Study On Static Dynamic Behavior Of Blended Yarns Based On Viscoelastic-Plastic Model

With the modern textile industry continues to develop towards intelligence,efficiency,and humanization,The use of blended yarns is becoming more and more widespread in textile weaving due to blended yarns` excellent quality and low cost.However,Due to creep and lateral vibration of the loom during production,the internal material properties of the yarn are easily damaged,resulting in yarn breakage and uneven density,so it is necessary to theoretical Analysis and simulate the stress-strain relationship characterized under various conditions of yarns through mechanical models.This paper focuses on six different polyester-cotton blended yarns and analyzes the possible situations of yarn breakage and wear during the production process through the construction of mechanical models,derivation of constitutive equations,tensile testing and data fitting,creep simulation,and lateral vibration simulation.The results provide a theoretical basis for establishing and verifying the mechanical models and setting parameters for the looms in the production process.Firstly,the commonly used constitutive model for yarns,namely the viscoelastic model,is analyzed.Based on the constitutive equations of these models,the shortcomings in describing mechanical behavior are identified.The Burgers model,which can best characterize the mechanical properties of yarn,is identified.Plastic material testing is performed on blended yarns,and it is assumed that the yarns exhibit plastic behavior.A new viscoelastic-plastic constitutive model is established based on the Burgers model and relevant equations are derived.The new model constitutive equations constructed by theoretical analysis have strong ability to describe the creep and stress relaxation processes and are universal.Secondly,creep and stress relaxation experiments were conducted on blended yarns,and the viscoelastic-plastic model was used to fit the experimental results and obtain the parameters of each component.Analysis of the fitting results revealed that the model’s fitting accuracy was over 99%,which is higher than other models.The higher the synthetic fiber content in the yarn,the greater the yield stress of the calculated component and the stronger the plasticity.The yield stress value can also reflect the stress decay of the yarn.The study of this model provides a macroscopic theoretical basis for analyzing internal damage of yarns.Furthermore,nonlinear constitutive theory was analyzed,and the viscoelastic-plastic model’s components were converted into module form using the method of superposition of strains in Simulink,and then combined.The software’s built-in solver was used to simulate the strain during creep,and the simulation results were compared with the experimental data,proving that this method can effectively simulate creep and verify the correctness of the constitutive equations of the component models.Finally,the analysis of transverse vibration of the yarn is conducted.The string vibration equation is introduced,and a mathematical model is established using the method of small element geometry.The constitutive equation of the viscoelastic-plastic model is incorporated into the vibration equation.The Galerkin truncation method is used to truncate the vibration equation to the first order,and a dimensionless constant is introduced to simplify the equation.The RKF method is used to solve the yarn vibration equation,and the effects of various parameters on the vibration are analyzed using the single-factor control method.The simulation results show that a shorter yarn operating length,a larger external tension,a smaller damping coefficient,and a smaller crosssectional area of the yarn can effectively reduce the vibration amplitude of the yarn and help to reduce yarn breakage during production.