A Low-Background Lead Chamber Optimization Design Method Based on Finite Element Simulation

Abstract

This invention discloses a low-background lead chamber optimization design method based on finite element simulation, specifically relating to the field of lead chamber simulation design technology. The method includes the following steps: establishing a three-dimensional parametric geometric model of the lead chamber, acquiring lead chamber parameters, predicting and analyzing lead creep through simulation, determining lead creep early warning, optimizing the anti-creep structure, and verifying the optimized scheme through simulation. This invention establishes a three-dimensional parametric geometric model of the lead chamber, acquires creep parameters of the low-background lead chamber, calculates the relative creep error and creep increment, evaluates the design based on simulation results, generates early warning results, optimizes the anti-creep structure, verifies the optimized scheme, updates the model, and re-simulates. It compresses the timescale of simulation calculations in a virtual environment, shortening the design cycle; it can output key creep data at multiple time points, providing a full lifecycle perspective for design iteration; and it uses a parametric geometric model to achieve model updates and scheme iterations, improving the efficiency of scheme achievement.

Description

Technical Field

[0001] This invention relates to the field of lead chamber simulation design technology, and more specifically, to a low-background lead chamber optimization design method based on finite element simulation. Background Technology

[0002] The low-background lead chamber is a key shielding device for low-background detectors (such as Ge detectors and NaI detectors). Its core function is to block background radiation such as gamma rays and cosmic rays from the environment, ensuring the accuracy of the detector's measurements. The low-background lead chamber has extremely high requirements for the purity of the lead material, and the dimensional stability of the inner cavity, the density of the lead layer, and the sealing of the joints directly affect the detector's positioning accuracy and background level.

[0003] However, it still has some drawbacks in actual use. For example, traditional lead chambers use pure lead as the shielding material, but lead has inherent material defects: low melting point (327.5°C), low hardness, high density, etc. Under long-term self-weight, it will creep and deform, leading to problems such as lead layer sinking, shielding door jamming, and detector support structure displacement, which seriously affect the positioning accuracy and service life of the detector.

[0004] Existing design methods for low-background lead chambers mainly suffer from the following problems: the structural design of lead chambers relies heavily on empirical formulas or simple static calculations, and a creep early warning mechanism has not been established, making it impossible to assess design risks in a timely manner; the lack of optimization logic leads to unreasonable structural designs; finite element simulation technology has been applied to engineering structural analysis, but there is still no evidence to combine it with the creep model of lead and systematically optimize the creep-resistant structure of low-background lead chambers. Summary of the Invention

[0005] To overcome the aforementioned deficiencies of the prior art, embodiments of the present invention provide a low-background lead chamber optimization design method based on finite element simulation, which is used to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a low-background lead chamber optimization design method based on finite element simulation, comprising the following steps: Step S01: Establishment of a three-dimensional parametric geometric model of the lead room: Establish a three-dimensional parametric geometric model of the lead room, the model including at least the lead layer, steel shell, internal steel support frame and shielding door assembly; Step S02: Lead chamber parameter acquisition: including creep parameter acquisition layer and time step setting layer. The creep parameter acquisition layer is used to acquire the creep characteristic parameters of the low background lead chamber, and the time step setting layer is used to acquire the total simulation time of the low background lead chamber. Step S03: Lead creep prediction simulation analysis: including creep strain rate analysis layer and finite element simulation execution layer, to analyze the creep characteristic parameters of low background lead chamber, to analyze the creep strain rate of lead chamber in each time step based on lead creep model, to import lead creep model into finite element simulation software for analysis, and to perform structural analysis of creep effect in each time step. Step S04: Lead creep early warning judgment: Based on the simulation results, evaluate the current design of the low background lead chamber and generate early warning results; Step S05: Creep Resistance Structure Optimization: When it is determined that the current lead chamber design has a serious creep risk, structural optimization is carried out. The optimization includes stress zone elimination, excessive porosity zone control, and improvement of interface pressure exceeding the standard zone. Step S06: Simulation verification of optimization scheme: Based on the optimization scheme output by the anti-creep structure optimization step, update the three-dimensional parametric geometric model of the lead chamber, and import the updated model into the finite element simulation software to perform lead creep prediction simulation analysis again.

[0007] Preferably, the three-dimensional parametric geometric model of the lead room includes at least a lead layer, a steel outer shell, an internal steel support frame, and a shielding door assembly, as detailed below: Step S11: Establish a parametric geometric model of the low-background lead chamber using SolidWorks or similar 3D modeling software. The model is an assembly structure and includes at least the following components: Lead layer: As the main shielding element, it is made of high-purity lead material; Steel casing: Encased outside the lead layer, serving as a seal and providing structural protection; Internal steel support frame: pre-embedded inside the lead layer or placed at the bottom of the lead layer, used to bear the main gravity load of the lead layer; Platform screen door components: including the door body and door frame; Step S12: The parameterization refers to the preset driving parameters in the model (such as lead layer thickness, support plate thickness, support spacing, etc.). By modifying the parameter values, the geometry of the model can be automatically updated, providing a geometric basis for subsequent optimization design.

[0008] Preferably, the specific content of the creep parameter acquisition layer is as follows: By preparing pure lead standard creep specimens, setting multiple levels of constant stress in the range of 0.5 to 4.0 MPa, carrying out uniaxial creep tests, obtaining creep strain-time curves under different stress levels, and extracting the stress and creep time in each time step; The specific content of the time step setting layer is as follows: obtain the predetermined service life of the lead chamber as the time endpoint of the simulation calculation, and set the time step.

[0009] Preferably, the specific content of the creep strain rate analysis layer is as follows: Step S31: The creep characteristic parameters are specifically as follows: The stress and creep time in each time step are obtained and input into the finite element simulation software. Based on the lead creep model, the creep strain rate of the lead chamber in each time step is analyzed. Step S32: Calculate the difference between the creep strain rate and the average strain rate obtained from multiple creep tests, further calculate the ratio of the difference to the average value, and take the absolute value of the difference to obtain the creep relative error; Step S33: Obtain the relative creep error and transmit it to the lead creep early warning judgment step to realize early warning triggering and processing.

[0010] Preferably, the finite element simulation execution layer specifically comprises: The structural analysis of creep effect based on finite element simulation software is as follows: Step S331: Discretize the three-dimensional parametric geometric model of the lead chamber into a mesh using adaptive mesh generation, with finer meshing in the lead layer region; Step S332: Obtain the predetermined service life of the lead chamber. The time step setting adopts automatic time step. The initial step is set to a short time, and then the step is gradually increased. Obtain each time step and extract the creep strain rate within each time step. Step S333: Based on the product of each time step and the creep strain rate, obtain the creep strain increment within that step. Step S334: After convergence at each time step, read the creep elongation of the lead chamber in the three orthogonal directions of x, y, and z; Step S335: Based on the sum of the creep elongation lengths of the lead chamber in the three orthogonal directions x, y, and z, obtain the creep increment within this step length; Step S336: Obtain the creep increment within each time step and sum them up to obtain the cumulative creep increment; Step S337: Obtain the creep increment and transmit it to the lead creep early warning judgment step to realize early warning triggering and processing.

[0011] Preferably, the specific content of the lead creep early warning judgment is as follows: Step S41: Based on the uniaxial creep test, set the creep error warning threshold, and based on the allowable change in the internal space of the lead chamber, set the creep increment threshold; Step S42: Obtain the relative creep error and creep increment within each time step from the finite element simulation output, and compare them with the set creep error warning threshold and creep increment threshold, respectively. When the relative creep error... Creep error warning threshold and creep increment When the creep increment threshold is reached, it indicates that the current design meets the creep stability requirements, and the current design is directly output. If the creep relative error is... Creep error warning threshold or creep increment When the creep increment threshold is exceeded (only one of the criteria is exceeded), it indicates that there is a creep risk in the current lead chamber design. An early warning signal is then generated, and the deformation trend is continuously monitored. If the creep relative error... Creep error warning threshold and creep increment When the creep increment threshold is exceeded (both criteria are exceeded), it indicates that the current lead chamber design has a serious creep risk, and the process proceeds to step S05 for structural optimization.

[0012] Preferably, the specific details of the anti-creep structure optimization are as follows: Step S51: After convergence at each time step, the finite element simulation reads the stress in the lead chamber within that step. If the stress is greater than the preset stress, the warning type is classified as a tensile stress zone. Based on the identified risk type, the corresponding measures are selected from the optimization measure library. Step S52: After convergence at each time step, the finite element simulation reads the cumulative creep increment within that step of the lead chamber. If the cumulative creep increment is greater than the preset cumulative creep increment, the warning type is classified as the excessively loose zone. Based on the identified risk type, the corresponding measures are selected from the optimization measure library. Step S53: After convergence at each time step, the finite element simulation reads the contact pressure in the lead chamber within that step. If the contact pressure is greater than the preset contact pressure, the warning type is classified as the interface pressure exceeding the standard area. Based on the identified risk type, the corresponding measures are selected from the optimization measure library. Step S54: Output the optimized model driving parameters to the three-dimensional parametric geometric model of the lead chamber.

[0013] Preferably, the priority order of the identified risk types is: tensile stress zone Excessively loose area In areas where interface pressure exceeds the limit, when the lead creep early warning judgment determines that the current lead chamber design has a serious creep risk, the aforementioned priority is used to perform an anti-creep structure optimization process. The optimization measures library includes measures to eliminate tensile stress zones, measures to control excessively loose zones, and measures to improve zones with excessive interface pressure. The measures to eliminate tensile stress zones include, but are not limited to, increasing local support points of the steel frame, increasing the thickness of the steel frame stiffeners, and adjusting the lead layer thickness distribution. The measures to control excessively loose zones include, but are not limited to, increasing the lead-steel sliding gap, adding an elastic pad, and applying pre-compression. The measures to improve zones with excessive interface pressure include, but are not limited to, increasing the lubrication / low-friction interface, adding a release groove, and segmented independent support.

[0014] Preferably, the simulation verification of the optimization scheme includes the following details: Step S61: Output the optimized model-driving parameters to the three-dimensional parametric geometric model of the lead chamber, and update the three-dimensional parametric geometric model of the lead chamber. Step S62: Perform the same lead creep prediction simulation analysis as in step S03 again, and calculate the optimized creep relative error and creep increment; Step S63: Verify whether the optimized simulation output meets the requirements of the lead creep early warning judgment step. If the verification is successful, output the final low background lead chamber design scheme and parameters. If it fails, return to step S05 to iterate again until the requirements are met.

[0015] The technical effects and advantages of this invention are as follows: 1. This invention provides an optimized design method for low-background lead chambers based on finite element simulation. It establishes a three-dimensional parametric geometric model of the lead chamber, includes a creep parameter acquisition layer to obtain creep characteristic parameters of the low-background lead chamber, and a time step setting layer to obtain the total simulation time for setting the low-background lead chamber. The creep characteristic parameters of the low-background lead chamber are analyzed, and the creep strain rate of the lead chamber in each time step is analyzed based on the lead creep model. The lead creep model is imported into finite element simulation software for analysis, and structural analysis of the creep effect is performed in each time step. Based on the simulation results, the current design of the low-background lead chamber is evaluated, and early warning results are generated. The lead creep model is embedded into the finite element simulation framework. Through creep analysis, the creep evolution prediction of the lead chamber's service life can be completed within hours. Specifically, traditional physical testing verification is time-consuming and lacks engineering feasibility. This invention compresses the time scale of simulation calculation in a virtual environment, shortening the design cycle; it can output key creep data at multiple time points within the lead chamber's service life, providing a full life-cycle perspective for design iteration. 2. This invention provides a low-background lead chamber optimization design method based on finite element simulation. When a serious creep risk is determined in the current lead chamber design, structural optimization is carried out. Based on the optimization scheme output by the anti-creep structural optimization steps, the three-dimensional parametric geometric model of the lead chamber is updated, and the updated model is imported into the finite element simulation software to perform lead creep prediction simulation analysis again. The optimization measures are divided into multi-level optimization decision-making levels, and a priority ranking logic is established, which is conducive to matching corresponding measures according to the risk type identified by simulation and avoiding blind adjustments. By using a parametric geometric model, after the optimization scheme is adjusted, the model can be automatically updated and re-simulated by modifying the driving parameters, which improves the adaptive adjustment capability of the design scheme and improves the efficiency of the scheme to meet the target by iterating the scheme. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the low-background lead chamber optimization design method based on finite element simulation of the present invention.

[0017] Figure 2This is a schematic diagram of the structure of step S03 of the present invention: lead creep prediction simulation analysis. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1 As shown, this invention provides a low-background lead chamber optimization design method based on finite element simulation, including the following steps: Step S01: Establishment of a three-dimensional parametric geometric model of the lead chamber: Establish a three-dimensional parametric geometric model of the lead chamber, the model including at least a lead layer, a steel outer shell, an internal steel support frame, and a shielding door assembly; In one possible design, the establishment of a three-dimensional parametric geometric model of the lead chamber includes at least a lead layer, a steel outer shell, an internal steel support frame, and a shielding door assembly, as detailed below: Step S11: Build a parametric geometric model of the low-background lead chamber using SolidWorks. The model is an assembly structure and includes at least the following components: Lead layer: As the main shielding element, it is made of high-purity lead material; Steel casing: Encased outside the lead layer, serving as a seal and providing structural protection; Internal steel support frame: pre-embedded inside the lead layer or placed at the bottom of the lead layer, used to bear the main gravity load of the lead layer; Platform screen door components: including the door body and door frame; Step S12: The parameterization refers to the preset driving parameters in the model (such as lead layer thickness, support plate thickness, support spacing, etc.). By modifying the parameter values, the geometry of the model can be automatically updated, providing a geometric basis for subsequent optimization design.

[0020] Step S02: Lead chamber parameter acquisition: includes a creep parameter acquisition layer and a time step setting layer. The creep parameter acquisition layer is used to acquire the creep characteristic parameters of the low background lead chamber, and the time step setting layer is used to acquire the total simulation time of the low background lead chamber.

[0021] In one possible design, the creep parameter acquisition layer specifically includes the following: Because lead has a low melting point, it exhibits obvious creep characteristics at room temperature and under its own weight stress. In this embodiment, a standard creep specimen of pure lead was prepared, and multiple levels of constant stress were set in the range of 0.5 to 4.0 MPa to carry out uniaxial creep tests. Creep strain-time curves under different stress levels were obtained, and the stress and creep time in each time step were extracted. The specific content of the time step setting layer is as follows: obtain the predetermined service life of the lead chamber as the time end point of the simulation calculation, and set the time step (such as 1 year, 5 years, 10 years, 30 years, etc.).

[0022] Please see Figure 2 As shown, step S03: Lead creep prediction simulation analysis includes a creep strain rate analysis layer and a finite element simulation execution layer. It analyzes the creep characteristic parameters of the low background lead chamber, analyzes the creep strain rate of the lead chamber in each time step based on the lead creep model, imports the lead creep model into the finite element simulation software for analysis, and performs structural analysis of the creep effect in each time step.

[0023] In one possible design, the creep strain rate analysis layer specifically includes the following: Step S31: The creep characteristic parameters are specifically as follows: The stress and creep time in each time step are obtained and input into the finite element simulation software. Based on the lead creep model, the creep strain rate of the lead chamber in each time step is analyzed. Step S32: Calculate the difference between the creep strain rate and the average strain rate obtained from multiple creep tests, further calculate the ratio of the difference to the average value, and take the absolute value of the difference to obtain the creep relative error; Step S33: Obtain the relative creep error and transmit it to the lead creep early warning judgment step to realize early warning triggering and processing.

[0024] In this embodiment, it should be specifically noted that the lead creep model is as follows: ; in, Expressed as creep strain rate, Represented as stress, Expressed as creep time, , , These are the creep parameters obtained through experimental fitting; Specifically, take the natural logarithm of the formula and linearize it: ; Using the least squares method, As the dependent variable, , As the independent variable, the fitting yielded... , , , The creep coefficient is related to the microstructure of the lead chamber and temperature, and determines the intrinsic trend of the creep rate. The creep index is used to indicate the stress sensitivity of lead, meaning that even a slight increase in stress will cause the creep rate to increase exponentially. This is a time exponent, taking a negative value, reflecting the degree of creep decay over time.

[0025] The present invention provides another specific embodiment, as follows: In the finite element simulation software, input the stress borne by a certain lead chamber element. ,in, , , Calculate its creep strain rate after 1 year of service (t=8760 hours): ; In the uniaxial creep test, stress, temperature, and creep time consistent with the finite element simulation were selected, and three parallel tests were conducted, recording the creep strain rate: Experiment 1: ; Experiment 2: ; Experiment 3: ; Calculate the average strain rate obtained from the creep test: ; According to the creep relative error formula: .

[0026] In one possible design, the finite element simulation execution layer specifically refers to: The structural analysis of creep effect based on finite element simulation software is as follows: Step S331: Discretize the three-dimensional parametric geometric model of the lead chamber into a mesh using adaptive mesh generation, with finer meshing in the lead layer region; Step S332: Obtain the predetermined service life of the lead chamber. The time step setting adopts automatic time step. The initial step is set to a short time, and then the step is gradually increased. Obtain each time step and extract the creep strain rate within each time step. Step S333: Based on the product of each time step and the creep strain rate, obtain the creep strain increment within that step. Step S334: After convergence at each time step, read the creep elongation of the lead chamber in the three orthogonal directions of x, y, and z; Step S335: Based on the sum of the creep elongation lengths of the lead chamber in the three orthogonal directions x, y, and z, obtain the creep increment within this step length; Step S336: Obtain the creep increment within each time step and sum them up to obtain the cumulative creep increment; Step S337: Obtain the creep increment and transmit it to the lead creep early warning judgment step to realize early warning triggering and processing.

[0027] Step S04: Lead creep early warning judgment: Based on simulation results: The creep relative error and creep increment transmitted in the lead creep prediction simulation analysis step are used to evaluate the current design of the low background lead chamber and generate early warning results.

[0028] In one possible design, the specific content of the lead creep early warning judgment is as follows: Step S41: Based on the uniaxial creep test, set the creep error warning threshold, and based on the allowable change in the internal space of the lead chamber, set the creep increment threshold; Step S42: Obtain the relative creep error and creep increment within each time step from the finite element simulation output, and compare them with the set creep error warning threshold and creep increment threshold, respectively. When the relative creep error... Creep error warning threshold and creep increment When the creep increment threshold is reached, it indicates that the current design meets the creep stability requirements, and the current design is directly output. If the creep relative error is... Creep error warning threshold or creep increment When the creep increment threshold is exceeded (only one of the criteria is exceeded), it indicates that there is a creep risk in the current lead chamber design. An early warning signal is then generated, and the deformation trend is continuously monitored. If the creep relative error... Creep error warning threshold and creep increment When the creep increment threshold is exceeded (both criteria are exceeded), it indicates that the current lead chamber design has a serious creep risk, and the process proceeds to step S05 for structural optimization.

[0029] Step S05: Creep Resistance Structure Optimization: When it is determined that the current lead chamber design has a serious creep risk, structural optimization is carried out. The optimization includes stress zone elimination, excessive loose zone control, and improvement of interface pressure exceeding the standard zone.

[0030] In one possible design, the specific details of the anti-creep structure optimization are as follows: Step S51: After convergence at each time step, the finite element simulation reads the stress in the lead chamber within that step. If the stress is greater than the preset stress, the warning type is classified as a tensile stress zone. Based on the identified risk type, the corresponding measures are selected from the optimization measure library. Step S52: After convergence at each time step, the finite element simulation reads the cumulative creep increment within that step of the lead chamber. If the cumulative creep increment is greater than the preset cumulative creep increment, the warning type is classified as the excessively loose zone. Based on the identified risk type, the corresponding measures are selected from the optimization measure library. Step S53: After convergence at each time step, the finite element simulation reads the contact pressure in the lead chamber within that step. If the contact pressure is greater than the preset contact pressure, the warning type is classified as the interface pressure exceeding the standard area. Based on the identified risk type, the corresponding measures are selected from the optimization measure library. Step S54: Output the optimized model driving parameters to the three-dimensional parametric geometric model of the lead chamber.

[0031] In one possible design, the priority order of the identified risk types is: tensile stress zone Excessively loose area In areas where interface pressure exceeds the limit, when the lead creep early warning judgment determines that the current lead chamber design has a serious creep risk, the aforementioned priority is used to perform an anti-creep structure optimization process. The optimization measures library includes measures to eliminate tensile stress zones, measures to control excessively loose zones, and measures to improve zones with excessive interface pressure. The measures to eliminate tensile stress zones include, but are not limited to, increasing local support points of the steel frame, increasing the thickness of the steel frame stiffeners, and adjusting the lead layer thickness distribution. The measures to control excessively loose zones include, but are not limited to, increasing the lead-steel sliding gap, adding an elastic pad, and applying pre-compression. The measures to improve zones with excessive interface pressure include, but are not limited to, increasing the lubrication / low-friction interface, adding a release groove, and segmented independent support.

[0032] In this embodiment, it should be specifically explained that the principle of eliminating the tensile stress zone is as follows: Lead creeps at a rate 1-2 orders of magnitude higher under tensile stress than under compressive stress, and tensile stress promotes the nucleation and expansion of micropores, leading to an increase in radon gas release. By increasing the support points of the steel frame and the thickness of the stiffeners, the stress state of the lead layer can be changed from tensile stress to compressive stress or zero stress, thereby controlling creep failure of low-background lead chambers. The principle of controlling the excessively loose area is as follows: Lead undergoes creep compaction under long-term compressive stress, resulting in volume reduction, which is beneficial for increasing shielding density. However, when the compressive stress is uneven or tensile stress zones exist, local volume expansion (porosity) may occur. By increasing the sliding gap or adding an elastic pad, the uneven stress inside the lead layer can be released, thereby suppressing the development of porosity in low-background lead chambers. The principle behind improving the interface pressure exceeding the standard area is as follows: Lead creep flows towards the gaps, causing an increase in the contact pressure at the lead-steel interface. Excessive contact pressure can lead to fretting wear, releasing lead particles and polluting the low-background environment. Using a low-friction interface or incorporating a release groove can effectively reduce interface pressure.

[0033] Step S06: Optimization scheme simulation verification: Based on the optimization scheme output by the anti-creep structure optimization step, update the three-dimensional parametric geometric model of the lead chamber, and import the updated model into the finite element simulation software to perform lead creep prediction simulation analysis again.

[0034] In one possible design, the simulation verification of the optimization scheme is as follows: Step S61: Output the optimized model-driving parameters to the three-dimensional parametric geometric model of the lead chamber, and update the three-dimensional parametric geometric model of the lead chamber. Step S62: Perform the same lead creep prediction simulation analysis as in step S03 again, and calculate the optimized creep relative error and creep increment; Step S63: Verify whether the optimized simulation output meets the requirements of the lead creep early warning judgment step. If the verification is successful, output the final low background lead chamber design scheme and parameters. If it fails, return to step S05 to iterate again until the requirements are met.

[0035] In this embodiment, it should be specifically explained that the present invention establishes a three-dimensional parametric geometric model of the lead chamber, with a creep parameter acquisition layer for acquiring the creep characteristic parameters of the low-background lead chamber, and a time step setting layer for acquiring the total simulation time of the low-background lead chamber. The creep characteristic parameters of the low-background lead chamber are analyzed, and the creep strain rate of the lead chamber in each time step is analyzed based on the lead creep model. The lead creep model is imported into finite element simulation software for analysis, and structural analysis of the creep effect is performed in each time step. Based on the simulation results, the current design of the low-background lead chamber is evaluated, and early warning results are generated. The lead creep model is embedded into the finite element simulation framework, and through creep analysis, the creep evolution prediction of the lead chamber's service life can be completed within a few hours. Specifically, traditional physical testing verification is time-consuming and lacks engineering feasibility. The present invention compresses the time scale of simulation calculation in a virtual environment, shortening the design cycle; it can output key creep data at multiple time points within the lead chamber's service life, providing a full life-cycle perspective for design iteration. This invention optimizes the structure of a lead chamber when a serious creep risk is identified in the current design. Based on the optimization scheme output from the anti-creep structural optimization steps, the three-dimensional parametric geometric model of the lead chamber is updated. The updated model is then imported into finite element simulation software, and lead creep prediction simulation analysis is performed again. The optimization measures are divided into multi-level optimization decision-making levels, and a priority ranking logic is established. This facilitates matching corresponding measures according to the risk type identified in the simulation, avoiding blind adjustments. By using a parametric geometric model, the model can be automatically updated and re-simulated after the optimization scheme is adjusted by modifying the driving parameters, improving the adaptive adjustment capability of the design scheme. Furthermore, by iterating the scheme, the efficiency of achieving the target is improved.

[0036] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-background lead chamber optimization design method based on finite element simulation, characterized in that, Includes the following steps: Step S01: Establishment of a three-dimensional parametric geometric model of the lead room: Establish a three-dimensional parametric geometric model of the lead room, the model including at least the lead layer, steel shell, internal steel support frame and shielding door assembly; Step S02: Lead chamber parameter acquisition: including creep parameter acquisition layer and time step setting layer. The creep parameter acquisition layer is used to acquire the creep characteristic parameters of the low background lead chamber, and the time step setting layer is used to acquire the total simulation time of the low background lead chamber. Step S03: Lead creep prediction simulation analysis: including creep strain rate analysis layer and finite element simulation execution layer, to analyze the creep characteristic parameters of low background lead chamber, to analyze the creep strain rate of lead chamber in each time step based on lead creep model, to import lead creep model into finite element simulation software for analysis, and to perform structural analysis of creep effect in each time step. Step S04: Lead creep early warning judgment: Based on the simulation results, evaluate the current design of the low background lead chamber and generate early warning results; Step S05: Creep Resistance Structure Optimization: When it is determined that the current lead chamber design has a serious creep risk, structural optimization is carried out. The optimization includes stress zone elimination, excessive porosity zone control, and improvement of interface pressure exceeding the standard zone. Step S06: Simulation verification of optimization scheme: Based on the optimization scheme output by the anti-creep structure optimization step, update the three-dimensional parametric geometric model of the lead chamber, and import the updated model into the finite element simulation software to perform lead creep prediction simulation analysis again.

2. The low-background lead chamber optimization design method based on finite element simulation according to claim 1, characterized in that: The establishment of a three-dimensional parametric geometric model of the lead chamber includes at least a lead layer, a steel outer shell, an internal steel support frame, and a shielding door assembly, as detailed below: Step S11: Use SolidWorks to create a parametric geometric model of the low-background lead chamber. The model is an assembly structure and includes at least the following components: Lead layer: As the main shielding element, it is made of high-purity lead material; Steel casing: Encased outside the lead layer, serving as a seal and providing structural protection; Internal steel support frame: pre-embedded inside the lead layer or placed at the bottom of the lead layer, used to bear the main gravity load of the lead layer; Platform screen door components: including the door body and door frame; Step S12: The parameterization refers to the preset driving parameters in the model. By modifying the parameter values, the geometry of the model can be automatically updated, providing a geometric basis for subsequent optimization design.

3. The low-background lead chamber optimization design method based on finite element simulation according to claim 1, characterized in that: The specific content of the creep parameter acquisition layer is as follows: By preparing pure lead standard creep specimens, setting multiple levels of constant stress in the range of 0.5 to 4.0 MPa, carrying out uniaxial creep tests, obtaining creep strain-time curves under different stress levels, and extracting the stress and creep time in each time step; The specific content of the time step setting layer is as follows: obtain the predetermined service life of the lead chamber as the time endpoint of the simulation calculation, and set the time step.

4. The low-background lead chamber optimization design method based on finite element simulation according to claim 1, characterized in that: The specific content of the creep strain rate analysis layer is as follows: Step S31: The creep characteristic parameters are specifically as follows: The stress and creep time in each time step are obtained and input into the finite element simulation software. Based on the lead creep model, the creep strain rate of the lead chamber in each time step is analyzed. Step S32: Calculate the difference between the creep strain rate and the average strain rate obtained from multiple creep tests, further calculate the ratio of the difference to the average value, and take the absolute value of the difference to obtain the creep relative error; Step S33: Obtain the relative creep error and transmit it to the lead creep early warning judgment step to realize early warning triggering and processing.

5. The low-background lead chamber optimization design method based on finite element simulation according to claim 1, characterized in that: The finite element simulation execution layer is specifically as follows: The structural analysis of creep effect based on finite element simulation software is as follows: Step S331: Discretize the three-dimensional parametric geometric model of the lead chamber into a mesh using adaptive mesh generation, with finer meshing in the lead layer region; Step S332: Obtain the predetermined service life of the lead chamber. The time step is set to automatic time step, and then the step is gradually increased to obtain each time step and extract the creep strain rate within each time step. Step S333: Based on the product of each time step and the creep strain rate, obtain the creep strain increment within that step. Step S334: After convergence at each time step, read the creep elongation of the lead chamber in the three orthogonal directions of x, y, and z; Step S335: Based on the sum of the creep elongation lengths of the lead chamber in the three orthogonal directions x, y, and z, obtain the creep increment within this step length; Step S336: Obtain the creep increment within each time step and sum them up to obtain the cumulative creep increment; Step S337: Obtain the creep increment and transmit it to the lead creep early warning judgment step to realize early warning triggering and processing.

6. The low-background lead chamber optimization design method based on finite element simulation according to claim 1, characterized in that: The specific details of the lead creep early warning judgment are as follows: Step S41: Based on the uniaxial creep test, set the creep error warning threshold, and based on the allowable change in the internal space of the lead chamber, set the creep increment threshold; Step S42: Obtain the creep relative error and creep increment within each time step from the finite element simulation output, and compare them with the set creep error warning threshold and creep increment threshold respectively; When creep relative error Creep error warning threshold and creep increment When the creep increment threshold is reached, it indicates that the current design meets the creep stability requirements, and the current design is output directly. If creep relative error Creep error warning threshold or creep increment When the creep increment threshold is reached, it indicates that there is a creep risk in the current lead chamber design, so an early warning signal is generated and the deformation trend is continuously monitored; If creep relative error Creep error warning threshold and creep increment When the creep increment threshold is exceeded (both criteria are exceeded), it indicates that the current lead chamber design has a serious creep risk, and the process proceeds to step S05 for structural optimization.

7. The low-background lead chamber optimization design method based on finite element simulation according to claim 1, characterized in that: The specific details of the anti-creep structure optimization are as follows: Step S51: After convergence at each time step, the finite element simulation reads the stress in the lead chamber within that step. If the stress is greater than the preset stress, the warning type is classified as a tensile stress zone. Based on the identified risk type, the corresponding measures are selected from the optimization measure library. Step S52: After convergence at each time step, the finite element simulation reads the cumulative creep increment within that step of the lead chamber. If the cumulative creep increment is greater than the preset cumulative creep increment, the warning type is classified as the excessively loose zone. Based on the identified risk type, the corresponding measures are selected from the optimization measure library. Step S53: After convergence at each time step, the finite element simulation reads the contact pressure in the lead chamber within that step. If the contact pressure is greater than the preset contact pressure, the warning type is classified as the interface pressure exceeding the standard area. Based on the identified risk type, the corresponding measures are selected from the optimization measure library. Step S54: Output the optimized model driving parameters to the three-dimensional parametric geometric model of the lead chamber.

8. The low-background lead chamber optimization design method based on finite element simulation according to claim 7, characterized in that: The identified risk types are prioritized as follows: tensile stress zone Excessively loose area In areas where interface pressure exceeds the limit, when the lead creep early warning judgment determines that the current lead chamber design has a serious creep risk, the aforementioned priority is used to perform an anti-creep structure optimization process. The optimization measures library includes measures to eliminate tensile stress zones, measures to control excessively loose zones, and measures to improve zones with excessive interface pressure. The measures to eliminate tensile stress zones include, but are not limited to, increasing local support points of the steel frame, increasing the thickness of the steel frame stiffeners, and adjusting the lead layer thickness distribution. The measures to control excessively loose zones include, but are not limited to, increasing the lead-steel sliding gap, adding an elastic pad, and applying pre-compression. The measures to improve zones with excessive interface pressure include, but are not limited to, increasing the lubrication / low-friction interface, adding a release groove, and segmented independent support.

9. The low-background lead chamber optimization design method based on finite element simulation according to claim 1, characterized in that: The specific details of the simulation verification of the optimization scheme are as follows: Step S61: Output the optimized model-driving parameters to the three-dimensional parametric geometric model of the lead chamber, and update the three-dimensional parametric geometric model of the lead chamber. Step S62: Perform the same lead creep prediction simulation analysis as in step S03 again, and calculate the optimized creep relative error and creep increment; Step S63: Verify whether the optimized simulation output meets the requirements of the lead creep early warning judgment step. If the verification is successful, output the final low background lead chamber design scheme and parameters. If it fails, return to step S05 to iterate again until the requirements are met.

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