A method for one-dimensional reconstruction analysis of fiber ring stress

Abstract

This invention relates to the field of optical fiber geometric reconstruction technology, specifically to a one-dimensional reconstruction analysis method for optical fiber ring stress, comprising: reading and processing finite metadata of the optical fiber ring to obtain Cartesian coordinate system node information; converting the Cartesian coordinate system node information to the cylindrical coordinate system; determining the forward and reverse optical fiber paths to which each node belongs; calibrating the length of each node based on the optical fiber winding process parameters and the optical fiber path to obtain the one-dimensional unfolded length of each node; interpolating based on the one-dimensional unfolded length to obtain a discrete point stress value sequence; conducting an actual optical fiber ring experiment based on the finite metadata to obtain a polarization coupling curve; comparing the polarization coupling curve with the discrete point stress value sequence to obtain the one-dimensional reconstruction accuracy result; this invention can improve the accuracy of optical fiber ring stress analysis results along the optical path.

Description

Technical Field

[0001] This invention relates to the field of optical fiber geometric reconstruction technology, and specifically to a one-dimensional reconstruction analysis method for optical fiber ring stress. Background Technology

[0002] In a fiber optic gyroscope, an actual fiber optic loop is a three-dimensional structure. The fiber is wound around a frame, and complex stress distributions may occur within it due to factors such as: tension during the winding process, shrinkage after curing, and mechanical stress caused by external vibration or pressure; thermal stress caused by the different coefficients of thermal expansion of the fiber, coating, and frame materials during temperature changes; and stress generated by the compression of the fiber at layer and turn changes by the frame sidewalls and inner fiber turns, which can easily lead to twisting deformation.

[0003] However, for optical fibers hundreds or thousands of meters long, performing a full three-dimensional finite element analysis would be extremely computationally expensive. The selected fiber loop had 68 layers, each with 150 turns. In ANSYS Workbench software, meshing based on the actual number of layers and turns would result in an extremely complex mesh with a massive number of nodes and elements, increasing computational difficulty and time, and potentially even causing software and computer crashes. Besides the increased computational load, low-quality meshes may also occur, severely impacting the accuracy and stability of the finite element method.

[0004] Therefore, there is an urgent need for a one-dimensional reconstruction analysis method for fiber ring stress to efficiently complete the stress distribution analysis along the fiber length. Summary of the Invention

[0005] In view of the above problems, the present invention provides a one-dimensional reconstruction analysis method for fiber optic ring stress, which solves the technical problem that the existing technology cannot extract the main stress information in highly complex simulation models.

[0006] This invention provides a one-dimensional reconstruction analysis method for fiber optic ring stress, comprising the following steps: Step S1: Read and process the finite metadata of the fiber optic ring to obtain the node information in the Cartesian coordinate system; Step S2: Establish a cylindrical coordinate system with the origin located at the geometric center of the fiber optic ring; transform the node information of the rectangular coordinate system into the cylindrical coordinate system to obtain the cylindrical coordinate system node information, which includes the cylindrical coordinate positions and stress tensor values ​​of multiple nodes; Step S3: Determine the current layer number of each node in the cylindrical coordinate system node information, including: determining the winding period of the fiber optic ring, and determining the fiber optic path to which each node belongs based on the remainder of dividing the current layer number of the node by the winding period; the fiber optic path to which each node belongs includes the forward fiber optic path and the reverse fiber optic path. Step S4: Based on the fiber winding process parameters and the fiber path to which each node belongs in the cylindrical coordinate system node information, the length of each node is calibrated to obtain the one-dimensional unfolded length of each node. Interpolation is performed on the one-dimensional unfolded length of each node in the cylindrical coordinate system node information to obtain a discrete point stress value sequence; the length coordinate position of each node in the discrete point stress value sequence is uniformly distributed in the direction of the one-dimensional unfolded length. Step S5: Based on the finite metadata, conduct an actual fiber optic ring experiment to obtain the polarization coupling curve. Compare the polarization coupling curve with the discrete point stress value sequence to obtain the one-dimensional reconstruction accuracy result.

[0007] Preferably, step S1 specifically includes: The mesh node data file generated by the finite element simulation of the fiber optic ring is analyzed, and the Cartesian coordinate position and stress tensor value of each mesh node are extracted from the data file.

[0008] Preferably, in step S2, the Z-axis of the cylindrical coordinate system coincides with the geometric center axis of the fiber optic ring; The following coordinate transformation expression is used to transform the node information of the rectangular coordinate system to the cylindrical coordinate system:

[0009] in, Radial distance, Polar angle, The height along the Z-axis in a rectangular coordinate system. The height along the Z-axis in the cylindrical coordinate system. Representing X and Y in a rectangular coordinate system respectively Y-axis coordinate.

[0010] Preferably, step S3 specifically includes: The corresponding processing is performed according to the winding method of the fiber optic ring. If the winding method of the fiber optic ring is an octagonal symmetrical winding method, then the winding period N=8 is defined. The judgment rule is: divide the current layer number k of the node by N. If the remainder is 1, 4, 6 or 7, then the node is determined to belong to the forward fiber optic path; if the remainder is 2, 3, 5 or 0, then the node is determined to belong to the reverse fiber optic path. If the fiber optic loop is wound in a four-pole symmetrical manner, then the winding period N=4 is defined. The determination rule is: divide the current layer number k of the node by N. If the remainder is 1 or 0, the node is determined to be on the forward fiber path; if the remainder is 2 or 3, the node is determined to be on the reverse fiber path. If the fiber optic loop is wound in a 16-pole symmetrical manner, then the winding period N is defined as 16. The determination rule is: divide the current layer number k of the node by N. If the remainder is 1, 4, 6, 7, 10, 11, 13 or 0, then the node is determined to be on the forward fiber path; if the remainder is 2, 3, 5, 8, 9, 12, 14 or 15, then the node is determined to be on the reverse fiber path.

[0011] Preferably, the step of calibrating the length of each node based on the fiber winding process parameters and the fiber path to which each node belongs in the cylindrical coordinate system node information, and obtaining the one-dimensional unfolded length of each node, specifically includes: The one-dimensional unfolded length of a node is determined based on the number of layers, turns, polar angle, fiber diameter, and fiber winding radius at the node's location. The expression is:

[0012] Where L represents the one-dimensional unfolding length, and j represents the turns index. Indicates the diameter of the optical fiber. This indicates the number of polar angle segments per turn, where i is the polar angle index; This represents the floor function. This indicates the correction factor for layer replacement and turn replacement. Represents the actual winding radius of the k-th layer.

[0013] one-dimensional unfolded length The positive and negative values ​​are determined and assigned, including: based on the fiber path to which each node belongs, if the node belongs to the forward fiber path, the one-dimensional unfolded length value is set to a positive value; if the node belongs to the forward fiber path, the one-dimensional unfolded length value is set to a negative value.

[0014] Preferably, in the step of interpolating based on the one-dimensional unfolded length of each node in the cylindrical coordinate system node information, linear interpolation or cubic spline interpolation methods are specifically used to complete the interpolation.

[0015] Preferably, the step of comparing the polarization coupling curve with the discrete point stress value sequence to obtain the one-dimensional reconstruction accuracy result specifically includes: The cross-correlation coefficient between the stress curve and the polarization coupling curve is calculated as the matching degree of the peak position; the mean square error between the stress curve and the polarization coupling curve is calculated as the matching degree of the variation trend.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: (1) This invention can convert the three-dimensional, discrete, and potentially non-uniformly distributed stress data output by finite element software such as ANSYS into a one-dimensional stress sequence along the actual propagation path of the optical fiber, thus realizing a dimensionality reduction expression of the stress field. This not only preserves the key stress information directly related to the propagation of the optical path, but also avoids the computational redundancy caused by the complexity of the three-dimensional mesh, significantly improving the efficiency of stress information extraction and subsequent analysis, and providing a more intuitive and usable data foundation for micromechanical modeling of optical fiber rings.

[0017] (2) This invention establishes a cylindrical coordinate system with the geometric center of the fiber ring as the origin, and combines fiber winding process parameters to assign paths and calibrate lengths of nodes. This allows for accurate differentiation between forward and reverse fiber paths, thus more realistically reflecting the actual distribution of stress along the length of the fiber ring. Compared to direct coarse reading or simple projection in three-dimensional space, this method effectively addresses stress extraction under low-density or non-uniform mesh conditions, improving the accuracy and physical consistency of stress reconstruction along the optical path.

[0018] (3) This invention compares the one-dimensional discrete stress value sequence with the polarization coupling curve obtained from the actual fiber optic ring experiment, which allows for experimental verification and accuracy evaluation of the reconstruction results, thus forming a closed-loop verification between the simulation model and the measured results. This mechanism not only enhances the credibility of the one-dimensional stress reconstruction results, but also provides accurate numerical model support for analyzing temperature non-reciprocity, stress non-reciprocity and their coupling effects in devices such as fiber optic gyroscopes, and has strong engineering application value. Attached Figure Description

[0019] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0020] Figure 1 The flowchart shows the one-dimensional reconstruction analysis method for fiber ring stress provided by this invention.

[0021] Figure 2 The schematic diagrams of the multi-pole symmetric winding process and the cross-section of the optical fiber ring provided by this invention are shown.

[0022] Figure 3 This is a schematic diagram of the discretization of the eight-level symmetrical winding ring section provided by the present invention.

[0023] Figure 4 A schematic diagram of the geometric model corresponding to the planar support and two-point support provided by the present invention.

[0024] Figure 5 A schematic diagram showing the distribution of stress along the fiber length in each direction for planar support and two-point support provided by the present invention.

[0025] Figure 6This is a schematic diagram of an actual planar support experiment provided by the present invention.

[0026] Figure 7 This is a schematic diagram comparing polarization coupling and stress results provided by the present invention. Detailed Implementation

[0027] To better understand the above-described objectives, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other. Furthermore, the present invention can be implemented in other ways different from those described herein; therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0028] To illustrate the effectiveness of the method proposed in this invention, the following detailed description of the above technical solution is provided through a specific embodiment, such as... Figure 1 As shown, a one-dimensional reconstruction analysis method for fiber ring stress is disclosed, and the specific implementation steps are as follows: Step S1: Read and process the finite metadata of the fiber optic ring to obtain the node information in the Cartesian coordinate system; In this step, finite element analysis software, such as ANSYS Workbench and COMSOL Multiphysics, is first used to model and simulate the complete three-dimensional structure of the fiber optic ring.

[0029] During the modeling process, the material properties of the fiber optic ring are input, including Young's modulus, Poisson's ratio, and coefficient of thermal expansion; the geometric parameters of the fiber optic ring are defined, including fiber diameter, skeleton size, number of winding layers, and number of turns; corresponding temperature loads or mechanical loads are applied, finite element solutions are performed, and the stress tensor field of each mesh node in the entire three-dimensional model is output.

[0030] Specifically, the mesh node data file generated by the finite element simulation of the fiber optic ring is analyzed, and the spatial rectangular coordinates (x, y, z) of each mesh node and the stress tensor value corresponding to the node are extracted from the data file. The stress tensor value includes components such as X-direction stress, Y-direction stress, and Z-direction stress.

[0031] In some embodiments, during the data import process, the present invention filters out auxiliary information such as node numbers that are not geometric physical quantities, and retains only coordinate data and physical field data, providing a data foundation for subsequent coordinate transformation and stress reconstruction.

[0032] The present invention obtains Cartesian coordinate system node information including the Cartesian coordinate positions and stress tensor values ​​of multiple nodes.

[0033] Step S2: Establish a cylindrical coordinate system with the origin located at the geometric center of the fiber optic ring; convert the node information of the rectangular coordinate system to the cylindrical coordinate system to obtain the cylindrical coordinate system node information, which includes the cylindrical coordinate positions and stress values ​​of multiple nodes; In this step, after obtaining the node coordinate positions and stress information in the Cartesian coordinate system, the present invention converts the coordinate system into a cylindrical coordinate system that is more suitable for describing the optical fiber ring circumferential structure.

[0034] Specifically, a cylindrical coordinate system is established with the Z-axis coinciding with the geometric center axis of the fiber optic ring, and the origin of the cylindrical coordinate system is located at the geometric center of the fiber optic ring. The cylindrical coordinate system uses (ρ, θ, ...) Three parameters describe spatial location, where ρ is the radial distance and θ is the polar angle. The height along the Z-axis in the cylindrical coordinate system.

[0035] Using inverse trigonometric functions and square root operations, the rectangular coordinates (x, y, ...) of the grid nodes are determined. This is mapped to coordinate parameters in cylindrical coordinates. The specific conversion formula is:

[0036] in, Radial distance, Polar angle, The height along the Z-axis in a rectangular coordinate system. The height along the Z-axis in the cylindrical coordinate system. Representing X and Y in a rectangular coordinate system respectively Y-axis coordinate.

[0037] In some embodiments, when using MATLAB for data processing, the sqrt and atan functions can be used to convert rectangular coordinates to polar coordinates. sqrt refers to the mathematical operation of square root. atan and atan2 are functions used to calculate the arctangent.

[0038] This step completes the transformation from a Cartesian coordinate system to a cylindrical coordinate system. The obtained cylindrical coordinate system node information includes the cylindrical coordinate positions (ρ, θ, ...) of multiple nodes. The corresponding stress values ​​provide convenience for subsequent fiber optic path determination and length calibration based on the characteristics of the circumferential structure.

[0039] Step S3: Determine the current layer number of each node in the cylindrical coordinate system node information, including: determining the winding period of the fiber optic ring, and determining the fiber optic path to which each node belongs based on the remainder of dividing the current layer number of the node by the winding period; the fiber optic path to which each node belongs includes the forward fiber optic path and the reverse fiber optic path. The fiber optic ring employs a multi-pole symmetrical precision winding method to suppress environmental stress interference; common methods include four-pole symmetrical, eight-pole symmetrical, or sixteen-pole symmetrical winding. The fiber optic path includes a forward fiber path and a reverse fiber path. The core objective of this step is to separate the complexly interwoven fiber into forward and reverse transmission parts based on the topological rules of the multi-pole symmetrical winding and using a layer periodicity identification algorithm.

[0040] A detailed explanation is given using the octagonal symmetrical winding method as an example; see [link / reference]. Figure 3 The diagram illustrates the multi-pole symmetric winding process. In octapole symmetric winding, a continuous optical fiber is split in two at its physical midpoint, labeled as the forward fiber path and the reverse fiber path. Each complete winding cycle consists of eight tightly packed layers of fiber. The forward fiber segment is responsible for winding layers 1, 4, 6, and 7 within one cycle, while the reverse fiber segment is responsible for winding layers 2, 3, 5, and 8.

[0041] Specifically, based on the multi-pole symmetrical winding topology of the fiber optic ring, a logical mapping relationship between the number of winding layers and the fiber transmission direction is established. Using the remainder function (rem in MATLAB), periodic calculations are performed on the current layer number, and the remainder value of the calculation result determines whether the fiber layer belongs to the forward or reverse fiber segment.

[0042] For the octet symmetrical winding method, the winding period N=8 is defined. The determination rule is: divide the current layer number k by N. If the remainder rem(k,8) is 1, 4, 6, or 7, then the layer is determined to belong to the forward fiber path; if the remainder is 2, 3, 5, or 0 (the remainder of the 8th layer divided by 8 is 0), then the layer is determined to belong to the reverse fiber path.

[0043] For the four-pole symmetrical winding method, the winding period N=4 is defined. The determination rule is: divide the current layer number k of the node by N. If the remainder is 1 or 0, the node is determined to belong to the forward fiber path; if the remainder is 2 or 3, the node is determined to belong to the reverse fiber path.

[0044] For the sixteen-pole symmetrical winding method, the winding period N is defined as 16. The determination rule is: divide the current layer number k of the node by N. If the remainder is 1, 4, 6, 7, 10, 11, 13 or 0, the node is determined to belong to the forward fiber path; if the remainder is 2, 3, 5, 8, 9, 12, 14 or 15, the node is determined to belong to the reverse fiber path.

[0045] By using the above-mentioned method based on the periodicity of the layer number, the fiber path type of each node in the cylindrical coordinate system node information is determined according to its layer number, thus realizing the accurate separation of the forward fiber path and the reverse fiber path. This is used for subsequent independent length accumulation and one-dimensional stress modeling of the two optical paths.

[0046] Step S4: Based on the fiber winding process parameters and the fiber path to which each node belongs in the cylindrical coordinate system node information, the length of each node is calibrated to obtain the one-dimensional unfolded length of each node. Interpolation is performed on the one-dimensional unfolded length of each node in the cylindrical coordinate system node information to obtain a discrete point stress value sequence; the length coordinate position of each node in the discrete point stress value sequence is uniformly distributed in the direction of the one-dimensional unfolded length. In this step, the discretely distributed nodes in three-dimensional space are mapped to a one-dimensional length coordinate along the direction of optical fiber propagation, and a uniformly distributed stress value sequence is obtained through an interpolation algorithm, as described in detail below.

[0047] (1) Fiber optic length calibration Based on the geometric parameters and winding process parameters of the fiber ring, the theoretical physical location of each layer and each turn of fiber is determined. A one-dimensional fiber length calculation model is constructed. For a discrete node located at the k-th layer, j-th turn, and polar angle θ, its polar coordinates can be expressed as: (Rq(k), dD*i, dH*j). Where Rq(k) is the average winding radius of the k-th layer, dD is the polar angle spacing, dH is the column height spacing, and i is the polar angle index.

[0048] Under ideal winding conditions, the formula for calculating the one-dimensional unfolded length corresponding to this node is:

[0049] Where L represents the one-dimensional unfolding length, and j represents the turns index. This represents the average winding radius of the k-th layer. Indicates the diameter of the optical fiber. This indicates the number of polar angle segments per turn, where i is the polar angle index.

[0050] The above formula combines the average winding radius of the layer, the arc length corresponding to the current polar angle, and the cumulative length of the previous number of turns and layers.

[0051] However, several non-ideal factors exist in the actual fiber optic winding process. A fiber loop turn refers to the length of one lap of fiber around the bobbin, and is the most basic unit constituting a loop. A layer consists of many tightly packed turns of fiber. Turn changing refers to the operation within the same layer, precisely moving from the end of the current turn to the beginning of the next turn. Layer changing refers to the operation of guiding the fiber from the end of one layer to the beginning of the next after the first layer is wound; this is a "climb" or "transition" action, such as... Figure 2 The image shows the climb angle.

[0052] The optical fibers in the layer-changing and turn-changing sections are subject to compression from the skeleton sidewalls and inner fiber turns, making them highly susceptible to twisting and deformation, resulting in additional fiber length that needs to be accounted for. Taking a quadrupole symmetrical structure as an example, each quadrupole structure exhibits a forward fiber layer-changing phenomenon from layer 1 to layer 4, while two adjacent quadrupole structures exhibit a reverse fiber layer-changing phenomenon from layer 3 to layer 6.

[0053] To compensate for geometric errors caused by non-ideal winding structures, layer and turn replacement correction factors are introduced during the length calibration process. For a quadrupole symmetric structure, the number of layers the fiber optic cable traverses is a fixed 3, regardless of whether it's moving from the first to the fourth layer or from the third to the sixth layer. Based on the fiber diameter *d*, the layer-switching height *H* can be considered as 3d. The climb angle during layer switching in a fiber optic gyroscope is defined. Since the fiber itself is very thin, the actual climb angle is approximately 1 degree. Therefore, the layer-switching correction length can be expressed as:

[0054] Furthermore, to more accurately characterize the non-ideals in the actual winding process, this invention introduces a layer thickness variation coefficient α based on the ideal one-dimensional length model. Due to fiber extrusion, uneven adhesive coating, and cable crossing, the actual equivalent winding radius and pitch are dynamically changing. This invention corrects the actual winding radius of the k-th layer to a value that includes the cumulative error of the preceding layers, expressed as:

[0055] in, This represents the actual winding radius of the k-th layer. This represents the coefficient of variation of the thickness of the m-th layer.

[0056] Layer replacement and turn replacement correction factors The length is calculated by superimposing it onto the one-dimensional unfolded length L and combining it with the actual winding radius of the k-th layer. The final length calculation formula is as follows:

[0057] in, This represents the floor function.

[0058] Based on the above calculation of the one-dimensional unfolded length, a three-layer loop structure is implemented using MATLAB programming. The outer loop traverses all layers k, the middle loop traverses the number of turns j in each layer, and the inner loop traverses the polar angle index i in each turn, and calculates the one-dimensional unfolded length value L corresponding to each node.

[0059] In addition, the present invention also determines the sign of the one-dimensional unfolded length value L. Based on the optical fiber path to which each node belongs as determined in the aforementioned steps, if the node belongs to the forward optical fiber path, the one-dimensional unfolded length value is set to a positive value; if the node belongs to the forward optical fiber path, the one-dimensional unfolded length value is set to a negative value.

[0060] Through the above steps, this invention realizes the transformation from the spatial position on the fiber ring in a three-dimensional rectangular coordinate system to the one-dimensional fiber length coordinate, which significantly reduces the complexity of stress field extraction position.

[0061] (2) Interpolation calculation to obtain discrete point stress value sequence Because the mesh generation in finite element software such as ANSYS is not entirely based on the actual number of turns and layers of the fiber optic ring, the obtained node data is spatially uneven and exhibits a discrete and irregular distribution along the one-dimensional unfolded length. To obtain stress data uniformly distributed along the fiber length, interpolation calculations are required to compensate for the data gaps caused by the uneven finite element mesh generation.

[0062] Specifically, using an interpolation algorithm, the stress value at the corresponding point on the one-dimensional unfolded length L is calculated based on the discrete nodal stress values ​​in the cylindrical coordinate system. MATLAB provides various interpolation methods, including two main categories: polynomial interpolation and non-polynomial interpolation. Polynomial interpolation uses polynomial functions to approximate data points, while non-polynomial interpolation uses other function forms to approximate data points.

[0063] Specifically, this invention can employ methods such as linear interpolation and cubic spline interpolation to ultimately obtain discrete nodes uniformly distributed along the one-dimensional unfolded length direction and their corresponding stress values.

[0064] See Figure 3 The schematic diagram of the discretized annular cross-section shown illustrates how interpolation calculations ultimately yield a sequence of discrete point stress values. The positions of each node in this sequence are uniformly distributed along the one-dimensional unfolded length. This discrete point stress value sequence includes stress components in all directions along the fiber length, providing a complete data foundation for subsequent stress analysis and optical effect evaluation.

[0065] This step successfully transformed the non-uniformly distributed finite element node data in three-dimensional space into a uniformly distributed stress value sequence on a one-dimensional fiber length coordinate, completing the one-dimensional reconstruction of fiber ring stress and providing an efficient numerical model for analyzing the distribution law of stress along the fiber propagation path.

[0066] It should be noted that the present invention can divide the discrete point stress value sequence according to the forward fiber path and the reverse fiber path to obtain two sequences, one describing the stress change on the forward fiber path and the other describing the stress change on the reverse fiber path.

[0067] Step S5: Based on the finite metadata, conduct an actual fiber optic ring experiment to obtain the polarization coupling curve. Compare the polarization coupling curve with the discrete point stress value sequence to obtain the one-dimensional reconstruction accuracy result.

[0068] This step determines the accuracy of the one-dimensional reconstruction of the fiber ring through actual experiments.

[0069] First, based on the physical model corresponding to the finite element model used, an actual fiber optic ring experiment was designed and conducted. A three-dimensional solid model corresponding to the finite element model was established using SolidWorks software, and different support conditions and loading methods were designed according to different research objectives.

[0070] In one specific embodiment, to study the stress response of an optical fiber ring under planar support conditions under pressure, a system is established as follows: Figure 4 The geometric model shown, in the case of planar support under pressure, consists of an optical fiber ring and a pressure ring. The aluminum pressure ring is in direct contact with the optical fiber ring and is located above it. The main function of the aluminum pressure ring is to provide the contact area. It should be noted that the contact area between the aluminum pressure ring and the optical fiber ring is the area of ​​the aluminum pressure ring's boss. The stress response model under two-point support under pressure consists of two gaskets, an optical fiber ring, and a rectangular mass block. The two gaskets mainly serve a supporting function and are located at either end of an arbitrary diameter below the optical fiber ring. The rectangular mass block mainly provides the contact area and is located at the diameter of the optical fiber ring perpendicular to the diameter of the two gaskets. Therefore, once the positions of the two gaskets are determined, the position of the rectangular mass block is unique.

[0071] like Figure 5 As shown, this invention obtained the stress distribution along the fiber length in each direction for two models through simulation, verifying the rationality of fiber one-dimensionalization. Three-dimensional modeling was performed using SolidWords to apply stress, and the simulation results of the three-dimensional model were then used to create a one-dimensional representation based on different stress conditions of the fiber optic gyroscope.

[0072] like Figure 6 As shown, a comparative analysis is conducted on the working condition of pressing a 20.75kg weight on top of an optical fiber ring under planar support conditions.

[0073] After setting up the experimental setup, a white-light interferometer was used to test the actual fiber optic ring. The white-light interferometer can measure the polarization coupling characteristics along the length of the fiber and obtain the polarization coupling curve. The polarization coupling and the stress distribution inside the fiber show a good correspondence at characteristic locations.

[0074] The stress distribution along the fiber length in the X-direction of the fiber loop obtained from finite element simulation is compared with the test results of the white light interferometer under the same operating condition. Figure 7 As shown.

[0075] After obtaining the polarization coupling curve, it is compared and analyzed with the discrete point stress value sequence obtained in step S4. Specifically, this includes: (1) Determine whether the position of the peak in the stress curve matches the position of the characteristic peak in the polarization coupling curve.

[0076] In some embodiments, the cross-correlation coefficient between the stress curve and the polarization coupling curve can be calculated to obtain the peak position matching degree.

[0077] (2) Determine whether the overall trend of stress value change (increasing, decreasing or remaining stable) along the fiber length direction is consistent with the trend of polarization coupling strength change. In some embodiments, the mean square error between the stress curve and the polarization coupling curve can be calculated to obtain the degree of matching of the changing trends.

[0078] Considering the limitations of the testing equipment and environmental factors, the first 100 meters of fiber were discarded. A comparative analysis was conducted on fiber lengths from 100 to 400 meters. The results, both from simulation and experiment, show three distinct large spikes every 100 meters. The height of these spikes increases from 100 to 400 meters, with a relatively gentle increase from 100 to 300 meters, and a steeper increase from 300 to 400 meters. This trend reflects the physical law that the stress on the outer fiber gradually increases with the number of layers.

[0079] The simulation results are largely consistent with the experimental results in key characteristics such as peak position, peak frequency, and amplitude variation trend, verifying the correctness and accuracy of the one-dimensional reconstruction modeling method for fiber optic ring stress proposed in this invention. It also verifies the rationality of the simplified finite element model of the fiber optic ring, the feasibility of the one-dimensional stress field technique, and the accuracy of the obtained equivalent elastic parameters.

[0080] While the specific embodiments of the present invention depict actions or steps in a particular order, this should be understood as requiring such actions or steps to be performed in the specific order shown or in sequential order, or requiring all illustrated actions or steps to be performed to achieve the desired result. In certain environments, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented individually or in any suitable sub-combination in multiple implementations.

[0081] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A one-dimensional reconstruction analysis method for fiber optic ring stress, characterized in that, Includes the following steps: Step S1: Read and process the finite metadata of the fiber optic ring to obtain the node information in the Cartesian coordinate system; Step S2: Establish a cylindrical coordinate system with the origin located at the geometric center of the fiber optic ring; transform the node information of the rectangular coordinate system into the cylindrical coordinate system to obtain the cylindrical coordinate system node information, which includes the cylindrical coordinate positions and stress tensor values ​​of multiple nodes; Step S3: Determine the current layer number of each node in the cylindrical coordinate system node information, including: determining the winding period of the fiber optic ring, and determining the fiber optic path to which each node belongs based on the remainder of dividing the current layer number of the node by the winding period; the fiber optic path to which each node belongs includes the forward fiber optic path and the reverse fiber optic path. Step S4: Based on the fiber winding process parameters and the fiber path to which each node belongs in the cylindrical coordinate system node information, the length of each node is calibrated to obtain the one-dimensional unfolded length of each node. Interpolation is performed on the one-dimensional unfolded length of each node in the cylindrical coordinate system node information to obtain a discrete point stress value sequence; the length coordinate position of each node in the discrete point stress value sequence is uniformly distributed in the direction of the one-dimensional unfolded length. Step S5: Based on the finite metadata, conduct an actual fiber optic ring experiment to obtain the polarization coupling curve. Compare the polarization coupling curve with the discrete point stress value sequence to obtain the one-dimensional reconstruction accuracy result.

2. The one-dimensional reconstruction analysis method for fiber optic ring stress according to claim 1, characterized in that, Step S1 specifically includes: The mesh node data file generated by the finite element simulation of the fiber optic ring is analyzed, and the Cartesian coordinate position and stress tensor value of each mesh node are extracted from it.

3. The one-dimensional reconstruction analysis method for fiber optic ring stress according to claim 2, characterized in that, In step S2, the Z-axis of the cylindrical coordinate system coincides with the geometric center axis of the fiber optic ring; The following coordinate transformation expression is used to transform the node information of the rectangular coordinate system to the cylindrical coordinate system: in, Radial distance, Polar angle, The height along the Z-axis in a rectangular coordinate system. The height along the Z-axis in the cylindrical coordinate system. Representing X and Y in a rectangular coordinate system respectively Y-axis coordinate.

4. The one-dimensional reconstruction analysis method for fiber optic ring stress according to claim 3, characterized in that, Step S3 specifically includes: The corresponding processing is performed according to the winding method of the fiber optic ring. If the winding method of the fiber optic ring is an octagonal symmetrical winding method, then the winding period N=8 is defined. The judgment rule is: divide the current layer number k of the node by N. If the remainder is 1, 4, 6 or 7, then the node is determined to belong to the forward fiber optic path; if the remainder is 2, 3, 5 or 0, then the node is determined to belong to the reverse fiber optic path. If the fiber optic loop is wound in a four-pole symmetrical manner, then the winding period N=4 is defined. The determination rule is: divide the current layer number k of the node by N. If the remainder is 1 or 0, the node is determined to be on the forward fiber path; if the remainder is 2 or 3, the node is determined to be on the reverse fiber path. If the fiber optic loop is wound in a 16-pole symmetrical manner, then the winding period N is defined as 16. The determination rule is: divide the current layer number k of the node by N. If the remainder is 1, 4, 6, 7, 10, 11, 13 or 0, then the node is determined to be on the forward fiber path; if the remainder is 2, 3, 5, 8, 9, 12, 14 or 15, then the node is determined to be on the reverse fiber path.

5. The one-dimensional reconstruction analysis method for fiber optic ring stress according to claim 4, characterized in that, In step S4, the step of calibrating the length of each node based on the fiber winding process parameters and the fiber path to which each node belongs in the cylindrical coordinate system node information, and obtaining the one-dimensional unfolded length of each node, specifically includes: The one-dimensional unfolded length of a node is determined based on the number of layers, turns, polar angle, fiber diameter, and fiber winding radius at the node's location. The expression is: Where L represents the one-dimensional unfolding length, and j represents the turns index. Indicates the diameter of the optical fiber. This indicates the number of polar angle segments per turn, where i is the polar angle index; This represents the floor function. This indicates the correction factor for layer replacement and turn replacement. This represents the actual winding radius of the k-th layer; one-dimensional unfolded length The positive and negative values ​​are determined and assigned, including: based on the fiber path to which each node belongs, if the node belongs to the forward fiber path, the one-dimensional unfolded length value is set to a positive value; if the node belongs to the forward fiber path, the one-dimensional unfolded length value is set to a negative value.

6. The one-dimensional reconstruction analysis method for fiber optic ring stress according to claim 5, characterized in that, In step S4, the step of interpolating based on the one-dimensional unfolded length of each node in the cylindrical coordinate system node information is specifically performed using linear interpolation or cubic spline interpolation methods.

7. The one-dimensional reconstruction analysis method for fiber optic ring stress according to claim 6, characterized in that, In step S5, the step of comparing the polarization coupling curve with the discrete point stress value sequence to obtain the one-dimensional reconstruction accuracy result specifically includes: The cross-correlation coefficient between the stress curve and the polarization coupling curve is calculated as the matching degree of the peak position; the mean square error between the stress curve and the polarization coupling curve is calculated as the matching degree of the variation trend.

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