The Mesomechanical Analysis Of Stresses Near Central Hole In Big Carbon Tow Plain-woven Composite

In pursuit of high performance and low cost today,a large tow woven plain fabric composite material with high cost performance has been valued.It is considered to have better application prospects.For the significant heterogeneous composites of this kind of large tow,the analysis of the macroscopic homogenization properties and methods may cause large deviations,especially the problem of local stress treatment.On the one hand,high efficiency is needed in the analysis of large structure or rough analysis;On the other hand,in some local areas,the uneven distribution of stress,especially when it involves the strength problem,requires high accuracy.Therefore,with the help of the meso scale mesoscopic analysis model,the relationship between the mesoscopic parameters and the macroscopic properties is established and the influence of the mesoscopic parameters on the distribution of the local stress?the hole-edge stress?is accurately analyzed.In order to analyze the properties of the woven composite materials and the stress distribution at the opening at the meso scale,the finite element simulation is carried out from three aspects:the establishment of the meso model,the prediction of the elastic constants of the braided materials and the distribution of the hole-edge stress,and the basic mechanical properties of the plain weave composites are measured.The modeling adopts TE XGEN new fabric software,finite element simulation is mainly based on ABAQUS software.The following conclusions can be drawn through experiment and numerical simulation:A double single cell meso scale meso model containing single fiber composite and weave node cells was established to predict and analyze the mechanical properties of the woven composites.The numerical example proved the validity of the model and method.The influence of braiding angle and fiber volume content on the basic elastic properties of braided composites was analyzed by meso cell model.It is found that when the braiding angle is constant,in-plane elastic modulus and shear modulus increase linearly with volume volume,and Poisson's ratio increases slightly.Under the premise of constant volume volume,the 45 degree braided angle corresponds to the minimum modulus and the largest shear modulus,and the Poisson's ratio has the maximum near 30 degrees.The basic elastic properties and components volume content of the plain woven carbon fiber composites were measured and the finite element simulation was carried out.The prediction results were in good agreement with the test results.The open hole tensile test shows that the tensile strength of large tow weave woven composite plates with a center hole.The results of linear elastic analysis show that the stress at the edge of double"cross"position has the maximum stress,and the stress at the hole edge of the"well shape"location is the smallest.Simulation analysis of different apertures shows that the stress values in all directions of holes are increasing with the increase of pore size.However,the proportion of hole edge stress increases differently.In the"double cruciform"model,the ratio of the hole edge stress?₁₁ increases along the stress direction,and the"cross shape"is the second and the"well shape"is the smallest.By simulating different models of lay up,it is found that the 45 degree ply angle can effectively reduce the maximum stress at the edge of the hole and diffuse the stress concentration around the hole.