A clothing pattern design method and system based on a virtual human body model

Abstract

The present invention discloses a clothing pattern design method and system based on a virtual human body model, specifically related to the field of intelligent clothing design, which is used to solve the problems of three-dimensional pattern flattening error and multi-layer structure deformation. An anisotropic mechanical field is established through a three-dimensional virtual human body model to accurately restore the mechanical properties of fabric in the warp direction stretching, weft direction shearing, and oblique direction non-linearity; by decomposing the warp direction principal stress flow and the weft direction shear stress flow, the warp direction compression residual amount and the weft direction deformation hysteresis amount are dynamically calculated to match the collaborative compensation ratio, eliminating stress accumulation in high-curvature regions such as the armhole arc, ensuring the flatness of the twill fabric edge and the accuracy of plaid alignment; the streamline diffusion algorithm is used to iteratively correct the cutting boundary of the three-dimensional clothing piece, making adjacent compensation vectors form continuous streamlines and suppressing the concentration of sewing stress; for multi-layer clothing pieces, through the calculation of the divergence of the interlayer stress field and the dynamic insertion technology of elastic inserts, the stress distribution of heterogeneous materials is balanced to solve the problem of interlayer deformation of the clothing composite structure.

Description

Technical Field

[0001] The present invention relates to the field of intelligent clothing design. More specifically, the present invention relates to a clothing pattern design method and system based on a virtual human body model. Background Art

[0002] In the field of clothing pattern design, when converting three-dimensional garment pieces that fit the surface of a three-dimensional virtual human body into two-dimensional flat cut pieces, the core assumption of traditional geometric unfolding algorithms is based on an idealized model of the isotropic mechanical properties of the fabric. However, under the influence of factors such as the warp and weft yarn densities, knitting angles, and post-finishing processes of actual textile fabrics, they generally exhibit significant anisotropic mechanical behaviors: the tensile stiffness in the warp direction is usually higher than that in the weft direction, and the shear deformation in the diagonal direction shows non-linear response characteristics. When using a flattening algorithm with a homogenization assumption to process such fabrics, the virtual flattening force field applied by the algorithm cannot accurately simulate the differential deformation characteristics of real fabrics in the warp and weft directions, resulting in systematic errors during the process of unfolding a three-dimensional surface into a two-dimensional plane. This error shows an asymmetric cumulative effect in areas with sharp changes in the curvature of the cut piece boundaries of three-dimensional garment pieces (such as the armhole arc, princess line division), and ultimately leads to uncontrollable distortion and deformation when the actually cut pieces are sewn due to the release of residual stresses in the warp and weft directions. Specifically, it is manifested as process defects such as wavy edges of twill fabrics and misalignment of checked patterns. More seriously, in the pattern design of multi-layer composite structures or elastic fabrics, the anisotropic differences between the materials of each layer will cause interlayer stress coupling, further amplifying local wrinkles and structural imbalances in the finished clothing, directly restricting the fit and aesthetic quality of high-precision customized clothing.

[0003] In order to solve the above problems, a technical solution is provided now. Summary of the Invention

[0004] To overcome the above-mentioned defects of the prior art, embodiments of the present invention provide a clothing pattern design method and system based on a virtual human body model. By establishing an anisotropic mechanical field through a three-dimensional virtual human body model, the tensile properties in the warp direction, shear properties in the weft direction, and non-linear mechanical properties in the diagonal direction of the fabric are accurately restored; by decomposing the principal stress flow in the warp direction and the shear stress flow in the weft direction, the residual compression amount in the warp direction and the deformation lag amount in the weft direction are dynamically calculated to match the collaborative compensation ratio, eliminating stress accumulation in high-curvature areas such as the armhole arc, ensuring the flatness of the edges of twill fabrics and the accuracy of checked pattern alignment; using a streamline diffusion algorithm to iteratively correct the cut piece boundaries of three-dimensional garment pieces, making adjacent compensation vectors form continuous streamlines and suppressing stress concentration during sewing; for multi-layer garment pieces, by calculating the divergence of the interlayer stress field and the dynamic insertion technology of elastic inserts, the stress distribution of heterogeneous materials is balanced, and the problem of interlayer deformation of the clothing composite structure is solved to solve the problems proposed in the above background art.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A clothing pattern design method based on a virtual human body model, comprising the steps of:

[0007] On the surface of a three-dimensional virtual human body model, a mechanical field is generated based on the warp tensile stiffness, weft shear stiffness, and oblique nonlinear response data of the fabric, where the mechanical properties of each microelement are defined by the warp and weft yarn densities and the knitting angles;

[0008] Based on the mechanical field, the process of flattening the three-dimensional garment piece is decomposed into a warp principal stress flow and a weft shear stress flow, and the warp compression residual amount and the weft deformation hysteresis amount are calculated;

[0009] According to the nonlinear relationship between the warp compression residual amount and the weft deformation hysteresis amount, the cooperative compensation ratio of the two is determined, and the warp compensation intensity and the weft compensation direction are adjusted;

[0010] Based on the distribution of the warp compensation intensity and the weft compensation direction, the streamline diffusion algorithm is used to iteratively correct the cutting boundary of the three-dimensional garment piece;

[0011] For multi-layer garment pieces, the divergence of the interlayer stress field is calculated, and elastic inserts with elastic stresses opposite to the direction of the interlayer stress field divergence are inserted until the projection error of the sewing boundary approaches zero.

[0012] In a preferred embodiment, on the surface of a three-dimensional virtual human body model, a mechanical field is generated based on the warp tensile stiffness, weft shear stiffness, and oblique nonlinear response data of the fabric, where the mechanical properties of each microelement are defined by the warp and weft yarn densities and the knitting angles. Specifically:

[0013] The surface of the three-dimensional virtual human body model is discretized into multiple microelements, and a local coordinate system is established on each microelement, where the coordinate axes of the local coordinate system are respectively along the warp, weft, and the direction perpendicular to the surface of the microelement; a stiffness matrix is constructed for each microelement, where the diagonal elements of the stiffness matrix respectively represent the warp tensile stiffness, weft tensile stiffness, and the stiffness perpendicular to the surface of the microelement, and the non-diagonal elements represent the oblique shear stiffness, and the stiffness matrix is modulated by the warp and weft yarn densities and the knitting angles; finally, the mechanical field is generated by aggregating the stiffness matrices of all microelements to reflect the anisotropic mechanical properties of the fabric on the surface of the three-dimensional virtual human body model.

[0014] In a preferred embodiment, based on the mechanical field, the process of flattening the three-dimensional garment piece is decomposed into a warp principal stress flow and a weft shear stress flow, and the warp compression residual amount and the weft deformation hysteresis amount are calculated. Specifically:

[0015] Based on the warp tensile stiffness and weft shear stiffness in the mechanical field, the virtual mechanical load of each microelement on the three-dimensional garment piece is calculated;

[0016] Using the finite element analysis method, the stress distribution of the three-dimensional garment piece is solved based on virtual mechanical loads, and the stress tensor of each microelement is generated;

[0017] The meridional normal stress component and the weft shear stress component are extracted from the stress tensor, and the meridional principal stress flow and the weft shear stress flow are obtained by cumulative summation along the meridional path and the weft path respectively;

[0018] The meridional strain of each microelement is calculated based on the meridional principal stress flow and the meridional tensile stiffness, and the meridional compression residual is obtained by the area-weighted sum of the cumulative meridional compression strain;

[0019] The weft shear strain of each microelement is calculated based on the weft shear stress flow and the weft shear stiffness, and the weft deformation hysteresis is obtained by the area-weighted sum of the cumulative deviation of the weft shear strain from the ideal state.

[0020] In a preferred embodiment, the cooperative compensation ratio is determined according to the non-linear relationship between the meridional compression residual and the weft deformation hysteresis, and the meridional compensation intensity and the weft compensation direction are adjusted:

[0021] Based on historical experimental data, the non-linear relationship function between the meridional compression residual and the weft deformation hysteresis is fitted; the partial derivative of the non-linear relationship function with respect to the meridional compression residual and the partial derivative with respect to the weft deformation hysteresis are calculated;

[0022] The absolute value of the partial derivative of the non-linear relationship function with respect to the meridional compression residual is divided by the sum of the absolute value of the partial derivative with respect to the meridional compression residual and the absolute value of the partial derivative with respect to the weft deformation hysteresis to obtain the meridional compensation ratio; the weft compensation ratio is defined as the difference of 1 minus the meridional compensation ratio;

[0023] The meridional compensation intensity is calculated as the product of the meridional compensation ratio and the absolute value of the meridional compression residual, and the weft compensation intensity is calculated as the product of the weft compensation ratio and the absolute value of the weft deformation hysteresis; the meridional compensation direction is determined as tension or compression according to the positive or negative sign of the meridional compression residual, and the weft compensation direction is determined as clockwise or counterclockwise shear according to the positive or negative sign of the weft deformation hysteresis.

[0024] In a preferred embodiment, when fitting the non-linear relationship function, a quadratic polynomial form is adopted, including the square term of the meridional compression residual, the square term of the weft deformation hysteresis, and the cross term of the meridional compression residual and the weft deformation hysteresis.

[0025] In a preferred embodiment, based on the distribution of the meridional compensation intensity and the weft compensation direction, the streamline diffusion algorithm is used to iteratively correct the cutting boundary of the three-dimensional garment piece, specifically:

[0026] Step 1: Based on the warp compensation intensity, weft compensation intensity, warp compensation direction, and weft compensation direction, construct a compensation vector field on the cutting boundary of the three-dimensional garment piece;

[0027] Step 2: By calculating the streamline divergence of adjacent boundary point compensation vectors, that is, the modulus of the difference between adjacent compensation vectors;

[0028] Step 3: Adjust the boundary point position according to the streamline divergence, and add a correction amount determined by the step size parameter, the average direction of adjacent compensation vectors, and the streamline divergence to the current boundary point position;

[0029] Step 4: Recalculate the compensation vector field based on the updated boundary point positions.

[0030] In a preferred embodiment, by iterating Steps 1 to 4 until the maximum value of the streamline divergence is less than a preset threshold or the preset number of iterations is reached, finally output the corrected cutting boundary of the three-dimensional garment piece.

[0031] In a preferred embodiment, based on the mechanical field and the interlayer stress field of each layer of the multi-layer garment piece, as well as the optimized stitching boundary, calculate the divergence of the adjacent interlayer stress fields. Specifically:

[0032] Calculate the sum of the transverse partial derivative and the longitudinal partial derivative of the interlayer stress field at each boundary point on the stitching boundary by the finite difference method to obtain the interlayer stress field divergence value; determine the insertion direction and insertion strength of the elastic insert according to the interlayer stress field divergence value, where the insertion direction is opposite to the interlayer stress field divergence direction, and the insertion strength is proportional to the absolute value of the interlayer stress field divergence and is adjusted by a proportionality coefficient; insert the elastic insert at each boundary point on the stitching boundary to adjust the interlayer stress distribution.

[0033] In a preferred embodiment, adopt an iterative optimization method to repeatedly calculate the divergence of the adjacent interlayer stress fields, insert the elastic inserts, and update the projection error of the stitching boundary until the projection error of the stitching boundary is less than the error threshold or the preset number of iterations is reached, and finally output the configuration of the elastic inserts.

[0034] A garment pattern design system based on a virtual human body model, comprising: a mechanical field generation module, a stress flow decomposition module, a compensation ratio adjustment module, a boundary correction and optimization module, and an interlayer stress balance module;

[0035] Mechanical field generation module: On the surface of the three-dimensional virtual human body model, based on the warp tensile stiffness, weft shear stiffness, and oblique nonlinear response data of the fabric, generate a mechanical field defined by the warp and weft yarn densities and the knitting angles, and transfer the mechanical field to the stress flow decomposition module;

[0036] Stress flow decomposition module: Based on the mechanical field, the three-dimensional garment flattening process is decomposed into the warp principal stress flow and the weft shear stress flow, and the warp compression residual and the weft deformation hysteresis are calculated, and the warp compression residual and the weft deformation hysteresis are output to the compensation ratio adjustment module;

[0037] Compensation ratio adjustment module: According to the nonlinear relationship between the warp compression residual and the weft deformation hysteresis, the coordinated compensation ratio is determined, and the warp compensation intensity and weft compensation direction are adjusted, and the warp compensation intensity and weft compensation direction are transmitted to the boundary correction optimization module;

[0038] Boundary correction optimization module: Based on the distribution of warp compensation strength and weft compensation direction, the streamline diffusion algorithm is used to iteratively correct the cutting boundary of the three-dimensional garment piece, so that adjacent compensation vectors form a continuous streamline at the boundary, and the optimized cutting boundary of the three-dimensional garment piece is transferred to the interlayer stress balance module;

[0039] Interlayer stress balance module: For multi-layer garment pieces, the interlayer stress field divergence is calculated, and elastic inserts with elastic stress in the opposite direction to the interlayer stress field divergence are inserted until the projection error of the stitching boundary approaches zero.

[0040] Technical effects and advantages of a clothing pattern design method and system based on a virtual human body model of the present invention:

[0041] The present invention establishes anisotropic mechanical fields based on a three-dimensional virtual human body model, accurately restores the warp stretching, weft shearing and oblique nonlinear mechanical properties of the fabric, and solves the deformation error of the cutting piece caused by the homogenization assumption of the traditional flattening algorithm; by decomposing the warp principal stress flow and the weft shear stress flow, dynamically calculating the warp compression residual and the weft deformation hysteresis, matching the synergistic compensation ratio according to the nonlinear coupling relationship, and adjusting the compensation parameters in a targeted manner, eliminating the stress accumulation in the high curvature area such as the armhole arc, and ensuring the flatness of the edge of the twill fabric and the alignment accuracy of the plaid; the streamline diffusion algorithm is used to iteratively correct the cutting piece boundaries of the three-dimensional clothing piece, so that the adjacent compensation vectors form a continuous streamline to suppress the concentration of stitching stress; for multi-layer clothing pieces, the interlayer stress field divergence calculation and the dynamic insertion technology of the elastic insert are used to balance the stress distribution of heterogeneous materials and solve the problem of interlayer deformation of the composite structure of clothing. Pre-compensation of the real deformation of the fabric from the mechanical origin ensures the accurate flattening of the cutting piece and the stability of stitching, significantly improves the one-time forming rate of high-end customized clothing, reduces the loss of high-value fabrics, and the finished garment has both human body fit and process quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The present invention is a flow chart of a method for designing a clothing pattern based on a virtual human body model.

[0043] Figure 2 The present invention is a structural schematic diagram of a clothing pattern design system based on a virtual human body model. Detailed implementation manners

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] Embodiment 1: Figure 1 A method for designing a clothing pattern based on a virtual human body model of the present invention is provided, including:

[0046] On the surface of a three-dimensional virtual human body model, a mechanical field is generated based on the warp tensile stiffness, weft shear stiffness, and diagonal nonlinear response data of the fabric, where the mechanical properties of each microelement are defined by the warp and weft yarn densities and the knitting angles;

[0047] Based on the mechanical field, the process of flattening the three-dimensional garment piece is decomposed into a warp principal stress flow and a weft shear stress flow, and the warp compression residual amount and the weft deformation hysteresis amount are calculated;

[0048] According to the nonlinear relationship between the warp compression residual amount and the weft deformation hysteresis amount, the cooperative compensation ratio of the two is determined, and the warp compensation intensity and the weft compensation direction are adjusted;

[0049] Based on the distribution of the warp compensation intensity and the weft compensation direction, the streamline diffusion algorithm is used to iteratively correct the cutting boundary of the three-dimensional garment piece, so that adjacent compensation vectors form continuous streamlines at the boundary;

[0050] For multi-layer garment pieces, the divergence of the interlayer stress field is calculated, and elastic inserts with elastic stress opposite to the direction of the interlayer stress field divergence are inserted until the projection error of the sewing boundary approaches zero.

[0051] In clothing pattern design, when traditional methods flatten the garment pieces on the surface of a three-dimensional virtual human body into two-dimensional cut pieces, they often do not fully consider the anisotropic mechanical properties of the fabric, such as the different mechanical responses in the warp, weft, and diagonal directions, resulting in deformation or wrinkles of the cut pieces during actual sewing, affecting the fit and aesthetics of the clothing. In view of this problem, the present invention proposes a method for designing a clothing pattern based on a three-dimensional virtual human body model, focusing on generating a mechanical field that reflects the anisotropic characteristics of the fabric by accurately modeling the mechanical behavior of the fabric, providing a reliable mechanical basis for the subsequent flattening process. This part specifically discusses the processing technical logic of generating a mechanical field on the surface of a three-dimensional virtual human body model, where the mechanical properties of each microelement are defined by the warp and weft yarn densities and the knitting angles, based on the warp tensile stiffness, weft shear stiffness, and diagonal nonlinear response data of the fabric.

[0052] The following is the specific processing technical logic for generating a mechanical field on the surface of a three-dimensional virtual human body model, where the mechanical properties of each microelement are defined by the warp and weft yarn densities and the knitting angles, based on the warp tensile stiffness, weft shear stiffness, and oblique nonlinear response data of the fabric. The processing object is the fabric microelement on the surface of the three-dimensional virtual human body model, and the goal is to generate a mechanical field through precise calculation to provide basic data for subsequent flat pattern development of the garment piece.

[0053] A1. Definition and preparation of input data:

[0054] Before generating the mechanical field, it is first necessary to prepare the mechanical property data of the fabric and the model parameters. These data include the warp tensile stiffness, weft shear stiffness, oblique nonlinear response data, warp and weft yarn densities, and knitting angles of the fabric.

[0055] Specifically:

[0056] The warp tensile stiffness represents the resistance of the fabric when it is stretched in the warp direction (i.e., the longitudinal direction of the yarn);

[0057] The weft shear stiffness represents the resistance of the fabric when it is sheared in the weft direction (i.e., the transverse direction of the yarn);

[0058] The oblique nonlinear response data represents the relationship between the shear stress and the shear angle when the fabric is sheared in the oblique direction (i.e., the direction of the angle between the warp and weft yarns), showing a nonlinear characteristic;

[0059] The warp and weft yarn densities respectively represent the distribution densities of the warp and weft yarns per unit length;

[0060] The knitting angle represents the angle between the warp and weft yarns.

[0061] These input data form the basis for generating the mechanical field, can reflect the mechanical behavior differences of the fabric in different directions, and provide accuracy guarantee for subsequent calculations.

[0062] B1. Establish a local coordinate system for the microelements on the surface of the three-dimensional virtual human body model:

[0063] To accurately map the mechanical properties of the fabric onto the surface of a 3D virtual human body model, it is necessary to discretize the surface of the 3D virtual human body model, divide it into multiple micro-elements, and establish a local coordinate system on each micro-element. The specific steps are as follows: First, the surface of the 3D virtual human body model is segmented into multiple micro-elements, each micro-element representing a small area on the surface of the 3D virtual human body model. Then, a local coordinate system is defined on each micro-element to ensure that the coordinate axes of the local coordinate system are aligned with the warp and weft directions of the fabric. Among them, the first coordinate axis of the local coordinate system is along the warp direction of the fabric, that is, the direction in which the warp tensile stiffness plays a dominant role; the second coordinate axis of the local coordinate system is along the weft direction of the fabric, that is, the direction in which the weft shear stiffness plays a dominant role; the third coordinate axis of the local coordinate system is perpendicular to the surface of the micro-element and points outside the 3D virtual human body model. By establishing the local coordinate system, it is ensured that the representation of the fabric's mechanical properties on the micro-element is consistent with the actual direction of the fabric, providing a correct reference frame for subsequent mechanical calculations. For example:

[0064] Discretize the surface of the 3D virtual human body model and divide it into micro-elements, and each micro-element is denoted as On each micro-element Define a local coordinate system:

[0065] The axis is along the warp direction of the fabric (i.e., the direction of the warp tensile stiffness).

[0066] The axis is along the weft direction of the fabric (i.e., the main direction of the weft shear stiffness).

[0067] The axis is perpendicular to the surface of the micro-element and points outside the model.

[0068] represents the serial numbers of multiple micro-elements generated after the discretization of the surface of the 3D virtual human body model.

[0069] Among them, the specific process of discretizing the surface of the 3D virtual human body model to divide it into multiple micro-elements is as follows: First, according to the geometric characteristics of the 3D virtual human body model and the accuracy requirements of clothing design, determine the size and shape of the micro-elements. Usually, triangular or quadrilateral meshes are selected as the basic units for discretization. Second, use the mesh generation technology in finite element analysis to divide the surface of the 3D virtual human body model into multiple interconnected micro-elements, ensuring that the size of each micro-element is sufficient to accurately capture the local mechanical response of the fabric on the human body surface, while controlling the total number of micro-elements to maintain the calculation efficiency. Finally, assign a unique identifier to each micro-element for identification and processing in subsequent mechanical calculations and data management. Through the above steps, the discretization of the surface of the 3D virtual human body model is achieved.

[0070] C1. Construct the micro - element stiffness matrix:

[0071] Based on the input data, construct the stiffness matrix for each micro - element to describe the mechanical response of the fabric in the local coordinate system. The stiffness matrix is a symmetric matrix that contains the mechanical properties of the fabric in the warp, weft, and diagonal directions. The calculation methods of its specific elements are as follows:

[0072] The calculation of the warp - direction tensile stiffness element reflects the tensile resistance ability of the fabric in the warp direction. The method is to combine the warp - direction tensile stiffness with the modulation effects of the warp - direction yarn density ratio and the knitting angle. The warp - direction yarn density ratio is represented by the ratio of the warp - direction yarn density divided by the sum of the warp - direction and weft - direction yarn densities, and the modulation of the knitting angle is adjusted through the sine function to reflect the influence of the knitting structure on the warp stiffness.

[0073] The calculation of the weft - direction tensile stiffness element reflects the tensile resistance ability of the fabric in the weft direction. The method is based on the weft - direction shear stiffness and is adjusted by the ratio of the weft - direction yarn density to the warp - direction yarn density and the cosine function of the knitting angle to reflect the contributions of the weft - direction yarn density and the knitting angle to the weft stiffness.

[0074] The calculation of the diagonal - direction shear stiffness element reflects the mechanical response of the fabric under diagonal shear. The method is to integrate the diagonal non - linear response data and modulate it through the double - angle cosine function of the knitting angle to capture the non - linear characteristics of the diagonal shear behavior.

[0075] The calculation of the vertical - direction stiffness element reflects the mechanical properties of the fabric in the direction perpendicular to the micro - element surface. The method is based on the weft - direction shear stiffness and is adjusted by the weft - direction yarn density ratio and the sine function of the knitting angle to reflect the influence of the yarn density and the knitting structure on the vertical stiffness.

[0076] For the calculation of other elements, it is assumed that the mechanical coupling effect between the vertical direction and the in - plane direction of the fabric is small, so their values are set to zero to simplify the calculation complexity.

[0077] The stiffness matrix constructed by the above - mentioned method can comprehensively reflect the mechanical properties of the fabric in different directions and provide accurate data support for the generation of the mechanical field.

[0078] For example:

[0079] Based on the input data, for each micro - element construct the stiffness matrix , which is used to describe the mechanical response of the fabric in the local coordinate system. The stiffness matrix is a symmetric matrix, and the specific element calculations are as follows:

[0080] The warp - direction tensile stiffness element :

[0081] ;

[0082] Among them, the warp tensile stiffness is , the warp yarn density is , the weft yarn density , the knitting angle is , represents the proportion of the warp yarn density, introduces the modulation effect of the knitting angle on the warp stiffness.

[0083] Weft tensile stiffness element :

[0084] ;

[0085] Among them, reflects the stiffness contribution of the weft yarn density relative to the warp, adjusts the influence of the knitting angle.

[0086] Oblique shear stiffness element :

[0087] ;

[0088] Among them, is the maximum shear angle, is the oblique non-linear response data, represents the shear angle, which is an angular variable describing the degree of oblique deformation of the fabric, reflects the non-linear modulation of the knitting angle on the oblique shear response.

[0089] Vertical direction stiffness element

[0090] ;

[0091] Among them, the weft shear stiffness is used as the basis, and the yarn density ratio and the knitting angle are adjusted. Other elements: Since it is assumed that the coupling effect between the vertical direction and the in-plane direction of the fabric is small, it is set that:

[0092] ;

[0093] Stiffness matrix has the form of:

[0094] .

[0095] D1. Generate the mechanical field

[0096] Based on the stiffness matrix of each microelement, a mechanical field on the surface of the entire three-dimensional virtual human body model is generated. The method of generating the mechanical field is to aggregate the stiffness matrices of all microelements into a whole, forming a data set that contains the mechanical properties of all microelements. This data set not only reflects the anisotropic responses of the fabric in the warp, weft, and bias directions, but also accurately captures the real mechanical behavior of the fabric through the modulation effects of yarn density and knitting angle. This generation method ensures that the mechanical field can comprehensively describe the mechanical distribution characteristics of the fabric on the surface of the three-dimensional virtual human body model.

[0097] After the generation of the mechanical field is completed, the output result is the mechanical field data containing the stiffness matrix of each microelement. These data provide precise mechanical support for the subsequent process of flattening the garment piece, ensuring that the calculation of the stress flow during the flattening process can accurately reflect the anisotropic characteristics of the fabric, thereby providing a reliable basis for clothing pattern design.

[0098] By generating a mechanical field that reflects the mechanical properties of the fabric on the surface of the three-dimensional virtual human body model, an accurate basis is provided for flattening the garment piece. However, relying solely on the mechanical field cannot fully solve the complex mechanical behavior during flattening. It is necessary to further decompose the flattening process into the warp principal stress flow and the weft shear stress flow, and calculate the warp compression residual amount and the weft deformation hysteresis amount to quantify the deformation characteristics of the fabric during flattening, providing data support for subsequent compensation and boundary correction. This section elaborates in detail on the technical logic of decomposing the stress flow based on the mechanical field and calculating the above two deformation amounts.

[0099] The following is the specific processing technical logic for decomposing the three-dimensional garment piece flattening process into the warp principal stress flow and the weft shear stress flow based on the mechanical field, and calculating the warp compression residual amount and the weft deformation hysteresis amount. The processing object is the three-dimensional garment piece covering the surface of the three-dimensional virtual human body model, and the goal is to accurately capture the mechanical behavior during flattening through mechanical decomposition and calculation.

[0100] A2. Establish the stress field on the three-dimensional garment piece:

[0101] To achieve the decomposition of the stress flow, it is necessary to establish a stress field on the three-dimensional garment piece. The specific steps are as follows:

[0102] For each microelement in the three-dimensional garment piece, according to the warp tensile stiffness and weft shear stiffness defined in the mechanical field, calculate the virtual mechanical load applied during the flattening process. This virtual mechanical load simulates the force required for the microelement to transform from the three-dimensional curved surface form to the two-dimensional planar form. Next, use the finite element analysis method to solve the stress distribution of the three-dimensional garment piece based on the calculated virtual mechanical load, generating the stress tensor of each microelement. The stress tensor includes the warp normal stress component and the weft shear stress component, respectively reflecting the stress states of the microelement in the warp and weft directions. Through the above steps, the stress field on the three-dimensional garment piece is established, providing the necessary data support for stress flow decomposition.

[0103] B2. Decompose the stress flow into the meridional principal stress flow and the zonal shear stress flow:

[0104] Based on the stress field established on the three-dimensional garment piece, decompose the stress flow during the flattening process into the meridional principal stress flow and the zonal shear stress flow. The specific decomposition method is as follows:

[0105] The meridional principal stress flow is defined as the stress flow transmitted along the warp direction of the fabric, reflecting the tensile or compressive behavior in the warp direction. The calculation method is to extract the meridional normal stress components from the stress tensor of each microelement and accumulate and sum these components along the meridional path to obtain the meridional principal stress flow.

[0106] The zonal shear stress flow is defined as the shear stress flow transmitted along the weft direction of the fabric, reflecting the shear deformation behavior in the weft direction. The calculation method is to extract the zonal shear stress components from the stress tensor of each microelement and accumulate and sum these components along the zonal path to obtain the zonal shear stress flow.

[0107] The decomposed meridional principal stress flow and zonal shear stress flow respectively characterize the mechanical responses of the fabric in the warp and weft directions during the flattening process.

[0108] C2. Calculate the meridional compression residual amount:

[0109] The meridional compression residual amount is defined as the cumulative amount of the fabric in the warp direction that is not fully released due to compressive deformation during the flattening process. The calculation method is described as follows:

[0110] Based on the decomposed meridional principal stress flow, calculate the meridional strain of each microelement. Divide the component of the meridional principal stress flow on this microelement by the meridional tensile stiffness of this microelement to obtain the meridional strain value of this microelement. Next, calculate the meridional compression residual amount. Select the cases where the meridional strain is negative among all microelements. These negative values indicate that the microelement is in a compressed state. Multiply the absolute values of these negative meridional strains by the areas of the corresponding microelements and then accumulate and sum them to obtain the meridional compression residual amount. The meridional compression residual amount quantifies the degree of meridional compressive deformation during the flattening process.

[0111] D2. Calculate the zonal deformation hysteresis amount:

[0112] The zonal deformation hysteresis amount is defined as the hysteresis effect generated by the fabric in the weft direction due to shear deformation during the flattening process. The calculation method is described as follows:

[0113] Based on the zonal shear stress flow obtained by decomposition, calculate the zonal shear strain of each microelement. Divide the component of the zonal shear stress flow on this microelement by the zonal shear stiffness of this microelement to obtain the value of the zonal shear strain of this microelement. Next, calculate the zonal deformation hysteresis. The method is to calculate the deviation of the zonal shear strain of each microelement from the zonal shear strain in the ideal flattened state. The zonal shear strain in the ideal flattened state is usually zero. Multiply the absolute values of these deviations by the area of the corresponding microelement and then accumulate and sum them to obtain the zonal deformation hysteresis. The zonal deformation hysteresis quantifies the deviation of the zonal shear deformation during the flattening process.

[0114] After completing the above analysis and processing, output the meridional compression residual and the zonal deformation hysteresis as the data basis for subsequent collaborative compensation and boundary correction.

[0115] By decomposing the meridional principal stress flow and the zonal shear stress flow, respectively dealing with the mechanical behaviors of the fabric in the meridional and zonal directions, accurately capturing the anisotropic response of the fabric, overcoming the limitation of the assumption in traditional methods that the fabric is regarded as a homogeneous material, and ensuring that the calculation results are consistent with the actual characteristics of the fabric. By calculating the meridional compression residual and the zonal deformation hysteresis, quantifying the deformation deviation during the flattening process, providing specific data support for subsequent compensation design, thereby improving the flattening accuracy of two-dimensional plane cut pieces. By precisely controlling the mechanical behavior during the flattening process, reducing the deformation and wrinkles in actual sewing, enhancing the fit between the customized clothing and the human body shape as well as the process stability, while reducing the loss of high-end fabrics during the trial production process, and improving production efficiency and economic benefits.

[0116] By generating a mechanical field reflecting the mechanical properties of the fabric on the surface of a three-dimensional virtual human body model, decomposing the flattening process into a meridional principal stress flow and a zonal shear stress flow, and calculating the meridional compression residual and the zonal deformation hysteresis to quantify the deformation characteristics. However, only quantifying the deformation characteristics is not enough to eliminate the flattening error. It is also necessary to determine the collaborative compensation ratio between the two according to the non-linear relationship between the meridional compression residual and the zonal deformation hysteresis, and adjust the meridional compensation intensity and the zonal compensation direction to achieve precise compensation for the deformation of the cut piece.

[0117] The following is the specific processing technical logic for determining the collaborative compensation ratio between the meridional compression residual and the zonal deformation hysteresis according to their non-linear relationship, and adjusting the meridional compensation intensity and the zonal compensation direction. The processing objects are the meridional compression residual and the zonal deformation hysteresis calculated in the previous steps, and the goal is to generate compensation parameters to optimize the flattening effect of the cut piece.

[0118] A3. Analyze the non-linear relationship between the meridional compression residual and the zonal deformation hysteresis:

[0119] To determine the collaborative compensation ratio, it is necessary to analyze the non-linear relationship between the warp compression residual amount and the weft deformation hysteresis amount. First, based on historical experimental data or theoretical simulation results, a non-linear relationship function describing the relationship between the warp compression residual amount and the weft deformation hysteresis amount is fitted. The quadratic polynomial form is adopted, including the square term of the warp compression residual amount, the square term of the weft deformation hysteresis amount, and the cross term of the two. The fitting coefficients are jointly determined by the warp yarn density, weft yarn density, and knitting angle of the fabric, reflecting the intensity of their interaction. Then, the partial derivatives of the non-linear relationship function with respect to the warp compression residual amount and with respect to the weft deformation hysteresis amount are calculated to quantify the degree of mutual influence between the two in the current state. The absolute value of the partial derivative represents the contribution of each anisotropic deformation to the overall flattening error, and the positive or negative sign of the partial derivative represents the direction of the influence. Through this analysis process, the coupling effect between the warp compression residual amount and the weft deformation hysteresis amount can be clarified. The following is an example:

[0120] To determine the collaborative compensation ratio, it is necessary to analyze the warp compression residual amount and the weft deformation hysteresis amount of the non-linear relationship. The specific steps are as follows:

[0121] Based on historical experimental data or theoretical simulation, fit and the non-linear relationship function . For example, assume the quadratic polynomial form:

[0122] ;

[0123] where is the fitting coefficient, which is determined by the warp and weft yarn densities and the knitting angle of the fabric, reflecting the interaction intensity between the two.

[0124] Calculate the partial derivative of with respect to and the partial derivative of with respect to , to quantify the mutual

[0125] influence degree in the current state:

[0126] ;

[0127] ;

[0128] where the magnitude of the partial derivative reflects the contribution of each anisotropic deformation to the overall error, and the sign reflects the direction of the influence.

[0129] Through the above analysis, clarify and The coupling effect provides a basis for subsequent ratio calculations.

[0130] B3. Determine the collaborative compensation ratio:

[0131] Based on the analysis of the non - linear relationship between the meridional compression residual and the latitudinal deformation hysteresis, determine the collaborative compensation ratios for the meridional and latitudinal directions. The specific method is as follows: Define the collaborative compensation ratio as the relative weight of meridional compensation in the total compensation. Its calculation method is to divide the absolute value of the partial derivative of the non - linear relationship function with respect to the meridional compression residual by the sum of the absolute value of the partial derivative with respect to the meridional compression residual and the absolute value of the partial derivative with respect to the latitudinal deformation hysteresis, obtaining the meridional compensation ratio; the latitudinal compensation ratio is defined as the difference between 1 and the meridional compensation ratio. The value range of the meridional compensation ratio is between 0 and 1. When the value of the meridional compensation ratio is close to 1, it indicates that the contribution of the meridional compression residual to the flattening error dominates, and the meridional direction needs to be compensated preferentially; when the value of the meridional compensation ratio is close to 0, it indicates that the contribution of the latitudinal deformation hysteresis to the flattening error dominates, and the latitudinal direction needs to be compensated preferentially. By calculating the meridional compensation ratio and the latitudinal compensation ratio, the dynamic balance of meridional and latitudinal compensations is achieved, ensuring the pertinence of the compensation process. For example:

[0132] Based on the non - linear relationship analysis, determine the collaborative compensation ratios for the meridional and latitudinal directions , and the specific method is as follows:

[0133] Define the collaborative compensation ratio as the relative weight of meridional compensation in the total compensation, and the calculation formula is:

[0134] ;

[0135] where is between 0 and 1; the latitudinal compensation ratio is then:

[0136] ;

[0137] The above formula uses the ratio of the absolute values of partial derivatives to reflect the relative influence of the meridional and latitudinal directions on the flattening error.

[0138] If is close to 1, then the meridional compression residual has a greater contribution to the flattening error, and the meridional direction needs to be compensated preferentially;

[0139] If is close to 0, then the latitudinal deformation hysteresis has a greater influence, and the latitudinal direction needs to be compensated preferentially.

[0140] By calculating and , achieve the dynamic balance of warp and weft compensation.

[0141] C3. Adjust the warp compensation intensity and weft compensation direction:

[0142] After determining the collaborative compensation ratio, adjust the warp compensation intensity and weft compensation direction based on this ratio. The specific steps are as follows: The warp compensation intensity is defined as the amplitude of warp compensation. Its calculation method is to multiply the warp compensation ratio by the absolute value of the warp compression residual amount to obtain the warp compensation intensity, and its unit is the same as that of the warp compression residual amount; The weft compensation intensity is defined as the amplitude of weft compensation. Its calculation method is to multiply the weft compensation ratio by the absolute value of the weft deformation hysteresis amount to obtain the weft compensation intensity, and its unit is the same as that of the weft deformation hysteresis amount. The warp compensation direction is determined according to the positive or negative sign of the warp compression residual amount: When the warp compression residual amount is positive, the compensation direction is warp tension to release excessive compression deformation; When the warp compression residual amount is negative, the compensation direction is warp compression to supplement insufficient tensile deformation. The weft compensation direction is determined according to the positive or negative sign of the weft deformation hysteresis amount: When the weft deformation hysteresis amount is positive, the compensation direction is clockwise shear to offset the clockwise deviation; When the weft deformation hysteresis amount is negative, the compensation direction is counterclockwise shear to offset the counterclockwise deviation. Through the above adjustments, ensure that the compensation parameters can specifically reduce the errors during the flattening process. For example:

[0143] Based on the collaborative compensation ratio and , adjust the warp compensation intensity and weft compensation direction. The specific steps are as follows:

[0144] The warp compensation intensity : is defined as the amplitude of warp compensation, and the calculation method is:

[0145] ;

[0146] Among them, represents the warp compensation amount to be applied, and the unit is the same as , and is proportional to the absolute value of and .

[0147] The weft compensation intensity : is defined as the amplitude of weft compensation, and the calculation method is:

[0148] ;

[0149] Among them, represents the weft compensation amount to be applied, and the unit is the same as , and is proportional to the absolute value of and .

[0150] Meridional compensation direction: determined according to the sign of

[0151] If , the compensation direction is meridional tension to release excessive compression;

[0152] If , the compensation direction is meridional compression to supplement insufficient tension.

[0153] Latitudinal compensation direction: determined according to the sign of

[0154] If , the compensation direction is clockwise shear to offset the positive deviation;

[0155] If , the compensation direction is counterclockwise shear to offset the negative deviation.

[0156] Through the above adjustments, ensure that the compensation parameters specifically reduce the flattening error.

[0157] After completing the above adjustments, output the meridional compensation intensity, latitudinal compensation intensity, meridional compensation direction, and latitudinal compensation direction as the precise basis for subsequent boundary correction based on the streamline diffusion algorithm. These output results will be directly used to guide the subsequent processing steps of fabric flattening to ensure the improvement of the flatness and accuracy of the final cut pieces.

[0158] The above processing technical logic analyzes the non-linear relationship between the meridional compression residual and the latitudinal deformation hysteresis, determines the collaborative compensation ratio, and adjusts the meridional compensation intensity and latitudinal compensation direction to achieve precise compensation for the flattening error. By fitting the non-linear relationship function and calculating the partial derivative, it can quantify the relative influence of the meridional compression residual and the latitudinal deformation hysteresis on the flattening error, overcome the deficiency of ignoring the coupling effect of fabric mechanical properties in traditional methods, and ensure that the compensation parameters have a scientific basis and pertinence; by dynamically calculating the collaborative compensation ratio, it realizes the balance of meridional and latitudinal compensations, avoids error accumulation caused by compensating only in a single direction, and thus improves the overall accuracy of cut piece flattening; by clarifying the specific values of the meridional compensation intensity, latitudinal compensation intensity, meridional compensation direction, and latitudinal compensation direction, it provides precise guiding parameters for subsequent boundary correction, reduces possible deformation and wrinkle problems in the actual sewing process, improves the fit and aesthetics of customized clothing, and at the same time improves production efficiency and economic benefits.

[0159] By generating a mechanical field on the surface of a three-dimensional virtual human body model, decomposing the stress flow during the flattening process, calculating the meridional compression residual and the latitudinal deformation hysteresis, and determining the collaborative compensation ratio based on the non-linear relationship, adjusting the meridional compensation intensity and the latitudinal compensation direction to achieve precise compensation for the deformation of the cut piece. However, simply adjusting the compensation parameters is not enough to completely eliminate the stress discontinuity at the boundary. Therefore, it is necessary to further optimize the cut piece boundary of the three-dimensional garment piece. This section details the specific technical logic of using the streamline diffusion algorithm to iteratively correct the cut piece boundary of the three-dimensional garment piece based on the distribution of the meridional compensation intensity and the latitudinal compensation direction, so that adjacent compensation vectors form continuous streamlines at the boundary, ensuring the continuity of the stress distribution at the cut piece boundary of the three-dimensional garment piece and providing an optimized basis for subsequent sewing and multi-layer garment piece processing.

[0160] The following is the specific processing technical logic of using the streamline diffusion algorithm to iteratively correct the cut piece boundary of the three-dimensional garment piece based on the distribution of the meridional compensation intensity and the latitudinal compensation direction, so that adjacent compensation vectors form continuous streamlines at the boundary. The processing object is the compensation vectors at the cut piece boundary of the three-dimensional garment piece, and the goal is to reduce the stress discontinuity at the boundary by iteratively optimizing the boundary shape.

[0161] A4. Construct a compensation vector field:

[0162] To achieve the correction of the cut piece boundary of the three-dimensional garment piece, it is necessary to construct a compensation vector field on the cut piece boundary of the three-dimensional garment piece to quantify the adjustment requirements of each boundary point. The specific steps are as follows:

[0163] For each boundary point on the cut piece boundary of the three-dimensional garment piece, according to the meridional compensation intensity, latitudinal compensation intensity, meridional compensation direction, and latitudinal compensation direction in the input data, define a compensation vector, which consists of two parts: a meridional component and a latitudinal component.

[0164] The meridional component is obtained by multiplying the meridional compensation intensity by the value of the meridional compensation direction, where the meridional compensation direction takes a positive value during stretching and a negative value during compression, and the result represents the adjustment amount in the meridional direction;

[0165] The latitudinal component is obtained by multiplying the latitudinal compensation intensity by the value of the latitudinal compensation direction, where the latitudinal compensation direction takes a positive value during clockwise shear and a negative value during counterclockwise shear, and the result represents the adjustment amount in the latitudinal direction.

[0166] Collect the compensation vectors of all boundary points to form a compensation vector field. Through the above steps, the compensation vector field is constructed, reflecting the adjustment requirements calculated based on the mechanical properties at the cut piece boundary of the three-dimensional garment piece and providing a data basis for subsequent boundary optimization.

[0167] Among them, the cutting boundary of the three-dimensional garment piece is defined as the contour line of the cutting piece, which consists of a series of boundary points, and each boundary point represents a specific position coordinate on the cutting boundary of the three-dimensional garment piece. These input data are obtained through the aforementioned mechanical field decomposition and compensation calculation steps to ensure close connection with the subsequent processing process.

[0168] B4. Use the streamline diffusion algorithm to iteratively correct the boundary:

[0169] To make the adjacent compensation vectors form continuous streamlines at the cutting boundary of the three-dimensional garment piece, the streamline diffusion algorithm is used to iteratively correct the cutting boundary of the three-dimensional garment piece to ensure the smoothness of the boundary stress distribution. The iterative process includes two main stages: initialization and iterative steps, which are described separately below.

[0170] Initialization: Before the iteration starts, set the number of iterations to zero, define the cutting boundary of the initial three-dimensional garment piece as the cutting boundary of the original three-dimensional garment piece, that is, the cutting boundary contour line of the three-dimensional garment piece defined in the input data; define the initial compensation vector field as the compensation vector field constructed in step A4 as the starting point of the iteration.

[0171] Iterative steps: The iterative steps include the following four steps S1-4, which are executed in sequence to achieve boundary correction:

[0172] S1. Calculate the streamline divergence:

[0173] For the compensation vector field on the cutting boundary of the current three-dimensional garment piece, calculate the streamline divergence between adjacent boundary points to measure the continuity difference between adjacent compensation vectors.

[0174] The specific calculation method is as follows: Take the compensation vectors of two adjacent boundary points, calculate the difference of their meridional components and the difference of their zonal components respectively, add the square of the difference of the meridional components and the square of the difference of the zonal components, and then take the square root of the result to obtain the streamline divergence value. The streamline divergence value reflects the direction and magnitude difference of adjacent compensation vectors and is used as the basis for subsequent adjustment.

[0175] S2. Update the position of the boundary point:

[0176] Based on the calculated streamline divergence, adjust the position of each boundary point to generate a new cutting boundary of the three-dimensional garment piece. The specific adjustment method is as follows: For each boundary point, calculate the average direction of the compensation vectors of its two adjacent boundary points, and this average direction is determined by adding the meridional components and zonal components of the two adjacent compensation vectors respectively and then taking the average;

[0177] Then, add a correction amount to the position of the current boundary point. This correction amount is jointly determined by the step size parameter, the average direction of the adjacent compensation vectors, and the streamline divergence. The step size parameter is a preset value between zero and one, used to control the adjustment amplitude. The magnitude of the correction amount is proportional to the streamline divergence, and the direction is the same as the average direction. Through this step, the position of the boundary point is updated.

[0178] S3. Update the compensation vector field:

[0179] Based on the updated boundary point positions, recalculate the compensation vector field.

[0180] The specific method is as follows: For each new boundary point, according to the meridional compensation intensity, zonal compensation intensity, meridional compensation direction, and zonal compensation direction in the input data, recalculate its compensation vector according to the rules when constructing the compensation vector field, ensuring that the compensation vector is consistent with the new boundary position.

[0181] S4. Check the convergence condition:

[0182] Calculate the maximum value of the streamline divergence of all boundary points on the cutting boundary of the current 3D garment piece, and compare it with the preset threshold. If the maximum value of the streamline divergence of all boundary points is less than the preset threshold, it is determined that the iteration converges and the iteration process stops; if it is greater than or equal to the preset threshold, increase the number of iterations and return to step S1 to continue execution.

[0183] The conditions for terminating the iteration are: the number of iterations reaches the preset maximum value, or the maximum value of the streamline divergence is less than the preset threshold. When either condition is met, output the cutting boundary of the final 3D garment piece.

[0184] Through the above iterative process, the compensation vectors at the cutting boundary of the 3D garment piece gradually tend to be continuous, forming smooth streamlines, and the discontinuity of the boundary stress distribution is reduced.

[0185] After completing the iterative correction, use the cutting boundary of the final 3D garment piece as the output result. This result is a series of updated boundary point coordinates, forming the corrected cutting contour line, which serves as the basic data for subsequent multi-layer garment piece processing, ensuring that the continuity and smoothness of the boundary stress distribution are optimized.

[0186] By quantifying the compensation requirements of each boundary point on the cutting boundary of the three-dimensional garment piece and adopting an iterative optimization method, the stress discontinuity phenomenon at the boundary can be effectively reduced. In traditional methods, the treatment of the cutting boundary of the three-dimensional garment piece often lacks smoothness, resulting in deformation problems during the sewing process. However, through the iterative adjustment of the streamline diffusion algorithm, this technology ensures the continuity of the boundary stress distribution, thereby improving the stability of the garment piece during flattening and sewing. By reducing the discontinuity of the boundary stress, the rework probability caused by uneven stress distribution during the sewing process can be reduced, thereby reducing material waste and improving production efficiency and economic benefits.

[0187] By generating a mechanical field on the surface of the three-dimensional virtual human model, combining the warp tensile stiffness, weft shear stiffness, and oblique nonlinear response data of the fabric, decomposing the stress flow during the flattening process, calculating the warp compression residual amount and the weft deformation hysteresis amount, and determining the collaborative compensation ratio based on the nonlinear relationship to adjust the compensation parameters. Finally, the cutting boundary of the three-dimensional garment piece is optimized through the streamline diffusion algorithm. However, for multi-layer garment pieces, the divergence difference of the interlayer stress field may lead to mismatching of the sewing boundary, affecting the flatness and fit of the garment. Therefore, this part details the specific technical logic of calculating the divergence of the interlayer stress field and inserting elastic inserts for multi-layer garment pieces to balance the interlayer stress and ensure that the projection error of the sewing boundary approaches zero.

[0188] The following is the specific processing technical logic for calculating the divergence of the interlayer stress field of multi-layer garment pieces and inserting elastic inserts until the projection error of the sewing boundary approaches zero. This part continues with the mechanical field and the cutting boundary data of the three-dimensional garment piece generated in the previous steps. The processing object is the interlayer stress field in multi-layer garment pieces, and the goal is to reduce the projection error of the sewing boundary by adjusting the interlayer stress distribution.

[0189] A5. Input data:

[0190] In the process of calculating the divergence of the interlayer stress field of multi-layer garment pieces and inserting elastic inserts to reduce the projection error of the sewing boundary, it is first necessary to clarify the content and source of the input data. The input data comes from the calculation results of the previous steps and the design parameters of multi-layer garment pieces, including the following aspects:

[0191] The multi-layer garment piece is composed of multiple single-layer garment pieces, and each layer of the garment piece has its own mechanical field, which is generated by the warp tensile stiffness, weft shear stiffness, and oblique nonlinear response data of the fabric, reflecting the mechanical properties of the fabric;

[0192] The interlayer stress field is defined as the stress distribution between adjacent layers of garment pieces, and is generated by calculating and adjusting the warp principal stress flow and weft shear stress flow decomposed from the aforementioned mechanical field;

[0193] The stitching boundary is the boundary line of multiple fabric pieces at the stitching location, consisting of a series of boundary points;

[0194] The projection error is defined as the deviation between the projection of the stitching boundary on a two-dimensional plane and the ideal flat state.

[0195] These input data provide the basis for subsequent calculations of the divergence of the interlayer stress field and the insertion of elastic inserts, ensuring data continuity and the accuracy of the processing procedure.

[0196] B5. Calculate the divergence of the interlayer stress field:

[0197] To quantify the differences in the interlayer stress field, it is necessary to calculate the divergence of adjacent interlayer stress fields. The specific steps are as follows:

[0198] For each pair of adjacent fabric pieces, at each boundary point on the stitching boundary, calculate the divergence of the interlayer stress field. The calculation uses the finite difference method. Specifically, the divergence of the interlayer stress field at the boundary point is expressed as the sum of the partial derivatives of the transverse and longitudinal components of the interlayer stress field. The transverse and longitudinal components of the interlayer stress field are obtained by decomposing the interlayer stress field.

[0199] The transverse partial derivative of the interlayer stress field is approximated by dividing the difference in the transverse stress component between adjacent boundary points by twice the distance between adjacent boundary points in the transverse direction;

[0200] The longitudinal partial derivative of the interlayer stress field is approximated by dividing the difference in the longitudinal stress component between adjacent boundary points by twice the distance between adjacent boundary points in the longitudinal direction.

[0201] The value of the divergence of the interlayer stress field is the sum of the transverse and longitudinal partial derivatives, reflecting the divergence or convergence trend of the interlayer stress at this boundary point.

[0202] Through this calculation, the divergence of the interlayer stress field at each boundary point is obtained, providing a quantitative basis for the subsequent insertion of elastic inserts. An example is as follows:

[0203] To quantify the differences in the interlayer stress field, calculate the divergence of adjacent interlayer stress fields. The specific steps are as follows:

[0204] For each pair of adjacent fabric pieces and , at the stitching boundary calculate the divergence of the interlayer stress field . The calculation is performed using the finite difference method: .

[0205] ;

[0206] Where:

[0207] The component of the interlayer stress field in the direction is obtained from Obtained by decomposition.

[0208] : The component of the interlayer stress field in the direction, obtained by decomposition.

[0209] Sutured boundary The th boundary point on.

[0210] Indicates the number of layers in the multi-layer clothing piece.

[0211] The transverse partial derivative of the interlayer stress field: ;

[0212] The longitudinal partial derivative of the interlayer stress field: ;

[0213] Where:

[0214] And : The stress component in the and directions at the boundary points .

[0215] and : The stress component in the and directions at the boundary points .

[0216] : The spacing between adjacent boundary points in the direction.

[0217] : The spacing between adjacent boundary points in the direction.

[0218] Through the above calculations, the divergence of the interlayer stress field at each boundary point is obtained, with the unit of Newton per square millimeter, reflecting the divergence (positive value) or convergence (negative value) trend of the interlayer stress at this point.

[0219] C5. Insert elastic inserts:

[0220] To balance the divergence of the interlayer stress field, elastic inserts with elastic stress opposite to the direction of the divergence of the interlayer stress field need to be inserted at the boundary points. The specific method is as follows: For each boundary point, determine the insertion direction and strength of the elastic insert according to the calculated divergence of the interlayer stress field.

[0221] The insertion direction is opposite to the divergence direction of the interlayer stress field: when the divergence of the interlayer stress field is positive, it indicates stress divergence, and the insertion direction is inward to reduce the divergence trend; when the divergence of the interlayer stress field is negative, it indicates stress convergence, and the insertion direction is outward to reduce the convergence trend. The insertion strength is proportional to the absolute value of the divergence of the interlayer stress field. The calculation method is to multiply the divergence value of the interlayer stress field by a negative proportionality coefficient to obtain the insertion strength, which represents the deformation amount of the insert piece.

[0222] The proportionality coefficient is determined by the elastic modulus of the fabric and is used to control the insertion amplitude. Based on the insertion strength, elastic inserts are inserted at the boundary points to adjust the interlayer stress distribution. High-elasticity fibers are selected as the material for the elastic inserts, and the size is determined according to the insertion strength to ensure that its mechanical response matches the insertion strength. By inserting elastic inserts, the divergence of the interlayer stress field is dynamically adjusted to reduce the stress imbalance at the stitching boundary.

[0223] D5. Iteratively optimize until the projection error approaches zero:

[0224] To ensure that the projection error at the stitching boundary approaches zero, an iterative optimization method is adopted, and the specific steps are as follows:

[0225] In the initialization stage, the iteration count is set to zero, and the initial projection error is defined as the projection error preliminarily calculated in step A5.

[0226] During the iteration process, the following steps are repeatedly executed:

[0227] The first step is to calculate the current divergence of the interlayer stress field according to the aforementioned method;

[0228] The second step is to insert elastic inserts according to the current divergence of the interlayer stress field, adjust the interlayer stress distribution, and generate a new interlayer stress field;

[0229] The third step is to recalculate the projection error of the stitching boundary based on the adjusted interlayer stress field;

[0230] The fourth step is to compare the current projection error with the error threshold. If the current projection error is less than the error threshold, the iteration stops; if the current projection error is greater than or equal to the error threshold, the iteration count is increased and the first step is returned to continue execution.

[0231] The iteration termination condition is that the iteration count reaches the preset maximum value or the projection error is less than the error threshold. When either condition is met, the final elastic insert configuration is output. Through this iterative optimization, it is ensured that the projection error is gradually reduced to meet the design requirements.

[0232] After completing the iterative optimization, the final elastic insert configuration is output, including the insertion position, insertion direction, and insertion strength of each boundary point, as the basic data for multi-layer panel sewing, ensuring interlayer stress balance and smooth sewing boundaries.

[0233] The above processing technical logic calculates the divergence of the interlayer stress field and inserts elastic inserts with elastic stress opposite to its direction, and iteratively optimizes until the projection error of the sewing boundary approaches zero; by quantifying the divergence of the interlayer stress field and inserting elastic inserts accordingly, it can effectively balance the stress differences between multi-layer panels and reduce the stress imbalance at the sewing boundary. In traditional methods, the treatment of interlayer stress in multi-layer panels relies on experience and is difficult to precisely control. However, this technology calculates the divergence of the interlayer stress field and iteratively optimizes it to ensure the smoothness and consistency of the interlayer stress distribution. This processing technical logic dynamically adjusts the interlayer stress field by inserting elastic inserts, gradually reducing the projection error of the sewing boundary to less than the error threshold, improving the flatness and fitness of multi-layer panels. The optimized elastic insert configuration provides precise technical support for subsequent garment sewing, reduces sewing rework caused by interlayer stress imbalance, and improves production efficiency and economic benefits.

[0234] Example 2: Figure 2 A garment pattern design system based on a virtual human model according to the present invention is given, including: a mechanical field generation module, a stress flow decomposition module, a compensation ratio adjustment module, a boundary correction and optimization module, and an interlayer stress balance module;

[0235] Mechanical field generation module: On the surface of a three-dimensional virtual human model, based on the warp tensile stiffness, weft shear stiffness, and oblique nonlinear response data of the fabric, a mechanical field defined by the warp and weft yarn densities and knitting angles is generated, and the mechanical field is transmitted to the stress flow decomposition module;

[0236] Stress flow decomposition module: Based on the mechanical field, the process of flattening a three-dimensional panel is decomposed into a warp principal stress flow and a weft shear stress flow, and the warp compression residual and weft deformation hysteresis are calculated, and the warp compression residual and weft deformation hysteresis are output to the compensation ratio adjustment module;

[0237] Compensation ratio adjustment module: According to the non-linear relationship between the warp compression residual and the weft deformation hysteresis, the collaborative compensation ratio is determined, and the warp compensation strength and weft compensation direction are adjusted, and the warp compensation strength and weft compensation direction are transmitted to the boundary correction and optimization module;

[0238] Boundary correction and optimization module: Based on the distribution of the warp compensation strength and the weft compensation direction, the streamline diffusion algorithm is used to iteratively correct the cutting boundary of the three-dimensional panel, so that adjacent compensation vectors form continuous streamlines at the boundary, and the optimized cutting boundary of the three-dimensional panel is transmitted to the interlayer stress balance module;

[0239] Interlayer stress balance module: For multi-layer garment pieces, calculate the divergence of the interlayer stress field, and insert elastic inserts with elastic stress in the direction opposite to the divergence of the interlayer stress field until the projection error of the stitching boundary approaches zero.

[0240] The above formulas are all dimensionless and take their numerical values for calculation. The formulas are obtained by collecting a large amount of data for software simulation to get a formula closest to the actual situation. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0241] It should be noted that the system of the present invention can be deployed on the device itself to achieve embedded applications, or can also run on a PC or other terminals with a user interface, so as to meet various hardware environments and usage requirements.

[0242] Only some exemplary embodiments of the present invention have been described above by way of illustration. Undoubtedly, for those of ordinary skill in the art, without departing from the spirit and scope of the present invention, the described embodiments can be modified in various different ways. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the protection scope of the claims of the present invention.

[0243] It should be noted that in this article, if there are relational terms such as first and second, etc., they are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0244] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A clothing pattern design method based on a virtual human body model, characterized in that, Including the steps: On the surface of a three-dimensional virtual human body model, generate a mechanical field based on the warp tensile stiffness, weft shear stiffness, and oblique nonlinear response data of the fabric, where the mechanical properties of each microelement are defined by the warp and weft yarn densities and the knitting angles; Decompose the process of flattening the three-dimensional garment piece into a warp principal stress flow and a weft shear stress flow based on the mechanical field, and calculate the warp compression residual and the weft deformation hysteresis; Determine the collaborative compensation ratio of the two according to the nonlinear relationship between the warp compression residual and the weft deformation hysteresis, and adjust the warp compensation intensity and the weft compensation direction; Based on the distribution of the warp compensation intensity and the weft compensation direction, use the streamline diffusion algorithm to iteratively correct the cutting boundary of the three-dimensional garment piece. Specifically: Step 1, construct a compensation vector field on the cutting boundary of the three-dimensional garment piece based on the warp compensation intensity, the weft compensation intensity, the warp compensation direction, and the weft compensation direction; Step 2, calculate the streamline divergence of the compensation vectors of adjacent boundary points, that is, the modulus of the difference between adjacent compensation vectors; Step 3, adjust the position of the boundary point according to the streamline divergence, and add the correction amount jointly determined by the step size parameter, the average direction of adjacent compensation vectors, and the streamline divergence to the current boundary point position; Step 4, recalculate the compensation vector field based on the updated boundary point position; Through iterative steps 1 to 4 until the maximum value of the streamline divergence is less than the preset threshold or the preset number of iterations is reached, finally output the corrected cutting boundary of the three-dimensional garment piece; For multi-layer garment pieces, calculate the divergence of the interlayer stress field, and insert elastic inserts with elastic stress in the opposite direction to the interlayer stress field divergence until the projection error of the stitching boundary approaches zero.

2. The method for designing a clothing pattern based on a virtual human body model according to claim 1, wherein On the surface of a three-dimensional virtual human body model, generate a mechanical field based on the warp tensile stiffness, weft shear stiffness, and oblique nonlinear response data of the fabric, where the mechanical properties of each microelement are defined by the warp and weft yarn densities and the knitting angles. Specifically: Discretize the surface of the three-dimensional virtual human body model into multiple microelements, and establish a local coordinate system on each microelement, where the coordinate axes of the local coordinate system are respectively along the warp direction, the weft direction, and the direction perpendicular to the surface of the microelement. Construct a stiffness matrix for each microelement, where the diagonal elements of the stiffness matrix respectively represent the warp tensile stiffness, the weft tensile stiffness, and the stiffness perpendicular to the surface of the microelement, and the off-diagonal elements represent the oblique shear stiffness, and modulate the stiffness matrix through the warp and weft yarn densities and the knitting angles; Generate a mechanical field by assembling the stiffness matrices of all microelements to reflect the anisotropic mechanical properties of the fabric on the surface of the three-dimensional virtual human body model.

3. The method for designing a clothing pattern based on a virtual human body model according to claim 2, wherein Decompose the process of flattening the three-dimensional garment piece into a warp principal stress flow and a weft shear stress flow based on the mechanical field, and calculate the warp compression residual and the weft deformation hysteresis. Specifically: Based on the warp tensile stiffness and the weft shear stiffness in the mechanical field, calculate the virtual mechanical load of each microelement on the three-dimensional garment piece; Adopt the finite element analysis method to solve the stress distribution of the three-dimensional garment piece based on the virtual mechanical load, and generate the stress tensor of each microelement; Extract the warp normal stress component and the weft shear stress component from the stress tensor, and accumulate and sum them along the warp path and the weft path respectively to obtain the warp principal stress flow and the weft shear stress flow; Calculate the meridional strain of each microelement based on the meridional principal stress flow and the meridional tensile stiffness, and obtain the meridional compression residual by cumulatively summing the area-weighted sum of the meridional compressive strain. Calculate the latitudinal shear strain of each microelement based on the latitudinal shear stress flow and the latitudinal shear stiffness, and obtain the latitudinal deformation hysteresis by cumulatively summing the area-weighted sum of the deviation of the latitudinal shear strain from the ideal state.

4. A method for designing a clothing pattern based on a virtual human body model according to claim 3, characterized in that, Determine the collaborative compensation ratio according to the non-linear relationship between the meridional compression residual and the latitudinal deformation hysteresis, and adjust the meridional compensation intensity and the latitudinal compensation direction: Based on historical experimental data, fit the non-linear relationship function between the meridional compression residual and the latitudinal deformation hysteresis. Calculate the partial derivative of the non-linear relationship function with respect to the meridional compression residual and the partial derivative with respect to the latitudinal deformation hysteresis. Divide the absolute value of the partial derivative of the non-linear relationship function with respect to the meridional compression residual by the sum of the absolute value of the partial derivative with respect to the meridional compression residual and the absolute value of the partial derivative with respect to the latitudinal deformation hysteresis to obtain the meridional compensation ratio; the latitudinal compensation ratio is defined as the difference between 1 and the meridional compensation ratio. Calculate the meridional compensation intensity as the product of the meridional compensation ratio and the absolute value of the meridional compression residual, and the latitudinal compensation intensity as the product of the latitudinal compensation ratio and the absolute value of the latitudinal deformation hysteresis; determine the meridional compensation direction as tension or compression according to the positive or negative sign of the meridional compression residual, and determine the latitudinal compensation direction as clockwise or counterclockwise shear according to the positive or negative sign of the latitudinal deformation hysteresis.

5. A method for designing a clothing pattern based on a virtual human body model according to claim 4, characterized in that: When fitting the non-linear relationship function, a quadratic polynomial form is adopted, including the square term of the meridional compression residual, the square term of the latitudinal deformation hysteresis, and the cross term of the meridional compression residual and the latitudinal deformation hysteresis.

6. The clothing pattern design method based on a virtual human body model according to claim 5, characterized in that Based on the mechanical field and the interlayer stress field of each layer of the multi-layer fabric pieces, and the optimized sewing boundary, calculate the divergence of the interlayer stress field. Specifically: Calculate the sum of the transverse partial derivative and the longitudinal partial derivative of the interlayer stress field at each boundary point on the sewing boundary by the finite difference method to obtain the divergence value of the interlayer stress field; determine the insertion direction and insertion intensity of the elastic insert according to the divergence value of the interlayer stress field, where the insertion direction is opposite to the direction of the interlayer stress field divergence, and the insertion intensity is proportional to the absolute value of the interlayer stress field divergence and is adjusted by a proportionality coefficient; insert the elastic insert at each boundary point on the sewing boundary to adjust the interlayer stress distribution.

7. A method for designing a clothing pattern based on a virtual human body model according to claim 6, characterized in that: Adopt an iterative optimization method to repeatedly calculate the divergence of the interlayer stress field, insert the elastic insert and update the projection error of the sewing boundary until the projection error of the sewing boundary is less than the error threshold or reaches the preset number of iterations, and finally output the configuration of the elastic insert.

8. A clothing pattern design system based on a virtual human body model, which is used to implement the clothing pattern design method based on a virtual human body model according to any one of claims 1-7, and is characterized in that, Including: A mechanical field generation module, a stress flow decomposition module, a compensation ratio adjustment module, a boundary correction and optimization module, and an interlayer stress balance module; Mechanical field generation module: On the surface of the three-dimensional virtual human body model, generate a mechanical field defined by the warp and weft yarn densities and knitting angles based on the warp tensile stiffness, weft shear stiffness, and oblique nonlinear response data of the fabric, and transfer the mechanical field to the stress flow decomposition module; Stress flow decomposition module: Decompose the flattening process of the three-dimensional garment piece into the warp principal stress flow and the weft shear stress flow based on the mechanical field, and calculate the warp compression residual amount and the weft deformation hysteresis amount, and output the warp compression residual amount and the weft deformation hysteresis amount to the compensation ratio adjustment module; Compensation ratio adjustment module: Determine the collaborative compensation ratio according to the nonlinear relationship between the warp compression residual amount and the weft deformation hysteresis amount, and adjust the warp compensation intensity and the weft compensation direction, and transfer the warp compensation intensity and the weft compensation direction to the boundary correction and optimization module; Boundary correction and optimization module: Based on the distribution of the warp compensation intensity and the weft compensation direction, use the streamline diffusion algorithm to iteratively correct the cutting boundary of the three-dimensional garment piece, so that adjacent compensation vectors form continuous streamlines at the boundary, and transfer the optimized cutting boundary of the three-dimensional garment piece to the interlayer stress balance module; Interlayer stress balance module: For multi-layer garment pieces, calculate the divergence of the interlayer stress field, and insert elastic inserts with the elastic stress opposite to the direction of the interlayer stress field divergence until the projection error of the stitching boundary approaches zero.

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