Damage Mechanism Of Three-point Bending Of Carbon Fiber Composite Thin-walled Tube

Composite materials are widely used in the field of automobile manufacturing because of their advantages such as light weight,high strength and designable structure shape.As the forming energy-absorbing composite,the application of carbon fiber composite thin-walled circular tube is the most widespread.The energy absorption effect of composite thin-walled tube under transverse bending is closely related to the fiber type,resin type,number of layers,structure type,etc.In this paper,carbon fiber composite thin-walled tubes with different structures(plain,twill,winding)are prepared,The mechanical response of fiber composite thin-walled circular tube has been researched under three-point bending load based on the experiments and simulation method.The paper extracts PCF,D_PCF,EA,Fmean,CFE,σ mechanical indexes from the load displacement curve of three-point bending experiment as damage characterization.The appearance of the sample was taken by the camera.The internal damage morphology of the sample was obtained by XCT scanning.The influence of plain,twill and winding structure on the damage mechanism was analyzed.The results show that under the three-point bending,the damaged areas of the plain and twill tubes are concentrated,and more tow breaks,resin cracking and interlayer delamination are caused.The damaged area of the winding tube is diffused along the axial direction of the tube,and more interlayer slip and delamination are caused.The twill tube has the best energy absorption capacity,but its resilience is poor.The winding tube has the worst energy absorption capacity,but the best resilience.In this paper,the finite element analysis software ABAQUS is used to build the macro model of thin-walled carbon fiber composite tube with continuous shell element.The three-point bending boundary condition is added to the established model.Fabric reinforced composite constitutive model is adopted for plain carbon fiber reinforced composite tube,two-dimensional Hashin failure model is adopted for carbon fiber winding reinforced composite tube,and bilinear traction separation constitutive model is adopted for interlaminar failure model.The numerical results show that the appearance and internal damage morphology of the tube obtained by the simulation are consistent with the experimental results,and the load displacement curve has a high degree of agreement.It is proved that the modeling method can correctly simulate the complex failure mode of CFRP tube under three-point bending.