three-dimensional Woven Composites

With the development of weaving technology,3D woven composites with the advantages of multidirectional load bearing and impact resistance have gradually become the research hotspot of scholars and future development due to their unique transverse properties.However,due to the complexity of the internal structure and the defects of the forming process,there are many problems to be solved in the evaluation of the mechanical properties of 3D woven composites,especially for the out-of-plane mechanical properties.Obviously,the out-of-plane performance is very important for the safety evaluation and material design.Therefore,in order to explore the out-of-plane shear properties of 3D woven composites,a set of research methods for this problem was established through experiments and numerical simulation.In the first chapter,through domestic and foreign literature investigation,it is found that there is a lack of sufficient research on the out-of-plane shear properties of three-dimensional woven composites.In addition,the research progress of composite shear test methods at home and abroad,composite shear test fixture,composite meso-model,and progressive damage research status of composite materials are introduced in detail.The research objective and significance of this paper are clarified.In the second chapter,a suitable method for the out-of-plane shear test of 3D woven composites is selected.The quasi-static out-of-plane shear test in 23 directions is carried out for a typical 3D woven composite with layered twill structure.The test results and the failure modes of the materials are discussed.In the third chapter,the appropriate damage initiation criteria and damage evolution model are selected as the theoretical basis of 3D woven composite simulation,and the ABAQUS user material subroutine is written by FORTRAN language to realize it.In the fourth chapter,a single cell model with periodic boundary conditions is established to simulate the experiment in this paper.The stress-strain curves of out-of-plane shear and the related cloud images in the loading process are obtained and compared with the experimental results,which provides a certain basis for the future research.