Method and system for detecting mechanical properties of textile composite material based on weaving forming

Abstract

The invention discloses a textile composite material mechanical property detection method and system based on weaving forming, and the method comprises the steps: carrying out the modeling of virtual yarns through a truss unit, and enabling the virtual yarns to be combined into a yarn interweaving model according to the interweaving rule of warp yarns and weft yarns in a three-dimensional angle interlocking woven fabric; influences of four parameters including warp traction and tensioning displacement, warp tension load, friction coefficient and fiber elasticity modulus in the weaving process on a yarn path and a cross section in the fabric forming process are considered, accurate modeling in the three-dimensional angle interlocking fabric weaving forming process is achieved, and a three-dimensional angle interlocking woven fabric preform model is obtained; the structural design and manufacturing precision of the textile composite material prefabricated body is improved; the mechanical property of the textile composite material is detected based on the three-dimensional angle interlocking woven fabric preform model, and the accuracy of mechanical property detection of the textile composite material is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of preform structure design, and particularly relates to a method and system for detecting the mechanical properties of textile composites based on woven forming. Background Art

[0002] Three-dimensional textile composites have good structural designability and anti-delamination properties, and are thus widely used in the field of engineering structures. The research on their mechanical properties usually relies on time-consuming and consumable experimental tests. Compared with traditional experimental tests, computer numerical simulation technology is not limited by experimental conditions and can quickly generate fabric structure models of any type, greatly saving research time and costs. The research on fabric forming at the macro and meso scales has become increasingly mature, but the research on geometric deformation of fiber fabrics during the woven forming process at the micro scale is still blank. Therefore, it is necessary to construct a high-precision modeling method at the micro scale that can describe the contact algorithm between fibers, the formulation of fiber / yarn units, and reflect the slippage and buckling phenomena of fibers during the woven forming process of three-dimensional angle interlock woven fabric structures, so as to improve the design and manufacturing accuracy of textile composite preform structures. Summary of the Invention

[0003] The purpose of the present invention is to provide a method and system for detecting the mechanical properties of textile composites based on woven forming.

[0004] In the first aspect, the present invention provides a method for detecting the mechanical properties of textile composites based on woven forming, which includes the following steps:

[0005] Simulate virtual fiber filaments through truss elements, form bundles with multiple virtual fiber filaments as virtual yarns; combine the virtual yarns into a yarn interweaving model according to the interweaving rules of warp and weft yarns inside the three-dimensional angle interlock woven fabric; set the virtual yarn tension and boundary conditions, and set the contact situation between two truss elements according to the acting force of each end point in two mutually contacting truss elements and the distance of mutual penetration between the two truss elements after contact; the contact situation includes adhesion and slippage; set the path of the warp yarn in the yarn interweaving model according to the midpoint of adjacent weft yarns in the same column of weft yarns and the turning point position coordinates of the weft yarn cross-section, and simulate the fabric forming process based on the above set conditions to obtain a three-dimensional angle interlock woven fabric preform model.

[0006] Preferably, the method for judging the contact situation between two truss elements is as follows:

[0007] If the equivalent frictional force between truss elements is less than the critical frictional force, the two truss elements are in an adhesive state; if the equivalent frictional force between truss elements is greater than or equal to the critical frictional force, the two truss elements are in a sliding state.

[0008] Preferably, the method for obtaining the critical frictional force is as follows:

[0009] Based on the contact mode of two truss elements, obtain the shortest distance between the intertwined center points of the two truss elements, and combine the distances between the contact points and the end points to obtain the acting forces on each end point of the two truss elements; according to the acting forces on each end point and the distance of mutual penetration between the two truss elements after contact, obtain the normal acting force between the two truss elements, and obtain the critical frictional force based on the normal acting force.

[0010] Preferably, the contact modes of the two truss elements include contact between end points, contact between an end point and a truss element rod, and contact between truss element rods.

[0011] Preferably, in the yarn interweaving model, the cross-section of the warp yarn is square, and the cross-section of the initial weft yarn is rectangular.

[0012] Preferably, set the weft yarn path to be a straight line, and the length of the weft yarn in the yarn interweaving model exceeds the layout range of the warp yarn arrangement.

[0013] Preferably, based on the cross-sectional areas of the warp and weft yarns constituting the actual fabric and the fiber diameters of the yarns, confirm the diameters of the virtual fiber filaments in the warp and weft yarns in the yarn interweaving model.

[0014] Preferably, the method for setting the virtual yarn tension is: apply a load tension at the ends of the virtual fiber filaments in the warp and weft yarns and increase it to the set value. The increasing speed of the load tension of the warp yarn during the fabric forming process is less than the increasing speed of the weft yarn during the simulation process.

[0015] Preferably, the virtual fiber filaments are composed of a plurality of sequentially connected truss elements to form a flexible truss element chain, and the connection nodes of adjacent truss element end points to end points share the same translational degree of freedom.

[0016] Preferably, the method for setting the boundary conditions is: set the displacement boundary shrinkage amount before and after warp yarn tension at both ends of each warp yarn, and the shrinkage amount is set to the difference between the length of the warp yarn in the yarn interweaving model and the length of the warp yarn in the actual fabric; fix both ends of the weft yarn; arrange analytical rigid bodies around the yarn interweaving model.

[0017] In the second aspect, the present invention provides a textile composite material mechanical property testing system based on weaving forming, which is used to execute the above-mentioned textile composite material mechanical property testing method; the textile composite material mechanical property testing system 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 interweaving 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.

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

[0019] 1. The present invention simulates the contact and extrusion of warp and weft yarns in three-dimensional angle-interlocked woven fabrics and the changes in yarn trajectory paths during the fabric forming process by setting the inter-fiber collision relationship between fibers in the yarn, reflecting the slip and buckling phenomena of the fabric structure during the weaving process, improving the structural design and manufacturing accuracy of textile composite material preforms, and thus improving the accuracy of mechanical property testing of textile composite materials.

[0020] 2. The present invention combines dynamic methods and continuum mechanics theory, applies truss units to virtual fibers with actual material properties, and models yarns into virtual fiber bundles. By combining the real loom weaving process, the traction motion and geometric deformation of the yarns during the weaving process are simulated. This can reflect the interaction between warp and weft yarns during weaving, accurately reflect the extrusion deformation of the yarn cross-section and the change of the path, and achieve accurate reconstruction of the fabric structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the overall flow chart of the present invention.

[0022] Figure 2 Schematic diagram of the fibers constituting the yarn interweaving model in the present invention.

[0023] Figure 3 Schematic diagram of the yarn interweaving model in the present invention; wherein, (a) is a schematic diagram of the yarn interweaving structure; (b) is a schematic diagram of the warp section; and (c) is a schematic diagram of the weft section.

[0024] Figure 4 Schematic diagram of the warp and weft cross sections of the yarn interweaving model in the present invention.

[0025] Figure 5 Schematic diagram of the interaction between warp yarn and weft yarn in the present invention; wherein, (a) is a schematic diagram of the weft yarn change; (b) is a schematic diagram of the weaving process.

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

[0027] Figure 7 Schematic diagram of load boundary conditions in the present invention.

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

[0029] Figure 9 This is a schematic diagram of obtaining the shortest distance between the interlaced center points of two truss units in the present invention.

[0030] Figure 10 Schematic diagram of the method for calculating the contact interaction force between two truss units in the present invention.

[0031] Figure 11 Schematic diagram of the initial warp yarn path of the yarn interweaving model in the present invention.

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

[0033] Figure 13 Flowchart of weaving three-dimensional angle interlocking woven fabrics in the present invention; wherein, (a) is a schematic diagram of shed; (b) is a schematic diagram of weft insertion; (c) is a schematic diagram of binding; and (d) is a schematic diagram of beating.

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

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

[0036] Fig.16 This is a micro-computed tomography image of the three-dimensional corner interlocking woven fabric of the present invention.

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

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

[0039] Fig.19 Schematic diagram for comparison of the warp paths between the fabric preform model and the real fabric in the present invention.

[0040] Fig. 20 Schematic diagram for comparison of the weft paths between the fabric preform model and the real fabric in the present invention.

[0041] Figure 21 Schematic diagram for comparison of the cross-sectional areas of the yarns between the fabric preform model and the real fabric in the present invention; wherein, (a) is the schematic diagram for comparison of the warp cross-sections; (b) is the schematic diagram for comparison of the weft cross-sections. Detailed implementation manners

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

[0043] As Figure 1 shown, a method for detecting the mechanical properties of a textile composite based on weaving forming, the textile composite mechanical property detection system adopted by which includes 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 interweaving model; the fabric forming simulation module is used to generate a three-dimensional angle-interlocked 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 according to the three-dimensional angle-interlocked woven fabric preform model.

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

[0045] Step 1: Construct an initially loose yarn interweaving model

[0046] As Figure 2As shown in the figure, an initial loose yarn interweaving model was created in the finite element analysis software Abaqus2020 using a Python language compiled script according to the interweaving pattern of the warp and weft yarns inside the fabric. Since three-dimensional angle interlocking woven fabrics are woven from multiple yarns, each yarn contains a large number of fiber filaments. In order to balance the efficiency of the calculation and the accuracy of the model, the number of fiber filaments inside the yarn is simplified. That is, a small number of virtual fiber filaments are used to form a bundle to represent a yarn, and the virtual fiber filaments are simulated by truss elements. The virtual fiber filaments are subdivided into multiple truss elements connected in sequence to form a flexible truss element chain. The truss element consists of two endpoints, each of which allows translational motion in only three directions and can only transmit axial forces. It does not bear forces and moments perpendicular to the truss element axis. In order to simulate the flexibility of the virtual fiber, the connection nodes between adjacent truss element endpoints share the same translational degree of freedom.

[0047] In this embodiment, each virtual fiber is constructed using a T3D2 truss unit (a three-dimensional truss unit with two endpoints). The truss unit length is 0.002 mm. According to the mechanical properties of glass fiber, the truss unit modulus E = 10000 MPa and the density ρ = 2.56 g / cm 3 , realizing virtual fiber monofilament simulation.

[0048] like Figure 3 As shown in the figure, multiple virtual fiber monofilaments are arranged to form virtual yarns, and then the virtual yarns are combined into a yarn interweaving model in a loose state before interweaving according to the three-dimensional angle interlocking woven fabric structure. After considering factors such as the influence of the initial cross section on the numerical simulation results and the complexity of the geometric modeling, the initial warp cross section is set to a square and the initial weft cross section is set to a rectangle, as shown in the figure. Figure 4 shown.

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

[0050] A weft =l·w (1)

[0051] Where l and w represent the length and width of the weft yarn section respectively:

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

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

[0054] Where d1 is the diameter of each fiber in the weft fiber bundle; f gap It is the fiber gap in the weft yarn fiber bundle.

[0055] The total area of the warp virtual yarn Awarp Expressed as:

[0056] A warp = L 2 (4)

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

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

[0059] In order to ensure that the cross-sectional area a of the yarn in the fabric model r is equal to the cross-sectional area of the actual fabric yarn, the diameters of the virtual fiber filaments in the warp and weft 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 cross-sectional area of the real fiber; 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 virtual yarn is 25; the number of virtual fibers in the weft virtual yarn is 32; the diameters d1 and d2 of the virtual fiber filaments in the warp and weft virtual yarns are 0.055 mm and 0.058 mm respectively.

[0065] Step Two: Construct the yarn tension and boundary conditions

[0066] The weaving and forming of three-dimensional angle interlock woven fabrics is a dynamic process, including key steps such as weft insertion, the up-and-down interlacing of warp yarns, the beating-up motion of the reed, and the winding and forming of the fabric. During the entire weaving cycle, due to the mutual interweaving and contact between warp and weft yarns, the friction and extrusion between the internal fibers of the yarns, and the large displacement changes of the rigid components of the loom, as well as the significant morphological changes of the yarns themselves, these factors together increase the complexity of the numerical simulation process. Therefore, in order to effectively simulate the forming process of the fabric, the entire weaving process of the loom is simplified. One is to reduce the contact complexity between the yarns and the loom components; the other is to simplify the up-and-down movement of the warp yarns and the beating-up operation of the reed.

[0067] As Figure 5 shown, based on the interaction between warp and weft yarns, the weaving process of three-dimensional angle interlock woven fabrics is divided into four consecutive stages: movement, contact, adhesion, and sliding. In this embodiment, both ends of the weft yarn are fixedly arranged. In the movement stage, the warp yarn moves towards the weft yarn; in the contact stage, the warp and weft yarns first intersect and contact, the internal stress of the weft yarn is small, and no deformation occurs, and the weft yarn points (A, B, C) are located at their starting positions; in the adhesion stage, the warp yarn continues to move towards the weft yarn, due to the action of friction, the weft yarn begins to deform, the normal component of the friction force and the interaction force between the warp and weft yarns cause changes in the yarn cross-section, and its tangential component causes the weft yarn to be axially stretched and bent; the bending angle of the weft yarn begins 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 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 will occur, and at this time, the curling angle of the weft yarn further increases. The friction force distribution on the weft yarn is symmetric throughout the process, and the interaction force contracts from both sides towards the midline.

[0068] Since during the interweaving process of warp and weft yarns, the weft yarn is quickly beaten into the fell of the cloth by the beating-up device, the tension of the weft yarn 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 heddle frame. Immediate loading may cause stress waves to propagate through the virtual fibers, causing the virtual fibers to vibrate and resulting in inaccurate results. Therefore, a magnitude function (smooth step) is set to eliminate the adverse effects. The analysis step duration is set to 0.2 s. The load tension is smoothly increased from 0 to the set value at the ends of the warp yarn fibers of the fabric, and the load tension at the ends of the weft yarn fibers of the fabric is linearly increased to the set value within 0.01 s and remains unchanged, as Figure 5 .

[0069] In the yarn interweaving model, the loose initial form begins to come into contact under the influence of yarn tension. Both warp and weft yarns are subject to lateral forces exerted by the surrounding yarns. However, the yarns located at the edge of the fabric model lack the action of lateral forces, which may lead to the shedding of the yarns near the boundary, thus losing the integrity of the overall fabric structure. 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 yarn fiber bundles to reduce the vibration and large slippage of the fibers during the fabric forming process. In addition, it is also necessary to establish contact pairs between the yarn and the boundary, between the yarn and the yarn, and between the fiber and the fiber to ensure that the entire forming process conforms to the actual form and maintains numerical stability, as Figure 7 shown.

[0070] Step 3: Construct the collision relationship between fibers

[0071] During the forming process of three-dimensional angle-interlocked woven fabrics, the mutual extrusion and contact between yarns are microscopically manifested as the mutual contact between fibers. There are two situations for the contact between fibers and between yarns: (a) adhesion between two truss units; (b) slippage between two truss units. The two contact situations are expressed as follows:

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

[0073] f eq ≥f crip (Slippage) (10)

[0074] Among them, f eq is the equivalent frictional force, and f crip is the critical frictional force. The expressions are as follows:

[0075]

[0076] f crip =μ·p (12)

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

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

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

[0080] Among them, p(·) is the normal acting force function; h is the distance of mutual penetration between two truss units after contact; X c and Yc respectively represent the intersection centers of two truss elements; R x and R y are the radii of the two truss elements respectively; ||X c -Y c || represents the distance between the intersection centers 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. The specific penetration distance is as shown in Figure 8 (a) in. If the equivalent friction force f eq is greater than the critical friction force f crip , then the shortest distance d between the intersection centers of the two truss elements must be obtained when calculating the contact between the two truss elements. min There are three contact modes between different two truss elements, namely the contact between the end points, the contact between the end point and the truss element rod, and the contact between the truss element rods. As shown in Figure 9 , assume that the two truss elements are the first truss element and the second truss element respectively; for the first truss element and the second truss element in different contact modes, the method for obtaining the shortest distance d min is as follows:

[0082] a. When the contact mode between the first truss element and the second truss element is the contact between the end points, as shown in Figure 8 (d) in, the expression of the shortest distance d min is as follows:

[0083]

[0084] where, Δx, Δy, and Δz are the distances of the end points of the two truss elements in the XYZ axis directions respectively.

[0085] b. When the contact mode between the first truss element and the second truss element is the contact between the end point of the first truss element and the truss element rod of the second truss element, as shown in Figure 8 (c) in, the expression of the shortest distance d min is as follows:

[0086]

[0087] where, r j,j+1 is the vector formed by the two end points of the second truss element; r i,j is the vector formed by the end point of the first truss element and the end point of the truss element rod of the second truss element; × represents the cross product between the two vectors.

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

[0089]

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

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

[0092]

[0093] where 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] According to the acting force F of each end point in the two truss units and the penetration distance h between the two truss units after contact, the normal acting force p is obtained, and based on the normal acting force p, the contact situation of the two truss units is judged to construct the collision relationship between fibers.

[0095] Step Four: As shown in Figure 11 , take the center of the weft yarn in the yarn interlacing model as the origin, define the warp yarn traction direction as the X-axis (i.e., direction 1 in the figure), the width direction as the Y-axis (i.e., direction 2 in the figure), and the thickness direction as the Z-axis (i.e., direction 3 in the figure). To obtain a more realistic fabric geometric structure, amplitude loads are applied at both ends of the initial loose structure. By applying tensile loads at both ends of the warp yarn in the X-axis direction and restricting the displacement of the weft yarn in the X-axis and Y-axis directions simultaneously, the extrusion effect between the warp and weft yarns and the tension change process of the fabric during the weaving process are simulated. The initial path of the warp yarn is defined by the "segmented point-taking" strategy. This method divides the warp yarn path into six sections and uses the following formula to determine the path of the warp yarn:

[0096]

[0097]

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

[0099] The coordinates of the I, III, IV, and VI sections of the warp path are defined by the mid - points of adjacent weft yarns in the same column of weft yarns, while the paths of the II and V sections are determined according to the position coordinates of the turning points of the weft - yarn cross - section, ensuring that there is no interference between the entire path and the weft yarns. To avoid the shedding of the warp yarns at the edge of the model during the interlacing tension process of the warp and weft yarns, the path of the weft yarn is set as a straight line, and the length of the weft yarn 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 3D angle - interlocked woven fabrics

[0101]

[0102] The yarn - interlacing model consists of 790,720 elements. In the Abaqus software simulation environment, the forming process of the fabric is simulated by adopting the explicit dynamic algorithm (Dynamic, Explicit Step), and the total duration of the analysis step is set to 0.2 s. To increase the calculation efficiency, the mass - scaling factor of the entire model is set to vary with the analysis - step interval frequency at 10 -5 changing. The contact action between fibers is processed by Abaqus's general contact algorithm, with Hard contact (Abaqus) as the fiber normal - contact mode, and the tangential friction coefficient is set to 0.2. During the numerical simulation of fabric weaving, displacement boundary conditions are set at both ends of each warp yarn, which are U1 = ΔU / 2 and U1' = - ΔU / 2 respectively; where U1 and U1' are the shrinkage amounts at both ends of the warp yarn, and ΔU is the shrinkage amount before and after the warp yarn is tensioned. The periodic warp - yarn length is obtained by using ImageJ software and the warp - yarn length within one period in the 3D angle - interlocked woven - fabric preform model is calculated according to the analytical formula of the warp - yarn path (Equations (22) to (26)) Figure 11 (I - IV in Based on the difference between these two length values, the shrinkage amount before and after the warp yarn is tensioned is determined Meanwhile, the boundary conditions of the 1 and 2 directions at the end of the weft yarn are fixed as U1 = U2 = 0. Through the virtual - fiber - structure modeling workflow, a 3D angle - interlocked woven - fabric preform model is established; the mechanical properties of the textile composite material are detected based on the 3D angle - interlocked woven - fabric preform model. The change of the 3D angle - interlocked woven - fabric preform model from loose to tensioned during the warp - yarn boundary - shrinkage process is as Figure 12 shown.

[0103] Step 5: Verify the accuracy of the fabric preform model

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

[0105] 5-1-1. Figure 13 As shown in the figure, weaving three-dimensional angle interlocking fabrics includes opening, weft insertion and beating-up. Alkali-free glass fiber materials are used to weave three-dimensional angle interlocking woven fabrics; a shed for the weft yarn to pass through is created between the interwoven warp yarn layers, and a weft insertion mechanism is used to pull the weft yarn through this shed and into the interlayer space of the warp yarn weaving; since there is no fixed constraint between the warp and weft yarns, in order to prevent the weft yarn from escaping the warp yarn layer, a structure of interlocking weft yarns between the upper and lower layers of warp yarns is used for connection; on this basis, a beating-up reed is used to press the interwoven yarns into the formed three-dimensional angle interlocking woven fabric, thereby completing the weaving process. The woven and formed three-dimensional angle interlocking woven fabric is shown in FIG. Figure 14 As shown. Three-dimensional angle interlock woven fabrics are divided according to layup and yarn orientation, and consist of five layers of warp yarns and six layers of weft yarns. In this structural setting, the warp yarn pulling direction of the fabric is 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 a direction perpendicular to the X-axis, while the warp yarns are arranged in five layers in parallel along the X-axis. In the Z-axis direction, the warp yarns run through two layers, and every two intervals have opposite waveforms, thus fixing the fabric in the thickness direction and giving it strength, forming a layered interlocking structure.

[0106] 5-1-2. Figure 15As shown, a textile composite material was prepared on a test bench for curing fabric samples using a vacuum-assisted resin transfer molding (VARTM) molding process. The specific process involved polishing and cleaning the mold and applying a release agent. A three-dimensional, angled interlocking woven fabric was cut to the desired size (250 mm × 300 mm) using an electric cutter and laid flat on the prepared mold to allow the subsequent resin mixture to penetrate the fabric more quickly. A guide mesh was placed on the three-dimensional, angled interlocking woven fabric and covered with a film. The fabric was sealed with a black sealant with good sealing properties, and the sealing effect of the entire closed system was tested. A negative pressure of 0.9 MPa was maintained for 20 minutes to ensure stable pressure and verify the reliability of the vacuum seal. The resin and curing agent were weighed and mixed in a ratio of 100:32. The mixture was stirred evenly with a glass rod to ensure thorough fusion, resulting in a resin mixture. The resin mixture is placed in a vacuum pressure vessel. A vacuum pump is used to remove air from the film and the vacuum pressure vessel, creating a low-pressure environment. The pressure differential drives the resin mixture into the vacuum-sealed film, where it penetrates and impregnates the fabric. The entire transfer process is complete when the resin mixture flows out of the other end of the vacuum-sealed film without bubbles. The resin mixture is then allowed to infiltrate the fabric and cure at room temperature (20°C) for 24 hours. The fabric is then heated in a constant temperature and humidity oven at 70°C for 16 hours. After cooling, the film is removed from the film to produce the textile composite. The final textile composite is 3.56 mm thick and measures 250 mm x 300 mm.

[0107] 5-2. Using Micro-Computed Tomography (Micro-CT) to Obtain the Internal Yarn Interweaving of Fabrics

[0108] An electric table saw is used to cut the cured textile composite material into CT (computed tomography) scanning specimens of 20 mm (weft) × 30 mm (warp). An X-ray scanning microscope consisting of an X-ray source, a rotating stage, and an X-ray detector is used to perform non-in-situ detection on the CT scanning specimen. The CT scanning specimen is placed on a rotating stage that can rotate 360 degrees, located between the X-ray source and the X-ray detector. When the rotating stage rotates, the X-ray beam emitted by the X-ray source is emitted from the source, passes through the CT scanning specimen, and is finally captured by the receiving plate on the X-ray detector to obtain the corresponding two-dimensional projection image, which is then reconstructed into a three-dimensional image to obtain a three-dimensional reconstruction of the CT scanning specimen, as shown in FIG. Fig.16 shown.

[0109] 5-3. Preprocess the Micro-CT images and use ImageJ software to collect image data. Extract the yarn path coordinate parameters and measure the cross-sectional area parameters from the images. At the same time, extract the yarn path and calculate the cross-sectional area of the fabric model numerical simulation results to achieve quantitative comparison of the models (see Figure 17), to evaluate the consistency between the yarn paths of the fabric model and those in the CT images, the Euclidean Distance (d ED ) is used as the evaluation criterion. First, analyze the numerical simulation results of the fabric model, extract the coordinate points of the virtual fiber yarn paths, and mark them as the coordinates of the i-th node Subsequently, use ImageJ software to extract the yarn path coordinates from the CT images at a fixed interval, and denote the coordinates of the i-th point as and ensure Finally, calculate the Euclidean distance, and the formula is as follows:

[0110]

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

[0112] As Figure 18 shown, the three-dimensional angle-interlock fabric model shows significant differences before and after numerical simulation. The internal geometric structure of the fabric model after weaving simulation is very similar to that of the actual fabric, as shown in Figure 18 (a) and (b). Due to the contact effect, the paths of both warp and weft yarns change significantly. The warp yarn path is "stepped" in the loose state and becomes smoother after simulation. The weft yarns were originally arranged in a straight line and become curved after simulation due to the interweaving and extrusion of the warp yarns. The contact and extrusion between warp and weft yarns also change the cross-sectional shape of the yarns from regular rectangles and squares in the loose state to "flat-round". The cross-sectional sizes and shapes of the yarns at different positions also show similarity.

[0113] In the Micro-CT images of the three-dimensional angle-interlock fabric, select two cross-sections at equal intervals along the 1-3 plane direction (the distance between the cross-sections is equal to the warp and weft density), and collect the path data of the warp yarns. These two adjacent warp yarns are interlocked in the fabric and are respectively marked as Warp-1 and Warp-2. Compare the warp yarn paths in the fabric preform model with those in the CT images, as Fig.19 shown. This comparison shows that the warp yarn paths in the model are consistent with those in the actual fabric samples, and the Euclidean distances are 0.048 and 0.059 respectively. Similarly, select two cross-sections at equal intervals along the 2-3 plane direction (the cross-section spacing is equal to the weft density), and name these two weft yarns as Weft-1 and Weft-2 respectively. Compare the weft yarn paths in the fabric preform model with those in the CT images, as Fig. 20 shown. This comparison also shows that the weft yarn paths in the model are basically consistent with those in the actual fabric samples, and the Euclidean distances are 0.084 and 0.039 respectively.

[0114] During the weaving process, the interweaving and squeezing of warp and weft yarns will cause the cross-sectional morphology and area to change. The yarn cross-sectional area data were obtained from the numerical simulation results of the fabric model and the CT image, and compared and analyzed. The yarn cross-sectional area was calculated by selecting two sections in the 1-3 plane direction and the 2-3 plane direction in the CT image of the fabric sample. The cross-sectional area of three rows of weft yarns was measured on the section in the 1-3 plane direction. A total of 18 data points were obtained; similarly, in the 2-3 plane direction section, the cross-sectional area of the middle three rows of warp yarns was measured. 15 data points were obtained. In order to make a corresponding comparison, in the fabric preform model, the cross sections at the same position in the 1-3 plane direction and the 2-3 plane direction were selected to measure the yarn cross-sectional area, which are and The cross-sectional area of the yarn in the fabric model is in good agreement with the measurement results obtained from Micro-CT images of the actual glass fiber sample, e.g. Figure 21 As shown in (a) and (b) in the figure. Warp yarn cross-sectional area and The mean values are 1.012 and 1.086, and the standard deviations are 0.035 and 0.032 respectively; and the cross-sectional area of the weft yarn is and The average values are 1.531 and 1.498, respectively, and their standard deviations are 0.126 and 0.107, respectively. Therefore, by performing Micro-CT scanning tests on actual fabric samples and comparing the geometric paths and cross-sectional structural characteristics of the yarns inside the samples and models, the effectiveness of the fabric modeling method was verified. The fabric preform model can accurately reflect the changes in yarn cross-sectional area caused by the interweaving and extrusion of warp and weft yarns.

Claims

1. A method for testing the mechanical properties of textile composite materials based on weaving, characterized in that: The following steps are involved: The virtual fiber monofilaments are simulated by truss units, and multiple virtual fiber monofilaments are bundled together as virtual yarns. The virtual yarns are combined into a yarn interweaving model according to the interweaving rules of the warp and weft yarns in the three-dimensional angle interlocking woven fabric. The virtual yarn tension and boundary conditions are set, and the contact conditions of the two truss units are set according to the force applied to each endpoint of the two contacting truss units and the distance at which the two truss units penetrate each other after contact; the contact conditions include adhesion and slippage; the paths of the warp yarns in the yarn interweaving model are set according to the position coordinates of the midpoints of adjacent weft yarns in the same column of weft yarns and the turning points of the weft yarn cross-sections, and the fabric forming process is simulated based on the above-set conditions to obtain a three-dimensional angle interlocking woven fabric preform model, and the mechanical properties of the textile composite material are tested based on the three-dimensional angle interlocking woven fabric preform model.

2. The method for testing mechanical properties of textile composite materials based on weaving according to claim 1, characterized in that: The method for determining the contact situation between two truss elements is as follows: If the equivalent friction force between the truss elements is less than the critical friction force, the two truss elements are in a sticking state; if the equivalent friction force between the truss elements is greater than or equal to the critical friction force, the two truss elements are in a sliding state.

3. The method for testing mechanical properties of textile composite materials based on weaving formation according to claim 2, characterized in that: The method for obtaining the critical friction force is as follows: Based on the contact mode of the two truss elements, the shortest distance between the interlaced center points of the two truss elements is obtained, and the force acting on each endpoint of the two truss elements is obtained by combining the distance between the contact point and the endpoint; According to the force at each end point and the mutual penetration distance of the two truss elements after contact, the normal force of the two truss elements is obtained, and the critical friction force is obtained based on the normal force.

4. The method for testing mechanical properties of textile composite materials based on weaving formation according to claim 3, characterized in that: The contact modes of the two truss units include contact between end points, contact between end points and truss unit rods, and contact between truss unit rods.

5. A method for detecting the mechanical properties of a textile composite material based on woven forming according to claim 1, characterized in that: In the yarn interweaving model, the cross section of the warp yarn is square and the initial cross section of the weft yarn is rectangular.

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

7. A method for detecting the mechanical properties of a textile composite material based on woven forming according to claim 1, characterized in that: The diameters of virtual fiber monofilaments in the warp and weft yarns in the yarn interweaving model are determined based on the cross-sectional areas of the warp and weft yarns constituting the actual fabric and the diameters of the fibers constituting the yarns.

8. A method for detecting the mechanical properties of a textile composite material based on woven forming according to claim 1, characterized in that: The method for setting the virtual yarn tension is: applying load tension to the ends of virtual fiber monofilaments in the warp and weft yarns and increasing the tension to a set value, wherein the speed at which the load tension of the warp yarn increases during the fabric forming process is slower than the speed at which the weft yarn increases during the simulation process.

9. A method for detecting the mechanical properties of a textile composite material based on woven forming according to claim 1, characterized in that: The method for setting the boundary conditions is as follows: the displacement boundary contraction amount before and after the warp yarn is tensioned is set at both ends of each warp yarn, and the contraction amount is set to the difference between the warp yarn length of the yarn interweaving model and the actual fabric; the two ends of the weft yarn are fixed; and an analytical rigid body is arranged around the yarn interweaving model.

10. A mechanical property detection system for textile composites based on weaving forming, characterized in that: Used to execute the method for testing the mechanical properties of textile composite materials based on weaving formation as described in claim 1; the textile composite material mechanical property testing system 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 interweaving 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.

Images