Research On Micromechanics And Impact Properties Of Looped Fabric Reinforced Composites

The looped fabric reinforced composite material is a new type of woven composite material.The loop between the fabric and the resin improves the connection mode between the fiber and the matrix.It can effectively improve the interlaminar properties and impact properties of composite materials,will be widely applied in future.In this thesis,the looped fabric reinforced composite laminates are studied.The micromechanics and impact properties of the material are studied by finite element method and mechanical properties experiments.The main contents include:1.According to the yarn orientation and weaving parameters of the loop fabric,the microstructure of the loop fabric composite is studied based on reasonable basic assumptions.The unit-cell model of single-sided looped fabric and double-sided looped fabric composite laminates are established.2.In the micromechanical research,periodic boundary conditions are introduced.Firstly,the equivalent elastic performance prediction model of the looped fabric composite laminate is established,and the elastic properties of the laminate are analyzed by finite element method.Secondly,by writing UMAT subroutine,the 3D Hashin criterion and von-Mises criterion are selected as the failure criterion.The finite element method is used to analyze the damage evolution process and strength of the laminate.Finally,the finite element analysis results are compared with the experimental results,and the accuracy of the finite element method is verified.3.Through the vacuum glue suction molding process,the test specimen of the looped fabric composite laminates are manufactured.A number of experimental studies on mechanical properties are carried out for the laminates.The mechanical properties of the 2D woven fabrics composite laminates with the same weaving parameters are compared and analyzed.The experimental results show that the interlaminar shear properties and the post-impact compression properties of the looped fabric composites are improved.4.Based on the ABAQUS/Explict dynamics module,the finite element model of the looped fabric composite laminate under low velocity impact is established by using the VUMAT subroutine and using the Cohesive element modeling method for the laminated adhesive layer.The finite element analysis of the impact performance and damage failure process is carried out.