A light and thin flexible fabric protective equipment for large tanks

Abstract

The application discloses a light and thin flexible fabric protective equipment for a large tank body, and a key protection layer of the protective equipment is a polypropylene plain weave fabric made of cross-shaped fibers. Through finite element simulation and impact experiment, the yarn cross-sectional shape and the fabric structure of the fabric with the highest impact resistance are jointly analyzed and verified, and are used as the preparation parameters of the fabric for manufacturing the protective equipment. Through the design of the fabric preparation parameters, the prepared protective equipment can effectively absorb and dissipate impact energy when impacted, and has the characteristics of lightness, thinness and compactness. The safety of the large tank body during transportation can be significantly improved, the deformation or damage caused by impact can be reduced, and the transportation efficiency can be improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of mechanical engineering, and in particular to a light and thin flexible fabric protective equipment for a large tank. BACKGROUND

[0002] With the rapid development of the aerospace industry, the number of rocket launch missions has significantly increased, and higher requirements have been put forward for the transportation safety of large tanks. In the transportation process of the rocket, especially when transported by railway, natural hazards such as falling rocks may be encountered, which pose a serious threat to the tank and the precise instruments inside. Due to the size limitation of the railway tunnel, the traditional metal protective equipment cannot meet the transportation requirements of large-size tanks because of its large thickness and high weight. Therefore, there is an urgent need for a new type of light and thin protective equipment to ensure the safety of large tanks during transportation.

[0003] Fabric-type protective equipment has gradually attracted attention due to its unique performance. When impacted, the fabric can effectively reduce the damage caused by external impact energy based on the viscoelastic deformation of its flexible material and the internal friction between the internal micro molecular chains and the external friction between the macro yarns and fibers. At present, the flexible fabric protective equipment for large tanks mainly uses non-woven fabric, but the non-woven fabric itself has a high density, poor energy absorption performance, large thickness, and is difficult to lay, which cannot meet the application requirements of the protective equipment for large tanks. SUMMARY

[0004] The embodiment of the application provides a light and thin flexible fabric protective equipment for a large tank, which improves the influence of the boundary conditions and the organizational structure of the fabric on the impact performance by design, and meets the transportation requirements of large tanks.

[0005] To achieve the above-mentioned purpose, the technical scheme of the embodiment of the application is as follows:

[0006] In a first aspect, the embodiment of the application provides a light and thin flexible fabric protective equipment for a large tank, and the key protective layer of the protective equipment is a polypropylene plain weave fabric made of cross-shaped fibers; wherein the preparation parameters of the fabric are determined by the following steps:

[0007] Using polypropylene as the raw material, the spinneret hole type selection, pump supply and winding speed of the spinning machine are controlled, the drawn fibers are post-drawn and combined by using the drawing equipment, and the multi-filament yarns with different mechanical properties and different cross-sectional shapes are prepared;

[0008] Using the prepared yarns with different cross-sectional shapes, the fabrics with different organizational structures are obtained through the plain weave, twill and satin weave processes;

[0009] The impact response characteristics of the prepared fabrics with different weave structures are simulated by using a preset finite element analysis software, and the influences of the mechanical properties of the yarns, the surface friction coefficients of the yarns and the weave structures of the fabrics on the impact energy loss performance of the fabrics are analyzed; the surface friction coefficients of the yarns are controlled by adjusting the twist and the cross-sectional shape of the yarns; the mechanical properties and the surface friction coefficients of the yarns are measured by a single yarn strength tester and a yarn friction coefficient tester;

[0010] According to the prepared fabrics with different weave structures, a drop ball impact experiment with the same parameters as the finite element simulation is designed to verify the accuracy of the finite element analysis results.

[0011] According to the results of the finite element simulation and the drop ball impact experiment, the impact resistance performance of the fabrics prepared by different yarn cross-sectional shapes and weave structures is evaluated.

[0012] The yarn cross-sectional shape and the weave structure of the fabric with the highest impact resistance performance are used as the preparation parameters of the fabric for making protective equipment.

[0013] In some possible implementations, the impact response characteristics of the fabrics with different weave structures are simulated by using a preset finite element analysis software, including:

[0014] The yarn center line equation is determined by the yarn cross-sectional shape and the yarn path, the yarn center line is drawn according to the yarn center line equation, and then a single yarn model is obtained by scanning the yarn cross-section along the yarn center line;

[0015] The yarns are arrayed according to the single yarn model to obtain a three-dimensional model of the fabric;

[0016] According to the anisotropy of the fiber material of the yarns, the elastic modulus, the shear modulus and the stiffness matrix of the yarn fibers in the axial and radial directions are determined, and a constitutive model of the fiber material is established; the constitutive model includes an elastic-plastic model and a failure model;

[0017] The finite element analysis preprocessing includes: in the preset finite element analysis software, the three-dimensional model of the fabric is imported; based on the constitutive model of the fiber material, the three-dimensional model of the fabric is meshed; the initial speed, the size and the position of the impact object and the boundary conditions of the fabric are set; the contact properties are defined, and the contact relationship between the impact object and the fabric is set;

[0018] The finite element simulation includes: the response characteristics of the fabric when impacted are simulated by using the explicit dynamics solver of the finite element analysis software; the displacement deformation, the speed change, the energy absorption and loss parameters of the fabric during the impact process are observed and recorded; the influences of different weave structures on the impact resistance performance of the fabric are analyzed, including the deformation degree of the fabric, the stress wave propagation form, etc.

[0019] In some possible implementation manners, the cross-sectional shape of the yarns includes a circle, a trilobal shape and a cross shape; the yarns with different cross-sectional shapes are prepared by adjusting the spinneret hole type of a spinning machine.

[0020] In some possible implementation manners, the preparation parameters further include the number of layers of the fabric; the drop ball impact experiment is performed by adjusting the number of layers of the fabric, so that the energy absorption performance and the impact resistance of the fabric are optimized.

[0021] The one or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0022] In the embodiments of the present application, the protective equipment is made of a polypropylene plain woven fabric made of cross-shaped fibers, and by designing the fabric preparation parameters, the protective equipment made of such shape fibers has better impact resistance than the traditional circular fiber plain woven fabric when impacted, and has the characteristics of lightness, thinness and compactness. The safety of the large tank during transportation can be significantly improved, the deformation or damage caused by impact can be reduced, and the transportation efficiency can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0024] Figure 1 A flexible fabric schematic diagram of a light and thin flexible fabric protective equipment for a large tank provided in the embodiments of the present application;

[0025] Figure 2a A yarn cross-sectional schematic diagram of a circular fiber;

[0026] Figure 2b A yarn cross-sectional schematic diagram of a trilobal fiber;

[0027] Figure 2c A yarn cross-sectional schematic diagram of a cross-shaped fiber;

[0028] Figure 3a A plain woven fabric structure schematic diagram;

[0029] Figure 3b A twill woven fabric structure schematic diagram;

[0030] Figure 3c A satin woven fabric structure schematic diagram;

[0031] Figure 4a A yarn weft basic unit schematic diagram in a plain woven fabric;

[0032] Figure 4b Schematic diagram of the yarn interlacing form of a plain fabric and determination of the yarn centerline path equation thereof;

[0033] Figure 5 Schematic diagram of the yarn interlacing form of a twill fabric and determination of the yarn centerline path equation thereof;

[0034] Figure 6 Schematic diagram of the yarn interlacing form of a satin fabric and determination of the yarn centerline path equation thereof;

[0035] Figure 7 Schematic diagram of the boundary of the maximum stress criterion and the maximum strain criterion in the stress space in the embodiment of the present application;

[0036] Figure 8 Schematic diagram of the stress propagation form of a plain fabric after being impacted in the embodiment of the present application;

[0037] Figure 9 Schematic diagram of the displacement-time curve of a fabric in the impact direction under different friction coefficients of yarns;

[0038] Figure 10 Schematic diagram of the velocity-time curve of a fabric under different friction coefficients of yarns;

[0039] Figure 11a Schematic diagram of the displacement-time curve of a fabric;

[0040] Figure 11b Schematic diagram of the velocity-time curve of an impactor;

[0041] Figure 12 Schematic diagram of the energy absorption-time curve of each factor of a fabric with different weave structures;

[0042] Figure 13 Schematic diagram of a fabric fixing platform;

[0043] Figure 14 Schematic diagram of the displacement-time curve of a woven fabric with different friction coefficients of yarns when impacted in the embodiment of the present application;

[0044] Figure 15a Impact experiment image of a twill fabric;

[0045] Figure 15b Impact experiment image of a sateen fabric;

[0046] Figure 16 Schematic diagram of the displacement curve of three different weave structure double-layer fabrics when impacted. DETAILED DESCRIPTION

[0047] With reference to the drawings, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort are within the protection scope of the present application.

[0048] In the related description of the embodiments, the terms "comprise, contain, have" and the like are open terms, which are generally preferred to be understood as including but not limited to; the term "at least one" is generally preferred to be understood as one or more, wherein "more" refers to two or more; the term "at least one of the following" or similar expressions refers to any combination of the terms, including any combination of single or multiple terms, for example, "at least one of a, b or c", or "at least one of a, b and c", which can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple; the symbol "A / B" is used to describe the selection relationship of the associated objects, which generally represents the relationship of "or".

[0049] In the following description of the embodiments of the present application, the terms used in the embodiments of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0050] Those skilled in the art should understand that in the following description of the embodiments of the present application, the order of the serial numbers does not mean the order of execution, and some or all steps can be executed in parallel or in sequence, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0051] Those skilled in the art should understand that the numerical ranges in the embodiments of the present application should be understood as also specifically disclosing each intermediate value between the upper limit and the lower limit of the range. Each smaller range between any stated value or stated range of values and any other stated value or stated range of values is also included within the present application. The upper and lower limits of these smaller ranges can be independently included or excluded from the ranges.

[0052] Technical / scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this application belongs unless otherwise indicated. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All documents mentioned herein are incorporated by reference to disclose and describe in full the methods and / or materials which are described therein. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails.

[0053] To illustrate the technical solutions of the present application, specific examples are used in the following description.

[0054] With the rapid development of the aerospace industry, the number of rocket launch missions has increased significantly, and higher requirements have been placed on the safety of large tank transportation. During the transportation of rockets, especially when transported by rail, natural hazards such as falling rocks may be encountered, which pose a serious threat to the tank and its internal precision instruments. Due to the size limitation of railway tunnels, traditional metal protective equipment cannot meet the transportation needs of large-sized tanks because of its large thickness and high weight. Therefore, there is an urgent need for a new type of light and thin protective equipment to ensure the safety of large tanks during transportation.

[0055] Fabric-type protective equipment has gradually attracted attention due to its unique performance. When impacted, the fabric can effectively reduce the longitudinal penetration of impact energy based on the viscoelastic deformation of its material and the internal friction between the micro molecular chains and the external friction of the macro yarns and fibers. Currently, the flexible fabric protective equipment for large tanks mainly uses non-woven fabric, but non-woven fabric itself has a high density, poor energy absorption performance, and a large thickness, making it difficult to lay and unable to meet the application requirements of protective equipment for large tanks.

[0056] Based on this, the embodiments of the present application provide a light and thin flexible fabric protective equipment for large tanks, which improves the impact performance by designing the boundary conditions and organizational structure of the fabric, and can meet the transportation needs of large tanks. Figure 1 A flexible fabric schematic diagram of a light and thin flexible fabric protective equipment for large tanks provided by the embodiments of the present application, the key protective layer of the light and thin flexible fabric protective equipment for large tanks is made of a polypropylene plain weave fabric made of cross-shaped fibers as shown in Figure 1 . Figure 1 In some embodiments, the preparation parameters of the fabric are determined by the following steps:

[0057] In some embodiments, the preparation parameters of the fabric are determined by the following steps:

[0058] S11 uses polypropylene as raw material. By selecting the spinneret orifice type, pump supply and winding speed of the melt spinning machine, and using the drawing equipment to perform post-drawing and doubling of the produced fibers, multifilament yarns with different mechanical properties and different cross-sectional shapes are prepared.

[0059] Understandably, as the basic unit of a fabric system, the mechanical properties of multifilament yarn significantly influence the overall impact resistance of the fabric. The primary failure mode of a fabric under impact is tensile fracture of the yarn. Most of the kinetic energy of the impactor is converted into strain energy dissipated during yarn elongation, including both elastic and plastic strain. The energy absorbed during yarn elongation can be expressed by the following formula:

[0060]

[0061] Among them, E tensi l e The total energy absorbed by the yarn during stretching and deformation, ε max Let σ(ε) be the ultimate strain of the yarn, and let σ(ε) be the stress-strain relationship of the yarn during the stretching process.

[0062] The amount of energy absorbed during yarn stretching is influenced by several factors, including the yarn's limiting strain rate and tensile strength at different strain rates. Polypropylene chips, in a molten state at high temperature, pass through spinneret holes and cool to form nascent fibers. At this stage, the fiber polymer chains are in a disordered and low-orientation state. The nascent fibers have high elongation but low tensile strength, making them unusable. After stretching, the molecular chains orient axially, resulting in better mechanical properties. Fibers acquire different mechanical properties after being stretched at different ratios. As the stretching ratio increases, the orientation of the fiber's macromolecular chains improves, increasing the fiber's axial elastic modulus while decreasing its elongation at break. This method can yield yarns with the same linear density and cross-sectional size but different elastic-plastic moduli and elongation at break. Different process parameters can be used to obtain nascent fibers with different linear densities. These process parameters can be expressed by the following formula:

[0063]

[0064] Where, N t c is the linear density of the monofilament, c is the extrusion rate per unit revolution of the metering pump, and v is the linear density of the monofilament. pump The metering pump speed is ρ, the solution density of the fiber material is v. win d is the final winding speed, and f is the number of spinneret holes.

[0065] In some embodiments, the cross-sectional shape of the yarns includes a circle, a trilobal shape, and a cross shape; the yarns with different cross-sectional shapes are prepared by adjusting the spinneret hole type of the spinning machine.

[0066] In the embodiments of the present application, by adjusting multiple parameters such as the spinneret hole type of the spinning machine, the pump supply, the winding speed, and the draft ratio, yarns with different cross-sectional shapes and mechanical properties can be prepared using polypropylene as the raw material.

[0067] Yarns with different cross-sectional shapes can be prepared by using spinnerets with different hole shapes. For example, Figures 2a to 2c are yarns with different cross-sectional shapes. Among them, Figure 2a is a schematic diagram of the cross section of a yarn with a circular fiber, Figure 2b is a schematic diagram of the cross section of a yarn with a trilobal fiber, Figure 2c is a schematic diagram of the cross section of a yarn with a cross-shaped fiber.

[0068] S12, using the yarns with different cross-sectional shapes and mechanical properties prepared, fabrics with different weave structures are obtained through the weaving processes of plain weave, twill weave, and satin weave;

[0069] It can be understood that the response characteristics of fabrics with different weave structures when subjected to impact are different, and the contact area of yarns in the fabrics is also different. Therefore, in the embodiments of the present application, when determining the fabric preparation parameters, the impact resistance performance of the fabrics is analyzed by preparing fabrics with different weave structures, so as to determine the weave structure of the fabric suitable for use in the large tank light and thin flexible fabric protective equipment.

[0070] Exemplarily, Figures 3a to 3c are schematic diagrams of the microsurfaces of fabrics with different weave structures. Among them, Figure 3a is a schematic diagram of a plain weave fabric, Figure 3b is a schematic diagram of a twill weave fabric, Figure 3c is a schematic diagram of a satin weave fabric.

[0071] S13, using the preset finite element analysis software, the impact response characteristics of the prepared fabrics with different weave structures are simulated by finite elements, the influence of the micro performance of the yarns, the surface friction coefficient of the yarns, and the weave structure of the fabric on the impact energy loss performance of the fabric is analyzed; wherein the surface friction coefficient of the yarns is controlled by adjusting the twist and cross-sectional shape of the yarns; the mechanical properties and the surface friction coefficient of the yarns are determined by a single yarn strength tester and a yarn friction coefficient tester;

[0072] S14, according to the prepared fabrics with different weave structures, a drop ball impact experiment with the same parameters as the finite element simulation is designed to verify the accuracy of the finite element analysis results;

[0073] S15, according to the results of the finite element simulation and the drop ball impact experiment, evaluating the impact resistance of the fabric prepared by different yarn cross-sectional shapes and fabric structures;

[0074] Specifically, in the step S13, the process of the finite element simulation specifically includes:

[0075] S131, determining the yarn center line equation through the yarn cross-sectional shape and the yarn path, drawing the yarn center line according to the center line equation, and obtaining the single yarn model through scanning the yarn cross-section along the yarn center line;

[0076] S132, arraying the yarn according to the single yarn model to obtain the three-dimensional model of the fabric;

[0077] S133, determining the elastic modulus, shear modulus and stiffness matrix of the yarn fiber in the axial and radial directions according to the anisotropy of the fiber material of the yarn, and establishing the constitutive model of the fiber material; the constitutive model includes an elastic-plastic model and a failure model;

[0078] S134, finite element analysis preprocessing, including: importing the three-dimensional model of the fabric in the preset finite element analysis software; based on the constitutive model of the fiber material, the three-dimensional model of the fabric is meshed; setting the initial speed, size and position of the impact object and the boundary conditions; defining the contact attribute, setting the contact relationship between the impact object and the fabric;

[0079] S135, performing finite element simulation, including: using the explicit dynamics solver of the finite element analysis software to simulate the response characteristics of the fabric when it is impacted; observing and recording the displacement deformation, velocity change, energy absorption and loss parameters of the fabric during the impact process; analyzing the influence of different mechanical properties and structures on the impact resistance of the fabric, including the size of the fabric deformation and the stress wave propagation form.

[0080] Specifically, when performing the finite element model of the fabric impact resistance, it is necessary to first establish the three-dimensional model of the fabric. The above-mentioned preset finite element software can be any existing three-dimensional simulation software, such as SolidWorks, Rhino, etc.

[0081] First, in order to facilitate the establishment of the model and the finite element analysis, the yarn and fabric structure can be properly idealized. Including: assuming that the cross-sectional shape of a single yarn in the fabric is the same everywhere, ignoring the change of the cross-sectional shape of the yarn due to extrusion and tension at a certain node; the yarns in the fabric are usually in close contact, but during the modeling process, the contact and interference problems will lead to the combination of the warp and weft yarns at the intersection to form a cross-shaped fixed node, and the friction between the yarns is ignored, which leads to distortion of the simulation, so a small gap is reserved between the warp and weft yarns during modeling. During the meshing process of finite element analysis, the smallest component should also satisfy at least four layers of mesh in different directions. Limited by computer computing efficiency, the smallest scale of the fabric model is established at the yarn level, and the space left in the fiber bundle inside the yarn and the friction between the fibers are ignored.

[0082] Yarn is an orthotropic, compressible viscoelastic material, which is twisted or held together by a plurality of fiber bundles inside. Due to the existence of internal tension and extrusion in the fabric, the cross section of the yarn is often not circular in the ideal case. The yarn cross-sectional parameters including cross-sectional shape, cross-sectional diameter are indispensable parameters for fabric model establishment. The yarn cross-sectional shape is affected by many factors, including twist, tension and spinning method.

[0083] When the yarn twist is high, the ratio of the long axis to the short axis of the yarn will also decrease accordingly. And the yarn cross-sectional shape after being woven into a sample cloth by a loom is usually irregular oval. In the embodiment of the present application, the yarn cross-sectional shape can be simplified during the establishment of the fabric model, for example, it is idealized as an ellipse with a long axis to short axis ratio of 2:1.

[0084] After determining the yarn cross-sectional shape, it is further necessary to determine the yarn path. The determination method of the yarn path includes the usual broken line method and the piecewise fitting method. The broken line method regards the yarn path as the splicing of multiple straight lines, and the discontinuity of the first derivative does not conform to the real path of the yarn in the fabric. The warp and weft yarn curve equations are established on the basis of the Peirce theoretical model to determine the path of the yarn center line in the coordinate system and the change of the curvature of the yarn, and the curve fitting is used to determine the equation of the yarn center line. At the same time, the path curve of the yarn is properly adjusted to avoid the distortion of the finite element analysis caused by the interference problem between the warp and weft yarns.

[0085] In the actual organization structure of the fabric, the yarn is divided into warp and weft, and there are slight differences in cross-sectional size and thickness between the two. But considering the balance of efficiency and the slight difference in performance, the structure size and material performance of all warp and weft yarns can be assumed to be the same in the fabric model.

[0086] Firstly, a yarn path curve equation in the plain fabric is constructed. The yarn path in the woven fabric of the plain fabric has regularity, and a basic unit of the weft yarn can be drawn as shown in Figure 4a , Figure 4a which is a basic unit of the weft yarn in the plain fabric in the embodiment of the present application. Referring to Figure 4a , the long axis and the short axis of the yarn are determined as a1 and b1 respectively, and the bending wave height of the yarn is h j , and the length between the adjacent yarns is S j .

[0087] The establishment of the warp yarn path curve equation in the woven fabric of the plain fabric comprises: in a rectangular coordinate system, the relative position relationship between the warp yarn and the weft yarn in the plain fabric is drawn as shown in Figure 4b . Wherein, x represents the warp yarn axial direction, y represents the weft yarn axial direction, and z represents the normal direction perpendicular to the fabric.

[0088] It is assumed that the path curve equation of the warp yarn is represented as Z=f(x), x∈(-S j , S j ), and the path equation f(x) is an even function about the central line Z axis, that is, only the expression of the equation Z=f(x) in the region of x∈(0, S j ) needs to be obtained. The warp yarn passes through three points A, B and C, and has a horizontal tangent at the two points B and C, and the slope is 0. The short axis of the yarn cross section is tangent to the point B, and the curvature radius of the yarn central line at this point is a1.

[0089] The polynomial curve fitting method is adopted for the yarn path, and the number of times is too high to increase the operation cost, and the number of times is too low to ensure the accuracy. In the embodiment of the present application, a quintic polynomial can be selected, and the central line track of the yarn is:

[0090] f(x)=α5x 5 +α4x 4 +α3x 3 +α2x 2 +α1x+α0

[0091] a1 to a5 can represent the long axis of the five consecutive five yarns respectively. The warp yarn path curve equation can be represented as:

[0092]

[0093] The weft yarn and the warp yarn have the same path curve equation, and based on the similar idea, the path curve equation of the weft yarn is represented as:

[0094]

[0095] The main difference between the yarn path of twill and satin fabric and the yarn path of plain fabric is the floats in the yarn. The BC and CD segments of floats in the yarn can be considered as straight lines due to the presence of tension in the yarn.

[0096] Exemplary, Figure 5 is a schematic diagram of the yarn path of twill fabric, Figure 6 is a schematic diagram of the yarn path of satin fabric.

[0097] The equation of the warp yarn centerline of twill fabric is represented as:

[0098]

[0099] The equation of the warp yarn centerline of satin fabric is represented as:

[0100]

[0101] where a0, a 1… a5 has the same value as the coefficient of the yarn centerline equation of plain fabric.

[0102] After obtaining the yarn centerline equation, the yarn centerline can be drawn by a curve driven by the equation, and a single yarn model can be obtained by scanning the yarn cross-section along the yarn centerline. After obtaining the single yarn model of the warp and weft directions of the fabric, the yarns are arrayed and checked for interference positions, and the curvature of the centerline of the yarns with interference positions is adjusted to construct a fabric model corresponding to different weave structures.

[0103] In some embodiments, in order to save computer computing power, only a 1 / 4 fabric model can be established, and the 1 / 4 model constructed can achieve the same simulation results as the full-size model through mirror symmetry.

[0104] In some embodiments, in step S133, the axial elastic modulus reflects the stress-strain relationship of the fiber when it is stretched or compressed in the axial direction. Through a standard tensile test, the ratio of stress increase to length change of the fiber in the axial direction can be measured, and thus the axial elastic modulus can be calculated. The shear modulus represents the ability of the fiber to resist deformation when subjected to shear force. For anisotropic materials, different shear moduli in different directions may need to be considered, such as axial-radial shear modulus and radial-radial shear modulus.

[0105] The stiffness matrix is a mathematical representation that describes the stress-strain relationship of a material in each direction. For anisotropic materials, the stiffness matrix will contain multiple independent elastic constants that reflect the response of the material in different loading directions. Through experimental measurement and theoretical derivation, a stiffness matrix reflecting the anisotropic properties of the yarn fiber can be constructed.

[0106] Elasto-plastic model combines elastic theory and plastic theory to describe the behavior of materials under different stress states, considering the elastic and plastic deformation stages that the fiber material may experience during the stress process. Due to the orientation of macromolecular chains in textile fibers, the mechanical properties of the fiber in the axial and radial directions are completely different, but the material properties in the radial plane are isotropic. Therefore, by determining the elastic modulus, shear modulus and stiffness matrix of the fiber in the axial and radial directions, a more realistic material model can be obtained.

[0107] In some embodiments, the elasto-plastic model of the fiber material can be represented as:

[0108]

[0109] where E is the elastic modulus in the axial direction, c is the strength of the yarn when reaching a total deformation of 1%, l is the clamping length of the single yarn tensile strength tester, N t is the linear density of the yarn, p is the density of the fiber material, s is the elongation of the yarn when reaching a total deformation of 1%, s is the tensile stress, and s is the tensile strain.

[0110] In some embodiments, the failure model of the fiber material includes a maximum stress failure criterion and a maximum strain failure criterion.

[0111] where the maximum stress failure criterion is represented as:

[0112]

[0113] τ 12 |<s LT

[0114] where, respectively represent the ultimate compressive stress and the ultimate tensile stress of the material in its longitudinal direction, respectively represent the ultimate compressive stress and the ultimate tensile stress of the material in its transverse direction, |τ 12 | represents the in-plane ultimate shear stress of the material.

[0115] The maximum strain failure criterion is represented as:

[0116]

[0117] γ 12 |<e LT

[0118] where, respectively represent the ultimate compressive strain and the ultimate tensile strain of the material in its longitudinal direction, respectively represent the ultimate compressive strain and the ultimate tensile strain of the material in its transverse direction, γ12 | represents the in-plane limit shear strain of the material.

[0119] The maximum strain failure criterion measures the failure of the material by the size of the strain, but in the usual practical structure analysis, it is also converted into the failure boundary of the material in the stress space. The relationship between the material stress and strain can be expressed as:

[0120]

[0121] There is also a stress-strain relationship in the lateral direction of the material, which can be obtained by further simplification:

[0122]

[0123] According to the above formula, the minimum boundary of the maximum stress failure criterion and the maximum strain failure criterion in the stress space can be expressed by Figure 7 . Figure 7 Figure 1 is a schematic diagram of the boundaries of the maximum stress criterion and the maximum strain criterion in the stress space in an embodiment of the present application. By observing Figure 7 the maximum stress failure criterion and the maximum strain failure criterion, it can be found that when the material is subjected to positive load at both ends, that is, subjected to tensile stress (represented by the position of the first quadrant in the figure), the maximum strain failure criterion is more relaxed than the maximum stress failure criterion, and the material can withstand greater tensile stress between the two axial directions, but the real situation is that the material has been damaged when it exceeds the first quadrant solid boundary. On the contrary, in the fourth quadrant of Figure 7 , that is, the longitudinal direction is tensile stress and the transverse direction is compressive stress, the maximum strain failure criterion is more stringent than the maximum stress failure criterion.

[0124] In some embodiments, the stress of the yarn in the fabric can be idealized as being subjected to tensile force in the transverse direction and compressive force in the longitudinal direction. The stress form in the stress space is the same as that in the fourth quadrant. In this quadrant, the maximum strain failure criterion is more stringent than the maximum stress failure criterion. Therefore, the fabric material model in an embodiment of the present application can be taken as the maximum strain failure criterion.

[0125] The present application can use ABAQUS finite element software to analyze the impact energy dissipation performance of the fabric. ABAQUS / Explicit is an explicit analysis solver of ABAQUS finite element software, which is suitable for simulating transient dynamics as the main finite element product. It can better solve the problems of complex contact, high nonlinearity and material failure degradation in high-speed dynamic events.

[0126] In some embodiments, in step S134, the above-constructed fabric model is imported into the finite element analysis software, and key parameters such as the density, elastic modulus, Poisson's ratio, yield strength, etc. of the material are input. These parameters will directly affect the accuracy of the simulation results. Considering the fiber direction and weaving method of the fabric, the orthotropy or anisotropy of the material is defined.

[0127] Specifically, in the ABAQUS-Part module, the finite element fabric model can adopt the above-mentioned 1 / 4 fabric model. In the ball impact experiment simulation, the fabric can be fixed in a square frame of, for example, 240mm*240mm, a three-dimensional fabric model with a size of 120mm*120mm is established, and the impact object of the model can select a steel ball with a radius of 20mm.

[0128] In the ABAQUS-Property module, considering the orthotropic anisotropy of the fiber material, the elastic modulus, shear modulus and Poisson's ratio of the yarn in three directions need to be determined, and the material principal direction needs to be determined when the yarn is material assigned. Select Part-Orientation to determine the principal direction of the yarn component and add material properties.

[0129] In the finite element simulation, the impact object can select a spherical impact object of structural steel. Since the modulus of structural steel itself is much higher than the modulus of fiber material in three directions, the deformation that occurs during impact can be ignored, so it is reasonable to regard the impact object as a rigid object, and the mass center point of the impact object is specified as the reference point. Its own grid element will not participate in the finite element solution calculation process. The fabric finite element model adopts the maximum strain failure criterion.

[0130] In the ABAQUS-Interaction module, the contact behavior is set to general contact. In the tangent direction, the yarn friction coefficient measured by the fiber friction coefficient tester is set, the friction formula adopts penalty, and in the normal direction, hard contact (HardContact) is adopted, and contact separation is allowed.

[0131] In the ABAQUS-Load module, first, the initial velocity perpendicular to the plane of the fabric is applied to the spherical impact object, and its displacement in the plane direction is constrained to be 0. Then the boundary of the fabric is constrained.

[0132] In the ABAQUS-Mesh module, the impactor and yarn were meshed respectively. Linear reduced integration hexahedral solid elements (C3D8R) were used for both impactor and yarn components. The advantage of this element type is that it is fast to compute, it does not tend to shear lock under bending loads, and it is accurate for displacement solutions. However, the element type (C3D8R) has only one integration point at the center of the element, which needs to be controlled. The impactor was meshed with three edges, and the global size was controlled to be 2.8 mm. Similarly, the yarn was meshed to meet the requirement that the number of layers in the long axis and short axis should not be less than four, and the global size could be controlled to be 0.7 mm.

[0133] In the ABAQUS-Visualization module, the stress propagation in the fabric, the displacement of the fabric in the impact direction, and the energy absorption ratio of each factor in the fabric absorbing the kinetic energy of the impactor were analyzed. The analysis process was designed to determine how different variables affect the impact energy dissipation performance of the fabric. The energy analysis method of the fabric absorbing the kinetic energy of the impactor was studied. In addition to the kinetic energy generated by the initial velocity of the spherical impactor in the initial step, there was no external energy input during the entire impact process, i.e., the entire system maintained energy conservation. The kinetic energy during the impact process was converted into multiple parts absorbed by the fabric, which can be represented by the following formula:

[0134] E I +E v +E FD +E KE -E W =E Total =constant

[0135] where E I is the internal energy, E v is the system damping viscous dissipation energy, E FD is the friction dissipation energy, E KE is the kinetic energy, and E W is the energy applied by the external load. The sum of these energies is the difference in the kinetic energy of the spherical impactor, and the change in the kinetic energy of the impactor can be represented by the following formula:

[0136]

[0137] where v initial is the initial velocity of the impactor, and v end is the remaining velocity of the impactor at the end of the impact process. In the numerical model, E Total must be a constant, but there is generally an error of less than 1%.

[0138] The energy conversion during the entire impact process was output through ODB-History Output, where E ldenoted by ALLIE, which can be further converted to:

[0139] ALLIE = ALLSE + ALLPD + ALLCD + ALLAE

[0140] where ALLSE represents the strain energy stored in the system, ALLPD represents the energy absorbed by the plastic strain of the system, ALLCD represents the viscoelastic dissipation energy, and ALLAE represents the pseudo-strain energy.

[0141] Since the fabric mesh is divided by C3D8R units, the single integration point of the C3D8R unit will cause a mathematical deformation that is not physically realized during the impact process. To keep the ratio of the pseudo-strain energy to the total energy of the system less than 10%, the fiber material model is defined as an elastic-plastic material in the embodiment of the present application, and due to the high flexibility of the whole fabric, the vibration and thermal energy phenomena caused by the system and material damping during the impact process are not considered. By studying the energy conversion during the impact process, it can be analyzed that how the fabric converts and absorbs the kinetic energy of the impact object during the impact process. In subsequent experiments, the energy conversion process is observed by changing the parameters of the yarn and fabric, and then the optimization rule of the impact resistance of the fabric is obtained.

[0142] In the above step S135, first, the impact resistance of the fabric woven by different mechanical performance yarns is simulated by finite element.

[0143] The impact response characteristics of the fabric under different impact velocities are simulated by the fabric model and the impact finite element model constructed above.

[0144] For example, taking the rockfall height as 20m and 80m as examples, that is, the impact object velocity is 20m / s and 40m / s, and the impact object is a steel ball with a radius of 20mm, and the initial kinetic energy of the corresponding spherical impact object, that is, the input energy of the whole system, is 12.9J and 51.6J. When the fabric is impacted, the stress propagation law in the fabric can be seen from Figure 8 , Figure 8 which is a schematic diagram of the stress propagation of the plain fabric after being impacted in the embodiment of the present application. Among them, Figure 8 a to d in the above are schematic diagrams of stress nephograms at different times.

[0145] According to the stress propagation form of the fabric when it is impacted, the yarn in direct contact with the impact object bears the maximum stress and deformation when the fabric is impacted. The maximum stress occurs when the velocity of the impact object is reduced to 0m / s, and the maximum stress borne by the yarn is 87.7Mpa, and the maximum deformation after the impact ends is 0.453. The maximum deformation of the model during the impact process is 0.453, which does not exceed the strain limit of the material itself 0.79.

[0146] The maximum stress value occurs in the central region of the fabric directly contacted by the impactor, and the maximum strain value also occurs in the same position, mainly in the form of plastic deformation. Even if the spherical impactor leaves the fabric due to the reverse speed after the speed decreases to 0 m / s, the deformation of the fabric does not recover. The maximum stress value and the maximum strain value both occur in the central region of the fabric directly contacted by the impactor, indicating that this position is the most likely position for the fabric to fail.

[0147] It can be understood that the displacement distance of the fabric in the impact direction is also an important characterization of the impact resistance performance of the fabric. The smaller the displacement distance in the impact direction, the better the impact resistance performance of the flexible fabric protective equipment, which reduces the force transmission from the fabric to the protected tank body, thereby avoiding deformation of the protected tank body.

[0148] Then, the effect of the yarn friction coefficient on the impact resistance performance of the fabric is analyzed.

[0149] Specifically, the same finite element model and fiber material are used, different surface friction coefficients of the yarn are set, and the results of the finite element simulation are comprehensively analyzed. For example, the yarn friction coefficient is set to 0.12, 0.25, 0.40, 0.55, and 0.70, respectively. The contact mode in the simulation can be referred to the general contact defined in the ABAQUS-Interaction module described above. The impact speed can be set to, for example, 20 m / s, and the analysis step, i.e., the impact time history, is also set to 8 ms, and the finite element simulation is performed.

[0150] The finite element simulation can obtain the change in the impact response characteristics of the fabric due to the change in the friction coefficient. The displacement-time curve of the fabric in the impact direction and the speed-time curve of the impactor with time can be obtained, as shown in Figure 9 and Figure 10 , respectively. Among them, Figure 9 is a schematic diagram of the displacement-time curve of the fabric in the impact direction under different friction coefficients of the yarn, Figure 10 is a schematic diagram of the speed-time curve of the fabric under different friction coefficients of the yarn. Referring to Figure 9 , it can be seen that the friction coefficient of the yarn has a direct impact on the displacement deformation of the fabric in the impact direction. With the increase of the friction coefficient between the yarns, the displacement deformation of the fabric in the impact direction gradually decreases, and the displacement deformation is more relevant when the friction coefficient is between 0.12 and 0.40. However, when the friction coefficient u exceeds 0.40, the increase of the friction coefficient has a gradually decreasing effect on the displacement deformation of the fabric.

[0151] Referring to Figure 10As shown, compared with the displacement deformation of the fabric in the impact direction, different yarn friction coefficients have no effect on the residual reverse speed of the impact object, but the speed of the impact object decreases more obviously when it contacts the fabric with a larger surface friction coefficient, and the speed will decrease to 0 m / s more quickly, but after the elastic deformation of the fabric recovers, the reverse speed of the impact object is the same, which is 7.2 m / s, and does not change due to the change of the yarn friction coefficient.

[0152] As can be understood, the friction energy absorption of the fabric caused by different friction coefficients also has the same trend as the displacement deformation of the fabric in the impact direction, which is more sensitive when the friction coefficient is 0.12-0.40, and the reason for the increase of the friction energy absorption is that the force required for the tangential movement of the yarn during the impact process is larger due to the increase of the friction coefficient. With the increase of the friction coefficient, the increase of the friction energy absorption gradually becomes flat.

[0153] Then, in the above step S135, the impact resistance of the fabric with different structures can be further simulated by the finite element method. The response characteristics of the fabrics with different structures are different when the fabrics are impacted, and the contact area of the yarns in the fabric is also different. The boundary condition definition of the fabric also has a great influence on the impact response of the fabric, and the propagation form of the stress wave in the fabric with different boundary conditions is also different.

[0154] The present application respectively adopts plain weave, twill weave and satin weave to analyze and verify the response characteristics of the fabrics with different structures when the fabrics are impacted.

[0155] Unlike the plain fabric, the twill fabric and the satin fabric cannot use the 1 / 4 model for finite element analysis due to the absence of mirror symmetry, so the full-size model of the twill fabric and the satin fabric is established. The three fabric models of plain weave, twill weave and satin weave adopt the same yarn cross-sectional coefficient, buckling wave height and distance between adjacent yarns.

[0156] For example, the displacement of the fabric in the impact direction and the speed of the impact object changing with time are shown in Figure 11a and 11b respectively. Among them, Figure 11a is a schematic diagram of the displacement deformation-time curve of the fabric, Figure 11b is a schematic diagram of the impact object speed-time curve.

[0157] As shown in Figure 11a and Figure 11b , when the fabrics with different structures are impacted, the displacement deformation of the plain fabric is the largest, which is 47.5 mm, and the displacement deformations of the twill fabric and the satin fabric in the impact direction are 42.9 mm and 41.4 mm respectively. From Figure 11aIt can be found that the rebound distance of the plain fabric in the z direction is the largest after reaching the maximum displacement deformation, the rebound distance of the twill fabric is in the middle, and the rebound distance of the satin fabric in the impact direction is the smallest. The impact object speed also has such a phenomenon, that is, the rebound speed of the impact object is larger when impacting the plain fabric, the speed reaches 7.1 m / s, and the rebound speeds when impacting the twill and satin fabrics are 5.6 m / s and 3.1 m / s, respectively. The rebound distance of the fabric and the reverse speed of the impact object depend on the elastic strain energy absorption size of the fabric during the impact process.

[0158] Exemplary, Figure 12 The schematic diagram of the energy absorption-time curve of each factor of the fabric with different organizational structures; Figure 12 In the figure, a is the elastic strain energy absorption-time curve, b is the plastic strain energy absorption-time curve, c is the fabric kinetic energy-time curve, and d is the friction energy absorption-time curve. Referring to Figure 12 As shown in the figure, the speed of the impact object can be found to be different when impacting fabrics with different organizational structures, and the speed attenuation trend of the impact object is obviously different. The speed attenuation is faster when impacting the satin fabric, followed by the twill fabric and the plain fabric. From the perspective of energy conversion, it can also be found that the elastic strain energy absorption, plastic strain energy absorption, and fabric kinetic energy of the satin fabric all reach the peak value first among the three different organizational structures of the fabric during the impact process. This mainly depends on the size of the yarn crimping degree in the fabric. The yarn crimping degree in different organizational structures of the fabric is different. The yarn crimping degree in the plain fabric is the highest, while the yarn crimping degree in the satin fabric is the lowest. The thickness of the fabric in the z direction is the same, that is, the yarn bending wave height is the same. It can be known that in the same length of the fabric, the yarn center line distance of the plain fabric is the longest, while the yarn center line distances of the twill fabric and the satin fabric are both smaller than that of the plain fabric.

[0159] When the fabric is impacted, the yarns in the impact center area to the edge area will present a V-shaped stress transfer. In the plain fabric, the main yarns have a longer length and a higher degree of crimp, so the main yarns need to present a greater deformation when they present a V shape, and more yarns are moved during the deformation process. Therefore, in the impact process, the time at which the peak value of the conversion and absorption of each type of energy in the plain fabric is significantly later than that in the twill fabric and the satin fabric, but the elastic strain energy absorption is higher than that in the latter two. The center line length of the main yarns in the satin fabric is the shortest, and the main yarns present a V shape earlier in the impact process, and the deformation occurs earlier, and the yield strength of the fiber material is deformed plastically earlier. In addition, due to the low degree of crimp, the driving effect on the adjacent yarns is weak, so the main energy absorption mode is plastic strain energy absorption. During the impact process, the main yarns in the plain fabric undergo more tangential motion before deforming into a V shape and more yarns are involved in the entire impact response, so the plain fabric removes more energy through friction, and the friction energy absorption of the twill fabric and the satin fabric is lower than that of the plain fabric. From the impact process analysis, in the low-speed impact, the performance of the satin fabric is the best, and the displacement of the fabric in the impact direction and the rebound speed of the impact object are the lowest, which shows that when the yarns in the fabric are relatively straight, the energy absorption performance is better.

[0160] In addition, in the case of higher speed impact, the satin fabric still has a faster response speed, and the fracture occurs earliest in the impact process, and the elastic strain energy absorption and the plastic strain energy absorption of the satin fabric also reach the peak value earliest, which is consistent with the performance when the impact speed is 20 m / s. Due to the low degree of crimp of the yarns in the twill fabric and the satin fabric, the overall elastic strain energy absorption and plastic strain energy absorption are also lower than those of the plain fabric. The main reason is that the center line distance of the yarns in the plain fabric is longer, and a single yarn absorbs more energy than the yarns in the twill fabric and the satin fabric.

[0161] On the other hand, for the analysis of the impact resistance of fabrics under different boundary conditions, the above finite element analysis method can also be used to determine it. By simulating different boundary conditions by finite element method, it can be determined that the fabric fixed on four sides has less displacement deformation when it is impacted, and the impact resistance of the fabric fixed on four sides is completely superior to that of the fabric with the other two fixed boundary conditions, and the energy absorption performance is better under the condition of different speed impact.

[0162] In the embodiment of the present application, the falling ball impact test platform mainly consists of a falling ball impact testing machine, a fabric fixing platform and a high-speed camera. The fabric fixing platform can adopt a steel fixing platform designed and processed by itself, and the size of the fixed frame end face is 320mmX320mm, and the size boundary of the fixed fabric is 240mmX240mm, which is consistent with the size of the fabric in the finite element analysis. The use of four equidistant bolts on one side ensures the tightness of the upper and lower end faces, so that the fabric can be completely fixed and the falling ball impact position can be ensured at the center position of the fixed fabric. The fabric fixing platform can be as shown in Figure 13

[0163] Firstly, the impact test is carried out on the fabric of different friction coefficient yarns.

[0164] The control of the friction coefficient of the yarn is mainly through the following method: twisting the yarn to make the surface of the yarn smoother, so as to reduce the friction coefficient of the surface of the yarn. For yarns with different fiber cross-sectional shapes, the friction coefficient can be changed by twisting. For example, the friction coefficient can be expressed as:

[0165]

[0166] wherein, f0, f1 are the tension on both ends of the fiber, μ is the friction coefficient of the fiber and the friction roller surface, θ is the contact angle between the fiber and the friction roller, is the radian unit, e is the natural constant, and f1 is the difference between the tension f0 and the hook load.

[0167] Exemplarily, Figure 14 is the displacement-time curve diagram of the woven fabric of different friction coefficient yarns in the embodiment of the present application when the fabric is impacted. Referring to Figure 14 It can be seen that through the falling ball impact test, it can be concluded that the different friction coefficients of the yarns in the fabric have an effect on the displacement of the fabric in the impact direction, and the trend is the same as the finite element simulation result: the greater the friction coefficient of the yarn itself, the smaller the displacement deformation of the fabric in the impact direction. But different from the finite element simulation, the effect of the different friction coefficients of the yarns on the displacement result of the fabric is more obvious in the impact test, and the displacement deformation of the fabric of the untwisted yarn is also reduced compared with the twisted yarn. The main reason is that the finite element model is based on the modeling of the yarn scale, and the friction between the internal fiber bundles of the yarn is ignored. The increase of the friction coefficient of the yarn is beneficial to enhance the impact resistance of the fabric, and the performance of the fabric woven by the untwisted yarn is better than that of the fabric woven by the twisted yarn.

[0168] Then, the falling ball impact test of fabrics with different weave structures is carried out. The falling ball impact test can be carried out on single-layer fabric and multi-layer (for example, double-layer) fabric respectively.

[0169] Exemplarily, Figure 15a ​The impact experiment image of the twill fabric, Figure 15b The impact experiment image of the twill fabric. Figure 16 The displacement-time curve diagram of the fabric with different weave structures when impacted.

[0170] From the results of the impact experiment, it can be seen that when facing low-speed impact that does not penetrate the fabric, the maximum displacement of the twill fabric and the satin fabric is smaller than that of the plain fabric, which is consistent with the trend of the finite element analysis result, and the recovery amount of the plain fabric, the twill fabric after the maximum displacement deformation is also larger than that of the satin fabric. From the finite element analysis, it is found that this phenomenon is because the main yarn of the satin fabric plastically deforms earlier after being impacted, thereby causing the rebound distance to be smaller.

[0171] It can be understood that when the fabric is impacted, the number of layers of the fabric and the displacement distance in the impact direction are nonlinear, and when the single-layer fabrics with different weave structures cooperate with each other, the overall impact resistance of the fabric will also be different. The impact experiment of the three kinds of double-layer fabrics of plain-plain, plain-twill, and plain-satin is designed, and the analysis of the experimental results shows the influence of the use of single-layer fabrics with different weave structures on the overall impact resistance. The speed and mass of the impact object in the impact experiment do not change, and the loading conditions of the impact experiment of the single-layer fabrics with different weave structures remain the same. The natural fitting treatment method of not adopting solid connection between the double-layer fabrics may cause slippage of the double-layer fabrics at the fixed boundary, so the upper end surface of the fabric fixing platform also needs to be treated with bubble-faced double-sided adhesive, and the upper and lower end surfaces of the bolts also need to be fully tightened to avoid deviation of the experimental results due to slippage. After the impact experiment of the double-layer fabric, no obvious wrinkles and overflow of the adhesive occur at the fixed boundary of the fabric, which indicates that no slippage occurs at the fixed boundary of the fabric when impacted.

[0172] For example, taking a double-layer fabric as an example, Figure 16 The displacement curve diagram of the three kinds of double-layer fabrics with different weave structures when impacted. Through the drop ball impact experiment of the fabrics with different weave structures, it can be determined that the displacement deformation of the double-layer fabric when impacted all decreases, but the decrease distance is not large. The displacement deformation of the plain fabric, the twill fabric, and the satin fabric all decreases when they are impacted with a layer of plain fabric. The time when the double-layer fabric reaches the maximum displacement is earlier than that of the single-layer fabric. The obvious point of the double-layer fabric relative to the single-layer fabric is that the rebound distance of the double-layer fabric is higher than that of the single-layer fabric. The rebound distance has a positive correlation with the elastic strain energy absorption of the fabric, and it can be known that the proportion of the elastic strain energy absorption of the double-layer fabric to the total kinetic energy of the impact object increases relative to the single-layer fabric. Therefore, the displacement of the double-layer fabric in the impact direction when impacted is smaller than that of the single-layer fabric, and the response speed is faster, and the maximum displacement deformation is reached earlier. The proportion of the elastic strain energy absorption of the double-layer fabric is higher than that of the single-layer fabric.

[0173] S16, the yarn cross-sectional shape and the fabric structure of the fabric with the highest impact resistance are determined as the preparation parameters of the fabric of the protective equipment.

[0174] In the embodiments of the present application, the impact response characteristics of different fabrics can be analyzed respectively according to the finite element simulation and the corresponding ball drop impact test verification. The factors such as micro yarn performance, yarn friction coefficient and woven fabric structure are studied to study the impact energy loss performance of the fabric, so as to determine the yarn cross-sectional shape and the fabric structure of the fabric with the highest impact resistance as the preparation parameters of the fabric of the protective equipment. It is determined that the cross-shaped fiber plain fabric has better impact resistance performance than the circular fiber plain fabric, and the circular fiber satin fabric has better impact resistance performance than the circular fiber plain fabric and the circular fiber twill fabric. And from the analysis and test results, it can be obtained that the impact resistance performance of the fabric is the best when the fabric is fixed on four sides. Therefore, the cross-shaped plain fabric prepared by using the preparation parameters can be one of the alternative solutions of the large tank protective equipment, which can effectively absorb and dissipate impact energy when impacted, and has the characteristics of light, thin and compact, which can significantly improve the safety of the large tank during transportation, reduce deformation or damage caused by impact, and improve transportation efficiency.

[0175] In some embodiments, the preparation parameters described above can also include the number of layers of the fabric; by adjusting the number of layers of the fabric, finite element simulation and corresponding ball drop impact test can be carried out to further optimize the energy absorption performance and impact resistance of the fabric.

[0176] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other, and each embodiment mainly explains the difference from other embodiments.

[0177] The above embodiments are only used to illustrate the technical solutions of the present application, and are not limited to the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A lightweight, flexible fabric protective garment for large tanks, characterized in that, The key protective layer of the protective equipment is made of a plain-weave polypropylene fabric with cross-shaped fibers; wherein the fabric preparation parameters are determined through the following steps: Using polypropylene as raw material, multi-parameter control is achieved by selecting the spinneret orifice type, pump supply and winding speed of the melt spinning machine, and using a drawing device to perform post-drawing and doubling of the produced fibers to prepare multifilament yarns with different mechanical properties and cross-sectional shapes. By using yarns with different cross-sectional shapes, fabrics with different weave structures can be obtained through plain weave, twill weave, and satin weave processes. Using pre-set finite element analysis software, the impact response characteristics of fabrics with different weave structures are simulated using finite element methods. The influence of the surface friction coefficient of the profiled fiber yarn and the fabric weave structure on the fabric's impact energy loss performance is analyzed. The surface friction coefficient of the yarn is controlled by adjusting the yarn twist and cross-sectional shape. The mechanical properties and surface friction coefficient of the yarn are measured using a single yarn strength tester and a yarn friction coefficient measuring instrument. The finite element simulation of the impact response characteristics of the fabrics with different weave structures using the pre-set finite element analysis software includes: The yarn centerline equation is determined by the yarn cross-sectional shape and yarn path. The yarn centerline is then drawn based on the centerline equation. Finally, a single yarn model is obtained by scanning the yarn cross-section along the yarn centerline. The yarns are arrayed based on the single yarn model to obtain a three-dimensional model of the fabric. Based on the anisotropy of the yarn fiber material, the elastic modulus, shear modulus, and stiffness matrix of the yarn fiber in the axial and radial directions are determined, and a constitutive model of the fiber material is established; the constitutive model includes an elastoplastic model and a failure model. Finite element analysis preprocessing includes: importing the three-dimensional model of the fabric into the preset finite element analysis software; meshing the three-dimensional model of the fabric based on the constitutive model of the fiber material; setting the initial velocity, size, and position of the impactor, as well as the boundary conditions of the fabric; defining contact properties and setting the contact relationship between the impactor and the fabric. The finite element simulation includes: using the explicit dynamic solver of the finite element analysis software to simulate the response characteristics of the fabric under impact; observing and recording the displacement deformation, velocity change, energy absorption and loss parameters of the fabric during the impact process; and analyzing the influence of different fabric structures on the impact resistance of the fabric. Based on the fabrics with different structures prepared, a falling ball impact test with the same parameters as the finite element simulation was designed to verify the accuracy of the finite element analysis results. Based on the results of the finite element simulation and the falling ball impact test, the impact resistance of fabrics prepared from fiber yarns with different cross-sectional shapes and fabric structures is evaluated. The yarn cross-sectional shape and fabric structure of the fabric with the highest impact resistance are used as the preparation parameters for the fabric used to make the protective equipment.

2. The lightweight, flexible fabric protective equipment for large tanks according to claim 1, characterized in that, The cross-sectional shape of the yarn includes circular, trilobal, and cross-shaped; yarns with different cross-sectional shapes are prepared by adjusting the spinneret orifice pattern of the spinning machine.

3. The lightweight, flexible fabric protective equipment for large tanks according to claim 2, characterized in that, The preparation parameters also include the number of fabric layers; by adjusting the number of fabric layers, finite element simulation and falling ball impact test with corresponding parameters are performed to optimize the energy absorption performance and impact resistance performance of the fabric.

Images