Progressive Failure Analysis And Reinforcement Of Mechanical Properties Of Carbon Fiber Composite Open-hole Plates

To meet the needs of wiring,maintenance,assembly,and weight reduction,carbon fiber composite structures often need to be perforated,which causes the fiber at the hole position to lose continuity,resulting in damage.In this paper,the properties of carbon fiber composite plates with the circular hole are systematically analyzed,and the damage evolution process and failure type of multi-directional composite plates with the circular hole are studied.In addition,the reinforcement effects of different layering schemes and fiber reference paths on the tensile properties of plates with the circular hole were analyzed.Firstly,based on the elastic method,classical laminate theory,and discretization idea,a mesoscopic and macroscopic cross-scale mechanical model was proposed.It was found that its validity was verified by numerical simulation.In the numerical simulation,the Hashin criterion was used as the failure criterion.Moreover,the damage evolution process,the failure mechanism,and the load capacity of CFRP plates with the circular hole were predicted by the Camanho stiffness degradation theory and the USDFLD subroutine in Fortran.Secondly,the composite laminate was made by combining autoclave technics and the vacuum infusion process.The test parts were cut by numerical control high-pressure water cutting technology.The load-displacement curve,fracture morphology,displacement field,and strain field were obtained by digital image correlation technology and tensile property test.Then,the tensile mechanical properties,progressive failure mechanism,and types of traditional multidirectional composite plates with the circular hole were analyzed by combining finite element simulation and experiment.The results show that the limit load of multidirectional composite laminates decreases greatly due to the perforating.The analysis of the strain field shows that perforating will cause strain disturbance within three times of circular hole diameter.With the increase of load,the degree and the range of strain disturbance produced by perforating gradually increase.The damage degree and evolution paths were predicted by USDFLD.The main failure types of plates with circular holes include fiber fracture of 0° fiber layer,matrix cracking of non-0° fiber layer along the fiber direction,and fly-out or delamination of the first layer.Finally,MATLAB and ABAQUS were used to establish the three-dimensional finite element models of the composite plates with variable stiffness.Moreover,the influence of different fiber reference paths,layering methods,and layering schemes on the load capacity of the composite plate was studied.The results show that the fiber path designed by the small-angle principle can effectively restrain the damage propagation of composite plates with the circular hole.The fiber paths make the in-plane stress distribution more uniform,and then improve the tensile mechanical properties of the plates with the circular hole.In this paper,the tensile properties,strain concentration,damage evolution,and failure type of carbon fiber composite plates with the circular hole were investigated.The mechanical properties of the composite plates were reinforced by the fiber placement technology,which provided a theoretical basis for the structural reinforcement of carbon fiber composite with the hole.