Cable structure tension simulation method based on cooling method
By defining temperature materials in the tooling cable and utilizing explicit dynamic nonlinear finite element analysis, the simulation of the cable structure construction process is simplified, achieving efficient and accurate construction process simulation and solving the problems of complexity and large errors in existing technologies.
Patent Information
- Application Number
- CN202511153262.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-18
- Publication Date
- 2025-12-09
AI Technical Summary
Existing technologies are insufficient to effectively simulate the large displacements and mechanical displacements during the construction of cable structures, especially in the case of multiple tension cables. Conventional methods are complex and difficult to achieve a complete simulation of the construction process.
The cooling method is adopted. By defining a temperature material and assigning a high elastic modulus to the tooling cable, the temperature change of the tooling cable is simulated using the explicit dynamic nonlinear finite element analysis software LS-DYNA to realize the tensioning process of the cable structure, simplifying the modeling and realizing the forward simulation of the complete construction process.
It achieves simplified modeling and efficient simulation of the cable structure construction process, reduces the analysis difficulty, and the simulation results are close to those of traditional methods with an error of less than 5%. It is suitable for construction monitoring and parameter provision of complex cable structures.
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Figure CN121093672A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of construction simulation analysis of cable structure, and particularly relates to a cable structure tension simulation method based on temperature drop method. BACKGROUND
[0002] The cable structure is a structure composed of cables, rods, beams and other units, can be self-structured, such as cable net and cable truss, or can be combined with other rigid structures to form a combined structure, such as beam string structure and cable dome, and is a structure with high nonlinear characteristics.
[0003] The on-site construction process of the cable structure mainly includes three steps of assembly connection, traction installation and tension forming. From the ground installation to the tension forming, super displacement, mechanism displacement and other phenomena occur, and gradually changes from the loose stress-free state to the tight stressed state. In order to ensure that the tension forming structure meets the design requirements, numerical simulation analysis of the construction process of the cable structure is needed before on-site construction, so as to master the state of the cable structure in the key construction stage and provide parameters and basis for construction and monitoring.
[0004] Unlike other types of structures, there is a large difference between the configuration of the construction process of the cable structure and the formed state of the structure. With traction installation and tension forming, the configuration of the cable structure gradually approaches and reaches the formed state. During the whole process, there are super displacements, mechanism displacements and cable relaxation phenomena, and the finite element method for conventional structures cannot be used to solve the problem.
[0005] The existing common method divides the analysis of the construction process of the cable structure into several construction stages, and analyzes the static equilibrium state of each stage. Taking the shape-finding analysis as an example, the shape-finding analysis methods for determining the static equilibrium state of the cable structure include nonlinear static finite element method, nonlinear force method and dynamic relaxation method. These methods need to artificially divide the complete tensioning process into several construction stages, which is relatively complex and difficult to implement.
[0006] Dynamic nonlinear analysis software (such as LS-DYNA) can also be used to perform forward direct analysis by using explicit dynamic analysis method. Common analysis methods include using safety belt unit to simulate tool cable and using displacement traction method. The safety belt unit is used for automobile simulation, and the simulation method is relatively complex. When the number of tool cables is large, it is difficult to control. The displacement traction method refers to traction of a specified node from a specified starting point to a specified target point, and the traction path is a straight line, which does not match the actual construction process. When there are multiple tensioning cables, it is difficult to traction them respectively. SUMMARY
[0007] The present application aims at the deficiencies of the prior art, and provides a cable structure tension simulation method based on temperature drop method.
[0008] The objective of this invention is achieved through the following technical solution: a method for simulating cable structure tension based on a cooling method, comprising the following sub-steps: (1) LS-DYNA was used to establish finite element analysis models for the tensioned cable structure and the tooling cable at the tensioning end. The cable structure includes radial cables and circumferential cables. The cable structure was established by translating to the ground in a zero state. The tooling cable was established by using the line connecting the tensioning end and the anchoring end of the cable structure as the configuration. Both the cable structure and the tooling cable used rod elements. The radial cables, circumferential cables and the tooling cable were divided into multiple elements as needed. The cable structure was defined as a material with real properties. The tooling cable was defined as a temperature material. The elastic modulus of the tooling cable was set to be no less than 1000 times the elastic modulus of the cable structure. Then, a fixed hinge constraint was applied to the node of the tooling cable at the anchoring end. The initial strain corresponding to the zero state was applied to the cable structure, and the self-weight was applied at the same time. Damping ratios of 1.0 to 10.0 were applied to the tensioned cable structure and the tooling cable at the tensioning end, respectively. (2) Perform explicit dynamic nonlinear finite element analysis. The analysis results at this stage are the suspended state of the cable structure being suspended in the air by the tooling cable. (3) Then all the tooling cables are cooled at the same time. When the temperature change value reaches the temperature change threshold, the remaining length of the tooling cable is less than 0.0005 of the original length, which means the tensioning process of the cable structure is completed. (4) The internal forces, deformations and strains of the cable structure during the entire tensioning process are obtained through the post-processing module of LS-DYNA.
[0009] Furthermore, in step (3), the change in length of the tooling cable during cooling... The calculation formula is: ,in, The original length of the tooling cable. The coefficient of linear expansion is 1 / 3. This represents the temperature change value.
[0010] The beneficial effects of this invention are: 1) The requirements for the basic model in this invention are basically the same as those for conventional finite element analysis. Only tooling cables are introduced on the basis of the original cable structure, which can simplify the modeling difficulty. 2) The core of the analytical method of this invention lies in the treatment of the tooling cable, which is set as a temperature material and given a large elastic modulus. The linear expansion coefficient and cooling value are determined according to the natural strain formula. The parameter values are clear and simple, and the operability is strong, which reduces the difficulty of analysis. 3) The simulation method of the present invention realizes a positive and complete construction simulation process. It does not require artificial division of construction states and can infinitely realize a complete construction process, and can positively and completely simulate the construction process. Attached Figure Description
[0011] Figure 1 Flow chart of a cable structure tension simulation method based on cooling method; Figure 2 Initial finite element model; Figure 3 Analysis result of the first stage; Figure 4 Configuration result of a certain state of the tension process; Figure 5 Configuration result at the completion of tension; Figure 6 Model diagram of Example 1; Figure 7 Schematic diagram of each state of the LS-DYNA model of Example 1, wherein, Figure 7 (a) is a schematic diagram of the initial state of the LS-DYNA model, Figure 7 (b) is a schematic diagram when just being lifted off the bottom surface, Figure 7 (c) is a schematic diagram when in the intermediate state of lifting, Figure 7 (d) is a schematic diagram when in the completed state of tension; Figure 8 Temperature loading curve diagram of Example 1; Figure 9 z-coordinate time history curve diagram of Example 1; Figure 10 Radial cable 1 cable force time history curve diagram of Example 1; Figure 11 Cable force and z-coordinate change curve diagram of Example 1; Figure 12 Schematic diagram of the analysis model of Example 2, wherein, Figure 12 (a) is an axonometric view of the analysis model, Figure 12 (b) is a front view of the analysis model, Figure 12 (c) is a top view of the analysis model; Figure 13 Schematic diagram of each state of the LS-DYNA model of Example 2, wherein, Figure 13 (a) is a schematic diagram of the initial state of the LS-DYNA model, Figure 13 (b) is a schematic diagram when just being lifted off the bottom surface, Figure 13 (c) is a schematic diagram when in the intermediate state of pulling, Figure 13 (d) is a schematic diagram when in the completed state of tension; Figure 14 Typical member cable force change curve diagram of Example 2; Figure 15 Typical node z-coordinate change curve diagram of Example 2; In the figure, 1 - tooling cable; 2 - radial cable; 3 - ring cable; 4 - tensioning end; 5 - tensioning end. DETAILED DESCRIPTION
[0012] In order to make the purpose, technical scheme and advantages of the present application more clear and obvious, the present application is further described in detail in combination with the drawings and examples, and it should be understood that the specific examples described herein are only used to explain the present application, rather than all examples. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0013] Example 1 As shown in Figure 1 , the present application provides a cable structure tensioning simulation method based on the cooling method, comprising the following sub-steps: (1) Establishing a cable structure finite element model The method disclosed in the present application adopts LS-DYNA for explicit dynamic nonlinear finite element analysis, so it is necessary to establish an LS-DYNA finite element model, as shown in Figure 2 .
[0014] Model configuration: The model contains the cable structure (including radial cable 2 and ring cable 3) to be tensioned and the tooling cable 1 connected to the tensioning end 4. The cable structure is established in the configuration of zero-state translation to the ground, and the tooling cable is established in the configuration of the line between the cable structure tensioning end and the anchoring point.
[0015] Element type: Both the cable structure and the tooling cable adopt bar elements, and the radial cable, ring cable and tooling cable can be divided into multiple elements as needed.
[0016] Material properties: The cable structure part is defined according to the actual material properties, and the tooling cable 1 is defined as a temperature material (defined by the keyword *MAT_ELASTIC_PLASTIC_THERMAL), so that the tooling cable 1 can respond to changes in temperature. In order to quantitatively simulate the tensioning of the cable structure, a very large elastic modulus needs to be assigned to the tooling cable 1 (such as 1000 times the elastic modulus of the cable structure material).
[0017] Boundary conditions: Fixed hinge constraints are applied to the nodes of the tooling cable at the anchoring end.
[0018] Load conditions: Apply the initial strain corresponding to the zero-state to the cable structure, and apply the self-weight at the same time.
[0019] Remaining settings: In order to control the cable structure to reduce the shock under the action of dynamic load and stabilize as soon as possible, a larger damping ratio (such as 10.0) needs to be assigned to the overall structure (set by the keyword *DAMPING_GLOBAL).
[0020] (2) First stage analysis The explicit dynamic nonlinear analysis is carried out under the above conditions. The cable structure will sag under the action of its own weight. The result obtained after convergence is that the cable structure is hung in the air in a sagging state by the tool cable (as shown in Figure 3 ). This state is equivalent to the state of the cable structure just being lifted off the ground during the lifting process. This state can be taken as the starting state of the subsequent traction and tension.
[0021] (3) Second stage analysis Under the state after the convergence of the first stage analysis, the tool cable 1 is cooled. At this time, the tool cable 1 will respond to the cooling and become shorter, while the cable structure will ignore the influence of the cooling, as shown in Figure 4 . Because the elastic modulus of the tool cable 1 is much larger than the elastic modulus of the cable structure, the shortening amount of the tool cable 1 under the action of cooling can be calculated using the natural strain formula, that is, , where is the original length of the tool cable, is the change in length of the tool cable, is the linear expansion coefficient, is the temperature change value, such as the linear expansion coefficient 0.01, and the temperature change value -800℃, then the change in length of the tool cable , that is, the remaining length of the tool cable at this time is 0.000335 , which is 0.0005 less than the original length , and is very close to 0. In the engineering field, it can be considered to have been shortened to 0, that is, the tensioning has been completed.
[0022] (4) Obtain the complete tensioning process result After the convergence of the second stage analysis, it can be considered that the length of the tool cable is 0, that is, the tensioning process of the cable structure is completed, as shown in Figure 5 . Thus, the complete tensioning process result is obtained. Using the post-processing function of LS-DYNA, the results at any state during the tensioning process can be obtained, including the internal force, deformation and strain results of the cable structure.
[0023] Example 1: Example 1 is composed of 4 radial cables and 4 ring cables, as shown in Figure 6 , the radial cables include 2 bearing cables and 2 stabilizing cables, the cross-sectional diameter of the cables is 30mm, the elastic modulus of the cables is 1.6×10 5 MPa, the Poisson's ratio of the cables is 0.3, the initial strain of the cables is 0.01, and the coordinates of the nodes in the zero state are shown in Table 1.
[0024] Table 1: Node coordinate table of Example 1 in zero state (mm) AsFigure 6 As shown in the figure, node ① is the node between radial cable 1, ring cable 1 and ring cable 4, node ② is the node between radial cable 2, ring cable 1 and ring cable 2, node ③ is the node between radial cable 3, ring cable 2 and ring cable 3, node ④ is the node between radial cable 4, ring cable 3 and ring cable 4, node ⑤ is the anchoring point of radial cable 1, node ⑥ is the anchoring point of radial cable 2, node ⑦ is the anchoring point of radial cable 3, and node ⑧ is the anchoring point of radial cable 4.
[0025] Ansys and LS-DYNA were used for comparative analysis. In Ansys analysis, hinged constraints were set at nodes ⑤~⑧, and direct nonlinear finite element analysis was performed; in LS-DYNA analysis, the 8-cable structure was translated downward by 10.0 m, and tool cables were established between nodes ⑤~⑧ and anchoring points ⑤~⑧, as shown in (a). Figure 7 (a). Temperature materials were assigned to the tool cables, and the cooling was considered in six cases (GK1~6) with linear expansion coefficients of 0.010, 0.011, 0.012, 0.013, 0.014 and 0.015, respectively. LS-DYNA analysis was divided into two stages: stage 1, natural sagging under initial strain and self-weight, the state obtained by solving the stability was equivalent to the state when the cable structure was just lifted off the ground, as shown in (b); stage 2, gradually applying cooling to the tool cables, the cable structure was gradually pulled up and tensioned into place by the tool cables, as shown in (c) and (d). Figure 7 Figure 7 Figure 7 LS-DYNA analysis used explicit dynamic algorithm, in order to shorten the analysis time, the loading time was usually compressed (such as compressing the actual 12-hour traction and tensioning time to 400s), therefore under the action of conventional load, nodes and elements would produce displacement and internal force, as well as speed which could not be ignored, leading to serious deviation of internal force from the true value. In order to solve the above problems, a larger damping ratio (such as 10.0) was assigned to the structure, and the temperature loading curve shown in (e) was used, two-stage loading method was used in each stage of loading: first stage, linear loading; second stage, maintaining loading. Figure 8 Figure 9 Figure 10 Figures (f) and (g) are the time history curves of node ① z coordinate and radial cable 1 cable force respectively, it can be seen that the shape and internal force will experience oscillation in the first loading stage, and will gradually tend to be stable in the second loading stage, obtaining the true displacement and internal force. The displacement and internal force at the stable time were extracted and plotted into the cable force and z coordinate of node ①, node ②, node ⑤ and node ⑥ varying with cooling of the traction and tensioning process of radial cable 1, radial cable 2, ring cable 1 and ring cable 4, as shown in (h). Figure 11
[0026] Table 2 and Table 3 are the cable force and node coordinate comparison data of LS-DYNA and Ansys when tensioning is completed. From GK1 to GK6, as the linear expansion coefficient gradually increases, the length of the tool cable after shortening under the action of cooling is closer and closer to 0, and the cable force obtained by LS-DYNA analysis is also closer to the analysis result of Ansys (the analysis result of Ansys can be considered as the result when the tool cable is completely shortened to 0). From the comparison results of Table 2 and Table 3, it can be known that the results obtained by the cooling method based on LS-DYNA are very close to the Ansys analysis results, the cable force error can be controlled within 5%, and the deformation error can be controlled within 0.5%.
[0027] Table 2: Cable force comparison (kN) Table 3: Node ① tensioning state coordinate comparison (m) Example 2 is a single-layer spoke cable net structure, which is extracted from the literature (Xu Xiaoming, Zhang Shichang, Luo Bin, et al. Suzhou Olympic Sports Center Single-layer Cable Net Structure Design and Construction Technology [M]. China Architecture and Industry Press, 2019.), which is composed of 20 radial cables and a ring cable, as shown in Figure 12 , the node coordinates, cross section, initial stress, load and other parameters are detailed in the literature. Based on LS-DYNA, the cooling method is used for traction tension simulation analysis, wherein the linear expansion coefficient is 0.01, and the temperature change value is-900℃.
[0028] As in Example 1, the tool cable is established, as shown in Figure 13 (a), and is analyzed in two stages to obtain the state when it is just lifted off the ground and the complete process of traction lifting, as shown in Figure 13 (b), Figure 13 (c) and Figure 13 (d), respectively.
[0029] Figure 14 and Figure 15 are the cable force and z coordinate of the typical node of the typical cable section during the traction tensioning process.
[0030] Table 4 and Table 5 respectively give the LS-DYNA analysis results of cable force (stress) and displacement compared with the literature results. Among them, the displacement refers to the z-direction deviation of the position when tensioning is completed relative to the zero state given in the literature.
[0031] Table 4: Cable force comparison of Example 2 Table 5: Displacement comparison of Example 2 (mm) From the comparison results, it can be seen that the simulation results based on the LS-DYNA cooling method are very close to the literature, and most of the results are controlled within 2%, and the errors of the radial cables BB' and EE' are slightly larger, which may be caused by the local data error or non-disclosure of the literature.
[0032] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for simulating cable structure tensioning based on a cooling method, characterized in that, Includes the following sub-steps: (1) LS-DYNA was used to establish finite element analysis models for the tensioned cable structure and the tooling cable at the tensioning end. The cable structure includes radial cables and circumferential cables. The cable structure was established by translating to the ground in a zero state. The tooling cable was established by using the line connecting the tensioning end and the anchoring end of the cable structure as the configuration. Both the cable structure and the tooling cable used rod elements. The radial cables, circumferential cables and the tooling cable were divided into multiple elements as needed. The cable structure was defined as a material with real properties. The tooling cable was defined as a temperature material. The elastic modulus of the tooling cable was set to be no less than 1000 times the elastic modulus of the cable structure. Then, a fixed hinge constraint was applied to the node of the tooling cable at the anchoring end. An initial strain corresponding to the zero state is applied to the cable structure, and its own weight is applied simultaneously; a damping ratio of 1.0 to 10.0 is applied to the tensioned cable structure and the tooling cable at the tensioning end, respectively; (2) Perform explicit dynamic nonlinear finite element analysis. The analysis results at this stage are the suspended state of the cable structure being suspended in the air by the tooling cable. (3) Then all the tooling cables are cooled at the same time. When the temperature change value reaches the temperature change threshold, the remaining length of the tooling cable is less than 0.0005 of the original length, which means the tensioning process of the cable structure is completed. (4) The internal forces, deformations and strains of the cable structure during the entire tensioning process are obtained through the post-processing module of LS-DYNA.
2. The cable structure tension simulation method based on cooling method according to claim 1, characterized in that, In step (3), the change in length of the tooling cable during cooling The calculation formula is ,in, The original length of the tooling cable. The coefficient of linear expansion is 1 / 3. This represents the temperature change value.