Composite gas cylinder winding stability evaluation method and system based on non-axisymmetric load

Abstract

The application discloses a composite gas cylinder winding stability evaluation method and system based on a non-axial symmetry load, relates to the technical field of composite material gas cylinder manufacturing and structure stability evaluation, and comprises the following steps: acquiring the curved surface geometric parameters, material parameters, winding path parameters and winding process parameters of the inner liner structure of a composite material gas cylinder; determining the contact path of the fiber band center line, the coverage area in the current winding stage, the contact path direction and the local curved surface position according to the curved surface geometric parameters, the winding path parameters and the winding process parameters, and establishing a non-axial symmetry load model; performing equivalent treatment on the non-axial symmetry load distribution to obtain equivalent load parameters; applying the equivalent load parameters to a stability analysis model for evaluation, and outputting a stability state, a dangerous area and an instability risk result. The application solves the problem that the existing axial symmetry layer loading method is difficult to identify the instability risk in the winding process, effectively improves the accuracy of stability risk identification, and reduces the modeling and calculation cost.

Description

Technical Field

[0001] This invention relates to the field of composite gas cylinder manufacturing and structural stability assessment technology, and in particular to a method and system for assessing the winding stability of composite gas cylinders based on non-axisymmetric loads. Background Technology

[0002] Composite gas cylinders, also known as composite gas cylinders, typically consist of an inner liner structure and a composite material winding reinforcement layer located on the outside of the inner liner structure. They are widely used in hydrogen storage, gas storage, energy storage, aerospace, and vehicle power supply. The inner liner structure can be made of metal, plastic, or composite materials, used to maintain airtightness and provide forming support; the composite material winding reinforcement layer is formed by laying fiber bundles or fiber strips according to a predetermined path, and is used to bear the main pressure load. Fiber winding is a key process in the manufacturing of this type of gas cylinder; the laying path, tension, and bonding state during the winding process affect the forming quality of the gas cylinder and the load-bearing state of the inner liner structure.

[0003] During the winding process, the fiber tape needs to maintain a certain tension to ensure stable laying trajectory and interlayer compaction. This tension is transmitted to the surface of the lining structure through contact, friction, and curved surface constraints between the fiber tape and the lining structure, forming normal compression and tangential traction. For lining structures with thin walls and low stiffness, before the external reinforcement layer forms effective support, the above-mentioned process loads may cause local deformation, overall eccentric loading, or even instability.

[0004] In existing stability analyses of composite gas cylinders, the winding load is typically simplified to an axisymmetric load. For example, the winding tension is equated to a uniformly distributed external pressure, or a continuous load is applied layer by layer according to the layup sequence. This type of method is suitable for situations where the winding layers have formed a relatively complete circumferential coverage and the load distribution is approximately uniform. However, in actual winding processes, the fiber tape is laid out step by step along a predetermined path. The coverage area at any stage is related to the path position, bandwidth, winding angle, number of turns, and the geometry of the inner lining surface. The surface load of the inner lining structure does not necessarily satisfy an axisymmetric distribution.

[0005] Especially during the winding stage where coverage is partial or uneven, the fiber tape acts only on a portion of the lining structure's surface, resulting in significant non-uniformity and path dependence of the load in the circumferential direction. At this point, the winding tension generates a localized normal compressive load due to the surface curvature, while friction generates a tangential traction load along the winding path. Both together form a non-axisymmetric load state. This non-axisymmetric load, in addition to producing an average compression effect, may also induce additional resultant forces, additional moments, and an overall bending tendency, making it a crucial factor affecting the winding stability of thin-walled lining structures.

[0006] Therefore, when using existing axisymmetric layered loading or uniformly distributed external pressure models for stability assessment, it is difficult to reflect the local coverage state caused by the actual winding path, and it is also difficult to characterize the off-center loading and bending effects caused by non-axisymmetric loads, which can easily lead to misjudgment of dangerous areas or omission of instability risks. If a complete fiber strip-lining contact model is directly established, there are problems such as complex modeling, high computational cost, and difficulty in rapid engineering assessment.

[0007] In summary, the existing technology still lacks a method that can characterize the non-axisymmetric load during the winding process of composite gas cylinders based on the winding path, fiber tension, friction, and the surface geometry of the liner structure, and convert it into equivalent load parameters that are easy to analyze for stability, thereby assessing the stability state, hazardous areas, and instability risk of the liner structure. Summary of the Invention

[0008] To address the aforementioned technical problems in related technologies, this invention proposes a method for evaluating the stability of composite gas cylinder winding based on non-axisymmetric loads.

[0009] In a first aspect, the present invention provides a method for evaluating the stability of composite gas cylinder winding based on non-axisymmetric loads, comprising the following steps:

[0010] S1. Obtain the surface geometry parameters, material parameters, winding path parameters, and winding process parameters of the inner lining structure of the composite gas cylinder;

[0011] S2. Based on the surface geometry parameters, winding path parameters, and winding process parameters, determine the contact path of the fiber tape centerline on the surface of the lining structure, as well as the coverage area, contact path direction, and local surface position under the current winding stage.

[0012] S3. Calculate the non-axisymmetric load based on the local curved surface position, contact path direction and winding process parameters, and establish a non-axisymmetric load model for the fiber strip to transfer the non-axisymmetric load to the surface of the inner lining structure.

[0013] S4. Perform equivalent processing on the non-axisymmetric load distribution of the non-axisymmetric load model to obtain equivalent load parameters for stability analysis;

[0014] S5. The equivalent load parameters are applied to the pre-established stability analysis model of the lining structure for evaluation, and the stability evaluation results of the composite gas cylinder during the winding process are obtained.

[0015] Specifically, the geometric parameters include the cylinder radius, cylinder length, end cap shape parameters, pole hole size, short neck size, transition region size, and wall thickness;

[0016] The material parameters include elastic modulus, Poisson's ratio, density, yield strength, and material nonlinear parameters;

[0017] The winding path parameters include path parameters and stage parameters; the path parameters include winding angle, winding start position and fiber tape centerline trajectory, and the stage parameters include the current number of winding turns and path coverage range.

[0018] The winding process parameters include fiber tape tension, fiber tape width, and coefficient of friction.

[0019] Specifically, step S2 includes:

[0020] S21. Determine the contact path of the fiber belt centerline on the surface of the lining structure based on the path parameters;

[0021] S22. Determine the coverage area under the current winding stage based on the contact path, the current number of winding turns, and the fiber tape width; the current winding stage includes partial coverage, non-uniform coverage, and path-related coverage.

[0022] S23. Determine the contact path direction of the fiber tape at each covering position according to the contact path, and determine the local curved surface position to which each covering position belongs according to the coordinates of each covering position on the surface of the lining structure.

[0023] Specifically, step S3 includes:

[0024] S31. Obtain the local curvature parameters and surface normal corresponding to the local surface position, and then determine the path normal curvature of the fiber strip in the contact path direction according to the contact path direction, local curvature parameters and surface normal.

[0025] S32. Calculate the normal compressive load acting on the surface of the inner lining structure based on the fiber belt tension, fiber belt width, and path normal curvature.

[0026] S33. Calculate the tangential traction load along the contact path direction based on the friction coefficient and the normal clamping load;

[0027] S34. Obtain the non-axisymmetric load distribution on the surface of the inner lining structure from the non-axisymmetric loads in each covered area under the current winding stage, and then construct a non-axisymmetric load model.

[0028] Specifically, step S4 includes:

[0029] S41. Divide the surface of the inner lining structure of the non-axisymmetric load model into multiple load equivalent regions, and obtain the total normal compressive load of the surface points in each load equivalent region according to the non-axisymmetric load distribution.

[0030] S42. The total normal clamping load of the surface points in each load equivalent region is averaged by area integration to obtain the equivalent regional pressure corresponding to each load equivalent region.

[0031] S43. Calculate the residual resultant force and residual moment based on the resultant force and moment corresponding to the non-axisymmetric load distribution and the resultant force and moment corresponding to the equivalent pressure in the region.

[0032] S44. The equivalent pressure, residual resultant force, and residual moment of the region are used as the equivalent load parameters.

[0033] Specifically, step S5 includes:

[0034] S51. Apply the equivalent pressure of the region as surface pressure to the corresponding load equivalent region.

[0035] S52. The residual resultant force and residual moment are applied to the reference point as concentrated force and concentrated moment, respectively, and transmitted to the stability analysis model of the inner lining structure through the coupling node loop or equivalent action region.

[0036] S53. Perform stability analysis on the inner lining structure stability analysis model to obtain the stability assessment results of the composite gas cylinder during the winding process; the stability analysis includes selecting linear buckling analysis and nonlinear buckling analysis.

[0037] Specifically, step S53 includes:

[0038] S531. Obtain the critical load coefficient and buckling mode based on linear buckling analysis, and then superimpose the buckling mode onto the initial geometry of the lining structure stability analysis model according to the preset defect amplitude. Subsequently, perform nonlinear stability analysis on the lining structure stability analysis model to obtain the load-displacement response path, critical load scaling factor, and displacement distribution, stress distribution, and instability deformation mode under critical instability state.

[0039] S532. Calculate the stability safety margin based on the critical load scaling factor and the working load scaling factor, and compare the stability safety margin with the stability safety threshold to determine the stability state; the stability state includes whether the stability requirements are met or not.

[0040] Among them, stability safety margin , This is the critical load scaling factor; This is the working load scaling factor corresponding to the current winding process;

[0041] when When the value is greater than the stability safety threshold, the current winding stage is determined to meet the stability requirements; when... If the value is less than or equal to the stability safety threshold, it is determined that there is a risk of instability in the current winding stage;

[0042] S533. Determine the critical area based on the amplitude distribution of the buckling modes or the displacement and stress distribution under the critical instability state, and use at least one of the following as instability risk information: stability safety margin, tension safety margin, critical winding tension, critical winding stage, and instability deformation mode; wherein, the critical winding tension is used as the instability risk information. and current winding tension Define tension safety margin ;

[0043] S534. The buckling mode, critical load factor, load-displacement response path, critical load scaling factor, and displacement distribution, stress distribution, instability deformation mode, stability state, hazardous area, and instability risk information under critical instability state shall be used as the stability assessment results.

[0044] Specifically, the method further includes:

[0045] S6. Adjust the surface geometry parameters, material parameters, or winding process parameters of the composite material gas cylinder based on the stability assessment results.

[0046] Specifically, step S6 includes:

[0047] When stability safety margin Less than the stability safety threshold, or the tension safety margin When the tension is less than the safety threshold, the current winding tension is determined to be insufficient to meet stability requirements. This is addressed by reducing fiber tape tension, increasing fiber tape width, adjusting the winding angle, changing the winding path coverage sequence, or adjusting the winding start position to reduce non-axisymmetric load concentration, residual resultant force, or residual moment. Stability is then reassessed until a stability safety margin is achieved. and tension safety margin Meets the preset requirements;

[0048] When the danger zone is located in the head zone, cylinder zone, or transition zone, adjust the head geometry, cylinder wall thickness, or transition zone dimensions for the corresponding zone. When the instability deformation mode is characterized by local depression, increase the local stiffness of the corresponding zone. When the instability deformation mode is characterized by overall bending or eccentric deformation, adjust the head geometry, cylinder length, or material parameters to reduce deformation concentration.

[0049] Candidate ranges are set for fiber tension, fiber width, winding angle, winding path, winding start position, and number of winding turns. Non-axisymmetric load modeling, equivalent load generation, and stability analysis are performed on each combination of process parameters. The parameter group with a stability safety margin greater than the stability safety threshold is determined as the process parameter combination that meets the stability requirements. The process parameter combination forms the process parameter range, which is used for winding tension selection, winding path optimization, and manufacturing process risk control.

[0050] Secondly, the present invention provides a composite gas cylinder winding stability evaluation system based on non-axisymmetric loads, which, based on the composite gas cylinder winding stability evaluation method based on non-axisymmetric loads described in the first aspect above, includes the following modules:

[0051] The parameter acquisition module is used to acquire the surface geometry parameters, material parameters, winding path parameters, and winding process parameters of the inner lining structure of the composite gas cylinder.

[0052] The path recognition module is used to determine the contact path of the fiber tape centerline on the surface of the inner lining structure, as well as the coverage area, contact path direction, and local surface position under the current winding stage, based on the surface geometry parameters, winding path parameters, and winding process parameters.

[0053] The non-axisymmetric load modeling module is used to calculate the non-axisymmetric load based on the local curved surface position, contact path direction and winding process parameters, and to establish a non-axisymmetric load model for the fiber strip to transmit the non-axisymmetric load to the surface of the inner lining structure.

[0054] The load equivalence module is used to perform equivalent processing on the non-axisymmetric load distribution of the non-axisymmetric load model to obtain equivalent load parameters for stability analysis.

[0055] The stability assessment module is used to apply the equivalent load parameters to a pre-established stability analysis model of the liner structure for evaluation, and obtain the stability assessment results of the composite gas cylinder during the winding process.

[0056] The feedback adjustment module is used to adjust the surface geometry parameters, material parameters, or winding process parameters of the composite material gas cylinder based on the stability assessment results.

[0057] This invention determines the contact path of the fiber strip centerline on the surface of the liner structure, as well as the coverage area, contact path direction, and local curved surface position under the current winding stage, based on the curved geometric parameters, material parameters, winding path parameters, and winding process parameters of the liner structure of the composite gas cylinder. It establishes a non-axisymmetric load model for the load transferred from the fiber strip to the liner structure surface, thus reflecting the non-axisymmetric load state caused by local coverage, path changes, and load offset. Furthermore, the non-axisymmetric load distribution is equivalently processed to obtain equivalent load parameters for stability analysis, preserving the overall off-center loading and bending effects caused by the non-axisymmetric load. These equivalent load parameters are then applied to the pre-established liner structure stability analysis model for evaluation, outputting the stability state, hazardous areas, and instability risk results. This effectively solves the problems of misjudgment or omission in stability risk identification during the uneven coverage stage, the initial winding stage, and other non-axisymmetric loading states, significantly improving the accuracy of stability risk identification.

[0058] This invention transforms complex non-axisymmetric winding loads into equivalent load parameters such as regional equivalent pressure, residual resultant force, and residual moment, which can be directly used for stability analysis. This avoids the need to establish complex fiber-liner contact models at each winding stage, which helps reduce modeling and calculation costs and facilitates its application in composite gas cylinder liner structure design, winding tension selection, winding path optimization, and manufacturing process risk control. Attached Figure Description

[0059] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0060] Figure 1 A schematic flowchart of the composite gas cylinder winding stability evaluation method based on non-axisymmetric load provided in an embodiment of the present invention;

[0061] Figure 2 This is a geometric schematic diagram of the composite material gas cylinder liner structure provided in an embodiment of the present invention;

[0062] Figure 3 This is a schematic diagram of the winding path and polar hole avoidance constraint provided in an embodiment of the present invention;

[0063] Figure 4 This is a schematic diagram of the path coverage state at different winding stages provided in an embodiment of the present invention; wherein, Figure 4 (a) in the diagram represents the initial, unwound state. Figure 4 (b) in the diagram represents the path coverage state after one loop; Figure 4 (c) in the diagram represents the path coverage state with 5 wraps; Figure 4 In the diagram, (d) represents the path coverage state after 10 wraps; Figure 4 In the diagram, (e) represents the path coverage state after 15 wraps; Figure 4 (f) in the diagram represents the path coverage state after 20 wraps;

[0064] Figure 5 This is a schematic diagram of the coordinates and local geometric parameters of the end cap surface provided in an embodiment of the present invention;

[0065] Figure 6 This is a schematic diagram of the tension transmission and load decomposition of the fiber belt in the end cap area provided in an embodiment of the present invention;

[0066] Figure 7 This is a schematic diagram of the spiral winding and load decomposition of the cylinder area provided in an embodiment of the present invention;

[0067] Figure 8 This is a schematic diagram of the equivalent treatment of non-axisymmetric loads provided in an embodiment of the present invention;

[0068] Figure 9 This is a schematic diagram illustrating the equivalent load region division of the inner lining structure provided in an embodiment of the present invention;

[0069] Figure 10 This is a schematic diagram of the equivalent load application and stability analysis model provided in an embodiment of the present invention;

[0070] Figure 11 This is a schematic diagram illustrating the stability evaluation results of a single winding stage provided in an embodiment of the present invention, wherein... Figure 11 In the diagram (a), the winding path and the non-axisymmetric load distribution are shown. Figure 11 In the equation (b), the residual resultant force component is represented. Figure 11 (c) in the equation represents the residual torque component. Figure 11 In the figure, (d) represents the displacement distribution under critical instability conditions;

[0071] Figure 12 This is a schematic diagram of the stability evaluation results for the multi-turn winding stage provided in an embodiment of the present invention, wherein:

[0072] Figure 12 (a1), (a2), and (a3) ​​are respectively schematic diagrams of the winding path and non-axisymmetric load distribution when winding 5 turns, side view and top view of displacement distribution under critical instability, and residual resultant force and residual moment components under critical instability.

[0073] Figure 12 (b1), (b2), and (b3) are respectively schematic diagrams of the winding path and non-axisymmetric load distribution when winding 10 turns, side view and top view of displacement distribution under critical instability, and residual resultant force and residual moment components under critical instability.

[0074] Figure 12 (c1), (c2), and (c3) are respectively schematic diagrams of the winding path and non-axisymmetric load distribution when winding 15 turns, side view and top view of displacement distribution under critical instability, and residual resultant force and residual moment components under critical instability.

[0075] Figure 12 In the diagram, (d1), (d2), and (d3) represent the winding path and non-axisymmetric load distribution when winding 20 turns, the side view and top view of the displacement distribution under critical instability, and the residual resultant force and residual moment components under critical instability, respectively.

[0076] Figure 13This is a schematic diagram of a composite gas cylinder winding stability evaluation system based on non-axisymmetric load, provided in an embodiment of the present invention. Detailed Implementation

[0077] The present invention will be explained in detail through the following embodiments. The purpose of this invention is to protect all technical improvements within its scope. In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0078] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0079] Example 1

[0080] refer to Figure 1 This embodiment provides a method for evaluating the stability of composite gas cylinder winding based on non-axisymmetric loads, including the following steps:

[0081] S1. Obtain the surface geometry parameters, material parameters, winding path parameters, and winding process parameters of the inner lining structure of the composite gas cylinder;

[0082] refer to Figure 2 The composite material gas cylinder includes an inner liner structure and a composite material reinforcing layer wrapped around the outside of the inner liner structure. The inner liner structure includes a cylinder body section, a head section, pole holes, a short neck, and a transition area between the head and the cylinder body.

[0083] In this embodiment, the inner lining structure is a thin-walled structure, and the inner lining structure material includes, but is not limited to, metal and plastic. Preferably, the inner lining structure material is metal. This invention is particularly suitable for thin-walled inner lining structures that are susceptible to local deformation or instability risks during the winding process due to fiber tension.

[0084] The surface geometry parameters include cylinder radius, cylinder length, end cap shape parameters, pole hole size, short neck size, transition region size, and wall thickness.

[0085] The material parameters include elastic modulus, Poisson's ratio, density, yield strength, and material nonlinear parameters.

[0086] The winding path parameters in this embodiment should at least include parameters that can determine the position of the fiber tape centerline and the coverage state of the current winding stage; the winding process parameters should at least include fiber tape tension, fiber tape width, and coefficient of friction used to calculate the winding load.

[0087] The winding path parameters include path parameters and stage parameters; the path parameters include winding angle, winding start position and fiber tape centerline trajectory, and the stage parameters include the current number of winding turns and path coverage range.

[0088] The winding process parameters include fiber tape tension, fiber tape width, and coefficient of friction, and may further include winding speed, laying sequence, and winding stage parameters.

[0089] S2. Based on the surface geometry parameters, winding path parameters, and winding process parameters, determine the contact path of the fiber tape centerline on the surface of the lining structure, as well as the coverage area, contact path direction, and local surface position under the current winding stage.

[0090] S21. Determine the contact path of the fiber belt centerline on the surface of the lining structure based on the path parameters;

[0091] S22. Determine the coverage area under the current winding stage based on the contact path, the current number of winding turns, and the fiber tape width; the current winding stage includes partial coverage, non-uniform coverage, and path-related coverage.

[0092] The inner lining structure includes a cylinder section, a head section, an pole hole, a short neck, and a transition area between the head and the cylinder. The overall shape of the covered area is the same as that of the inner lining structure.

[0093] refer to Figure 3 The contact path of the fiber ribbon centerline on the surface of the liner structure includes the head region path and the shell region path. The head region path extends from near the equator toward the pole hole, satisfies the avoidance constraint near the pole hole region, and then returns to near the equator to continuously connect with the shell spiral path.

[0094] To avoid interference between the fiber tape and the electrode aperture or short neck region, an electrode aperture clearance radius can be set. Let the radius of the electrode aperture or short neck region be... The fiber strip width is The safety margin is Δ Then the radius of the polar hole avoidance It can be represented as:

[0095] ,

[0096] The contact path of the fiber belt centerline on the surface of the lining structure is denoted as... (s), where s is the arc length of the path along the centerline of the fiber strip. Based on the width of the fiber strip, the coverage area of ​​the fiber strip on the surface of the lining structure can be determined.

[0097] Determining the strip coverage area based on the centerline trajectory and bandwidth is a conventional geometric process and is existing technology, so it will not be elaborated here.

[0098] Specifically, the surface area of ​​the lining structure located within half a bandwidth on both sides of the fiber belt centerline can be defined as the fiber belt coverage area.

[0099] refer to Figure 4 Different winding stages correspond to different coverage states. When the number of winding turns is small, the fiber tape only covers a local area of ​​the inner lining structure surface, and the coverage state is uneven in the circumferential direction; as the number of winding turns increases, the fiber tape path gradually becomes denser, and the coverage state gradually becomes more sufficient.

[0100] Therefore, the current winding stage includes:

[0101] The fiber tape has not yet formed a complete and uniform wrapping around the circumference of the inner lining structure, i.e., a partial wrapping state;

[0102] The fiber tape forms a partially or non-uniformly covered winding state on the surface of the inner lining structure, i.e., a non-uniformly covered state.

[0103] The fiber tape is laid out circle by circle along the predetermined centerline trajectory. The position and range of the covered area change with the winding path and the current number of winding circles, i.e., path-related coverage state.

[0104] Therefore, this embodiment determines the actual coverage area of ​​the lining structure surface in the current stage based on the winding path, fiber width, and number of winding turns in the current winding stage.

[0105] Based on the winding path, fiber strip width, and number of winding turns at the current winding stage, the actual coverage area of ​​the lining structure surface at the current stage is determined using a conventional path coverage area determination method, which is used to provide the actual range of action for subsequent non-axisymmetric load models.

[0106] S23. Determine the contact path direction of the fiber tape at each covering position according to the contact path, and determine the local curved surface position to which each covering position belongs according to the coordinates of each covering position on the surface of the inner lining structure.

[0107] After determining the fiber tape coverage area, for each coverage point within the coverage area, the contact path direction of that point is determined based on the fiber tape contact path. Then, the local curved surface position corresponding to that point is determined based on its coordinates on the surface of the lining structure. This local curved surface position includes the end cap section, the cylinder section, and the transition area between the end cap and the cylinder. Subsequently, the corresponding local curvature parameters and surface normal can be obtained. Then, based on the local curvature parameters, surface normal, fiber tape path direction, fiber tape tension, fiber tape width, and friction coefficient, the normal compressive load and tangential traction load at that point are calculated.

[0108] For the surface points of the lining structure within the area covered by the fiber strip, a surface load consisting of a normal compressive load and a tangential traction load is applied; for the surface area not covered by the current fiber strip, no local load corresponding to the current fiber strip is applied, thereby determining the actual range of action of the non-axisymmetric load.

[0109] S3. Calculate the non-axisymmetric load based on the local curved surface position, contact path direction and winding process parameters, and establish a non-axisymmetric load model for the fiber strip to transfer the non-axisymmetric load to the surface of the inner lining structure.

[0110] S31. Obtain the local curvature parameters and surface normal corresponding to the local surface position, and then determine the path normal curvature of the fiber strip in the contact path direction according to the contact path direction, local curvature parameters and surface normal.

[0111] The local curvature parameters include the meridional radius of curvature and the circumferential radius of curvature; the local curvature parameters and the surface normal can be obtained by conventional surface geometry methods based on the surface geometry model of the lining structure. This acquisition process is existing technology and will not be described in detail here.

[0112] The curvature parameters differ at different local surface locations. Specifically, the meridional and circumferential curvature parameters of the head section are determined based on the head surface. The circumferential curvature of the body section is determined by the body radius, while the meridional curvature is zero. The transition region is determined based on the actual transition surface. Since the pole holes and short neck regions are not within the fiber belt covered area, their path-normal curvature does not need to be calculated.

[0113] refer to Figure 5 In this embodiment, the end cap section of the inner lining structure is an ellipsoidal end cap. The end cap surface can be described using meridional coordinates and circumferential coordinates, and the surface normal, contact path direction, and local curvature parameters of any point on the end cap surface can be determined.

[0114] For an ellipsoidal head, its meridional section can be expressed as:

[0115] ,

[0116] Where r is the radial distance from the point on the end cap surface to the central axis of the gas cylinder, z is the axial coordinate, a is the equatorial radius of the end cap, and b is the length of the polar semi-axis of the end cap.

[0117] On the surface of the end cap, the angle between the fiber path direction and the circumferential direction is denoted as α, based on the meridional radius of curvature of the end cap surface. and circumferential radius of curvature The path normal curvature in the fiber belt path direction can be determined. :

[0118] .

[0119] It should be noted that the ellipsoidal head described above is only one example of a head segment. For hemispherical heads, dished heads, or other continuous curved surface heads, as long as the normal curvature and path direction can be obtained, the method described in this invention can be used for subsequent load calculations.

[0120] refer to Figure 7 In the cylindrical section, the fiber tape is laid along a helical path. Let the radius of the cylindrical section be R, and the angle between the contact path direction of the fiber tape and the circumferential direction of the cylindrical section be β. Then, the path normal curvature along the fiber tape path direction is... It can be represented as:

[0121] ,

[0122] S32. Calculate the normal compressive load acting on the surface of the inner lining structure based on the fiber belt tension, fiber belt width, and path normal curvature.

[0123] The tension of the fiber tape comes from the winding process parameters;

[0124] refer to Figure 6 When the fiber tape is laid along the curved path in the end cap area, the tension of the fiber tape is transmitted to the surface of the inner lining structure through the geometric constraints of the curved surface and the interfacial friction.

[0125] Because the fiber tape is laid along a curved path, its tension direction changes with the curvature of the path, thus subjecting the surface of the lining structure to a normal compressive load. This normal compressive load can be determined based on the fiber tape tension, fiber tape width, and the normal curvature of the path.

[0126] ,

[0127] Where p is the normal compressive load acting on the surface of the lining structure, T is the fiber tape tension, and w is the fiber tape width. denoted as the path curvature in the fiber path direction.

[0128] refer to Figure 7 The radial clamping load, i.e. the normal clamping load, in the cylinder area can be expressed as:

[0129] ,

[0130] S33. Calculate the tangential traction load along the contact path direction based on the friction coefficient and the normal clamping load;

[0131] Due to the friction between the fiber tape and the lining structure, the fiber tape also transmits a tangential traction load along its path to the surface of the lining structure. This tangential traction load can be determined based on the friction coefficient, the normal compressive load, and the fiber tape's path direction.

[0132] The tangential traction load along the contact path in the head region can be expressed as:

[0133] ,

[0134] in, For tangential traction load, It represents the coefficient of friction between the fiber belt and the inner lining structure.

[0135] In the cylinder region, the tangential traction load acts along the helical path. Since the helical path has both circumferential and axial components, the tangential traction load... It can be further decomposed into circumferential traction component and axial traction component.

[0136] Tangential traction load in the cylinder area along the contact path direction It can be represented as:

[0137] ( ),

[0138] in, The unit vector in the circumferential direction of the cylinder. It is a unit vector along the axis.

[0139] S34. Obtain the non-axisymmetric load distribution on the surface of the inner lining structure from the non-axisymmetric loads in each covered area under the current winding stage, and then construct a non-axisymmetric load model; the non-axisymmetric loads include normal compressive loads and tangential traction loads.

[0140] Specifically, the surface load (non-axisymmetric load) of the head region can be expressed as a combination of normal compressive load and tangential traction load;

[0141] set up The outward normal unit vector of the surface. Let the fiber path direction be a unit vector, then the surface load vector of the end cap region can be expressed as:

[0142] ,

[0143] in, This is the load vector transmitted from the fiber strip to the surface of the lining structure.

[0144] Specifically, the winding load in the cylinder area includes not only the normal compressive load (radial compressive load), but also the tangential traction load that is decomposed along the circumferential and axial directions.

[0145] Let the unit vector of the cylinder circumferential direction be... The axial unit vector is The surface load vector of the cylinder region can then be expressed as:

[0146] .

[0147] This embodiment determines the actual coverage area of ​​the lining structure surface at the current stage based on the current winding path, fiber tape width, and number of winding turns. Since the coverage area varies with the winding path and winding process, the load transmitted from the fiber tape to the lining structure surface exhibits path dependence and non-axisymmetry.

[0148] After determining the fiber tape coverage area, for each location point within the coverage area, the corresponding end cap section, cylinder section, or transition area is determined based on the location of the location point on the surface of the inner lining structure, and the corresponding local curvature parameters and fiber tape path direction are obtained; then, based on the local curvature parameters, fiber tape path direction, fiber tape tension, fiber tape width, and friction coefficient, the normal compressive load and tangential traction load at that location point are calculated.

[0149] For the surface points of the lining structure within the area covered by the fiber strip, a surface load (non-axisymmetric load) consisting of a normal compressive load and a tangential traction load is applied; for surface areas not covered by the current fiber strip, no local load corresponding to the current fiber strip is applied.

[0150] This embodiment constructs an expression for the non-axisymmetric load under the current winding stage based on the normal / tangential decomposition relationship of the surface load (non-axisymmetric load) and the path coverage state of the fiber strip on the surface of the lining structure.

[0151] Specifically, for those containing The current winding stage of the already laid fiber tape path, lining structure surface points The non-axisymmetric load distribution at a certain point can be expressed as:

[0152] ,

[0153] in, This refers to the load vector at point x on the surface of the inner lining structure after completing the Nth winding, where N is the current number of windings completed and i is the fiber tape path number. For the first The indicator function for the area covered by the fiber strip path, when the surface point Located in the When the area is covered by the fiber strip, ;otherwise, ; For the first Fiber strip path at surface point The normal clamping load generated at the location; For the first Fiber strip path at surface point The tangential traction load generated at the location; It is the unit vector normal to the surface; For the first Fiber strip path at surface point The tangential unit vector generated at that point.

[0154] The above-mentioned non-axis load distribution varies with the winding path, coverage area and winding stage, which can characterize the local covering load and off-center load that are difficult to reflect by the traditional axisymmetric layer loading model. Therefore, a non-axisymmetric load model that characterizes the stress condition of the liner structure can be constructed by the non-axis load distribution of each surface point of the liner structure.

[0155] S4. Perform equivalent processing on the non-axisymmetric load distribution of the non-axisymmetric load model to obtain equivalent load parameters for stability analysis;

[0156] To facilitate engineering stability analysis, this invention equates the non-axisymmetric load distribution of the non-axisymmetric load model to equivalent regional pressure, residual resultant force, and residual moment, as referenced. Figure 8 .

[0157] The regional equivalent pressure is used to characterize the average compressive effect in non-axisymmetric loads; the residual resultant force and residual moment are used to characterize the overall eccentric loading and bending effects caused by local coverage, path offset and circumferential load inhomogeneity.

[0158] S41. Divide the surface of the inner lining structure of the non-axisymmetric load model into multiple load equivalent regions, and obtain the total normal compressive load of the surface points in each load equivalent region according to the non-axisymmetric load distribution.

[0159] refer to Figure 9 The surface of the lining structure in the non-axisymmetric load model is divided into multiple load-equivalent regions along the axial direction, meridional direction, or winding path-related direction. Let the first... The equivalent region of each load is Its area is ;

[0160] For the current entanglement stage, let... (x) represents the normal compressive load generated by the i-th fiber strip at point x on the surface. (x) is an indicator function for the area covered by the i-th fiber strip path. Then, the total normal compressive load formed at surface point x after the superposition of all laid paths is... It can be represented as:

[0161] ,

[0162] S42. The total normal clamping load of the surface points in each load equivalent region is averaged by area integration to obtain the equivalent regional pressure corresponding to each load equivalent region.

[0163] The equivalent pressure in the region of the j-th load equivalent region It can be determined by the following formula:

[0164] ,

[0165] Where N is the number of fiber tape paths laid in the current winding stage. It is a surface area micro-element.

[0166] S43. Based on the resultant force and moment corresponding to the non-axisymmetric load distribution before equivalent processing obtained in step S34, and the resultant force and moment corresponding to the equivalent pressure in the region, calculate the residual resultant force and residual moment.

[0167] The non-axisymmetric load distribution before the equivalent treatment refers to the non-axisymmetric load distribution formed by the superposition of the normal compressive load and the tangential traction load generated by each laid fiber tape on the surface of the lining structure during the current winding stage. The non-axisymmetric load distribution is defined over the entire outer surface of the lining structure, wherein the load within the fiber-covered area is determined according to step S34, and the load in the uncovered area is zero;

[0168] Integrating the non-axisymmetric load distributed across the entire outer surface of the lining structure yields the corresponding resultant force. and torque Integrating the equivalent pressure in each region over the corresponding load equivalent region yields the resultant force corresponding to the equivalent pressure in that region. and torque Then the residual resultant force and residual torque They are respectively:

[0169] ,

[0170] ,

[0171] in, Characterizes the overall off-center load effect remaining after the non-axisymmetric load is applied relative to the equivalent regional pressure. Characterizes the overall bending or torsional effect remaining after a non-axisymmetric load is applied relative to the equivalent regional pressure.

[0172] S44. The equivalent pressure, residual resultant force, and residual moment of the region are used as equivalent load parameters.

[0173] Equivalent load parameters for stability analysis It can be represented as:

[0174] ,

[0175] in, This represents the number of load-equivalent regions.

[0176] The value of the number of load equivalent regions m is selected according to actual needs. Preferably, the surface of the inner lining structure can be divided into three load equivalent regions, and the equivalent pressure of the three regions can be obtained. , , In other embodiments, the surface of the lining structure can be divided into two, four or more load-equivalent regions according to the geometry of the lining structure, the coverage state of the winding path and the calculation accuracy requirements.

[0177] S5. The equivalent load parameters are applied to the pre-established stability analysis model of the lining structure for evaluation, and the stability evaluation results of the composite gas cylinder during the winding process are obtained.

[0178] S51. Apply the equivalent pressure of the region as surface pressure to the corresponding load equivalent region.

[0179] S52. The residual resultant force and residual moment are applied as concentrated force and concentrated moment to the reference point, respectively, and transferred to the stability analysis model of the lining structure through the coupling node loop or equivalent action region:

[0180] refer to Figure 10 After obtaining the equivalent load parameters, a stability analysis model for the composite gas cylinder liner structure is established. This stability analysis model can be a shell finite element model or other computational models suitable for assessing the stability of thin-walled structures.

[0181] In one embodiment, a shell element is used to establish a finite element model of the inner lining structure, and boundary conditions are set according to the clamping, support or positioning states in the actual winding manufacturing process.

[0182] Preferably, constraints can be applied to the short neck region, the region near the pole hole, or other fixed regions corresponding to the tooling clamping, to simulate the constraint state of the inner liner structure during the winding manufacturing process; the fixed regions are used for boundary constraints, which are different from the reference points, coupling node loops, or equivalent action regions used below to apply or transmit residual resultant forces and residual moments.

[0183] When a load is applied, the equivalent pressure in the region will be... As surface pressure, it is applied to the corresponding load equivalent region. This is used to characterize the average compressive effect of the winding load; the residual resultant force is used to characterize the average compressive effect of the winding load. and residual torque They are applied to the reference point as concentrated force and concentrated moment, respectively, and transmitted to the stability analysis model of the inner lining structure through the coupling node loop or equivalent action region, to characterize the overall eccentric load and bending effect of the non-axisymmetric load;

[0184] The transmission methods include: transmission to the coupling node loop or equivalent action region through motion coupling, distributed coupling, or equivalent constraints;

[0185] The coupling node ring can be determined based on the equivalent action position of the residual resultant force and residual moment. Specifically, it can be a ring of finite element nodes on the surface of the inner lining structure at the corresponding axial position, such as the node ring near the equator, the transition position between the end cap and the cylinder, the boundary of the load equivalent region, or the main action region of the residual load. The equivalent action region can be determined based on the main coverage area of ​​the non-axisymmetric load, the action position of the residual resultant force, or the equivalent action position of the residual moment. The above loads can be applied in the finite element modeling tool through surface pressure, concentrated force, concentrated moment, and coupling constraints.

[0186] Preferably, the reference point is set at a predetermined position on the axis of the lining structure and connected to the corresponding node ring of the lining structure through coupling constraints. In this way, the residual resultant force and residual moment can be stably transferred to the stability analysis model of the lining structure.

[0187] S53. Perform stability analysis on the inner lining structure stability analysis model to obtain the stability assessment results of the composite gas cylinder during the winding process; the stability analysis includes linear buckling analysis and nonlinear buckling analysis.

[0188] Step S53 specifically includes:

[0189] S531. Obtain the critical load coefficient and buckling mode based on linear buckling analysis, and then superimpose the buckling mode onto the initial geometry of the lining structure stability analysis model according to the preset defect amplitude. Subsequently, perform nonlinear stability analysis on the lining structure stability analysis model, that is, perform nonlinear buckling analysis with initial geometric defects on the lining structure stability analysis model to obtain the load-displacement response path, critical load scaling factor, and displacement distribution, stress distribution and instability deformation mode under critical instability state.

[0190] The stability analysis can be selected from linear buckling analysis or nonlinear buckling analysis according to the evaluation purpose; the nonlinear buckling analysis also includes nonlinear buckling analysis with initial geometric defects.

[0191] Among them, linear buckling analysis is selected to obtain the critical load coefficient and buckling mode; or nonlinear buckling analysis is selected to obtain the load-displacement response path, critical load scaling factor, and displacement distribution, stress distribution and instability deformation mode under critical instability state; the nonlinear buckling analysis can introduce initial geometric defects as needed; nonlinear buckling analysis with initial geometric defects is used to consider the defect sensitivity of thin-walled liner structures.

[0192] Preferably, the buckling mode is first obtained through linear buckling analysis, the preset defect amplitude is determined according to manufacturing tolerances, measured defects or design requirements, and the buckling mode is superimposed on the initial geometry of the inner lining structure stability analysis model according to the defect amplitude, and then nonlinear buckling analysis is performed;

[0193] The buckling mode, critical load factor, load-displacement response path, critical load scaling factor, and displacement distribution, stress distribution, and instability deformation mode under the critical instability state are used as preliminary stability assessment results; among them, the stress distribution is the stress field of the liner structure output by the nonlinear buckling analysis under the corresponding calculation increment of the critical instability state.

[0194] Based on the preliminary stability assessment results, the output stability status, danger zones, and instability risks are further determined.

[0195] When using linear buckling analysis, the following eigenvalue problem can be solved:

[0196] ,

[0197] in, Here is the structural stiffness matrix. The geometric stiffness matrix is... The buckling load factor is... It is a buckling mode.

[0198] Solving the above eigenvalue problem yields multiple buckling load coefficients and their corresponding buckling modes. The smallest positive eigenvalue among these buckling load coefficients is denoted as... This serves as the critical load coefficient under the current equivalent load condition and can also be used as the critical load scaling factor. The source of its value; and The corresponding buckling modes are used to characterize the possible unstable deformation forms of the lining structure, and areas with large mode amplitudes can be used as one of the criteria for identifying dangerous areas;

[0199] When using nonlinear buckling analysis, the load-displacement response path of the lining structure can be obtained based on the load proportioning factor and the displacement of the characteristic position of the lining structure. The critical instability state can be determined based on the load peak, displacement or deformation abrupt change in the load-displacement response path, or based on the preset instability criterion, thereby obtaining the load proportioning factor, displacement distribution, stress distribution and instability deformation mode under the critical instability state.

[0200] In nonlinear stability analysis, the critical instability state is defined as the point of limit, the point of sudden deformation change, or the preset instability criterion.

[0201] Identifying the limit point and determining the critical instability state based on the load-displacement curve is a routine procedure in nonlinear structural stability analysis, and will not be elaborated here.

[0202] The critical load scaling factor is taken as the minimum positive buckling characteristic value in linear buckling analysis, and as the load scaling factor corresponding to the critical instability state in nonlinear buckling analysis.

[0203] S532. Calculate the stability safety margin based on the critical load scaling factor and the working load scaling factor, and compare the stability safety margin with the stability safety threshold to determine the stability state; the stability state includes whether the stability requirements are met or not.

[0204] The stability safety margin is defined based on the critical load scaling factor and the working load scaling factor. :

[0205] ,

[0206] in, It is the critical load scaling factor, obtained from stability analysis. It can be the minimum positive eigenvalue of the critical load coefficient in linear buckling analysis, or the load scaling factor when the critical instability state is reached in nonlinear analysis. This is the working load scaling factor corresponding to the current winding process, used to represent the ratio of the current actual winding load to the reference load in the stability analysis; when the equivalent load corresponding to the current winding condition is used as the reference load, the working load scaling factor... One is acceptable;

[0207] when When the value is greater than the stability safety threshold, the current winding stage can be determined to meet the stability requirements; when... When the value is less than or equal to the stability safety threshold, it can be determined that there is a risk of instability in the current winding stage;

[0208] The stability safety threshold can be determined based on the gas cylinder design specifications, manufacturing process requirements, lining structure defect sensitivity, or test verification results, and is usually taken as a value greater than 1 to ensure that there is sufficient margin between the current winding stage and the critical instability state.

[0209] S533. Determine the danger zone based on the amplitude distribution of the buckling mode or the displacement and stress distribution under the critical instability state, and take at least one of the following as instability risk information: stability safety margin, tension safety margin, critical winding tension, critical winding stage, and instability deformation mode.

[0210] The tension safety margin is defined based on the critical winding tension and the current winding tension. :

[0211] ,

[0212] Among them, the critical winding tension To achieve the tension value corresponding to the critical instability state in the stability analysis when performing parametric calculations on the winding tension; the current winding tension. These are the set values ​​for the winding process or the values ​​measured by the tension control system.

[0213] Critical winding tension The tension of the fiber belt can be parameterized and amplified or iteratively calculated, and determined by the tension value corresponding to the critical instability state in the stability analysis.

[0214] S534. The buckling mode, critical load factor, load-displacement response path, critical load scaling factor, and displacement distribution, stress distribution, instability deformation mode, stability state, hazardous area, and instability risk information under critical instability state shall be used as the stability assessment results.

[0215] The stability assessment results include the aforementioned preliminary stability assessment results, as well as the stability status, hazardous areas, and instability risk information determined therefrom.

[0216] Specifically, the stability state is determined by comparing the stability safety margin with the stability safety threshold; the danger zone is determined according to the stability analysis method used, wherein, in linear buckling analysis, the region where the absolute amplitude of the buckling mode appears to be a local maximum is determined as the danger zone, and in nonlinear buckling analysis or nonlinear buckling analysis with initial geometric defects, the region where the displacement amplitude or stress value appears to be a local maximum under the critical instability state is determined as the danger zone; the instability risk information is determined based on the stability safety margin, the ratio of the critical winding tension to the current winding tension, or the deformation abrupt change.

[0217] like Figure 11 As shown, in one specific embodiment, a stability assessment is performed on a single winding stage. During this stage, the fiber tape only covers a localized area of ​​the lining structure surface, exhibiting a clear asymmetry in its coverage.

[0218] Using the method of this invention, the coverage area is first determined based on a winding path, and then the non-axisymmetric load distribution is calculated based on the fiber tension, bandwidth, friction coefficient, and surface geometry of the lining structure. Subsequently, the non-axisymmetric load is equivalent to the regional equivalent pressure, residual resultant force, and residual moment, and the equivalent load parameters are applied to the stability analysis model.

[0219] In this embodiment, the residual resultant force and residual moment are used to retain the overall off-center loading and bending effects caused by local overlay. Stability analysis reveals the danger zone, stability state, and instability risk during one winding stage. This embodiment illustrates that the present invention can identify local overlay off-center loading instability risks that are difficult to capture using traditional axisymmetric layer-by-layer loading methods.

[0220] like Figure 12As shown, in another specific embodiment, a stability assessment is performed on the multi-turn winding stage. The multi-turn winding stage may include five turns, ten turns, fifteen turns, twenty turns, or any other number of winding turns.

[0221] For any winding stage, a corresponding non-axisymmetric load distribution can be generated based on the path coverage state under the current number of turns, and the corresponding equivalent load parameters can be further obtained. By performing stability analysis on different winding stages, results such as critical load coefficient, load-displacement response path, stress distribution, or buckling mode can be obtained, and the stability state, critical area, and instability risk information can be determined accordingly. The stability state is determined by comparing the stability safety margin (SF) with the stability safety threshold; the critical area is determined based on displacement concentration areas, stress concentration areas, or areas with large buckling mode amplitudes; and the instability risk information includes the tension safety margin. Critical winding tension, critical winding stage, or instability deformation mode.

[0222] As the number of winding turns increases, the fiber tape coverage area gradually becomes denser, and the average compression effect represented by the regional equivalent pressure intensifies. Simultaneously, the residual resultant force and residual moment can still reflect the phase changes and off-center loading effects in the hazardous area caused by uneven path coverage. This embodiment illustrates that the present invention is applicable not only to strongly non-axisymmetric local coverage stages but also to staged stability assessments after coverage gradually becomes denser.

[0223] S6. Adjust the surface geometry parameters, material parameters, or winding process parameters of the composite material gas cylinder based on the stability assessment results.

[0224] In this invention, the stability assessment results can also be used for engineering design and process control in the manufacturing process of composite gas cylinders, and the corresponding parameters can be adjusted according to the performance of different stability assessment results.

[0225] In one application approach, stability safety margin or tension safety margin Compared with a preset safety threshold, when the stability safety margin Less than the stability safety threshold, or the tension safety margin When the tension is below the safety threshold, the current winding tension is deemed insufficient to meet stability requirements. In this case, measures such as reducing fiber tape tension, increasing fiber tape width, adjusting the winding angle, changing the winding path coverage sequence, or adjusting the winding start position can be taken to reduce non-axisymmetric load concentration, residual resultant force, or residual moment. The stability should then be reassessed until a stability safety margin is achieved. and tension safety margin Meets preset requirements (when stability safety margin) Greater than or equal to the stability safety threshold, and tension safety margin (greater than or equal to the tension safety threshold), thereby improving the stability safety margin.

[0226] In another application, the design of the lining structure is adjusted based on the location of the hazardous area and the instability deformation patterns in the instability risk information. These instability deformation patterns include localized indentation, overall bending, and eccentric deformation.

[0227] Specifically, when the danger zone is located in the head region, cylinder region, or transition region, the geometric parameters of the head, the wall thickness of the cylinder, or the size of the transition region are adjusted accordingly. When the instability deformation mode is manifested as local depression, the local stiffness of the corresponding region is increased. When the instability deformation mode is manifested as overall bending or eccentric deformation, the geometry of the head, the length of the cylinder, or the material parameters are adjusted to reduce deformation concentration.

[0228] In another application, candidate ranges are set for fiber tension, fiber width, winding angle, winding path, winding start position, and number of winding turns. Non-axisymmetric load modeling, equivalent load generation, and stability analysis are performed on each combination of process parameters. The parameter group with a stability safety margin greater than the stability safety threshold is determined as the process parameter combination that meets the stability requirements. The process parameter combination forms a process parameter range, which is used for winding tension selection, winding path optimization, and manufacturing process risk control. This forms a process parameter range that meets the stability requirements, effectively reducing modeling and calculation costs.

[0229] This embodiment illustrates that the present invention can identify local coverage off-center load instability risks that are difficult to capture by traditional axisymmetric layer loading methods. It is applicable not only to the strong non-axisymmetric local coverage stage, but also to the staged stability assessment after the coverage gradually becomes denser. It can effectively reduce the misjudgment of dangerous areas or the omission of instability risks that may be caused by using traditional layer loading methods, and effectively improve the accuracy of stability risk identification.

[0230] This embodiment transforms complex non-axisymmetric winding loads into equivalent load parameters such as regional equivalent pressure, residual resultant force, and residual moment, which can be directly used for stability analysis. This avoids establishing complex fiber-liner contact models at each winding stage, which helps reduce modeling and calculation costs and facilitates its application in composite gas cylinder liner structure design, winding tension selection, winding path optimization, and manufacturing process risk control.

[0231] This embodiment can characterize the non-axisymmetric load features caused by local coverage, path changes and load bias during the winding process, and solves the problem that the existing axisymmetric layer loading method is difficult to identify the instability risk during the winding process. It can be used for composite gas cylinder liner structure design, winding process optimization and manufacturing process safety assessment.

[0232] Example 2

[0233] refer to Figure 13 This embodiment provides a composite gas cylinder winding stability evaluation system based on non-axisymmetric loads, including the following modules:

[0234] The parameter acquisition module is used to acquire the surface geometry parameters, material parameters, winding path parameters, and winding process parameters of the inner lining structure of the composite gas cylinder.

[0235] The path recognition module is used to determine the contact path of the fiber tape centerline on the surface of the inner lining structure, as well as the coverage area, contact path direction, and local surface position under the current winding stage, based on the surface geometry parameters, winding path parameters, and winding process parameters.

[0236] The non-axisymmetric load modeling module is used to calculate the non-axisymmetric load based on the local curved surface position, contact path direction and winding process parameters, and to establish a non-axisymmetric load model for the fiber strip to transmit the non-axisymmetric load to the surface of the inner lining structure.

[0237] The load equivalence module is used to perform equivalent processing on the non-axisymmetric load distribution of the non-axisymmetric load model to obtain equivalent load parameters for stability analysis.

[0238] The stability assessment module is used to apply the equivalent load parameters to a pre-established stability analysis model of the liner structure for evaluation, and obtain the stability assessment results of the composite gas cylinder during the winding process.

[0239] The feedback adjustment module is used to adjust the surface geometry parameters, material parameters, or winding process parameters of the composite material gas cylinder based on the stability assessment results.

[0240] This specification is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this specification. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 A process, multiple processes, and / or boxes Figure 1 Devices that specify the functions in one or more boxes.

[0241] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including an instruction device, which is implemented in a process Figure 1One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0242] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0243] The parts of this invention not described in detail are prior art. It will be apparent to those skilled in the art that this invention is not limited to the details of the above exemplary embodiments, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and are intended to encompass all changes falling within the meaning and scope of equivalents within this invention.

Claims

1. A method for evaluating the stability of composite gas cylinder winding based on non-axisymmetric loads, characterized in that, Includes the following steps: S1. Obtain the surface geometry parameters, material parameters, winding path parameters, and winding process parameters of the inner lining structure of the composite gas cylinder; S2. Based on the surface geometry parameters, winding path parameters, and winding process parameters, determine the contact path of the fiber tape centerline on the surface of the lining structure, as well as the coverage area, contact path direction, and local surface position under the current winding stage. S3. Calculate the non-axisymmetric load based on the local curved surface position, contact path direction and winding process parameters, and establish a non-axisymmetric load model for the fiber strip to transfer the non-axisymmetric load to the surface of the inner lining structure. S4. Perform equivalent processing on the non-axisymmetric load distribution of the non-axisymmetric load model to obtain equivalent load parameters for stability analysis; S5. The equivalent load parameters are applied to the pre-established stability analysis model of the lining structure for evaluation, and the stability evaluation results of the composite gas cylinder during the winding process are obtained.

2. The method for evaluating the stability of composite gas cylinder winding according to claim 1, characterized in that, The geometric parameters include cylinder radius, cylinder length, end cap shape parameters, pole hole size, short neck size, transition area size, and wall thickness; The material parameters include elastic modulus, Poisson's ratio, density, yield strength, and material nonlinear parameters; The winding path parameters include path parameters and stage parameters; the path parameters include winding angle, winding start position and fiber tape centerline trajectory, and the stage parameters include the current number of winding turns and path coverage range. The winding process parameters include fiber tape tension, fiber tape width, and coefficient of friction.

3. The method for evaluating the stability of composite gas cylinder winding according to claim 2, characterized in that, Step S2 specifically includes: S21. Determine the contact path of the fiber belt centerline on the surface of the lining structure based on the path parameters; S22. Determine the coverage area under the current winding stage based on the contact path, the current number of winding turns, and the fiber tape width; the current winding stage includes partial coverage, non-uniform coverage, and path-related coverage. S23. Determine the contact path direction of the fiber tape at each covering position according to the contact path, and determine the local curved surface position to which each covering position belongs according to the coordinates of each covering position on the surface of the lining structure.

4. The method for evaluating the stability of composite gas cylinder winding according to claim 2, characterized in that, Step S3 specifically includes: S31. Obtain the local curvature parameters and surface normal corresponding to the local surface position, and then determine the path normal curvature of the fiber strip in the contact path direction according to the contact path direction, local curvature parameters and surface normal. S32. Calculate the normal compressive load acting on the surface of the inner lining structure based on the fiber belt tension, fiber belt width, and path normal curvature. S33. Calculate the tangential traction load along the contact path direction based on the friction coefficient and the normal clamping load; S34. Obtain the non-axisymmetric load distribution on the surface of the inner lining structure from the non-axisymmetric loads in each covered area under the current winding stage, and then construct a non-axisymmetric load model.

5. The method for evaluating the stability of composite gas cylinder winding according to claim 2, characterized in that, Step S4 specifically includes: S41. Divide the surface of the inner lining structure of the non-axisymmetric load model into multiple load equivalent regions, and obtain the total normal compressive load of the surface points in each load equivalent region according to the non-axisymmetric load distribution. S42. The total normal clamping load of the surface points in each load equivalent region is averaged by area integration to obtain the equivalent regional pressure corresponding to each load equivalent region. S43. Calculate the residual resultant force and residual moment based on the resultant force and moment corresponding to the non-axisymmetric load distribution and the resultant force and moment corresponding to the equivalent pressure in the region. S44. The equivalent pressure, residual resultant force, and residual moment of the region are used as the equivalent load parameters.

6. The method for evaluating the stability of composite gas cylinder winding according to claim 5, characterized in that, Step S5 specifically includes: S51. Apply the equivalent pressure of the region as surface pressure to the corresponding load equivalent region. S52. The residual resultant force and residual moment are applied to the reference point as concentrated force and concentrated moment, respectively, and transmitted to the stability analysis model of the inner lining structure through the coupling node loop or equivalent action region. S53. Perform stability analysis on the inner lining structure stability analysis model to obtain the stability assessment results of the composite gas cylinder during the winding process; the stability analysis includes selecting linear buckling analysis and nonlinear buckling analysis.

7. The method for evaluating the stability of composite gas cylinder winding according to claim 6, characterized in that, Step S53 specifically includes: S531. Obtain the critical load coefficient and buckling mode based on linear buckling analysis, and then superimpose the buckling mode onto the initial geometry of the lining structure stability analysis model according to the preset defect amplitude. Subsequently, perform nonlinear stability analysis on the lining structure stability analysis model to obtain the load-displacement response path, critical load scaling factor, and displacement distribution, stress distribution, and instability deformation mode under critical instability state. S532. Calculate the stability safety margin based on the critical load scaling factor and the working load scaling factor, and compare the stability safety margin with the stability safety threshold to determine the stability state; the stability state includes whether the stability requirements are met or not. Among them, stability safety margin , This is the critical load scaling factor; This is the working load scaling factor corresponding to the current winding process; when When the value is greater than the stability safety threshold, the current winding stage is determined to meet the stability requirements; when... If the value is less than or equal to the stability safety threshold, it is determined that there is a risk of instability in the current winding stage; S533. Determine the critical area based on the amplitude distribution of the buckling modes or the displacement and stress distribution under the critical instability state, and use at least one of the following as instability risk information: stability safety margin, tension safety margin, critical winding tension, critical winding stage, and instability deformation mode; wherein, the critical winding tension is used as the instability risk information. and current winding tension Define tension safety margin ; S534. The buckling mode, critical load factor, load-displacement response path, critical load scaling factor, and displacement distribution, stress distribution, instability deformation mode, stability state, hazardous area, and instability risk information under critical instability state shall be used as the stability assessment results.

8. The method for evaluating the stability of composite gas cylinder winding according to claim 7, characterized in that, The method further includes: S6. Adjust the surface geometry parameters, material parameters, or winding process parameters of the composite material gas cylinder based on the stability assessment results.

9. The method for evaluating the stability of composite gas cylinder winding according to claim 8, characterized in that, Step S6 specifically includes: When stability safety margin Less than the stability safety threshold, or the tension safety margin When the tension is less than the safety threshold, the current winding tension is determined to be insufficient to meet stability requirements. This is addressed by reducing fiber tape tension, increasing fiber tape width, adjusting the winding angle, changing the winding path coverage sequence, or adjusting the winding start position to reduce non-axisymmetric load concentration, residual resultant force, or residual moment. Stability is then reassessed until a stability safety margin is achieved. and tension safety margin Meets the preset requirements; When the danger zone is located in the head zone, cylinder zone, or transition zone, adjust the head geometry, cylinder wall thickness, or transition zone dimensions for the corresponding zone. When the instability deformation mode is characterized by local depression, increase the local stiffness of the corresponding zone. When the instability deformation mode is characterized by overall bending or eccentric deformation, adjust the head geometry, cylinder length, or material parameters to reduce deformation concentration. Candidate ranges are set for fiber tension, fiber width, winding angle, winding path, winding start position, and number of winding turns. Non-axisymmetric load modeling, equivalent load generation, and stability analysis are performed on each combination of process parameters. The parameter group with a stability safety margin greater than the stability safety threshold is determined as the process parameter combination that meets the stability requirements. The process parameter combination forms the process parameter range, which is used for winding tension selection, winding path optimization, and manufacturing process risk control.

10. A composite gas cylinder winding stability evaluation system based on non-axisymmetric load, characterized in that, The method for evaluating the stability of composite gas cylinder winding based on non-axisymmetric load according to any one of claims 1-9 includes the following modules: The parameter acquisition module is used to acquire the surface geometry parameters, material parameters, winding path parameters, and winding process parameters of the inner lining structure of the composite gas cylinder. The path recognition module is used to determine the contact path of the fiber tape centerline on the surface of the inner lining structure, as well as the coverage area, contact path direction, and local surface position under the current winding stage, based on the surface geometry parameters, winding path parameters, and winding process parameters. The non-axisymmetric load modeling module is used to calculate the non-axisymmetric load based on the local curved surface position, contact path direction and winding process parameters, and to establish a non-axisymmetric load model for the fiber strip to transmit the non-axisymmetric load to the surface of the inner lining structure. The load equivalence module is used to perform equivalent processing on the non-axisymmetric load distribution of the non-axisymmetric load model to obtain equivalent load parameters for stability analysis. The stability assessment module is used to apply the equivalent load parameters to a pre-established stability analysis model of the lining structure for evaluation, and to obtain the stability assessment results of the composite gas cylinder during the winding process.

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