Numerical Simulation And Experimental Validation Of Yarn Splicing Under The Role Of Rotating Airflow

In the textile industry,pneumatic splicing is a common technology used for joining two separated yarn ends in order to improve the quality of yarn.The performance of pneumatic spliced yarn is affected by many factors,such as splicing pressure,splicing duration,fiber material and geometrical structure of splicing chamber.Among them,geometrical structure of splicing chamber is a crucial factor.So the research with respect to the effect of groove structure on performance of pneumatic spliced joint has important significance,which could promote the optimization of splicing chamber and improve the quality of splice.In addition,the splice of yarn is essentially the fiber winding behavior under the action of airflow,therefore it is necessary to study the motion of fiber in the splicing chamber.In this paper,firstly,we do some research about the effect of groove structure on performance of pneumatic spliced joint.The geometrical structure of splicing chamber has a significant influence on performance of spliced joint with respect to appearance and strength.The air characteristic inside splicing chambers with different structure,namely no groove,1mmwidth groove and 2mm-width groove,were numerically investigated using CFD modeling technology.A spiral ratio of airflow,which is composed by velocity circulation indicating the circumference airflow and average velocity in axial direction,was extracted from the numerical results to describe the role of air flow on the joint forming.The splicing experiments were conducted on the corresponding chambers.The appearance of splicing joint was captured by an optical camera and the splicing strength was evaluated by a yarn strength test machine.Finally,the influence of groove width on the performance of pneumatic yarn is studied in combination with numerical simulation analysis and experimental data.Next,in order to further study the rotational motion behavior of fiber in the splicing chamber,the fiber-to-fiber calculation model is put forward to simulate the deformation of yarn splicing under the action of airflow.First of all,the elastic rod unit and node are used to modeling the single fiber.Second,the force of fiber inside a splicing chamber is analyzed in detail.The nonlinear motion of fiber is calculated by ABAQUS/Explicit solver.In the following,based on the effective simulation data,the fluid-fiber coupling algorithm is proposed for calculating the deformation of fiber using the Java programming language.And the software is tested by fiber-wrap-rod model calculation under the airflow in the 2mm-chamber.Finally,the software simulates the fiber-to-fiber calculation model under two of splicing conditions in which the length of the composite is 3.5cm and 2cm respectively.And the visualization experiment with two kinds of splicing conditions was conducted and the high speed camera is used to capture the dynamic images of yarn twisting process.On the one hand,the experimental results are used for the verification of simulation results.On the other hand,the experiments and simulations are used to analyze the rotation and winding behavior of the fibers.At last,combined with the splicing yarn appearance recorded by optical camera,the redfiber-tracer method is adopted to study the effect of different initial position of fiber splicing behavior in 2mm-groove chamber.The phenomenon has been made some analysis using the CFD simulation.