A method and system for simulating impact resistance of fasteners in low temperature environments

Abstract

The present application relates to the field of fastener, more particularly, the present application relates to a kind of fastener in low temperature environment under impact simulation method and system.The method comprises: the rough cell division of the constructed fastener three-dimensional model is carried out to obtain cell, the global thermal stress gradient mean and global impact stress gradient mean of all cells are calculated;The stress distance of any two cells is calculated to obtain evaluation distance, all cells are clustered, the edge length of cell in cluster is updated, and the updated edge length is obtained;The face gradient tensor of marker grid is calculated, the stress dominant weight of any face of marker grid is calculated according to face gradient tensor, the self-adapting norm stress is obtained by weighting norm equivalent stress, the model is constructed, and the evaluation of the low temperature impact resistance of fastener is completed.Through the technical scheme of the present application, the precision of fastener impact resistance evaluation result can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fasteners. More particularly, the present application relates to a method and system for simulating the impact resistance of a fastener in a low-temperature environment. BACKGROUND

[0002] Fasteners are used in key industrial fields such as aerospace, rail transit, nuclear power, deep-sea equipment, etc., such as aircraft operating at high altitudes or in polar regions, rapid loading in liquid nitrogen / liquid hydrogen cooling systems, rapid temperature drop-impact processes in aircraft engines, etc. The structural integrity of fasteners in such working conditions is directly related to system safety. Under such working conditions, the fastener material will produce thermal contraction deformation due to rapid cooling, and the fastening structure is usually constrained by geometric or assembly boundaries, resulting in the accumulation of residual thermal stress inside the structure. The coupling of thermal stress and impact stress causes local yield, cracking, shear failure or brittle fracture.

[0003] However, the evaluation of the impact resistance of fasteners in the prior art usually relies on the calculation of the norm equivalent stress and assumes that the stress distribution is isotropic. This ignores the complex stress distribution of fasteners in a low-temperature environment, especially the coupling of thermal stress and impact stress, resulting in inaccurate evaluation results. SUMMARY

[0004] To solve the problem of inaccurate evaluation results of the impact resistance of fasteners, the present application provides solutions in the following aspects.

[0005] In a first aspect, the present application discloses a method for simulating the impact resistance of a fastener in a low-temperature environment, comprising: performing coarse cell division on a constructed three-dimensional model of the fastener to obtain cells, wherein the dimensions include the positive direction of the horizontal axis, the positive direction of the vertical axis and the positive direction of the vertical axis, obtaining the thermal stress gradient amplitude and the impact stress gradient amplitude of any cell to calculate the global thermal stress gradient mean and the global impact stress gradient mean of all cells; taking the global thermal stress gradient mean and the global impact stress gradient mean as weights to calculate the stress distance of any two cells, and taking the sum of the stress distance and the spatial distance as the evaluation distance, clustering all cells according to the evaluation distance to obtain a plurality of clustering clusters, for any clustering cluster, calculating the local thermal stress gradient mean and the local impact stress gradient mean, updating the cell edge length in the clustering cluster to obtain the updated edge length; taking any adjusted cell as a marker cell, obtaining the target thermal stress tensor and the target impact stress tensor of the marker cell, taking the sum of the target thermal stress tensor and the target impact stress tensor as the comprehensive tensor to calculate the face gradient tensor of the marker cell, calculating the stress dominant weight of any face of the marker cell according to the face gradient tensor, weighting the norm equivalent stress to obtain the adaptive norm stress, and constructing a model according to the adaptive norm stress of each cell in the three-dimensional model of the fastener to complete the evaluation of the low-temperature impact resistance of the fastener.

[0006] Preferably, the obtaining of the thermal stress gradient amplitude and the impact stress gradient amplitude of any cell comprises: taking a cell adjacent to the any cell in the positive direction of the horizontal axis as a reference cell, taking the difference between the thermal stress tensor component of the any cell in the positive direction of the horizontal axis and the thermal stress tensor component of the reference cell in the positive direction of the horizontal axis as the thermal stress gradient of the any cell in the positive direction of the horizontal axis, and traversing to obtain the thermal stress gradient of the any cell in the positive direction of the vertical axis and the thermal stress gradient of the any cell in the positive direction of the vertical axis; taking the square root of the sum of the square of the thermal stress gradient of the any cell in the positive direction of the horizontal axis, the square of the thermal stress gradient of the any cell in the positive direction of the vertical axis, and the square of the thermal stress gradient of the any cell in the positive direction of the vertical axis as the thermal stress gradient amplitude; and obtaining the impact stress gradient amplitude of the any cell in the same manner.

[0007] Preferably, the stress distance comprises: taking the sum of the global thermal stress gradient mean value and the global impact stress gradient mean value as a mean sum, taking the ratio of the global thermal stress gradient mean value to the mean sum as a thermal stress weight, and taking the ratio of the global impact stress gradient mean value to the mean sum as an impact stress weight; calculating the thermal stress distance of the thermal stress gradient amplitudes of any two cells, and calculating the impact stress distance of the impact stress gradient amplitudes of any two cells; calculating a first product of the thermal stress weight and the thermal stress distance, and a second product of the impact stress weight and the impact stress distance; and taking the sum of the first product and the second product as the stress distance.

[0008] Preferably, the spatial distance is the position distance of any two cells in the three-dimensional model.

[0009] Preferably, the calculation of the local thermal stress gradient mean value and the local impact stress gradient mean value, the updating of the cell edge length in the clustering cluster, and the obtaining of the updated edge length comprise: for the same clustering cluster, taking the mean value of the thermal stress gradient amplitudes of all cells as the local thermal stress gradient mean value, taking the mean value of the impact stress gradient amplitudes of all cells as the local impact stress gradient mean value, and calculating a first sum value of the local thermal stress gradient mean value and the local impact stress gradient mean value; calculating a second sum value of the global thermal stress gradient mean value and the global impact stress gradient mean value; and taking the ratio of the second sum value to the first sum value as a weight, and multiplying the weight by the edge length of the cell to obtain the updated edge length.

[0010] Preferably, the calculation of the face gradient tensor of the marker cell comprises: obtaining a comprehensive gradient of a dimension to which any face belongs, the dimension being two dimensions, and taking the product of the comprehensive gradients of the two dimensions as the face gradient tensor.

[0011] Preferably, the stress-dominant weight of any face of the calculation mark grid comprises: for the same cluster, traversing the face gradient tensor of each mark grid on any face to calculate the mean value of the face gradient tensor of any face; traversing the mean value of the face gradient tensor of three faces including the face where the positive direction of the horizontal axis and the positive direction of the vertical axis are located, the face where the positive direction of the horizontal axis and the positive direction of the vertical axis are located, and the face where the positive direction of the vertical axis and the positive direction of the vertical axis are located; taking the sum of the mean values of the face gradient tensors of the three faces as a comprehensive value, and taking the ratio of the mean value of the face gradient tensor of any face to the comprehensive value as the stress-dominant weight of any face.

[0012] Preferably, the stress-dominant weight of any face of the calculation mark grid comprises: for the same cluster, traversing the face gradient tensor of each mark grid on any face to calculate the mean value of the face gradient tensor of any face; traversing the mean value of the face gradient tensor of three faces including the face where the positive direction of the horizontal axis and the positive direction of the vertical axis are located, the face where the positive direction of the horizontal axis and the positive direction of the vertical axis are located, and the face where the positive direction of the vertical axis and the positive direction of the vertical axis are located; taking the sum of the mean values of the face gradient tensors of the three faces as a comprehensive value, and taking the ratio of the mean value of the face gradient tensor of any face to the comprehensive value as the stress-dominant weight of any face.

[0013] In a second aspect, the present application discloses a fastener anti-impact simulation system in a low-temperature environment, comprising: a processor and a memory, the memory storing computer program instructions, when the computer program instructions are executed by the processor, realizing any one of the fastener anti-impact simulation methods in a low-temperature environment.

[0014] The beneficial effects of the present application are:

[0015] The present application can simulate the stress response of each cell more accurately by performing fine thermal stress and impact stress gradient analysis on the fastener three-dimensional model, combining multi-dimensional stress clustering and weight calculation. This not only helps to identify potential high-risk areas in low-temperature environments, but also optimizes the design of fasteners, improving their safety and reliability in extreme environments. In addition, through the weighted analysis of adaptive norm stress, the evaluation accuracy is further improved, so that the anti-impact capability of the fastener in actual application is more accurately evaluated, which helps to improve product quality and reduce the risk of failure caused by impact in low-temperature environments. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a flowchart of a fastener anti-impact simulation method in a low-temperature environment according to an embodiment of the present application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all embodiments.

[0018] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0019] Referring to Figure 1 A fastener impact resistance simulation method in low temperature environment includes steps S1-S3, which are described in detail below.

[0020] S1: coarse cell division is performed on the constructed fastener three-dimensional model to obtain a cell, wherein the dimensions include the positive direction of the horizontal axis, the positive direction of the vertical axis and the positive direction of the vertical axis, the thermal stress gradient amplitude and the impact stress gradient amplitude of any cell are obtained to calculate the global thermal stress gradient mean value and the global impact stress gradient mean value of all cells.

[0021] In one embodiment, a three-dimensional model of the fastener to be evaluated is constructed using CAD (Computer Aided Design), and coarse grid division is performed on the three-dimensional model of the fastener, and each grid becomes a cell, wherein the dimensions include the positive direction of the horizontal axis, the positive direction of the vertical axis and the positive direction of the vertical axis.

[0022] The boundary conditions of material properties, thermal stress field and impact stress field and specific impact working conditions are obtained from the control system. These parameters will serve as the basis for subsequent modeling and solving. Based on these boundary conditions, material properties and impact working conditions, an initial temperature field is constructed, and a mathematical model of impact loading is established in combination with nonlinear dynamic characteristics. In terms of material model selection, the Johnson-Cook model is adopted, which can better describe the deformation behavior of the material under high stress, thereby obtaining a basic stress response model. Next, the Ansys LS-Dyna solver is used in combination with the finite element method to solve the initial temperature field and the nonlinear dynamic model, and then the thermal stress field and the impact stress field are obtained. Through these stress field data, the thermal stress tensor and the impact stress tensor of each cell can be extracted to further analyze the stress distribution and deformation behavior of the material under different working conditions. The construction of the model and the solving of the stress field are both prior art, and will not be described in detail here.

[0023] The cell adjacent to the any cell in the positive direction of the horizontal axis is taken as a reference grid, and the difference between the thermal stress tensor component of the any cell in the positive direction of the horizontal axis and the thermal stress tensor component of the reference grid in the positive direction of the horizontal axis is taken as the thermal stress gradient of the any cell in the positive direction of the horizontal axis. The thermal stress gradient of the any cell in the positive direction of the vertical axis and the thermal stress gradient of the any cell in the positive direction of the vertical axis are obtained by traversing.

[0024] The sum of the square of the thermal stress gradient of the any cell in the positive direction of the horizontal axis, the square of the thermal stress gradient of the any cell in the positive direction of the vertical axis and the square of the thermal stress gradient of the any cell in the positive direction of the vertical axis is taken as the thermal stress gradient amplitude, and the specific thermal stress gradient amplitude satisfies the relationship: , represents the thermal stress gradient amplitude, represents the thermal stress gradient in the positive direction of the horizontal axis, represents the thermal stress gradient in the positive direction of the vertical axis, represents the thermal stress gradient in the positive direction of the vertical axis.

[0025] The impact stress gradient amplitude of any cell is obtained in the same way.

[0026] The global thermal stress gradient mean and the global impact stress gradient mean of all cells are further obtained.

[0027] S2: The stress distance between any two cells is calculated by taking the global thermal stress gradient mean and the global impact stress gradient mean as weights, and the sum of the stress distance and the spatial distance is taken as the evaluation distance, and all cells are clustered according to the evaluation distance to obtain a plurality of clustering clusters. For any clustering cluster, the local thermal stress gradient mean and the local impact stress gradient mean are calculated, and the edge length of the cells in the clustering cluster is updated to obtain the updated edge length.

[0028] It should be noted that since the fastener will produce thermal stress in different directions due to thermal contraction in the direction of fastener compression forming under low temperature environment, the actual stress of each cell should be the sum of thermal stress and impact stress. The prior art sets key areas for refinement of the grid in the area by artificially analyzing the impact stress distribution, ignoring the thermal stress under low temperature environment, and the actual stress of part of the area is misjudged, resulting in the phenomenon that part of the area is regarded as a non-key area and the equivalent stress in the area norm is too large or too small. Therefore, the stress distance between cells is calculated by the difference between the thermal stress gradient tensor and the impact stress gradient tensor of different cells, and all cells are clustered according to the stress distance and the spatial distance to realize the area division.

[0029] The stress distance between any two cells is calculated: the sum of the global thermal stress gradient mean and the global impact stress gradient mean is taken as the mean sum, the ratio of the global thermal stress gradient mean to the mean sum is taken as the thermal stress weight, and the ratio of the global impact stress gradient mean to the mean sum is taken as the impact stress weight.

[0030] The thermal stress distance of the thermal stress gradient amplitude of any two cells is calculated, and the impact stress distance of the impact stress gradient amplitude of any two cells is calculated.

[0031] The first product of the thermal stress weight and the thermal stress distance, and the second product of the impact stress weight and the impact stress distance are calculated, and the sum of the first product and the second product is taken as the stress distance.

[0032] The stress distance satisfies the relationship: , represents the stress distance, represents the global thermal stress gradient mean value, represents the global impact stress gradient mean value, represents the thermal stress distance, represents the impact stress distance.

[0033] By comprehensively considering the effects of thermal stress and impact stress, the complexity of the internal stress distribution of the fastener under different working conditions can be effectively described. By introducing the weight coefficients of thermal stress and impact stress, the influences of the two are quantified respectively, so that the stress distance not only considers the gradient change of each, but also can comprehensively evaluate their joint action on the material behavior. This method helps to accurately capture and predict the response of the material in the low-temperature impact environment, and further provides more realistic and detailed simulation data for the design and performance evaluation of the fastener, avoiding the limitations of single stress factor.

[0034] The sum of the stress distance and the spatial distance is taken as the evaluation distance, and the spatial distance is the position distance of any two cells in the three-dimensional model.

[0035] The cells are clustered according to the evaluation distance, and the clustering method uses a density clustering algorithm, and one cluster corresponds to one region.

[0036] Traditional region division is usually based on artificial experience to analyze impact stress to divide regions, and the present application considers the difference in thermal stress and impact stress of cells at different positions for region division, which takes into account the thermal stress field of material thermal contraction in low-temperature scenes, and the region division is more accurate compared with single impact stress field.

[0037] For any cluster, the local thermal stress gradient mean value and the local impact stress gradient mean value are calculated, and the cell edge length in the cluster is updated to obtain the updated edge length. Specifically, it includes:

[0038] For the same cluster, the mean value of the thermal stress gradient amplitude of all cells is taken as the local thermal stress gradient mean value, and the mean value of the impact stress gradient amplitude of all cells is taken as the local impact stress gradient mean value, and the first sum value of the local thermal stress gradient mean value and the local impact stress gradient mean value is calculated.

[0039] The second sum value of the global thermal stress gradient mean value and the global impact stress gradient mean value is calculated.

[0040] The ratio of the second sum value to the first sum value is taken as the weight, and the updated edge length is obtained by multiplying the edge length of the cell, and the updated edge length satisfies the relationship: , represents the updated edge length, represents the edge length, represents the global thermal stress gradient mean value, represents the global impact stress gradient mean value, represents the local thermal stress gradient mean value, represents the local impact stress gradient mean value.

[0041] The larger the gradient of a region, the faster the stress changes in the region, and a coarser mesh will result in a larger deviation in stress calculation. Therefore, when the gradient of a region is larger than the overall global gradient, a finer mesh should be used.

[0042] Based on the boundary conditions, material properties, and impact conditions, a secondary temperature field and a secondary nonlinear dynamics model are reconstructed. The Ansys Ls-Dyna solver and the finite element method are used to solve the secondary temperature field and the secondary nonlinear dynamics model to obtain the thermal stress field and the impact stress field under the region adaptive meshing.

[0043] S3: Taking the adjusted any cell as a marker grid, obtaining the target thermal stress tensor and the target impact stress tensor of the marker grid, taking the sum of the target thermal stress tensor and the target impact stress tensor as a comprehensive tensor to calculate the face gradient tensor of the marker grid, calculating the stress dominance weight of any face of the marker grid according to the face gradient tensor, weighting the norm equivalent stress to obtain an adaptive norm stress, constructing a model according to the adaptive norm stress of each cell in the fastener three-dimensional model, and completing the evaluation of the low-temperature impact resistance of the fastener.

[0044] It should be noted that, due to the differences in regularity and compression in different directions during the forming process of the fastener, the stress propagation speed and manner in different directions will also be different when the fastener is impacted. However, the existing technology usually uses the norm equivalent stress yield criterion to evaluate the stress of each unit and constructs a stress contour map based on this. The norm equivalent stress assumes that the stress propagation in different directions is equivalent, ignoring the difference in stress propagation speed in different directions, which leads to the model failing to accurately reflect the stress propagation characteristics in different directions. This simplifying assumption leads to a deviation in the equivalent stress value of each unit, which may cause the stress of some regions to be overestimated or underestimated, resulting in a large error in the stress contour map, and ultimately leading to the impact resistance of the fastener in a low-temperature environment being misestimated, affecting the performance in actual use.

[0045] In one embodiment, the adjusted any cell is taken as a marker grid, and the thermal stress field and the impact stress field under the region adaptive meshing are obtained according to the secondary temperature field and the secondary nonlinear dynamics model obtained in step S2, so that the target thermal stress tensor and the target impact stress tensor of the marker grid can be directly obtained. The sum of the target thermal stress tensor and the target impact stress tensor is taken as a comprehensive tensor to calculate the face gradient tensor of the marker grid.

[0046] For example, the comprehensive tensor of the marker grid can be calculated according to the calculation method of the thermal stress gradient amplitude in step S1, which can be , This represents the composite tensor components along the positive horizontal axis. This represents the composite tensor component in the positive direction of the vertical axis. Representing the composite tensor components in the positive vertical direction, we can obtain the surface gradient tensor, i.e. The surface gradient tensor of the surface is Similarly, The surface gradient tensor of the surface is , The surface gradient tensor of the surface is .

[0047] For the same cluster, iterate through the cells to obtain the surface gradient tensor of each labeled cell on any face, calculate the mean of the surface gradient tensor of any face, and iterate through the cells to obtain the mean of the surface gradient tensors of three faces, including the faces containing the positive horizontal and vertical axes. The plane, the plane containing the positive directions of the horizontal and vertical axes. The plane, the plane containing the positive directions of the vertical axis and the positive directions of the longitudinal axis. noodle.

[0048] The sum of the mean values ​​of the surface gradient tensors of the three surfaces is taken as the comprehensive value, and the ratio of the mean value of the surface gradient tensor of any surface to the comprehensive value is taken as the stress dominance weight of that surface.

[0049] The larger the surface gradient tensor on a surface, the faster the stress changes in that direction. It should be the dominant direction for stress propagation and distribution. When calculating the normal stress of this marked lattice, more attention should be paid to the stress components and shear stress on this surface.

[0050] The adaptive paradigm stress is obtained by weighting the paradigm equivalent stress according to the stress dominance weights of the three surfaces. The existing paradigm equivalent stress formula satisfies the following relationship:

[0051] , Represents the paradigm stress, Indicates the first The target stress on each surface in direction 1, Indicates the first The target stress on the surface in direction 2, This represents shear stress.

[0052] This invention weights the equivalent stress of the paradigm, and the adaptive paradigm stress satisfies the following relationship:

[0053] , Represents the paradigm stress, Indicates the first The target stress on each surface in direction 1, Indicates the first The target stress on the surface in direction 2, represents a shear stress, represents the stress dominant weight of the th face.

[0054] The conventional normative stress assumes that the stress component weights on each face are the same and that the stress changes in each direction are the same. The present application considers the differences in stress changes in different directions of the fastener, and the adaptive normative stress of each unit can be accurately calculated by weighting and fusing through the weight of each face, so that the accurate stress distribution of the fastener is obtained, and the low-temperature impact resistance of the fastener is accurately evaluated.

[0055] At this point, according to the adaptive normative stress of each unit cell in the three-dimensional model of the fastener, a double-layer impact simulation finite element model can be constructed, and a stress nephogram of the fastener to be evaluated after being impacted under a low-temperature environment can be obtained according to the double-layer impact simulation finite element model, and the low-temperature impact resistance of the fastener is evaluated through the stress nephogram.

[0056] The system comprises a processor and a memory, and the memory stores computer program instructions which, when executed by the processor, implement the fastener impact simulation method in a low-temperature environment according to the first aspect of the present application.

[0057] The system further comprises a communication bus and a communication interface and other components familiar to those skilled in the art, the settings and functions of which are known in the art, and thus will not be described here.

[0058] It should be noted that, for those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A method of simulating impact resistance of a fastener in a cryogenic environment, characterized by, The method comprises the following steps: performing coarse cell division on the constructed fastener three-dimensional model to obtain cells, wherein the dimensions include a positive direction of a horizontal axis, a positive direction of a vertical axis, and a positive direction of a vertical axis, the thermal stress gradient amplitude and the impact stress gradient amplitude of any cell are obtained to calculate the global thermal stress gradient mean and the global impact stress gradient mean of all cells; the global thermal stress gradient mean and the global impact stress gradient mean are taken as weights to calculate the stress distance of any two cells, and the sum of the stress distance and the spatial distance is taken as the evaluation distance, the evaluation distance is used to cluster all cells to obtain a plurality of clustering clusters, for any clustering cluster, the local thermal stress gradient mean and the local impact stress gradient mean are calculated, the cell edge length in the clustering cluster is updated to obtain the updated edge length; any adjusted cell is taken as a marker grid, the target thermal stress tensor and the target impact stress tensor of the marker grid are obtained, the sum of the target thermal stress tensor and the target impact stress tensor is taken as a comprehensive tensor to calculate the face gradient tensor of the marker grid, the stress dominant weight of any face of the marker grid is calculated according to the face gradient tensor, the adaptive norm stress is obtained by weighting the norm equivalent stress, and the model is constructed according to the adaptive norm stress of each cell in the fastener three-dimensional model to complete the evaluation of the low-temperature impact resistance of the fastener.

2. The method of claim 1, wherein the fastener is subjected to a simulated impact in a low temperature environment. The method comprises the following steps: a cell adjacent to the any cell in the positive direction of the horizontal axis is taken as a reference grid, the difference between the thermal stress tensor component of the any cell in the positive direction of the horizontal axis and the thermal stress tensor component of the reference grid in the positive direction of the horizontal axis is taken as the thermal stress gradient of the any cell in the positive direction of the horizontal axis, and the thermal stress gradient of the any cell in the positive direction of the vertical axis and the thermal stress gradient of the any cell in the positive direction of the vertical axis are obtained by iteration; the sum of the square of the thermal stress gradient of the any cell in the positive direction of the horizontal axis, the square of the thermal stress gradient of the any cell in the positive direction of the vertical axis, and the square of the thermal stress gradient of the any cell in the positive direction of the vertical axis is taken as the thermal stress gradient amplitude by taking the square root; the impact stress gradient amplitude of the any cell is obtained in the same way.

3. The method of claim 1, wherein the fastener is subjected to a simulated impact in a low temperature environment. The stress distance comprises: the sum of the global thermal stress gradient mean and the global impact stress gradient mean is taken as a mean sum, the ratio of the global thermal stress gradient mean to the mean sum is taken as a thermal stress weight, and the ratio of the global impact stress gradient mean to the mean sum is taken as an impact stress weight; the thermal stress distance of the thermal stress gradient amplitude of any two cells is calculated, and the impact stress distance of the impact stress gradient amplitude of any two cells is calculated; the first product of the thermal stress weight and the thermal stress distance and the second product of the impact stress weight and the impact stress distance are calculated, and the sum of the first product and the second product is taken as the stress distance.

4. The method of claim 1, wherein, The spatial distance is the position distance of any two cells in the three-dimensional model.

5. The method of claim 1, wherein the fastener is subjected to a simulated impact in a cryogenic environment. The calculation of the local thermal stress gradient mean and the local impact stress gradient mean, the updating of the cell edge length in the clustering cluster, and the obtaining of the updated edge length comprise: For the same cluster, the mean value of the thermal stress gradient amplitude of all cells is taken as the local thermal stress gradient mean value, and the mean value of the impact stress gradient amplitude of all cells is taken as the local impact stress gradient mean value, to calculate the first sum value of the local thermal stress gradient mean value and the local impact stress gradient mean value; The second sum value of the global thermal stress gradient mean value and the global impact stress gradient mean value is calculated; The ratio of the second sum value to the first sum value is taken as the weight, and the updated edge length is obtained by multiplying the edge length of the cell.

6. The method of claim 1, wherein the fastener is subjected to a simulated impact in a cryogenic environment. The face gradient tensor of the marker grid is calculated, including: The comprehensive gradient of any face belongs to the dimension, and the product of the comprehensive gradients of the two dimensions is taken as the face gradient tensor.

7. The method of claim 1, wherein the fastener is subjected to a simulated impact in a cryogenic environment. The stress dominance weight of any face of the marker grid is calculated, including: For the same cluster, the face gradient tensor of each marker grid on any face is obtained by traversal, and the mean value of the face gradient tensor of any face is calculated; The mean values of the face gradient tensors of three faces are obtained by traversal, including the face where the positive direction of the horizontal axis and the positive direction of the vertical axis are located, the face where the positive direction of the horizontal axis and the positive direction of the vertical axis are located, and the face where the positive direction of the vertical axis and the positive direction of the vertical axis are located. The sum of the mean values of the face gradient tensors of the three faces is taken as the comprehensive value, and the ratio of the mean value of the face gradient tensor of any face to the comprehensive value is taken as the stress dominance weight of any face.

8. The method of claim 1, wherein the fastener is subjected to a simulated impact in a cryogenic environment. The evaluation of the low-temperature impact resistance of the fastener is completed according to the adaptive norm stress of each cell in the three-dimensional model of the fastener, including: According to the adaptive norm stress of each cell in the three-dimensional model of the fastener, a double-layer impact simulation finite element model is constructed, and a stress cloud map of the fastener to be evaluated after being impacted in a low-temperature environment is obtained according to the double-layer impact simulation finite element model, and the low-temperature impact resistance of the fastener is evaluated through the stress cloud map.

9. A system for simulating impact resistance of fasteners in cryogenic environments, comprising: It includes: A processor and a memory, the memory stores computer program instructions, when the computer program instructions are executed by the processor, a method for simulating the impact resistance of a fastener in a low-temperature environment according to any one of claims 1-8 is realized.

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