Numerical And Experimental Study On Effect Of Braiding Angle On Low-velocity Transverse Punch Response Of Braided Composite Tube

Thin-walled composites have the advantages of high specific strength,energy absorption and corrosion resistance.They have been considered as a potential counterpart of traditional metal materials and can be used in automotive,marine engineering and aerospace applications.Tubal braided composite possesses excellent damage tolerance and impact performance because of its special interweaving pattern.In addition,the braided reinforcement can be manufactured automatic manner and the mass production of braided composite can be achieved with the assistant of resin transfer molding technology(RTM)to meet production needs.Automobile frames,aircraft components,and mechanical equipment are inevitably subjected to accidental impact loads in practice,resulting in structural damage.Therefore,understanding the impact damage mechanism of braided composites is of great significance for improving safety performanceIn this study,numerical simulation and experimental methods were used to study the effects of different braiding angles on the composite tube under low-velocity transverse punch loads.First of all,three samples of braiding angles(30°,45° and 60°)were prepared and subjected to a transverse punch experimental on a drop-hammer impact teste bench.After that,a mesoscopic finite element model of the composite tube was built to simulate the impact process.Finally,the experimental data and simulation results are compared.On the basis of ensuring the feasibility of the simulation results,the impact mechanical response and damage mechanism of the tube fittings are elaborated.The specific content of this article will be expanded from the following chaptersIn the first section,the performance characteristics and practical application fields of composite tube are introduced,and the research significance of braided composite tube is explained from the aspects of production efficiency and development prospect.In addition,through reading the domestic and foreign literature,I understand the research status of composite tube fittings at home and abroad,and thus determine the research direction of this paper.In the second section,the preparation technology and test process of braided composite tube are introduced.In terms of sample preparation,several common forming processes of composite tube were briefly introduced,and then the braided forming process and curing process selected in this paper were described in detail.It mainly includes the braiding principle of the circular braiding machine,the braiding process of the braided tube,the flow and operation method of the vacuum assisted resin transfer molding process,and finally three kinds of samples needed for the test are obtained.In addition,the thickness and fiber volume content of the three samples were measured,and the reasons for their differences were explained.In terms of the test,the impact device of the drop hammer is firstly introduced.The data are collected by adding force sensor and acceleration sensor,and the whole impact process is recorded by a high-speed camera.Secondly,the processing method of data is expoundedIn the third section,the establishment of a finite element model for braided composite tube is introduced.It includes geometric modeling of braided yarn part and resin part and finite element modeling in finite element simulation software.Firstly,the geometric model of the braided yarn is established in solidworks according to the weaving trajectory and the assumption that the yarn cross section is rectangular.The braided yarn model is then introduced into the ABAQUS to complete the modeling and assembly of the resin portion.Finally,in the software,the meshing of the braided composite tube,the assignment of material properties,the contact setting and the boundary conditions are set,and the finite element model consistent with the test conditions is completed.In addition,material constitutive equations and failure criteria are also introducedIn the fourth section,low-velocity transverse punch experiments were performed on composite tubes of three different braiding angles.The time-impact force curve,the displacement-impact force curve,the time-displacement curve,and the energy absorption amount are obtained by the data processing method described above.High-speed cameras record high-speed photos by recording the impact process.In addition,the sample after the impact was destroyed.Firstly,the influence of the weaving angle on the impact resistance of the composite tube was analyzed from the mechanical response results,and the mechanical response was further verified by high-speed photographs.Then,the effect of braiding angle on failure mode was explained according to the fracture morphology.In the fifth section,the calculated finite element model is solved.The numerical results are well correlated with the experimental data.Therefore,combined with the simulation results,the damage development and failure mechanism of the composite tube are analyzed and explained from the local deformation law of the impact region of the tube,the overall stress distribution,the crack propagation of the resin,and the failure modeIn the sixth section,the research work of this paper is summarized and future research is prospected.