A Coupled Structure Loading Method Based on PepS Model Fusion

Abstract

This invention relates to a coupled structural loading method based on PepS model fusion. This method connects the pipeline model to be calculated with the main loop model using rigid elements. A dummy constraint point is set in the model to ensure that the geometric properties of the models used for merging remain consistent. By modifying the constraint stiffness of this dummy constraint point in different models, coupled analysis of the main loop dynamic analysis model and the connected pipeline model is achieved in PepS. This invention simplifies the analysis process for pipelines connected to the main loop, making the results of structural simulation analysis more consistent with engineering reality.

Description

Technical Field

[0001] This invention belongs to the field of pipeline system simulation calculation technology, specifically involving a coupled structure loading method based on PepS model fusion. Background Technology

[0002] PepS software can perform linear elastic analysis of three-dimensional piping systems under various loading conditions. Currently owned by the Swiss company DST Software, this software is user-friendly and continuously maintained, with the number of applicable standards constantly increasing as nuclear power plant piping evaluation standards are upgraded, such as the French RCC-M standard and the German KTA standard. The program is now widely used in the analysis and design of nuclear power plants worldwide.

[0003] In nuclear power plant piping analysis, different calculation requirements apply to pipes directly connected to the main loop under different load conditions. 1) When calculating self-weight loads, thermal expansion and internal pressure loads, and pipe rupture loads, the piping model is usually decoupled from the main loop model due to the complexity of the main loop load conditions. The displacement of the main loop at the pipe connection location is calculated separately under thermal expansion and pipe rupture loads, and then the obtained displacement value is applied as a forced displacement at the connection between the piping system and the main loop. 2) However, when calculating seismic loads, seismic excitation on the reactor building's civil structure is transmitted to the piping through the main loop and pipe supports. Therefore, the main loop dynamic analysis model and the piping model must be coupled together for overall analysis.

[0004] In PepS software, for pipes directly connected to the main loop model, the calculation conditions to be considered cannot be applied in a single model; they need to be applied separately in different models and then merged. To correctly analyze pipes directly connected to the main loop model, a method is needed to implement coupled analysis of the main loop dynamic analysis model and the pipe model within the PepS program. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a coupled structure loading method based on PepS model fusion.

[0006] The technical solution of this invention is as follows: A coupled structure loading method based on PepS model fusion, comprising the following steps:

[0007] (1) Connect the pipeline model to be calculated with the main loop model using rigid elements;

[0008] (2) Write a temperature load calculation file, set the connection point between the calculation pipeline and the main loop model as a fixed constraint point, and apply the displacement value generated by the main loop model near the nozzle position under the thermal expansion condition as a forced displacement to the nozzle to realize the calculation of the thermal expansion condition of the coupled model.

[0009] (3) Load the temperature load calculation file into the PepS software to obtain the temperature result file;

[0010] (4) Write a seismic load calculation file, set the connection point between the calculation pipeline and the main loop model as a fixed constraint point, and define the stiffness value of the fixed constraint point as a minimum value to realize the calculation of the seismic working condition of the coupled model;

[0011] (5) Load the earthquake load calculation file into the PepS software to obtain the earthquake result file;

[0012] (6) Use the RSMERSG program of PepS software to merge the obtained temperature result file with the seismic result file to obtain the merged result file;

[0013] (7) Compile a load case combination file, and combine the load cases only for the temperature load calculation file and the seismic load calculation file to obtain the final calculation results;

[0014] (8) Load the working condition combination file in the PepS software, and load the result merge file as the calculation input of the working condition combination file to complete the complete analysis of the coupled structure.

[0015] Furthermore, in the coupled structure loading method based on PepS model fusion as described above, when writing temperature load calculation files and seismic load calculation files in steps (2) and (4), the pipeline model to be calculated should be added on the basis of the main loop model, including material properties, cross-sectional properties, and geometric model, and the required operating temperature and internal pressure load conditions should be defined for stress analysis calculation of the pipeline part.

[0016] Furthermore, in the coupled structure loading method based on PepS model fusion as described above, in step (2), the displacement value generated by the main loop model near the nozzle position under LOCA condition is also applied to the nozzle as a forced displacement.

[0017] Furthermore, in the coupled structure loading method based on PepS model fusion as described above, the minimum value mentioned in step (4) refers to the translational stiffness KX, KY, and KZ in the X, Y, and Z directions being less than 10. -6 kN / mm, torsional stiffness MX,MY,MZ less than 10 -6 kNm / rad.

[0018] Furthermore, in the coupled structure loading method based on PepS model fusion as described above, the fixed constraint point in step (2) has a constraint effect but no connection effect; the fixed constraint point in step (4) has a connection effect but no constraint effect.

[0019] Furthermore, in the coupled structure loading method based on PepS model fusion as described above, the result merging file mentioned in step (6) is an rmg file, which contains the calculation results data of all basic load conditions in the temperature result file and the seismic result file.

[0020] Furthermore, in the coupled structure loading method based on PepS model fusion as described above, in step (7), when writing the working condition combination file, the processing method for the connection point between the calculation pipeline and the main loop model is the same as the processing method in the temperature load calculation file.

[0021] The beneficial effects of this invention are as follows: This invention sets a dummy constraint point in the model to ensure that the geometric properties of the models used for merging remain consistent. By modifying the constraint stiffness of the dummy constraint point in different models, the main loop dynamic analysis model and the connected pipeline model are coupled and analyzed in PepS. This simplifies the analysis process of the pipeline connected to the main loop and makes the results of structural simulation analysis more consistent with engineering reality. Attached Figure Description

[0022] Figure 1 This is a flowchart of the coupled structure loading method based on PepS model fusion according to the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] This invention provides a coupled structure loading method based on PepS model fusion. According to the program calculation requirements, the models to be merged must have the same geometric characteristics, including the same number and order of supports, the same number of elements, and the same number of mass points. The physical properties of the models can differ, such as elastic modulus and support stiffness. This method sets a dummy constraint point in the model to ensure that the geometric characteristics of the models used for merging remain consistent. Different coupling methods are achieved by modifying the constraint stiffness of this dummy constraint point in different models. Specifically: in the dynamic analysis model, the stiffness value of this constraint is set to a minimum to simulate actual engineering conditions; in this case, the constraint point has a connecting function but no constraint function. In the temperature analysis model, the constraint point has a constraint function but no connecting function, and is used to apply forced displacement to the pipe model.

[0025] This invention requires three calculation files: File 1 calculates temperature loads, File 2 calculates seismic loads, and File 3 performs no calculations, only load case combinations. The model of the calculation piping system consists of two parts: a main loop model and a calculation piping model. When writing the calculation files, the calculation piping model should be added to the main loop model, including material properties, cross-sectional properties, and geometric models. The required operating temperature and internal pressure load conditions should be defined for the calculation piping part to perform stress analysis calculations. The specific implementation steps are as follows:

[0026] 1) The corresponding nodes (P116) of the pipeline model and the main loop model are connected using rigid RIGD elements. The implementation method in the program is as follows:

[0027] JUNC PT=P116

[0028] MATL CD=300

[0029] CROS CD=3001

[0030] RIGD PT=1EW=2DX=1.5115DY=0.2397DZ=-0.3720 AL= / XRCS001PO-11 /

[0031] 2) Compile the temperature load calculation file (File 1), setting the connection point between the calculation pipeline and the main loop model as a fixed constraint point. The displacement value generated by the main loop model near the nozzle location under thermal expansion conditions is applied as a forced displacement at the nozzle. The final calculation parameters are shown in the table below:

[0032] Table 1 Thermal expansion displacement at the main pump connection point

[0033] Operating conditions X(mm) Y(mm) Z(mm) Thermal expansion (343℃) -29.7863 43.5196 5.5540

[0034] The implementation method in the program is as follows:

[0035] ANCH PT = P116

[0036] AMVT PT=P116 CA=20 EX=-29.7863 DY=43.5196 DZ=5.5540 AL= / TH /

[0037] AMVT PT=P116 CA=21 DX=-29.7863 DY=43.5196 DZ=5.5540 AL= / TH /

[0038] AMVT PT=P116 CA=36 DX=-29.7863 DY=43.5196 DZ=5.5540 AL= / TH /

[0039] The displacement information generated near the main pump inlet location in the main loop model under LOCA conditions is also applied directly as a forced displacement at the connection between the main pump and the calculated piping system. The calculation parameters used are shown in the table below:

[0040] Table 2 LOCA Displacement at Main Pump Connection Point

[0041] Operating conditions X(mm) Y(mm) Z(mm) LOCA 1.217 3.838 0.287

[0042] The implementation method in the program is as follows:

[0043] AMVT PT=P116 CA=45 DX=1.217 AL= / LOCA-X /

[0044] AMVT PT=P116 CA=46 DY=3.838 AL= / LOCA-Y /

[0045] AMVT PT=P116 CA=47 DZ=0.287 AL= / LOCA-Z /

[0046] 3) Load calculation file 1 into Peps to obtain the temperature result file.

[0047] 4) Compile the seismic load calculation file (File 2). Due to the program's requirements for merging model files, the connection point between the calculation pipeline and the main loop model still needs to be set as a fixed constraint point. If the program's default setting for the stiffness of the fixed constraint point is used, the seismic load calculation model will not conform to actual engineering conditions. However, the program allows changing the stiffness value of this constraint. Therefore, the stiffness value of this fixed constraint point can be defined as a minimum value, thereby satisfying the program requirements while rigidly connecting the main loop model and the calculation pipeline, conforming to actual engineering conditions, and realizing the calculation of seismic load cases for the coupled model. The implementation method in the program is as follows:

[0048] ANCH PT=P116 KX=1.E-8 KY=1.E-8 KZ=1.E-8

[0049] MX=1.E-8 MY=1.E-8 MZ=1.E-8 LV=4

[0050] 5) Load calculation file 2 into Peps to obtain the earthquake results file.

[0051] 6) Use PepS's RSMERSG program to merge the temperature result files obtained in steps 3) and 5) with the seismic result files to obtain a merged result file in the format rmg. This file contains the calculation result data of all basic load cases in the temperature result files and the seismic result files.

[0052] 7) Compile the operating condition combination file (File 3). No further calculations are performed at this stage; instead, the operating conditions of the previously calculated files are combined according to the standards required by the nuclear power plant (such as RCC-M, ASME, etc.) to obtain the final calculation results. The handling of the connection points between the calculated pipelines and the main loop model is the same as that in the temperature load calculation file (File 1).

[0053] 8) Load the load case combination file in PepS, and load the merged file obtained in step 6) as the calculation input for the load case combination file to complete the full analysis of the coupled structure.

[0054] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0055] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A coupled structure loading method based on PepS model fusion, characterized in that, Includes the following steps: (1) Connect the pipeline model to be calculated with the main loop model using rigid elements; (2) Write a temperature load calculation file, set the connection point between the calculation pipeline and the main loop model as a fixed constraint point. This fixed constraint point has a constraint effect but no connection effect. Apply the displacement value generated by the main loop model near the nozzle position under the thermal expansion condition as a forced displacement to the nozzle to realize the calculation of the thermal expansion condition of the coupled model. (3) Load the temperature load calculation file into the PepS software to obtain the temperature result file; (4) Compile the seismic load calculation file, set the connection point between the calculation pipeline and the main loop model as a fixed constraint point. This fixed constraint point has a connection function but no constraint function, and define the stiffness value of this fixed constraint point as a minimum value to realize the calculation of the seismic load case of the coupled model; the minimum value refers to the translational stiffness KX,KY,KZ in the three directions of X, Y, and Z being less than 10. - 6 kN / mm, torsional stiffness MX,MY,MZ less than 10 -6 kN·m / rad; (5) Load the earthquake load calculation file into the PepS software to obtain the earthquake result file; (6) Use the RSMERSG program of PepS software to merge the obtained temperature result file with the seismic result file to obtain the merged result file; (7) Compile a load case combination file, and combine the load cases only for the temperature load calculation file and the seismic load calculation file to obtain the final calculation results; (8) Load the working condition combination file in the PepS software, and load the result merge file as the calculation input of the working condition combination file to complete the complete analysis of the coupled structure.

2. The coupled structure loading method based on PepS model fusion as described in claim 1, characterized in that, When writing temperature load calculation files and seismic load calculation files in steps (2) and (4), the pipeline models to be calculated should be added on the basis of the main loop model, including material properties, cross-sectional properties, and geometric models. The required operating temperature and internal pressure load conditions should be defined for the pipeline part to perform stress analysis calculation.

3. The coupled structure loading method based on PepS model fusion as described in claim 1 or 2, characterized in that, In step (2), the displacement value generated by the main circuit model near the nozzle position under LOCA condition is also applied to the nozzle as a forced displacement.

4. The coupled structure loading method based on PepS model fusion as described in claim 1, characterized in that, In step (7), when writing the operating condition combination file, the method of handling the connection point between the calculated pipeline and the main loop model is the same as that in the temperature load calculation file.

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