Research On Circular Braiding Process And Fabric Realistic Geometric Modeling

After decades of development,braiding technology has become an important method for the production of composite reinforcements.It is widely used in the aerospace industry and automotive industry.It is usually used to produce the fiber reinforced composite parts with internal hollow structure.In the circular braiding,the mandrel with specific shape is used.By controlling the various technological parameters during the braiding process,the braiding spools are moved along the specific "8" trajectory by the dial to form the crosswise or interweave to form a spatial net structure.The structural parameters of final braid reinforcement are three: a)braiding angle;b)yarn volume coefficient;c)fabric covering coefficient,the most important of braiding reinforcement is the braiding angle ?.The braided angle reflects the orientation of the yarn in the length direction of the mandrel,which is the most intuitional parameter which reflects the structure of the braid reinforcement,and determines the structure of the braid reinforcement and the mechanical properties of the braid reinforcement.Therefore,in order to ensure that the braiding fabric to enhance the mechanical properties to meet the requirements,we must ensure that braid reinforcement braided angle and the expected value of a high consistency.However,the braiding yarns are complex in the whole process and there is a lot of contact interaction between the yarns,which will eventually lead to the deviation of the braiding angle and the theoretical braiding angle of the actual braid reinforcement.It is difficult to fabricate the braid reinforcement with exact parameters and strict mechanical properties,which is an important factor to restrict the development of braided composites.Therefore,it is an urgent problem to study the influence of various factors on the braiding angle of the braiding process In this paper for the circular braiding field at home and abroad were reviewed,expounds the circular braiding reinforcing composite materials research and the present situation,and establishes the research direction.Then describe circular braiding principle and braiding structure parameters,circular braiding process and principle,and analyzes the mutual contact force between yarn in braiding process and its mechanism of action,and summarize the fabric braiding angle changes of the three main influencing factors.According to the actual braiding to build the finite element simulation model,adopting the continuous rod unit to modeling of flexible yarn,through setting boundary conditions are stress and contact friction between the yarns for braiding process of finite element simulation.Set up the circular braiding experiment platform,the experiment by adjusting the tension spring type,yarn and braiding yarn used for friction coefficient of three parameters of the effects of woven enhance body braided angle.Finally the experimental value,the simulation values were compared with the theoretical analysis on the conclusion more powerful.Finally sums up the different yarn tension,yarn friction coefficient,the number of yarn for braiding reinforcing structure parameters,the influence of the braiding angle rule: when yarn friction coefficient is larger,which results in the braiding process of yarn appeared more obvious deviation,lead to braiding reinforcing braiding angle is less than the theoretical value;Yarn tension by the increase of braiding angle is more close to the theoretical value,in production should be appropriately increase the yarn tension to ensure the accuracy of woven enhance body structure parameters;Increase in the number of yarn number used in the braiding process,yarns contact number increased to enhance the influence of interaction effect between each other,the braided angle is less than the theoretical value.In order to further enhance body braiding of composite structure accuracy to provide certain reference and theoretical basis.