CN-121981023-A - Yarn untwisting fluid-solid coupling modeling method and device based on cohesive force friction

CN121981023ACN 121981023 ACN121981023 ACN 121981023ACN-121981023-A

Abstract

The invention provides a yarn untwisting fluid-solid coupling modeling method and device based on cohesive force friction, and relates to the technical field of spinning; introducing cohesive contact model into contact interface between cotton fibers, constructing shearing traction force-separation displacement constitutive relation to obtain target cohesive contact yarn model, establishing three-dimensional stationary flow field calculation domain for untwisting working condition, setting inlet, outlet and turbulence boundary conditions, introducing the model into the three-dimensional stationary flow field model for untwisting simulation, establishing fluid-solid coupling numerical model between yarn and flow field to obtain data and cloud image of displacement, stress, strain and speed of yarn, analyzing and correcting breaking strength, linear density and twist of yarn until parameter convergence of target cohesive contact yarn model is completed.

Inventors

ZHOU JIACHENG
FENG QIANQIAN
XIONG XIAOSHUANG
YU LIANQING
SHEN MIN
FAN FEI
CAO LONGCHAO

Assignees

武汉纺织大学

Dates

Publication Date: 20260505
Application Date: 20260407

Claims (10)

1. The yarn untwisting fluid-solid coupling modeling method based on cohesive friction is characterized by comprising the following steps of: Acquiring yarn structure data comprising yarn twist, yarn diameter and cotton fiber diameter, and constructing a three-dimensional spiral fiber bundle geometric model based on the yarn structure data; Introducing a cohesive contact model of cotton fiber spiral distribution and friction shearing action among cotton fibers into a contact interface between two adjacent cotton fibers in the three-dimensional spiral fiber bundle geometric model, constructing a shearing traction force-separation displacement constitutive relation comprising damage initiation, damage evolution and breaking energy constraint, and obtaining a target cohesive contact yarn model so as to simulate microscopic interlayer bonding, slippage, stripping and nonlinear friction mechanical response generated in the fiber untwisting process; aiming at the untwisting working condition, a three-dimensional steady flow field calculation domain is established, inlet, outlet and turbulence boundary conditions are set, and the target cohesive contact yarn model is led into the three-dimensional steady flow field model for untwisting simulation; establishing a fluid-solid coupling numerical model between the yarns and the flow field by adopting a bidirectional strong coupling algorithm through a fluid dynamic control equation and a solid nonlinear dynamic equation to obtain data and cloud patterns of displacement, stress, strain and speed of the yarns; Based on the data obtained by simulation and the cloud picture, the breaking strength, the linear density and the twist of the yarn are analyzed, and the calculated domain size and the coupling time step are subjected to iterative correction according to theoretical expectation until the parameter convergence of the target cohesive contacting the yarn model is completed.
2. The method for modeling untwisting fluid-solid coupling of yarn based on cohesive force friction as defined in claim 1, wherein said step of constructing a three-dimensional spiral fiber bundle geometric model based on said yarn structure data specifically comprises: the pitch of the cotton fibers is calculated according to the yarn twist, and the distribution radius of the cotton fibers is used as a parameter, and a three-dimensional geometric path of each cotton fiber is generated according to a space spiral track equation of the center line of the cotton fibers.
3. The method for modeling untwisting fluid-solid coupling of yarn based on cohesive friction according to claim 1, wherein said step of constructing a shear traction-separation displacement constitutive relation comprising damage initiation, damage evolution and breaking energy constraint comprises: the damage initiation is triggered by the shear stress reaching a preset maximum shear strength peak value; The damage evolution is described by a nonlinear softening curve, wherein the degree of stiffness degradation in the nonlinear softening curve is gradually increased along with the increase of separation displacement, and a damage variable increases from zero until reaching one, so that the interface is completely invalid; the fracture energy constraint ensures that the area under the shear stress-separation displacement curve is equal to a preset fracture energy value to conform the model to energy conservation.
4. The cohesive friction-based yarn untwisting fluid-solid coupling modeling method according to claim 3, wherein the shear traction-separation displacement constitutive relation formula is: ; wherein: For shear traction-separation displacement constitutive relation, At the point of maximum shear stress, the shear stress, In order to separate the displacement, In order to correspond to the displacement of the displacement, In order for the displacement to occur at the onset of injury, In order to displace the device in the event of complete failure, Fitting parameters for controlling the shape of the curve; The fracture energy constraint formula is: ; wherein: is type II fracture energy.
5. The modeling method for untwisting fluid-solid coupling of yarn based on cohesive force friction according to claim 1, wherein the step of establishing a fluid-solid coupling numerical model between yarn and flow field by adopting a bidirectional strong coupling algorithm through a fluid dynamics control equation and a solid nonlinear dynamics equation specifically comprises: alternately solving a fluid domain control equation and a solid domain control equation in each coupling time step; Converting the surface pressure vector obtained by calculating the flow field into equivalent physical force acting on fiber discrete grid nodes in real time through a load mapping function, and realizing bidirectional data exchange between the flow field and yarns; And extracting displacement, stress, strain and speed data of the yarn, and visually displaying dynamic response of the yarn in the untwisting process in a cloud picture form.
6. The method for modeling untwisting fluid-solid coupling of yarn based on cohesive friction according to claim 1, wherein the step of analyzing breaking strength, linear density and twist of yarn specifically comprises: comparing the stress field cloud image with the failure criterion of the material by monitoring the maximum main stress or Mi Saisi equivalent stress of the yarn unit in real time, positioning the initial breaking position and identifying the critical load during breaking so as to analyze the breaking strength; The equivalent dynamic linear density of the yarn in the simulation is calculated, and compared with the theoretical linear density considering geometric deformation, the mass conservation precision of the model in the untwisting process is evaluated, so that linear density analysis is carried out; The twist analysis is performed by tracking the change of the helix angle of the fiber on the surface of the yarn, calculating the retention rate of the structural twist, and quantifying the untwisting degree and the structural stability.
7. The modeling method of untwisting fluid-solid coupling of yarn based on cohesive force friction according to claim 6, wherein the step of iteratively correcting the calculated domain size and the coupling time step according to theoretical expectations comprises: Evaluating the progress degree of macroscopic layering of the yarn by counting the proportion of cohesive units in total volume of all cohesive units which enter a softening or failure stage so as to quantitatively analyze the failure degree of an internal interface of the yarn; the quantification of the interface failure degree adopts a damage volume ratio index, whether each cohesive unit is completely failed or not is judged by setting a critical threshold value of a rigidity degradation variable, and the percentage of the total volume and the total volume of the failed units is calculated; And iteratively adjusting interlayer rigidity, damage evolution parameters, tangential friction coefficient, size of a flow field calculation domain and coupling time step of the cohesive contact model according to analysis results of fracture strength, linear density, twist and interface failure degree until errors of simulation output and theoretical expected values of the yarn model are within a preset range.
8. A yarn untwisting fluid-solid coupling modeling device based on cohesive friction, which is characterized by comprising: The acquisition module is used for acquiring yarn structure data comprising yarn twist, yarn diameter and cotton fiber diameter, and constructing a three-dimensional spiral fiber bundle geometric model based on the yarn structure data; the yarn modeling module is used for introducing a cohesive contact model of cotton fiber spiral distribution and friction shearing action among cotton fibers into a contact interface between two adjacent cotton fibers in the three-dimensional spiral fiber bundle geometric model, constructing a shearing traction force-separation displacement constitutive relation comprising damage initiation, damage evolution and breaking energy constraint, and obtaining a target cohesive contact yarn model so as to simulate microscopic interlayer bonding, slippage, stripping and nonlinear friction mechanical response generated in the untwisting process of the fibers; The flow field modeling module is used for establishing a three-dimensional steady flow field calculation domain aiming at untwisting working conditions, setting inlet, outlet and turbulence boundary conditions, and guiding the target cohesive contact yarn model into the three-dimensional steady flow field model for untwisting simulation; The simulation calculation module is used for establishing a fluid-solid coupling numerical model between the yarns and the flow field by adopting a two-way strong coupling algorithm through a fluid dynamic control equation and a solid nonlinear dynamic equation to obtain data and cloud patterns of the displacement, stress, strain and speed of the yarns; And the parameter correction module is used for analyzing the breaking strength, the linear density and the twist of the yarn based on the data and the cloud picture obtained by simulation, and carrying out iterative correction on the calculated domain size and the coupling time step according to theoretical expectation until the parameter convergence of the target cohesive contacting the yarn model is completed.
9. An electronic device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor, when executing the computer program, implements the steps of the cohesive friction based yarn untwisting fluid-solid coupling modeling method of any of claims 1-7.
10. A non-transitory computer readable storage medium having stored thereon a computer program, characterized in that the computer program when executed by a processor implements the steps of the cohesive friction based yarn untwisting fluid-solid coupling modeling method of any of claims 1 to 7.

Description

Yarn untwisting fluid-solid coupling modeling method and device based on cohesive force friction Technical Field The invention relates to the technical field of spinning, in particular to a yarn untwisting fluid-solid coupling modeling method and device based on cohesive friction. Background With the increase of textile demands and the increase of production efficiency, the untwisting resistance of yarns is a core index for determining the structural stability and mechanical strength of the yarns in the field of dynamic research of high-performance fiber products and flexible composite materials. When the yarn is in a specific flow velocity environment, the stress balance among fibers in the yarn can be changed by the shearing moment induced by the fluid, so that untwisting behavior is initiated, and the yarn is loose in structure, low in strength and even ineffective. Therefore, a set of numerical models capable of accurately simulating yarn untwisting behaviors under the action of a flow field is established, and the method has important engineering significance for optimizing yarn structures and predicting dynamic responses of the yarns. However, existing numerical modeling techniques have significant limitations in addressing such issues. Traditional macroscopic modeling methods tend to simplify the yarn into a homogeneous cylindrical beam unit or a simple elastic continuum, and this approach thoroughly ignores the microscopic nature of the yarn, which is formed by twisting hundreds or thousands of discrete fibers. During untwisting, there is not a simple rigid contact between the fibers, but rather a complex viscous, micro-slip, stripping and nonlinear lesion evolution. The traditional coulomb friction model can only describe the sliding resistance under constant pressure, and is difficult to capture the evolution process of 'bonding-failure-re-sliding' generated between fibers due to the action of a binder or surface cohesion, so that the simulation result has serious defect in precision when simulating the transition of yarns from a compact structure to a loose structure. Disclosure of Invention The invention aims to provide a yarn untwisting fluid-solid coupling modeling method and device based on cohesive force friction, which are used for solving the problems that the traditional coulomb friction model mentioned in the background art only can describe sliding resistance under constant pressure, and is difficult to capture the evolution process of bonding-failure-re-sliding between fibers due to the action of a bonding agent or surface cohesive force, so that the simulation result has serious insufficient precision when the simulation yarn is converted from a compact structure to a loose structure. The technical scheme includes that yarn structure data comprising yarn twist, yarn diameter and cotton fiber diameter are obtained, a three-dimensional spiral fiber bundle geometric model is built based on the yarn structure data, a cohesive contact model of cotton fiber spiral distribution and friction shearing action between cotton fibers is introduced into a contact interface between two adjacent cotton fibers in the three-dimensional spiral fiber bundle geometric model, a shearing traction-separation displacement constitutive relation comprising damage initiation, damage evolution and breaking energy constraint is built, a target cohesive force contact yarn model is obtained, microscopic interlayer bonding, slippage, stripping and nonlinear friction mechanical response generated in a fiber untwisting process are simulated, a three-dimensional constant flow field calculation domain is built for untwisting working conditions, inlet, outlet and turbulence boundary conditions are set, the target cohesive force contact yarn model is introduced into the three-dimensional constant flow field model to conduct solution simulation, a fluid dynamic control equation and solid nonlinear dynamic equation are adopted to build a fluid-solid coupling numerical value between the yarn and the flow field, a yarn, a graph of the yarn, a stress and strain and expected time and a graph are obtained, the cloud graph is corrected according to the theoretical graph is obtained, and the target tensile strength and the cloud graph is calculated, and the target strength and the cloud graph is corrected according to the theoretical graph is calculated. Optionally, the step of constructing the three-dimensional spiral fiber bundle geometric model based on the yarn structure data specifically comprises the steps of calculating the pitch of cotton fibers according to yarn twist, and generating a three-dimensional geometric path of each cotton fiber according to a space spiral track equation of the center line of the cotton fiber by taking the distribution radius of the cotton fibers as a parameter. Optionally, the step of constructing the shear traction force-separation displacement constitutive relation comprising damage initiation