A method and system for detecting mechanical properties of a textile composite based on weaving formation

Abstract

The application discloses a kind of based on weaving forming textile composite mechanical property detection method and system, the textile composite mechanical property detection method is modeled to virtual yarn by truss unit, and virtual yarn is combined into yarn interlacing model according to the interlacing rule of warp and weft in three-dimensional angle interlocking woven fabric;Considering the influence of four parameters, warp tension displacement, warp tension load, friction coefficient and fiber elastic modulus in the weaving process on the yarn path and cross section of the fabric forming process, accurate modeling of the three-dimensional angle interlocking fabric weaving forming process is realized, the three-dimensional angle interlocking woven fabric preform model is obtained, and the precision of textile composite preform structure design and manufacturing is improved;Based on three-dimensional angle interlocking woven fabric preform model, the mechanical properties of textile composite are detected, and the accuracy of textile composite mechanical property detection is increased.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preform structure design, and particularly relates to a textile composite mechanical property detection method and system based on weaving forming. BACKGROUND

[0002] Three-dimensional textile composites have good structural designability and anti-delamination, and are widely used in engineering structure fields. The mechanical property research thereof usually relies on time-consuming and material-consuming experimental tests. Compared with traditional experimental tests, computer numerical simulation technology is not limited by experimental conditions, can quickly generate any type of fabric structure model, and greatly saves research time and cost. The fabric forming research on the macro and meso scales has become mature, but the research on the geometric deformation of fibers in the fabric forming process on the micro scale is still a blank. Therefore, a micro-scale high-precision modeling method needs to be constructed, which can describe the contact algorithm between fibers, the formulation of fiber / yarn units, reflect the fiber slippage and buckling phenomenon of three-dimensional angle interlocking woven fabric structures in the fabric forming process, so as to improve the design and manufacturing precision of textile composite preform structures. SUMMARY

[0003] The application aims to provide a textile composite mechanical property detection method and system based on weaving forming.

[0004] In a first aspect, the application provides a textile composite mechanical property detection method based on weaving forming, which comprises the following steps:

[0005] Virtual fiber monofilaments are simulated by truss units, and a plurality of virtual fiber monofilaments form a bundle as a virtual yarn; the virtual yarn is combined into a yarn interlacing model according to the interlacing rule of the warp yarn and the weft yarn inside the three-dimensional angle interlocking woven fabric; the virtual yarn tension and the boundary conditions are set, and the contact condition of the two truss units is set according to the force of each end point of the two truss units in contact with each other and the distance of mutual penetration of the two truss units after contact; the contact condition includes adhesion and slippage; the path of the warp yarn in the yarn interlacing model is set according to the position coordinates of the midpoint of the adjacent weft yarn and the turning point position of the weft yarn section in the same column of weft yarn, and the fabric forming process is simulated based on the above set conditions to obtain a three-dimensional angle interlocking woven fabric preform model.

[0006] As a preferred, the judgment method of the contact condition of the two truss units is as follows:

[0007] If the equivalent friction force between the truss units is less than the critical friction force, the two truss units are in the adhesion state; if the equivalent friction force between the truss units is greater than or equal to the critical friction force, the two truss units are in the slippage state.

[0008] As preferred, the method for obtaining the critical friction force is as follows:

[0009] The shortest distance between the interlaced center points of the two truss units is obtained based on the contact mode of the two truss units, and the force of each end point on the two truss units is obtained in combination with the distance between the contact points and the end points; the normal force of the two truss units is obtained according to the force of each end point and the distance of mutual penetration of the two truss units after contact, and the critical friction force is obtained based on the normal force.

[0010] As preferred, the contact mode of the two truss units includes the contact between the end points, the contact between the end points and the truss unit rods, and the contact between the truss unit rods.

[0011] As preferred, in the yarn interlacing model, the cross section of the warp yarn is square, and the initial cross section of the weft yarn is rectangular.

[0012] As preferred, the path of the weft yarn is set as a straight line, and the length of the weft yarn in the yarn interlacing model exceeds the layout range of the warp yarn arrangement.

[0013] As preferred, the diameter of the virtual fiber monofilament in the warp yarn and the weft yarn in the yarn interlacing model is determined based on the cross-sectional area of the warp yarn and the weft yarn constituting the actual fabric and the fiber diameter constituting the yarn.

[0014] As preferred, the method for setting the virtual yarn tension is that a load tension is applied to the end of the virtual fiber monofilament in the warp yarn and the weft yarn, and the load tension of the warp yarn increases at a speed smaller than that of the weft yarn in the simulation process during the fabric forming process.

[0015] As preferred, the virtual fiber monofilament is composed of a plurality of sequentially connected truss units to form a flexible truss unit chain, and the connection nodes of the end points of adjacent truss units share the same translational degree of freedom.

[0016] As preferred, the method for setting the boundary condition is that the displacement boundary shrinkage amount before and after the warp yarn tension of each warp yarn is set, and the shrinkage amount is set as the difference between the length of the warp yarn in the yarn interlacing model and the actual fabric; the two ends of the weft yarn are fixedly set; and an analytical rigid body is arranged around the yarn interlacing model.

[0017] In a second aspect, the present application provides a textile composite mechanical property detection system based on woven forming, which is used to execute the above-mentioned textile composite mechanical property detection method; the textile composite mechanical property detection system comprises a loose model construction module, a constraint configuration module, a fabric forming simulation module and a mechanical property detection module; the loose model construction module is used to construct a yarn interlacing model; the fabric forming simulation module is used to generate a three-dimensional angle interlocking woven fabric preform model according to the conditions set by the constraint configuration module; and the mechanical property detection module is used to detect the mechanical property of the textile composite according to the three-dimensional angle interlocking woven fabric preform model.

[0018] The present application has the following beneficial effects:

[0019] 1、The present application simulates the contact and extrusion effect of warp yarn and weft yarn and the change of yarn trajectory path in the three-dimensional angle interlocking woven fabric during the fabric forming process by setting the fiber collision relationship between the fibers in the yarn, reflects the slippage and buckling phenomenon of the fabric structure during the weaving forming process, improves the precision of the textile composite preform structure design and manufacturing, and thus improves the accuracy of the mechanical property detection of the textile composite.

[0020] 2、The present application applies the truss element to the virtual fiber with actual material properties by combining the kinetic method and the continuum mechanics theory, models the yarn into a virtual fiber bundle, simulates the traction movement and geometric deformation of the yarn during the weaving process by combining the real loom weaving process, can reflect the interaction of warp yarn and weft yarn during weaving, accurately reflects the extrusion deformation of the yarn cross section and the change of the path, and realizes the accurate reconstruction of the fabric structure. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The present application is a whole flowchart.

[0022] Figure 2 The present application is a schematic diagram of the fiber constituting the yarn interlacing model.

[0023] Figure 3 The present application is a schematic diagram of the yarn interlacing model; wherein (a) is a schematic diagram of the yarn interlacing structure; (b) is a schematic diagram of the warp direction cross section; and (c) is a schematic diagram of the weft direction cross section.

[0024] Figure 4 The present application is a schematic diagram of the warp yarn cross section and the weft yarn cross section of the yarn interlacing model.

[0025] Figure 5 The present application is a schematic diagram of the interaction of warp yarn and weft yarn; wherein (a) is a schematic diagram of the weft yarn change; and (b) is a schematic diagram of the weaving process.

[0026] Figure 6Schematic diagram of yarn tension-time curve in the application.

[0027] Figure 7 Schematic diagram of load boundary condition in the application.

[0028] Figure 8 Schematic diagram of contact mode of different truss units in the application; wherein, (a) is a schematic diagram of penetration distance between two truss units; (b) is a schematic diagram of normal force of truss unit; (c) is a schematic diagram of contact between end point and truss unit rod; (d) is a schematic diagram of contact between end point and end point; (e) is a schematic diagram of contact between truss unit rod and truss unit rod.

[0029] Figure 9 Schematic diagram of obtaining the shortest distance between the interlacing center points of two truss units in the application.

[0030] Figure 10 Schematic diagram of contact interaction force calculation method of two truss units in the application.

[0031] Figure 11 Schematic diagram of warp yarn initial path of yarn interlacing model in the application.

[0032] Figure 12 Schematic diagram of warp yarn boundary shrinkage process of three-dimensional angle interlocking woven fabric preform model in the application; wherein, (a) is a displacement nephogram; (b) is a stress nephogram.

[0033] Figure 13 Flow chart of weaving three-dimensional angle interlocking woven fabric in the application; wherein, (a) is a schematic diagram of shed; (b) is a schematic diagram of weft insertion; (c) is a schematic diagram of stitching; (d) is a schematic diagram of beating-up.

[0034] Figure 14 Schematic diagram of three-dimensional angle interlocking woven fabric sample in the application.

[0035] Figure 15 Schematic diagram of vacuum assisted resin transfer molding process in the application; wherein, (a) is a process diagram; (b) is a yarn path of sample cross section.

[0036] Figure 16 Micro-computed tomography of three-dimensional angle interlocking woven fabric in the application.

[0037] Figure 17 Schematic diagram of fabric preform model in the application.

[0038] Figure 18This is a comparative schematic diagram of the yarn paths of the fabric preform model and the real fabric in this invention; wherein, (a) is a schematic diagram of the warp path of the real fabric; (b) is a schematic diagram of the weft path of the real fabric; (c) is a schematic diagram of the warp path of the fabric preform model; and (d) is a schematic diagram of the weft path of the fabric preform model.

[0039] Figure 19 This is a schematic diagram comparing the warp paths of the fabric prefabricated model and the actual fabric in this invention.

[0040] Figure 20 This is a schematic diagram comparing the weft yarn paths of the fabric prefabrication model and the actual fabric in this invention.

[0041] Figure 21 This is a schematic diagram comparing the cross-sectional area of ​​the yarns in the fabric prefabricated model and the actual fabric in this invention; wherein, (a) is a schematic diagram comparing the warp yarn cross-section; and (b) is a schematic diagram comparing the weft yarn cross-section. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings.

[0043] like Figure 1 As shown, a method for testing the mechanical properties of textile composite materials based on weaving and forming is presented. The mechanical property testing system for textile composite materials includes a loose model construction module, a constraint configuration module, a fabric forming simulation module, and a mechanical property testing module. The loose model construction module is used to construct a yarn interlacing model. The fabric forming simulation module is used to generate a three-dimensional angle interlocking woven fabric preform model according to the conditions set by the constraint configuration module. The mechanical property testing module is used to test the mechanical properties of the textile composite material based on the three-dimensional angle interlocking woven fabric preform model.

[0044] The method for testing the mechanical properties of textile composite materials includes the following steps:

[0045] Step 1: Construct an initial loose yarn interlacing model

[0046] like Figure 2As shown, according to the interlacing rule of the warp and weft inside the fabric, a yarn interlacing model in loose state is created in Abaqus2020 by using Python language compiling script. Since the 3D angle interlocking fabric is woven by multiple yarns, each yarn contains a large number of fiber filaments. In order to balance the calculation efficiency and the accuracy of the model, the number of fiber filaments inside the yarn is simplified, that is, a bundle of a small number of virtual fiber filaments is used to represent a yarn, and the virtual fiber filaments are simulated by truss elements. The virtual fiber filaments are divided into multiple truss elements connected in sequence to form a flexible truss element chain. The truss element is composed of two end points, each end point allows translation movement in three directions, and can only transmit axial force, and cannot bear force and torque perpendicular to the axis of the truss element. In order to simulate the flexibility of the virtual fiber, the connection nodes between adjacent truss element end points share the same translation degree of freedom.

[0047] In this embodiment, each virtual fiber is constructed using T3D2 truss elements (three-dimensional truss elements with two end points), the truss element length is 0.002mm, and the truss element modulus E=10000MPa and density p=2.56g / cm 3 are defined according to the mechanical properties of glass fiber to realize virtual fiber filament simulation.

[0048] As shown in Figure 3 , a plurality of virtual fiber filaments are arranged to form a virtual yarn, and then the virtual yarn is combined into a yarn interlacing model in loose state before interlacing according to the structure of the 3D angle interlocking fabric. After considering the influence of the initial cross section on the numerical simulation results and the complexity of geometric modeling, the initial warp cross section is set as a square and the initial weft cross section is set as a rectangle, as shown in Figure 4 .

[0049] The total area A weft of the weft virtual yarn is represented as:

[0050] A weft = l·w (1)

[0051] Wherein, l and w represent the length and width of the weft cross section respectively:

[0052] l = 8d1 + 7f gap (2)

[0053] w = 4d1 + 3f gap (3)

[0054] Wherein, d1 is the diameter of each fiber in the weft fiber bundle; f gap is the fiber gap in the weft fiber bundle.

[0055] The total area Awarp is represented as:

[0056] A warp = L 2 (4)

[0057] L = 5d2+ 6f gap (5)

[0058] wherein, L is the length of the cross section; d2 is the diameter of each fiber in the warp yarn fiber bundle; f gap is the fiber gap in the warp yarn fiber bundle.

[0059] In order to ensure that the yarn cross-sectional area a r in the fabric model is equal to the actual fabric yarn cross-sectional area, the diameter of the virtual fiber filaments in the warp yarn and weft yarn virtual yarns can be obtained through calculation, and the obtaining method is as follows:

[0060]

[0061] A r = n r · a r (7)

[0062]

[0063] wherein, d r is the diameter of the virtual yarn; A r is the true fiber cross-sectional area; n r is the evaluation coefficient; n is the number of virtual fiber filaments in the actual single yarn; d f is the diameter of the actual fiber filament; N is the number of virtual fibers in the virtual yarn; D is the diameter of the virtual fiber filament.

[0064] In this embodiment, the number of fiber filaments n in the actual single yarn is 30,000; the diameter d f of the actual fiber filament is 12.5 μm; the number of virtual fibers in the warp yarn virtual yarn is 25; the number of virtual fibers in the weft yarn virtual yarn is 32; the diameters d1 and d2 of the virtual fiber filaments in the warp yarn and weft yarn virtual yarns are 0.055 mm and 0.058 mm, respectively.

[0065] Step two, constructing yarn tension and boundary conditions

[0066] The weaving formation of 3D angle interlock fabric is a dynamic process, including the key steps of weft insertion, warp yarns up-and-down interlacing, reed beating and fabric take-up formation. During the whole weaving period, the interlacing and touching of warp and weft yarns, the friction and extrusion between the internal fibers of yarns, and the displacement changes of the rigid components of the loom, as well as the large changes in the appearance of the yarns themselves, all these factors together increase the complexity of the numerical simulation process. Therefore, in order to effectively simulate the formation process of the fabric, the necessary simplification of the whole weaving process of the loom is carried out. Firstly, the complexity of the contact between the yarns and the components of the loom is reduced; secondly, the up-and-down movement of the warp yarns and the beating operation of the reed are simplified.

[0067] As shown in Figure 5 , based on the interaction between warp and weft yarns, the weaving process of 3D angle interlock fabric is divided into four continuous stages: moving, contacting, sticking and sliding. In this embodiment, the two ends of the weft yarn are fixedly arranged. In the moving stage, the warp yarn moves towards the weft yarn; in the contacting stage, the warp and weft yarns are initially interlaced and contacted, the internal stress of the weft yarn is small, and the weft yarn does not deform, and the weft yarn points (A, B, C) are located at their initial positions; in the sticking stage, the warp yarn continues to move towards the weft yarn, under the action of friction force, the weft yarn starts to deform, the normal component of the friction force and the interaction force between the warp and weft yarns cause the cross-section of the yarn to change, and the tangential component causes the weft yarn to be stretched in the axial direction and to be bent and deformed; the bending angle of the weft yarn starts to increase until the warp yarn reaches the fully horizontal position, and the weft yarn points (A, B, C) move to new positions (A1, B1, C1); d1 and d2 mark the start and end points of the contact. In the sliding stage, when the product of the interaction force between the warp and weft yarns and the friction coefficient exceeds the static friction force, sliding occurs, and at this time the curling angle of the weft yarn further increases. The friction force distribution on the weft yarn is symmetrical throughout the process, and the interaction force shrinks from both sides to the center line.

[0068] Because the weft yarn is quickly beaten into the shed by the beating-up device during the interlacing of the warp and weft yarns, the weft yarn tension reaches a constant value in a very short time, while the tension of the warp yarn changes with the up-and-down traction of the heald frame. Immediate loading may cause stress waves to propagate through the virtual fibers, causing the virtual fibers to vibrate and resulting in inaccurate results, so a magnitude function (smooth step) is set to eliminate the adverse effects, and the analysis step time is set to 0.2s, the load tension is smoothly increased from 0 to the set value at the end of the warp fiber of the fabric, and the load tension is linearly increased to the set value at the end of the weft fiber of the fabric within 0.01s and remains unchanged, as shown in Figure 5 .

[0069] In the yarn interlacing model, the loose initial form starts to contact under the influence of yarn tension, both warp and weft yarns are subjected to lateral forces exerted by surrounding yarns, while the yarns located at the edge of the fabric model lack lateral force action, which may cause the yarns near the boundary to be scattered, thereby losing the integrity of the overall structure of the fabric. Therefore, it is necessary to arrange analytical rigid bodies around the fabric model as the boundary of the overall fabric, and set boundaries for each column of warp and weft fiber bundles to reduce fiber shaking and large slip during fabric forming. In addition, it is necessary to establish contact pairs between yarns and boundaries, yarns and yarns, and fibers and fibers to ensure that the entire forming process conforms to the actual form and maintains numerical stability, as shown in Figure 7 .

[0070] Step three, build the collision relationship between fibers

[0071] In the process of forming three-dimensional angle interlocking woven fabric, the mutual extrusion and contact between yarns presents as the mutual touch between fibers at the micro level. The contact between fibers and between yarns can be divided into two cases: (a) adhesion between two truss units; (b) slip between two truss units. The two contact cases are represented as follows:

[0072] f eq f crip (Adhesion) (9)

[0073] f eq f crip (Slip) (10)

[0074] Where f eq is the equivalent friction force, f crip is the critical friction force, and the expression is as follows:

[0075]

[0076] f crip = μ·p (12)

[0077] Where f1 and f2 are two components in the tangential plane of contact respectively; μ is the static friction coefficient; p is the normal force, and its expression is as follows:

[0078] p = p(h) (13)

[0079] h = |||X c -Y c ||-(R x + R y )| (14)

[0080] Where p(·) is the normal force function; h is the distance of mutual penetration of two truss units after contact; X c and Yc These represent the interlacing center points of the two truss units; R x and R y Let X be the radius of the two truss elements; c -Y c || represents the distance between the center points of the two truss elements; |·| is the absolute value symbol.

[0081] The normal force p between truss elements is proportional to the penetration distance h between them, as shown in the figure. Figure 8 As shown in (a) above. If the equivalent frictional force f eq Greater than the critical friction force f crip When calculating the contact between two truss elements, the shortest distance d between the interlacing center points of the two truss elements must be obtained. min There are three types of contact between two different truss elements: contact between endpoints, contact between an endpoint and a truss element member, and contact between two truss element members. For example... Figure 9 As shown, two truss elements are defined as the first truss element and the second truss element; the shortest distance d between the first truss element and the second truss element under different contact methods is... min The method to obtain it is as follows:

[0082] a. When the contact method between the first truss unit and the second truss unit is end-to-end contact, such as... Figure 8 As shown in (d), the shortest distance d min The expression is as follows:

[0083]

[0084] Where Δx, Δy, and Δz are the distances between the endpoints of the two truss elements along the X, Y, and Z axes, respectively.

[0085] b. When the contact between the first truss unit and the second truss unit is such that the end point of the first truss unit is in contact with the truss element member of the second truss unit, as... Figure 8 As shown in (c), the shortest distance d min The expression is as follows:

[0086]

[0087] Where, r j,j+1 The vector formed by the two endpoints of the second truss element; r i,j The vector formed by the endpoints of the first truss element and the second truss element; × represents the cross product between the two vectors.

[0088] c. When the contact mode of the first truss unit and the second truss unit is the contact between the truss unit rod and the truss unit rod, as shown in (e) of Figure 8 , the shortest distance d min is expressed as follows:

[0089]

[0090] wherein r i,i+1 is a vector formed by two end points of the first truss unit; * represents a dot product symbol between two vectors.

[0091] As shown in (f) of Figure 10 , the force F of each end point is obtained according to the shortest distance d min when the different truss units are in contact, and the expression is as follows:

[0092]

[0093] wherein D1 represents the distance between the contact point of the first truss unit and the end point node[1] of the first truss unit; D2 represents the distance between the contact point of the second truss unit and the end point node[2] of the second truss unit; k is a preset parameter; r i and r j are the end point coordinates of the first truss unit and the second truss unit, respectively.

[0094] The normal force p is obtained according to the force F of each end point of the two truss units and the distance h of mutual penetration of the two truss units after being in contact, and the contact of the two truss units is judged based on the normal force p, and the inter-fiber collision relationship is constructed.

[0095] Step four, as shown in (g) of Figure 11 , the center of the weft yarn in the yarn interlacing model is taken as the origin, the warp yarn pulling direction is defined as the X axis (i.e. the 1 direction in the figure), the width direction is defined as the Y axis (i.e. the 2 direction in the figure), and the thickness direction is defined as the Z axis (i.e. the 3 direction in the figure). In order to obtain a more realistic fabric geometric structure, an amplitude load is applied at both ends of the initial loose structure, a tensile load is applied at both ends of the warp yarn in the X axis direction, and the displacement of the weft yarn is limited in the X axis and Y axis directions, so as to simulate the extrusion action between the warp and weft yarns and the tension change process of the fabric during weaving. The initial path of the warp yarn is defined by the "segment point taking" strategy, which divides the warp yarn path into six segments, and the path of the warp yarn is established by using the following formula:

[0096]

[0097]

[0098] wherein Z1, Z2, Z 3,4Z5, Z6 are the initial Z-axis coordinates of the warp yarns in different segments; h is the interlaminar distance between weft yarns; x is the initial X-axis coordinate of the warp yarns; L weft is the horizontal distance between adjacent weft yarns; I and w represent the length and width of the weft yarn cross-section.

[0099] The coordinates of the I, III, IV and VI segments of the warp yarn path are defined by the midpoints of adjacent weft yarns in the same column, while the II and V segments are determined according to the coordinates of the turning points of the weft yarn cross-section, ensuring that the entire path does not interfere with the weft yarns. To prevent the warp yarns at the edge of the model from falling off during the tight interweaving process, the path of the weft yarns is set as a straight line, and the length of the weft yarns in the model exceeds the layout range of the warp yarn arrangement. The specific geometric parameters in the model are shown in Table 1.

[0100] Table 1 Modeling parameters of three-dimensional angle interlocking woven fabric

[0101]

[0102] The yarn interweaving model includes 790,720 units. In the Abaqus software simulation environment, the explicit dynamic algorithm (Dynamic, Explicit Step) is used to simulate the fabric forming process, and the total analysis step duration is set to 0.2s. To increase the efficiency of the calculation, the entire model mass scaling factor is set to vary with the analysis step interval frequency at a rate of 10 -5 The contact between fibers is handled by the Abaqus general contact algorithm, with Hard contact (Abaqus) as the fiber normal contact mode and the tangential friction coefficient set to 0.2. During the numerical simulation of fabric weaving, displacement boundary conditions are set for both ends of each warp yarn, with U1 = ΔU / 2 and U1' = -ΔU / 2; where U1 and U1' are the shrinkage amounts at both ends of the warp yarn; ΔU is the shrinkage amount before and after the warp yarn is tensioned. The periodic warp yarn length is obtained using the ImageJ software, and the warp yarn length in one period range in the three-dimensional angle interlocking woven fabric preform model is calculated according to the analytical formula of the warp yarn path (equations (22) to (26)) Figure 11 I-IV Based on the difference between the two length values, the shrinkage amount before and after the warp yarn is tensioned is determined At the same time, the direction boundary conditions of the weft yarn end 1,2 are fixed as U1 = U2 = 0. Through the virtual fiber structure modeling workflow, a three-dimensional angle interlocking woven fabric preform model is established; and the mechanical properties of the textile composite material are tested based on the three-dimensional angle interlocking woven fabric preform model. The change of the three-dimensional angle interlocking woven fabric preform model from loose to tensioned during the warp yarn boundary shrinkage process is shown in Figure 12 .

[0103] Step five, verifying the accuracy of the fabric preform model

[0104] 5-1. After the fabric model exhibits similarity to the actual fabric, to further verify the accuracy of the fabric model, a textile composite material is prepared, the specific process as follows:

[0105] 5-1-1. As shown in Figure 13 , the three-dimensional angle interlocking fabric is woven including opening, weft insertion and beating-up. The three-dimensional angle interlocking woven fabric is woven by using alkali-free glass fiber material; a shed is created between the layers of interlaced warp yarns for weft yarns to pass through, the weft insertion mechanism is used to pull the weft yarns through the shed and into the interlaced space between the layers of warp woven fabric; since there is no fixed constraint between the warp and weft yarns, in order to prevent the weft yarns from escaping from the warp layer, the structure of interlocking weft yarns between the upper and lower layers of warp yarns is used for stitching; on this basis, the interlaced yarns are pressed into the three-dimensional angle interlocking woven fabric formed by using beating-up reed, thereby completing the process of weaving formation, and the three-dimensional angle interlocking woven fabric formed by weaving is shown in Figure 14 . The three-dimensional angle interlocking woven fabric is divided according to the layer and yarn guide, which is composed of five layers of warp yarns and six layers of weft yarns. In this structure setting, the warp yarns of the fabric are defined as the X-axis, the width direction is defined as the Y-axis, and the thickness direction is defined as the Z-axis, the six layers of weft yarns are arranged in parallel along the direction perpendicular to the X-axis, and the five layers of warp yarns are arranged in parallel in the X-axis direction. In the Z-axis direction, the warp yarns penetrate two layers, and every two interval positions are in opposite wave shape, thereby fixing the fabric in the thickness direction and giving it strength, forming a layer-by-layer interlocking structure.

[0106] 5-1-2. As shown in Figure 15The textile composite material was prepared on a vacuum-assisted resin transfer molding (VARTM) curing fabric sample experimental bench, as shown in the specific process: polishing and cleaning the mold, and coating the mold release agent on the mold. The three-dimensional angle interlocking woven fabric was cut to the required size (250 mm x 300 mm) using an electric cutting machine, and was laid flat on the treated mold to enable the subsequent resin mixture to infiltrate the fabric more quickly. The flow guide net was placed on the three-dimensional angle interlocking woven fabric, and the film was covered; the sealing was closed using a well-sealed black sealant, and the sealing effect of the entire closed system was checked. The pressure was maintained at 0.9 MPa for 20 minutes to ensure stable pressure to verify the reliability of the vacuum sealing. The resin and curing agent were weighed and mixed in a ratio of 100:32, and were stirred uniformly using a glass rod to ensure complete fusion to obtain the resin mixture. The resin mixture was placed in a vacuum pressure container, and the air in the vacuum pressure container and the film was pumped out using a vacuum pump to create a low-pressure environment, and the resin mixture was introduced into the vacuum-sealed film by differential pressure driving to infiltrate the fabric; when the resin mixture flowed out from the other end of the vacuum-sealed film without bubbles, the entire delivery process was completed; the resin mixture infiltrated the fabric at room temperature of 20°C for 24 hours, and then the temperature was adjusted to 70°C in a constant temperature and humidity oven for heating for 16 hours, and the film was removed after cooling to obtain the textile composite material. The thickness of the finally shaped textile composite material was 3.56 mm, and the size was 250 mm x 300 mm.

[0107] 5-2. Using micro-computed tomography (Micro-CT) to obtain the internal yarn interweaving of the fabric

[0108] The cured textile composite material was cut into a CT (computed tomography) scan sample with a size of 20 mm (weft direction) x 30 mm (warp direction) using an electric table saw. The CT scan sample was detected in situ using an X-ray scanning microscope composed of an X-ray source, a rotating table, and an X-ray detector. The CT scan sample was placed on the rotating table which could rotate 360 degrees between the X-ray source and the X-ray detector. When the rotating table rotated, the X-ray beam emitted by the X-ray source was emitted from the source, passed through the CT scan sample, and was finally captured by the receiving plate on the X-ray detector to obtain the corresponding two-dimensional projection image, which was then reconstructed into a three-dimensional image to obtain the three-dimensional reconstruction image of the CT scan sample, as shown in Figure 16 .

[0109] 5-3. The Micro-CT image was preprocessed, and the ImageJ software was used for image data acquisition to extract the yarn path coordinate parameters and measure the cross-sectional area parameters from the image. At the same time, the yarn path of the fabric model numerical simulation result was extracted and the cross-sectional area was calculated to realize the quantitative comparison of the model (see Figure 17), the Euclidean Distance (d ED ) was used as the evaluation criterion. Firstly, the numerical simulation results of the fabric model were analyzed, and the virtual fiber yarn path coordinate points were extracted, which were marked as the coordinates of the i-th node Subsequently, the ImageJ software was used to extract the yarn path coordinates from the CT image at a fixed interval, and the coordinates of the i-th point were marked as and ensured that Finally, the Euclidean distance was calculated, and the formula was as follows:

[0110]

[0111] where n represents the number of nodes on the yarn path.

[0112] As shown in Figure 18 , the three-dimensional angle interlock fabric model showed significant differences before and after numerical simulation. The internal geometric structure of the fabric model after weaving simulation was very similar to the actual fabric, as shown in Figure 18 (a) and (b). Due to the contact effect, the paths of warp and weft yarns changed significantly. The warp yarn path was "stepped" in the loose state, and became smoother after simulation. The weft yarns were originally arranged in a straight line, and after simulation, they were bent due to the interlacing and extrusion of warp yarns. The contact and extrusion of warp and weft yarns also changed the cross-sectional shape of the yarns from regular rectangles and squares in the loose state to "oblate circles". The cross-sectional size and shape of the yarns at different positions also showed similarity.

[0113] In the Micro-CT image of the three-dimensional angle interlock fabric, two cross sections were selected at equal intervals along the 1-3 plane direction (the distance between the cross sections was equal to the warp and weft density), and the path data of the warp yarns were collected. The two adjacent warp yarns in the fabric showed interlocking, and were marked as Warp-1 and Warp-2, respectively. The comparison of the warp yarn path in the fabric preform model and the path in the CT image was shown in Figure 19 . This comparison showed that the path of the warp yarn in the model was consistent with the path of the warp yarn in the actual fabric sample, and the Euclidean distance was 0.048 and 0.059, respectively. Similarly, two cross sections were selected at equal intervals along the 2-3 plane direction (the distance between the cross sections was equal to the weft density), and the two weft yarns were named as Weft-1 and Weft-2, respectively. The comparison of the weft yarn path in the fabric preform model and the CT image was shown in Figure 20 . This comparison also showed that the path of the weft yarn in the model was basically consistent with the path of the weft yarn in the actual fabric sample, and the Euclidean distance was 0.084 and 0.039, respectively.

[0114] During the weaving process, the interlacing and extrusion of warp and weft yarns can change the cross-sectional morphology and area. The yarn cross-sectional area data were obtained from the numerical simulation results of the fabric model and CT images, respectively, and were compared and analyzed. By selecting the 1-3 plane direction and 2-3 plane direction cross sections in the CT images of the fabric sample, the yarn cross-sectional area was calculated. In the 1-3 plane direction cross section, the cross-sectional areas of three weft yarns were measured and 18 data points were obtained; similarly, in the 2-3 plane direction cross section, the cross-sectional areas of the middle three warp yarns were measured and 15 data points were obtained. To make a corresponding comparison, in the fabric preform model, the same position cross sections in the 1-3 plane direction and 2-3 plane direction were selected to measure the yarn cross-sectional area, which were and The yarn cross-sectional area in the fabric model was extremely consistent with the measurement results obtained by Micro-CT images of the actual glass fiber sample, as shown in Figure 21 (a) and (b). The average values of the warp yarn cross-sectional area and were 1.012 and 1.086, respectively, and the standard deviations were 0.035 and 0.032, respectively; while the average values of the weft yarn cross-sectional area and were 1.531 and 1.498, respectively, and the standard deviations were 0.126 and 0.107, respectively. Therefore, by testing the actual fabric sample with Micro-CT scanning, the sample and the model internal yarn geometric path and cross-sectional variation structure characteristics were compared, verifying the effectiveness of the fabric modeling method, and the fabric preform model can accurately reflect the change of the yarn cross-sectional area caused by the interlacing and extrusion of warp and weft yarns.

Claims

1. A method for detecting the mechanical properties of a textile composite based on woven formation, characterized in that: The method comprises the following steps: Simulating virtual fiber filaments by truss units, and forming a bundle of virtual fiber filaments as a virtual yarn, and combining the virtual yarn into a yarn interlacing model according to the interlacing rule of the warp and weft inside a three-dimensional angle interlock fabric; Setting the virtual yarn tension and boundary conditions, and setting the contact condition of the two truss units according to the force of each end point of the two truss units in contact and the distance of mutual penetration of the two truss units after contact; the contact condition includes adhesion and sliding; setting the path of the warp in the yarn interlacing model according to the position coordinates of the midpoint of the adjacent weft in the same column and the turning point of the weft cross section, and simulating the fabric forming process based on the above conditions to obtain a three-dimensional angle interlock fabric preform model, and detecting the mechanical properties of the textile composite material based on the three-dimensional angle interlock fabric preform model; The method for setting the virtual yarn tension is to increase the load tension at the end of the virtual fiber filaments in the warp and weft to a set value, and the speed of increasing the load tension of the warp is less than that of the weft in the simulation process.

2. The method for detecting the mechanical properties of a textile composite material based on weaving patterns according to claim 1, characterized in that: The judgment method of the contact condition of the two truss units is as follows: If the equivalent friction between the truss units is less than the critical friction, the two truss units are in an adhesion state; if the equivalent friction between the truss units is greater than or equal to the critical friction, the two truss units are in a sliding state.

3. The method for detecting the mechanical properties of a textile composite material based on weaving patterns according to claim 2, characterized in that: The method for obtaining the critical friction is as follows: Obtain the shortest distance between the interlacing center points of the two truss units based on the contact mode of the two truss units, and obtain the force of each end point of the two truss units based on the distance between the contact points and the end points; Obtain the normal force of the two truss units according to the force of each end point and the distance of mutual penetration of the two truss units after contact, and obtain the critical friction based on the normal force.

4. The method for detecting the mechanical properties of a textile composite material based on weaving patterns according to claim 3, characterized in that: The contact mode of the two truss units includes the contact between the end points and the end points, the contact between the end points and the truss unit rods, and the contact between the truss unit rods and the truss unit rods.

5. The method for detecting the mechanical properties of the textile composite material based on the weaving pattern according to claim 1, characterized in that: In the yarn interlacing model, the cross section of the warp is a square, and the initial cross section of the weft is a rectangle.

6. The method for detecting the mechanical properties of a textile composite material based on weaving patterns according to claim 1, characterized in that: The path of the weft is set as a straight line, and the length of the weft in the yarn interlacing model exceeds the layout range of the warp arrangement.

7. The method for detecting the mechanical properties of a textile composite material based on weaving patterns according to claim 1, characterized in that: Based on the cross-sectional area of the warp and weft constituting the actual fabric and the fiber diameter constituting the yarn, the diameter of the virtual fiber filaments in the warp and weft in the yarn interlacing model is confirmed.

8. The method for detecting the mechanical properties of a textile composite material based on weaving patterns according to claim 1, characterized in that: The method for setting the boundary conditions is to set the displacement boundary contraction amount before and after the tension of each warp, and the contraction amount is set as the difference between the length of the warp in the yarn interlacing model and the actual fabric; the two ends of the weft are fixedly set; and an analytical rigid body is arranged around the yarn interlacing model.

9. A system for detecting the mechanical properties of a textile composite based on a woven architecture, characterized in that it comprises: A method for detecting the mechanical properties of a textile composite material based on fabric formation according to claim 1; the textile composite material mechanical property detection system comprises a loose model construction module, a constraint configuration module, a fabric formation simulation module, and a mechanical property detection module; the loose model construction module is used to construct a yarn interlacing model; the fabric formation simulation module is used to generate a three-dimensional angle interlocking woven fabric preform model according to the conditions set by the constraint configuration module; the mechanical property detection module is used to detect the mechanical properties of the textile composite material according to the three-dimensional angle interlocking woven fabric preform model.

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