Condenser critical component strength analysis system

Abstract

The present application relates to the field of condenser strength analysis, in particular to a condenser key component strength analysis system, the system comprises a topology matching mapping module; a topology mapping data set is generated; a coupling strength quantitative calculation module; each sub-component domain is discretized by a hexahedral structured grid through the topology mapping data set, and a full calculation domain quantitative result is output; a checking and state identification module; the strength of the single calculation parameter of the full calculation domain quantitative result is checked. The present application adopts hexahedral structured grid to discretize the calculation domain, the grid is encrypted for the stress concentration area and the smooth transition is completed, the precision of finite element calculation is improved, the initial damage field of the full calculation domain is formed, the coupling analysis is realized, and the strength calculation result is more suitable for the actual strength state of the material and structure.

Description

Technical Field

[0001] This invention relates to the field of condenser strength analysis, and more specifically to a strength analysis system for key condenser components. Background Technology

[0002] As a core heat exchange component of steam turbine power systems, condensers are widely used in industrial fields such as shipbuilding and thermal power generation. The structural strength and fatigue life of their key components directly determine the safe and stable operation and service life of the entire power system, making them a core research area for equipment reliability design and operation and maintenance monitoring. The condenser's structural system is complex, comprising multiple component groups such as supports, shells, and tubes. The load transfer and constraint coupling relationships between these components are close, and in actual operation, they must withstand the combined effects of various loads, including steady-state pressure, thermal expansion, dynamic impact, and environmental corrosion. Simultaneously, the low-cycle fatigue loads during equipment start-up and shutdown are superimposed with the high-cycle fatigue loads during continuous operation, posing stringent requirements for the strength design and analysis of key components.

[0003] Currently, the industry still faces many challenges and shortcomings in the strength analysis technology for key condenser components, making it difficult to meet the needs of refined and comprehensive analysis. For example, the disassembly of condenser components lacks a standardized hierarchical topology framework, the component division is vague, and the calculation units are arbitrarily merged, making it impossible to achieve accurate mapping between loads, constraints, and specific load-bearing components. Furthermore, the lack of a unified structured attribute label system leads to chaotic basic data for analysis. Moreover, the coupling effect of high-cycle and low-cycle fatigue loads is ignored, making it impossible to truly restore the load state during equipment start-up, shutdown, and continuous operation. It is also difficult to adapt to the strength analysis needs of condensers of different specifications and application scenarios. Summary of the Invention

[0004] This invention addresses the technical problems existing in the prior art by providing a strength analysis system for key components of condensers.

[0005] The technical solution of this invention to solve the above-mentioned technical problems is as follows: a strength analysis system for key components of a condenser, the system comprising: The topology matching and mapping module is used to build a three-level decomposition framework based on the key components of the condenser, including primary component groups, secondary sub-components, and tertiary minimum computing units. It completes the hierarchical topology decomposition of the key components of the condenser, performs label assignment and matching for each minimum computing unit, maps each type of load to the corresponding sub-component, and performs topology association matching between the sub-components and constraint boundaries. After completing all matching, it integrates and generates a topology mapping dataset. The coupling strength quantization calculation module is used to discretize the structural domain of each sub-component using a hexahedral structured mesh through a topology mapping dataset. Based on the labels of each sub-component, it constructs a discretized fracture network model, completes the initial damage field construction based on the discretized fracture network model, obtains the high- and low-cycle composite fatigue load spectrum according to the full range of loads corresponding to each sub-component, and maps it to each mesh element in the computational domain. It constructs a fully coupled constraint field based on the connection relationship of the first-level component group, fuses the fully coupled constraint field, and iteratively calculates the discretized fracture network model according to each mesh element mapped to the computational domain, outputting the quantization result of the entire computational domain. Verification and status identification module: Performs strength verification on individual calculation parameters of the full computational domain quantization results, performs secondary verification on the damage field and composite fatigue life data in the full computational domain quantization results, and obtains the corresponding sub-components by locating the critical failure points obtained from the verification.

[0006] In a preferred embodiment, the topology matching mapping module is divided into a primary component group based on the key components of the condenser, including a support type component group, a shell component group, and a tube side component group. The support-type component assembly is disassembled into two sub-components, including a throat expansion joint, a bottom rigid support, a throat fixing structure, a bottom spring support, a throat suspension structure, and a bottom suspension constraint structure. The shell component assembly is disassembled into two sub-components, including the shell body, shell flange, shell expansion joint, shell opening pipe, shell manhole, shell handhole, support structure, and heat exchange tube bundle; The tube-side component assembly is disassembled into two sub-components, including the water chamber shell, water chamber flange, water chamber connector, water chamber connector flange, water chamber manhole, water chamber handhole, tube sheet, and heat exchange tube end connection structure. Each secondary sub-component is broken down into tertiary minimum calculation units, and each minimum calculation unit corresponds to an independent strength calculation item. After obtaining the smallest calculation unit, extract the drawing dimension of the corresponding smallest calculation unit in the initial design drawing of the condenser to obtain the dimension parameters, and bind each dimension parameter to the corresponding smallest calculation unit to complete the assignment of structural dimension labels. Extract all material parameters from the material standard corresponding to the smallest calculation unit, bind each material parameter to the corresponding smallest calculation unit, and complete the assignment of material property labels. Then, extract the environmental parameters that each smallest calculation unit in the initial design drawings of the condenser is in contact with, and assign a medium environment label to each smallest calculation unit. Extract the connection methods between the smallest calculation unit in the condenser installation design drawings and adjacent components, steam turbine, and ship foundation, define the constraint types according to the connection methods, and complete the assignment of boundary constraint labels.

[0007] In a preferred embodiment, the topology matching mapping module divides the loads on key components of the condenser into steady-state pressure loads, thermal loads, dynamic loads, and environmental loads. Each type of load is mapped to the corresponding sub-component, specifically: the throat expansion joint and the shell expansion joint are mapped to thermal load, steady-state pressure load, and dynamic impact load; The shell body is mapped to steady-state internal pressure and / or external pressure loads, thermal loads, impact loads, and external pressure stability loads; Map the tube sheet to the shell-and-tube pressure differential load, thermal expansion differential load, and heat exchange tube loading load; Map all flange components to steady-state pressure loads, bolt preload torque loads, and pipe reaction loads; The supporting structure is mapped to equipment weight load, impact inertial load, and hull sway load; The heat exchanger tube bundle is mapped to flow-induced vibration load, turbine rotation frequency alternating load, and thermal expansion difference load. Then, the sub-components are topologically associated and matched with the constraint boundaries, specifically as follows: The constraint boundaries between the throat expansion joint and the bottom rigid support are set as the displacement boundary between the throat expansion joint and the turbine interface, and the fixed constraint boundary between the bottom rigid support and the hull foundation, and the three-dimensional thermal expansion displacement release boundary is synchronously mapped. The constraint boundaries of the throat fixed structure and the bottom spring support are set as the fixed constraint boundary of the throat and the turbine interface, the elastic constraint boundary of the bottom spring support, and the triaxial displacement release boundary of the spring deformation are synchronously mapped. The constraint boundaries of the throat suspension structure and the bottom suspended structure are set as the suspension constraint boundary of the throat suspension structure and the turbine interface, the free displacement boundary of the bottom without constraint, and the inertial constraint boundary of the impact load is synchronously mapped. The topology matching and mapping module sorts all the smallest computational units bound with attribute labels, load mappings, and constraint boundaries according to a three-level decomposition framework to form a structured dataset framework. It then organizes all the parameters of each smallest computational unit into a one-to-one corresponding parameter group, generating the final topology mapping dataset for the entire condenser component.

[0008] In a preferred embodiment, the coupling strength quantification calculation module extracts the three-dimensional geometric models of all the smallest computing units from the topology mapping dataset and splices them together according to the sub-component connection relationship to form a geometric model of the condenser's full structural computing domain. Clean up the computational domain geometry model by removing features including chamfers, fillets, internal threads of bolt holes, and non-pressure bearing markings that are less than 1 mm in diameter. Then, perform topology repair on the cleaned geometry model to fix free edges, overlapping surfaces, gaps, and discontinuous entities in the computational domain geometry model. The basic mesh size and stress concentration region of each minimum computational unit are determined, and the geometric model of the computational domain is divided into structured topological blocks according to the structural characteristics of each minimum computational unit. Each topological block corresponds to a regular hexahedral structure. For each divided topological block, a structured hexahedral mesh is generated according to the determined basic mesh size. The edges of the structured hexahedral mesh are fully aligned with the edges of the topological block. The mesh nodes of adjacent topological blocks are fully shared. In the topological blocks of the force concentration region, a densification size is set, and a transition processing is performed between the densified and undensified regions. The structural size label, material property label, constraint boundary, and mapping load parameters of each smallest computational unit in the topology mapping dataset are mapped to the corresponding mesh element, thus completing the hexahedral structured mesh discretization of the computational domain geometric model of the entire computational domain.

[0009] In a preferred embodiment, the coupling strength quantification calculation module extracts the material property parameters and medium environment parameters corresponding to each grid cell, sets the initial crack statistical parameters for each grid cell, and uses the Monte Carlo random generation method to randomly generate the center point position of the crack in the three-dimensional space of the grid cell, and then randomly generates the direction and dip angle of the crack to complete the generation of the initial crack in each grid cell, and constructs a discrete crack network model of the entire computational domain. Based on the material parameters of each grid cell in the topological mapping dataset, the total volume of all initial cracks in the corresponding grid cell is statistically analyzed through the discrete crack network model corresponding to each grid cell. Then, the ratio of the total volume of the initial cracks to the total volume of the grid cell is calculated to obtain the initial crack damage variables. After that, the initial equivalent macroscopic mechanical parameters of each grid cell are calculated. The initial crack damage variables and initial equivalent macroscopic mechanical parameters of each grid cell are mapped to the corresponding grid cell to form the initial damage field of the entire computational domain.

[0010] In a preferred embodiment, the coupling strength quantification calculation module extracts all loads mapped by each grid cell based on the topology mapping dataset and classifies them into low-cycle fatigue loads and high-cycle fatigue loads. The low-cycle fatigue loads are discretized in the time domain to generate a low-cycle load time series that matches the design life of the equipment, with the time step corresponding to one start-stop cycle of the equipment. The high-cycle fatigue loads are discretized in the time domain to generate a high-cycle load time series that is completely synchronized with the low-cycle load time series. Each low-cycle time step contains a complete high-cycle load cycle sequence. For each grid cell, the ratio of macroscopic stress generated by low-cycle load to the material yield limit is extracted as the load interaction coefficient. The corresponding low-cycle load amplitude and high-cycle load amplitude are synchronously superimposed at the same time point. After performing synchronous superposition operation on all time points, the high-low cycle composite fatigue load spectrum in the whole time domain is generated. The generated high- and low-cycle composite fatigue load spectrum is mapped onto the corresponding grid cells of the entire computational domain, and the boundary correction of the high- and low-cycle composite fatigue load spectrum is performed according to the constraint boundary in the topology mapping dataset, thus completing the construction of the full computational domain driving load field.

[0011] In a preferred embodiment, the coupling strength quantification calculation module divides the discrete fracture network model of the entire computational domain into three mutually coupled subsystems according to the connection relationship of the primary component groups, specifically: The support and constraint subsystem includes all support structures, suspension structures, spring supports, and rigid supports. It is responsible for transferring equipment loads to the ship's foundation and serves as the constraint boundary for the entire equipment. The shell subsystem includes the shell body, shell expansion joints, shell flanges, shell openings and nozzles, shell manholes and handholes, and heat exchange tube bundles. It is the pressure-bearing structure for the shell-side medium, coupled to the tube-side subsystem through the tube sheet, and coupled to the support and constraint subsystem through the support structure. The tube-side tube bundle subsystem includes the water chamber shell, water chamber flange, water chamber nozzle, tube sheet, and heat exchange tubes. It is the pressure-bearing structure for the tube-side medium, coupled to the shell subsystem through the tube sheet, and coupled to the turbine through the throat interface. Extract the initial equivalent macroscopic mechanical parameters, structural dimension parameters, and grid node coordinates of all grid elements in each coupled subsystem. Multiply the volume of each grid element by the density of the material to obtain the mass of each element. Then, distribute the mass of each element to the grid nodes of that element to obtain the mass of each node. Arrange the masses of all nodes in the order of the node coordinates to form the mass matrix of each coupled subsystem. Based on the equivalent elastic modulus, Poisson's ratio, and element shape of each mesh element, the element stiffness matrix of each mesh element is calculated, and the damping matrix of each subsystem is also calculated. Based on the mass matrix, stiffness matrix, and damping matrix, the initial dynamic stiffness matrix of each subsystem is constructed. For each coupled connection interface, the dynamic stiffness of all mesh nodes on the interface is extracted, and the equivalent dynamic stiffness of the corresponding interface is calculated.

[0012] In a preferred embodiment, the coupling strength quantification calculation module uses the ratio of the equivalent dynamic stiffness of the two coupled subsystems as the stiffness matching degree for the connection interface of each group of adjacent coupled subsystems, and divides 1 by the stiffness matching degree as the load amplification factor of the corresponding connection interface. For each connection interface, the calculated load amplification factor is mapped to all mesh elements on the corresponding interface. The constraint boundaries and load amplification factors of each subsystem are mapped onto the grid cells of the entire computational domain to construct a coupled constraint field of the entire computational domain. The coupling strength quantification calculation module sets the calculation step size for damage evolution through the observation discrete crack network model. After the calculation step size is fully aligned with the time step size of the low-cycle fatigue load, the total number of calculation steps is set. For the current calculation step size, the high- and low-cycle composite fatigue load amplitude corresponding to the calculation step size and the load amplification factor corresponding to the calculation step size are extracted. The load amplitude is multiplied by the load amplification factor to obtain the total load amplitude actually applied at the calculation step size. The total load amplitude is then applied to the observation discrete crack network model of the entire computational domain according to the load direction and the mesh element on which it is applied, while the constraint conditions of the coupling constraint field are applied. The linear elastic finite element method is used to calculate the macroscopic stress and strain fields of each grid element in the entire computational domain, thus obtaining the stress and strain fields of the entire computational domain. Based on the macroscopic stress and strain fields of each grid element, the propagation length, propagation direction, and aperture changes of each crack in the current step size discrete crack network model are calculated, and the discrete crack network model of the entire computational domain is updated. The initial equivalent macroscopic mechanical parameters of each grid element and the dynamic stiffness matrix of the three coupled subsystems are recalculated using the discrete fracture network model of the entire computational domain. After the final iteration converges, the result set of multi-field coupling calculations for all components of the condenser is output.

[0013] In a preferred embodiment, the verification and state identification module performs strength verification of the throat expansion joint and shell expansion joint, strength verification of the shell body and external pressure stability, strength verification of the shell and / or water chamber flange and pipe flange, reinforcement verification of the shell and tube side openings, vibration verification of the heat exchange tubes, strength verification of the support structure, and strength verification of the tube sheet based on the calculation parameters in the full computational domain quantization results. It outputs the strength verification results and performs secondary verification based on the damage field and composite fatigue life data to obtain the location of the secondary failure point with insufficient fatigue life. The corresponding sub-component is obtained by positioning.

[0014] The beneficial effects of this invention are: the computational domain is discretized using a hexahedral structured mesh, and the mesh is refined and smoothed for stress concentration areas, thereby improving the accuracy of finite element calculations; at the same time, an initial model of a discrete crack network is constructed, and differentiated initial crack parameters are set according to the differences in the medium environment to form an initial damage field for the entire computational domain, realizing coupled analysis. This makes up for the shortcomings of traditional analysis, which only considers macroscopic aspects and ignores microscopic initial damage and evolution, so that the strength calculation results are more consistent with the actual strength state of materials and structures. The condenser was divided into three coupled subsystems based on the connection relationship of the primary component groups: support constraints, shell, and tube bundle. The dynamic stiffness matrix of each subsystem and the stiffness matching degree and load amplification factor of the coupling interface were quantitatively calculated. A coupled constraint field of the entire computational domain was constructed, which fully considered the load transfer, constraint coupling and load amplification effect between the subsystems. This solved the problem of incomplete consideration of coupling constraints in traditional analysis and significantly improved the authenticity and reliability of strength calculation. Attached Figure Description

[0015] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] As attached Figure 1 As shown, this embodiment provides a strength analysis system for key components of a condenser, which consists of the following modules: The topology matching and mapping module is used to build a three-level decomposition framework based on the key components of the condenser, including primary component groups, secondary sub-components, and tertiary minimum computing units. It completes the hierarchical topology decomposition of the key components of the condenser, performs label assignment and matching for each minimum computing unit, maps each type of load to the corresponding sub-component, and performs topology association matching between the sub-components and constraint boundaries. After completing all matching, it integrates and generates a topology mapping dataset. The coupling strength quantization calculation module is used to discretize the structural domain of each sub-component using a hexahedral structured mesh through a topology mapping dataset. Based on the labels of each sub-component, it constructs a discretized fracture network model, completes the initial damage field construction based on the discretized fracture network model, obtains the high- and low-cycle composite fatigue load spectrum according to the full range of loads corresponding to each sub-component, and maps it to each mesh element in the computational domain. It constructs a fully coupled constraint field based on the connection relationship of the first-level component group, fuses the fully coupled constraint field, and iteratively calculates the discretized fracture network model according to each mesh element mapped to the computational domain, outputting the quantization result of the entire computational domain. Verification and status identification module: Performs strength verification on individual calculation parameters of the full computational domain quantization results, performs secondary verification on the damage field and composite fatigue life data in the full computational domain quantization results, and obtains the corresponding sub-components by locating the critical failure points obtained from the verification.

[0018] The specific steps of the above system in performing intensity analysis are as follows: S1. Based on the key components of the condenser, a three-level decomposition framework is built, including a first-level component group, a second-level sub-component, and a third-level minimum calculation unit. The hierarchical topology decomposition of the key components of the condenser is completed, and each minimum calculation unit is labeled and assigned a value. Each type of load is mapped and matched to the corresponding sub-component, and the sub-component is topologically associated with the constraint boundary. After all the matching is completed, the topology mapping dataset is generated. Based on the key components of the condenser, it is divided into primary component groups, including support type component group, shell component group, and tube side component group; The support-type component assembly is disassembled into two sub-components, including a throat expansion joint, a bottom rigid support, a throat fixing structure, a bottom spring support, a throat suspension structure, and a bottom suspension constraint structure. The shell component assembly is disassembled into two sub-components, including the shell body, shell flange, shell expansion joint, shell opening pipe, shell manhole, shell handhole, support structure, and heat exchange tube bundle; The tube-side component assembly is disassembled into two sub-components, including the water chamber shell, water chamber flange, water chamber connector, water chamber connector flange, water chamber manhole, water chamber handhole, tube sheet, and heat exchange tube end connection structure. Each secondary sub-component is broken down into a tertiary minimum calculation unit. Each minimum calculation unit corresponds to an independent strength calculation item. For example, the shell flange is broken down into four minimum calculation units: flange plate, flange neck, bolt connection pair, and gasket. These correspond to the calculation objects of flange axial stress, radial stress, and tangential stress, respectively, ensuring that each minimum calculation unit has a clear corresponding strength calculation item and no ambiguous merged units. After obtaining the minimum calculation unit, the drawing dimensions corresponding to the minimum calculation unit in the initial design drawings of the condenser are extracted to obtain the dimension parameters. Each dimension parameter is then bound to the corresponding minimum calculation unit to complete the assignment of structural dimension labels. The dimension parameters include inner diameter / outer diameter, effective thickness, calculated diameter, expansion joint wave height, expansion joint pitch, flange bolt center circle diameter, etc. Extract all material parameters from the material standard corresponding to the smallest calculation unit, and bind each material parameter to the corresponding smallest calculation unit. The material standard refers to the preset material quality certificate and national material standard. The material parameters include allowable stress, yield strength, elastic modulus at design temperature, corrosion allowance, thickness allowance, weld coefficient, etc., and complete the assignment of material property labels. Then, the environmental parameters of each smallest calculation unit in the initial design drawings of the condenser are extracted, and each smallest calculation unit is assigned a medium environment label. The environmental parameters include medium type, operating temperature range, operating pressure fluctuation range, and medium corrosivity level. The components with seawater medium in the tube side are marked as strongly corrosive environment, and the components with steam medium in the shell are marked as weakly corrosive environment, corresponding to different initial damage parameters. Extract the connection methods between the smallest calculation unit in the condenser installation design drawings and adjacent components, steam turbine, and ship foundation, and define the constraint types according to the connection methods. Complete the assignment of boundary constraint labels. The connection methods include fixed constraints, elastic constraints, free displacement constraints, and hinge constraints. At the same time, clarify the displacement release direction of the unit, such as the axial displacement release of the expansion joint and the three-dimensional displacement release of the spring support.

[0019] The loads on key components of the condenser are classified into steady-state pressure load, thermal load, dynamic load, and environmental load. Each type of load is mapped to the corresponding sub-component, specifically: the throat expansion joint and the shell expansion joint are mapped to thermal load, steady-state pressure load, and dynamic impact load; The shell body is mapped to steady-state internal pressure and / or external pressure loads, thermal loads, impact loads, and external pressure stability loads; Map the tube sheet to the shell-and-tube pressure differential load, thermal expansion differential load, and heat exchange tube loading load; Map all flange components to steady-state pressure loads, bolt preload torque loads, and pipe reaction loads; The supporting structure is mapped to equipment weight load, impact inertial load, and hull sway load; The heat exchanger tube bundle is mapped to flow-induced vibration load, turbine rotation frequency alternating load, and thermal expansion difference load. Then, the sub-components are topologically associated and matched with the constraint boundaries, specifically as follows: The constraint boundaries between the throat expansion joint and the bottom rigid support are set as the displacement boundary between the throat expansion joint and the turbine interface, and the fixed constraint boundary between the bottom rigid support and the hull foundation, and the three-dimensional thermal expansion displacement release boundary is synchronously mapped. The constraint boundaries of the throat fixed structure and the bottom spring support are set as the fixed constraint boundary of the throat and the turbine interface, the elastic constraint boundary of the bottom spring support, and the triaxial displacement release boundary of the spring deformation are synchronously mapped. The constraint boundaries of the throat suspension structure and the bottom suspended structure are set as the suspension constraint boundary of the throat suspension structure and the turbine interface, the free displacement boundary of the bottom without constraint, and the inertial constraint boundary of the impact load is synchronously mapped. The topology matching and mapping module sorts all the smallest computational units bound with attribute labels, load mappings, and constraint boundaries according to a three-level decomposition framework to form a structured dataset framework. All parameters of each smallest computational unit are organized into one-to-one corresponding parameter groups in the order of structural dimension parameters, material property parameters, medium environment parameters, constraint boundary parameters, and mapped load parameters, generating the final topology mapping dataset for the entire condenser component.

[0020] S2. The structural domain of each sub-component is discretized into a hexahedral structured mesh using a topology mapping dataset. A discrete crack network model is constructed based on the label of each sub-component. The initial damage field is constructed based on the discrete crack network model. The high- and low-cycle composite fatigue load spectrum is obtained according to the full range of loads corresponding to each sub-component and mapped to each grid cell in the computational domain. A fully coupled constraint field is constructed based on the connection relationship of the first-level component group. The fully coupled constraint field is fused and the discrete crack network model is iteratively calculated according to each grid cell mapped to the computational domain. The full computational domain quantization result is output. From the topology mapping dataset, extract the three-dimensional geometric models of all the smallest computational units and stitch them together according to the connection relationship of the sub-components to form the geometric model of the entire computational domain of the condenser. The computational domain geometry model is cleaned up to remove features including chamfers, fillets, internal threads in bolt holes, and non-pressure-bearing markings smaller than 1mm. The removal criteria are: after removing the feature, the load-bearing area, load-bearing structure, and constraint boundaries of the component are not changed, ensuring that the load-bearing characteristics of the computational domain geometry model are completely consistent with those of the actual design structure. The cleaned geometry model is then topologically repaired to fix free edges, overlapping surfaces, gaps, and discontinuous entities in the computational domain geometry model. For each minimum computational unit, a corresponding basic mesh size and stress concentration region are determined. It should be noted that the basic mesh size is no greater than 1 / 5 of the minimum structural feature size of the unit. For example, if the effective thickness of the shell is 20mm, the basic mesh size is no greater than 4mm. At the same time, for the stress concentration regions clearly defined in the document, including the edges of openings, weld locations, variable cross-section locations, expansion joint crests and troughs, flange necks, and tube sheet hole edges, a fine mesh size is planned. The fine mesh size is 1 / 2 of the basic mesh size to ensure the calculation accuracy of the stress concentration regions. The computational domain geometric model is divided into structured topological blocks according to the structural features of each minimum computational unit. Each topological block corresponds to a regular hexahedral structure. For complex curved surface structures, a mapping partitioning method is used to map the curved surface structure to regular hexahedral topological blocks. For each partitioned topological block, a structured hexahedral mesh is generated according to the determined basic mesh size. The edges of the structured hexahedral mesh are fully aligned with the edges of the topological block, and the mesh nodes of adjacent topological blocks are fully shared, with no node mismatches or mesh penetrations, ensuring that the mesh of the entire computational domain is a continuous whole. In the topological blocks of the force concentration region, a finer mesh size is set, and the mesh of this region is divided into finer hexahedral elements. The mesh between the finer and unfiner regions is transitioned to ensure that the mesh size transitions smoothly without abrupt mesh size differences, thus avoiding computational errors. The structural size label, material property label, constraint boundary, and mapping load parameters of each smallest computational unit in the topology mapping dataset are mapped to the corresponding mesh element, thus completing the hexahedral structured mesh discretization of the computational domain geometric model of the entire computational domain.

[0021] Material properties and environmental parameters of the medium are extracted from each grid cell. Statistical parameters for initial cracks are set for each grid cell. For grid cells in a highly corrosive environment where the pipe side is in contact with seawater, the initial crack density is set to 1.5 times that of the shell in a weakly corrosive environment. For grid cells in stress concentration areas, the initial crack density is set to 2 times that of the smooth area. For grid cells at weld locations, the initial crack density is set to 1.8 times that of the base material area. Based on the set initial crack statistical parameters, a Monte Carlo random generation method is used to randomly generate the center point of the crack in the three-dimensional space of the grid cell, and then randomly generate the direction and inclination of the crack, thus completing the generation of initial cracks in each grid cell. A discrete crack network model with full computational domain is constructed. Based on the material parameters corresponding to each grid cell in the topological mapping dataset, the total volume of all initial cracks in the corresponding grid cell is statistically analyzed through the discrete crack network model corresponding to each grid cell. Then, the ratio of the total volume of the initial cracks to the total volume of the grid cell is calculated to obtain the initial crack damage variable. After that, the initial equivalent macroscopic mechanical parameters of each grid cell are calculated. This application further discloses its calculation rules. The effective elastic modulus is equal to the undamaged initial elastic modulus multiplied by 1 minus the difference of the initial damage variable. The equivalent Poisson's ratio, equivalent allowable stress, and equivalent yield limit are all calculated using the same rules. The undamaged initial parameters are multiplied by 1 minus the difference of the initial damage variable. The undamaged initial parameters are determined by the material parameters. The initial crack damage variable and the initial equivalent macroscopic mechanical parameters of each grid cell are mapped to the corresponding grid cell to form the initial damage field of the entire computational domain.

[0022] Based on the topology mapping dataset, all loads mapped to each grid cell are extracted and classified into low-cycle fatigue loads and high-cycle fatigue loads. Low-cycle fatigue loads refer to loads generated during equipment start-up and shutdown, with a low cycle number and large load amplitude. Specifically, they include steady-state design internal pressure, steady-state design external pressure, hydrostatic test pressure, thermal stress generated by shell-and-tube temperature difference, and static load generated by equipment self-weight. High-cycle fatigue loads refer to loads generated during continuous equipment operation, with a high cycle number and small load amplitude. Specifically, they include impact overload generated by hull swaying, flow-induced vibration load of heat exchange tubes, alternating load generated by turbine rotation, water hammer impact load generated by valve opening and closing, and reaction force load generated by safety valve opening. The low-cycle fatigue loads are discretized in the time domain to generate a low-cycle load time series that matches the equipment design life. The time step corresponds to one start-up and shutdown cycle of the equipment. The high-cycle fatigue loads are discretized in the time domain to generate a high-cycle load time series that is completely synchronized with the low-cycle load time series. Each low-cycle time step contains a complete high-cycle load cycle sequence. For each grid cell, the ratio of macroscopic stress generated by low-cycle load to the material yield limit is extracted as the load interaction coefficient. At the same time point, the corresponding low-cycle load amplitude and high-cycle load amplitude are synchronously superimposed. The superposition rule is that the total load amplitude is equal to the low-cycle load amplitude plus the high-cycle load amplitude multiplied by the load interaction coefficient, ensuring that the acceleration effect of high-cycle load is quantified into the total load. After performing synchronous superposition operation on all time points, a high-low cycle composite fatigue load spectrum in the full time domain is generated. The generated high- and low-cycle composite fatigue load spectrum is mapped onto the corresponding grid cells of the entire computational domain, and the boundary correction of the high- and low-cycle composite fatigue load spectrum is performed according to the constraint boundary in the topology mapping dataset, thus completing the construction of the full computational domain driving load field.

[0023] Based on the connection relationships of the primary component groups, the discrete fracture network model of the entire computational domain is divided into three mutually coupled subsystems, specifically: The support and constraint subsystem includes all support structures, suspension structures, spring supports, and rigid supports. It is responsible for transferring equipment loads to the ship's foundation and serves as the constraint boundary for the entire equipment. The shell subsystem includes the shell body, shell expansion joints, shell flanges, shell openings and nozzles, shell manholes and handholes, and heat exchange tube bundles. It is the pressure-bearing structure for the shell-side medium, coupled to the tube-side subsystem through the tube sheet, and coupled to the support and constraint subsystem through the support structure. The tube-side tube bundle subsystem includes the water chamber shell, water chamber flange, water chamber nozzle, tube sheet, and heat exchange tubes. It is the pressure-bearing structure for the tube-side medium, coupled to the shell subsystem through the tube sheet, and coupled to the turbine through the throat interface. Extract the initial equivalent macroscopic mechanical parameters, structural dimension parameters, and grid node coordinates of all grid elements in each coupled subsystem. Multiply the volume of each grid element by the density of the material to obtain the mass of each element. Then, distribute the mass of each element to the grid nodes of that element to obtain the mass of each node. Arrange the masses of all nodes in the order of the node coordinates to form the mass matrix of each coupled subsystem. Based on the equivalent elastic modulus, Poisson's ratio, and element shape of each mesh element, obtained from structural dimension parameters and mesh-related parameters, the element stiffness matrix of each mesh element is calculated, and the damping matrix of each subsystem is also calculated. The damping matrix is ​​equal to the mass matrix multiplied by the Rayleigh damping mass coefficient, plus the stiffness matrix multiplied by the Rayleigh damping stiffness coefficient. Both coefficients are calculated based on the material's damping ratio and the subsystem's natural frequency. Based on the mass matrix, stiffness matrix, and damping matrix, the initial dynamic stiffness matrix of each subsystem is constructed. For each coupled connection interface, the dynamic stiffness of all mesh nodes on the interface is extracted, and the equivalent dynamic stiffness of the corresponding interface is calculated. The equivalent dynamic stiffness is equal to the average of the dynamic stiffness of all nodes on the interface, representing the overall deformation resistance of the interface.

[0024] The stiffness matching degree is taken as the ratio of the equivalent dynamic stiffness of the two coupled subsystems at the connection interface of each pair of adjacent coupled subsystems. 1 is divided by the stiffness matching degree as the load amplification factor of the corresponding connection interface. For each connection interface, the calculated load amplification factor is mapped to all mesh elements on the corresponding interface. The constraint boundaries and load amplification factors of each subsystem are mapped onto the grid cells of the entire computational domain to construct a coupled constraint field of the entire computational domain. The coupling strength quantification calculation module sets the calculation step size for damage evolution by observing the discrete crack network model. After the calculation step size is fully aligned with the time step size of the low-cycle fatigue load, the total number of calculation steps is set. The total number of steps is equal to the total number of start-stop cycles within the design life, which is also the total number of cycles of the low-cycle fatigue load. For the current calculation step, extract the high and low cycle composite fatigue load amplitude corresponding to the calculation step and the load amplification factor corresponding to the calculation step. Multiply the load amplitude by the load amplification factor to obtain the total load amplitude actually applied at the calculation step. Apply the total load amplitude to the discrete crack network model of the entire computational domain according to the load direction and the mesh element on which it is applied, and apply the constraint conditions of the coupled constraint field at the same time. The linear elastic finite element method is used to calculate the macroscopic stress and strain fields of each mesh element in the entire computational domain, thus obtaining the stress and strain fields of the entire computational domain. The specific calculation process adopted in this application is as follows: based on the equivalent macroscopic mechanical parameters, applied loads, and constraints of each element, the force equilibrium equation of each element is established; then, the force equilibrium equations of all elements are assembled into the overall equilibrium equation of the entire computational domain according to the shared nodes; finally, the overall equilibrium equation is solved to obtain the displacement of each mesh node, and then the stress and strain of each element are calculated based on the node displacements to obtain the stress and strain fields of the entire computational domain. By using the macroscopic stress and strain field of each grid cell, the propagation length, propagation direction, and aperture change of each crack in the current step size discrete crack network model are calculated, and the discrete crack network model of the entire computational domain is updated. The initial equivalent macroscopic mechanical parameters of each grid element and the dynamic stiffness matrix of the three coupled subsystems are recalculated using the discrete fracture network model of the entire computational domain. After the final iteration converges, the output is a set of multi-field coupling calculation results for all components of the condenser, which includes two core contents: one is all individual calculation parameters, namely, the stress of the expansion joint in all directions, the allowable external pressure of the shell, the stress of the flange in all directions, the area of ​​the opening reinforcement, the vibration damping margin of the heat exchange tube, the calculated stress of the tube sheet, etc.; the other is the stress field, damage field, composite fatigue life, and stiffness matching degree data of the entire component.

[0025] S3. Perform strength verification on the individual calculation parameters of the full computational domain quantization results, perform secondary verification on the damage field and composite fatigue life data in the full computational domain quantization results, and obtain the corresponding sub-components by locating the critical failure points obtained from the verification.

[0026] Based on the calculation parameters in the full computational domain quantization results, the strength of the throat expansion joint and shell expansion joint, the strength and external pressure stability of the shell body, the strength of the shell and / or water chamber flanges and connecting flanges, the reinforcement of the shell and tube side openings, the vibration of the heat exchange tubes, the strength of the supporting structure, and the strength of the tube sheet are checked. The strength check results are output, and secondary checks are performed using damage field and composite fatigue life data to obtain the location of secondary failure points with insufficient fatigue life. The corresponding sub-components are obtained by locating these points.

[0027] Here, this application further discloses the specific methods and algorithms for obtaining individual computational parameters from the discrete fracture network model of the entire computational domain: Strength calculation of throat expansion joint and shell expansion joint: The throat expansion joint can absorb the three-dimensional relative thermal expansion between the turbine and the condenser; when there is a large temperature difference between the shell and the tube bundle, or when there is a large axial temperature difference in the shell itself, a significant thermal stress will be generated. The shell expansion joint can absorb the thermal expansion difference, greatly reduce the axial load on the shell and the heat exchange tubes, protect the connection between the heat exchange tubes and the tube sheet, and prevent the tube sheet from deforming and leaking.

[0028] The main stress calculation process for the strength calculation of the throat expansion joint and the shell expansion joint is as follows: In the formula, To design pressure, This is the average diameter of the expansion joint. This represents the number of expansion joint layers. For the expansion joint wave height, For expansion joint pitch, To design the temperature modulus of elasticity, For each wave of axial displacement, This is the minimum effective thickness of the expansion joint. The effective wall thickness of the cylinder. This is the diameter of the expansion joint. The internal pressure generates circumferential membrane stress. Radial membrane stress is generated by internal pressure. The internal pressure generates radial bending stress. This refers to the radial membrane stress caused by axial displacement. Radial bending stress caused by axial displacement. , and For combined stress, External pressure is allowed.

[0029] Strength calculation of the shell body: The strength calculation of the shell body is the basis of the design. The shell is subjected to internal pressure, which generates membrane stress. The strength calculation ensures that the overall stress level of the shell is lower than the allowable stress of the material under normal operation and test pressure conditions, so as to prevent excessive deformation or strength failure.

[0030] The main stress calculation process is as follows: In the formula, For shell stress, This is the water pressure test pressure. The equivalent inner diameter of the shell. The effective thickness.

[0031] Shell external pressure stability calculation: When the condenser is in operation or under maintenance, the shell is subjected to external pressure. Thin-walled shells are more prone to instability when subjected to external pressure. The critical pressure is much lower than the strength failure pressure. Calculation of shell external pressure stability is the key to ensuring the shell's resistance to instability.

[0032] The main calculation process is as follows: In the formula, Where B is the allowable external pressure, and B is the external pressure stress coefficient. For effective thickness, The outer diameter of the shell.

[0033] Flange strength calculation: Shell flanges are critical sealing structures connecting the shell to pipe boxes, pipelines, or other components. They must ensure the flange does not fail under the bending moment generated by bolt preload and medium pressure, while also preventing excessive deformation that could lead to gasket seal failure and leakage. Water chamber flanges are used to connect water chamber covers or connect to pipe flanges. They require extremely high sealing performance due to the high pressure and susceptibility to leakage of the medium in the pipe side. This calculation ensures the flange maintains sufficient strength and provides stable clamping force to maintain the gasket seal under bolt preload and operating pressure. Pipe flanges are critical interfaces connecting to external pipe flanges. Their strength directly affects the sealing reliability of the interface. Insufficient flange strength or stiffness can lead to warping or excessive deformation under bolt preload and pipe reaction forces, resulting in gasket leakage.

[0034] The main stress calculation process is as follows: In the formula, For axial stress, Radial stress, For tangential stress, For combined stress, For the overall flange coefficient, For flange design torque, and For parameters, The effective thickness of the large end of the flange neck. The diameter of the flange bolt center circle. The effective thickness of the flange. and is a coefficient.

[0035] Stress analysis and calculation for perforation reinforcement: Perforations in the shell can cause structural discontinuities and local wall thickness reduction, resulting in significant stress concentration at the perforation edges. The peak stress may reach several times the shell membrane stress, making it a high-risk area for fatigue crack initiation.

[0036] The main calculation process for shell opening reinforcement is as follows: In the formula, To supplement the total area, This refers to the excess metal area of ​​the end cap. Take over excess metal area, To control the weld area, This represents the reinforcement area required for the opening. The diameter of the opening. Calculate the thickness of the shell. For the nominal thickness of the takeover, Additional allowance for pipe material thickness. This is the strength reduction coefficient.

[0037] Impact load verification of shell strength: In addition to stable operating conditions, equipment may be subjected to dynamic loads under abnormal or accidental conditions, such as severe shaking, water hammer effect caused by rapid valve opening and closing, and reaction force caused by safety valve tripping. The stress generated by these impact loads is transient and one-time, but the peak value is very high, requiring separate verification. Typically, analytical design methods are used, employing finite element simulation tools to calculate stress and verify strength under impact loads.

[0038] Vibration calculation of heat exchanger tubes: When the steam in the shell side flows laterally across the tube bundle, it may induce flow-induced vibration in the heat exchanger tubes. Continuous vibration can lead to fatigue fracture of the tube wall or the connection between the tube and the tube sheet, as well as problems such as collision and friction between the tube and the baffle orifice or adjacent tubes, and noise. Vibration prediction and prevention are key to ensuring the long-term stable operation of the condenser.

[0039] The main calculation process is as follows: First-order vibration damping margin of steam turbine: Second-order vibration damping margin of steam turbine: In the formula, The turbine's rotational frequency, The first natural frequency of the heat exchanger tube. This is the second-order natural frequency of the heat exchanger tube.

[0040] Support strength calculation: The support structure transfers the weight of the entire equipment and impact loads to the foundation. It is necessary to ensure that the support components themselves are strong enough and that the local stress generated by the support structure on the shell is within a safe range.

[0041] The main stress calculation process is as follows: Stress in stiffeners: In the formula, For stiffening stress, For the actual load borne by the support, Calculate the width of the stiffening slab. For the thickness of the stiffening plate, For the number of stiffening plates, To calculate the tilt angle.

[0042] Base plate stress: In the formula, For the stress of the base plate, The actual bending moment borne by the base plate. This refers to the thickness of the base plate.

[0043] Strength calculation for water chamber connection pipes: The connection pipe is not only a channel for condensate water but also an interface connecting to external pipes. It needs to withstand the membrane stress generated by internal pressure, the thrust, bending moment, and shear force transmitted by external pipes, and the additional load caused by thermal expansion differences. Strength calculations ensure that the connection pipe itself can safely bear the load without affecting the sealing performance of the connection due to excessive deformation.

[0044] The main stress calculation process is as follows: In the formula, The stress on the pipe during the hydrostatic test. This is the water pressure test pressure. For the inner diameter of the connector, To ensure the effective thickness of the grassroots level.

[0045] Strength Calculation of Manholes and Handholes in Water Chambers: Manholes are large openings for personnel to enter equipment for maintenance and inspection. Their large size significantly weakens the shell's strength, making them high-risk areas for stress concentration. Strength calculations include not only opening reinforcement but also the strength and stiffness of pressure-bearing and load-bearing components such as manhole covers, hinges, and locking devices, ensuring their safety and reliability under opening, closing, and pressure conditions. Handholes are used for internal inspections or the insertion of small tools without entering the equipment. Their function is similar to manholes, but their size is smaller. The purpose of strength calculations is also to ensure the strength and sealing of the opening area. Due to their smaller size, their structure is usually more standardized, but the calculation principles are the same.

[0046] The main calculation process is as follows: In the formula, Calculate the thickness for the orifice cover. Calculate the diameter for the orifice cover. This is the flat cover coefficient during operation. To design pressure, The allowable stress of the material, For weld coefficient, The effective thickness of the hole cover, The nominal thickness of the hole cover. For negative deviation of steel plate, This is the corrosion allowance.

[0047] Tube sheet strength calculation: The tube sheet is one of the core components of the condenser and one of the most complex load-bearing structures. It primarily bears the bending moment load caused by the pressure difference between the tube side and the shell side, the loading effect of thousands of heat exchange tubes, the thermal expansion difference between the tube sheet and the heat exchange tubes, and between the tube sheet and the shell, as well as the weakening of strength due to the perforations in the tubes. Tube sheet strength calculation is crucial to preventing strength failure, excessive deformation, heat exchange tube connection failure, and vibration problems.

[0048] The main stress calculation process is as follows: In the formula, Calculate the stress for the tube sheet. The equivalent pressure borne by the tube sheet. For the tube sheet, the coefficients are dimensionless. For the tube sheet radius, For tube sheet thickness, For the dimensionless coefficient of the torque load, For the allowable bending stress of the tube sheet, This represents the allowable stress of the tube sheet.

[0049] Based on the calculation results, the strength verification was completed, and this application further discloses the following: Strength verification of throat expansion joint and shell expansion joint: In the formula, The internal pressure generates circumferential membrane stress. Radial membrane stress is generated by internal pressure. and For combined stress, To design pressure, For the allowable stress of the material, The yield strength of the material at the design temperature. To allow external pressure, This is the planar buckling pressure of the expansion joint.

[0050] Stress check of the shell during compression test: In the formula, For shell stress, The yield strength of the shell material. This represents the weld coefficient.

[0051] External pressure stability strength check of the shell: In the formula, The design external pressure that the shell can withstand. External pressure is allowed.

[0052] Flange strength verification: In the formula, For axial stress, Radial stress, For tangential stress, For combined stress, This represents the allowable stress of the material.

[0053] Stress check for hole reinforcement: In the formula, To supplement the total area, This represents the reinforcement area required for the opening.

[0054] Vibration calculation and verification of heat exchanger tubes: In the formula, For the first-order vibration damping margin of the steam turbine, This represents the second-order vibration damping margin of the steam turbine.

[0055] Support strength verification: Strength check of stiffeners: In the formula, For stiffening stress, For the allowable stress of the stiffening material, This is the reduction factor.

[0056] Base plate strength check: In the formula, For the stress of the base plate, This represents the allowable stress of the base plate material.

[0057] In the formula, For water pressure testing, the pressure is determined based on pipe stress. To determine the yield strength of the material being handled, This represents the weld coefficient.

[0058] Strength verification of water chamber manholes and handholes: In the formula, Calculate the thickness for the orifice cover. The effective thickness of the hole cover.

[0059] Tube sheet strength verification: In the formula, Calculate the stress for the tube sheet. This represents the allowable bending stress of the tube sheet.

Claims

1. A strength analysis system for key components of a condenser, characterized in that, The system includes: The topology matching and mapping module is used to build a three-level decomposition framework based on the key components of the condenser, including primary component groups, secondary sub-components, and tertiary minimum computing units. It completes the hierarchical topology decomposition of the key components of the condenser, performs label assignment and matching for each minimum computing unit, maps each type of load to the corresponding sub-component, and performs topology association matching between the sub-components and constraint boundaries. After completing all matching, it integrates and generates a topology mapping dataset. The coupling strength quantization calculation module is used to discretize the structural domain of each sub-component using a hexahedral structured mesh through a topology mapping dataset. Based on the labels of each sub-component, it constructs a discretized fracture network model, completes the initial damage field construction based on the discretized fracture network model, obtains the high- and low-cycle composite fatigue load spectrum according to the full range of loads corresponding to each sub-component, and maps it to each mesh element in the computational domain. It constructs a fully coupled constraint field based on the connection relationship of the first-level component group, fuses the fully coupled constraint field, and iteratively calculates the discretized fracture network model according to each mesh element mapped to the computational domain, outputting the quantization result of the entire computational domain. The verification and status identification module is used to perform strength verification on individual calculation parameters of the full computational domain quantization results, perform secondary verification on the damage field and composite fatigue life data in the full computational domain quantization results, and obtain the corresponding sub-components by locating the critical failure points obtained from the verification.

2. The condenser key component strength analysis system according to claim 1, characterized in that, The topology matching mapping module is based on the key components of the condenser and is divided into a primary component group, which includes a support type component group, a shell component group, and a tube side component group. The support-type component assembly is disassembled into two sub-components, including a throat expansion joint, a bottom rigid support, a throat fixing structure, a bottom spring support, a throat suspension structure, and a bottom suspension constraint structure. The shell component assembly is disassembled into two sub-components, including the shell body, shell flange, shell expansion joint, shell opening pipe, shell manhole, shell handhole, support structure, and heat exchange tube bundle; The tube-side component assembly is disassembled into two sub-components, including the water chamber shell, water chamber flange, water chamber connector, water chamber connector flange, water chamber manhole, water chamber handhole, tube sheet, and heat exchange tube end connection structure. Each secondary sub-component is broken down into a tertiary minimum calculation unit, and each minimum calculation unit corresponds to an independent strength calculation item. After obtaining the smallest calculation unit, extract the drawing dimension of the corresponding smallest calculation unit in the initial design drawing of the condenser to obtain the dimension parameters, and bind each dimension parameter to the corresponding smallest calculation unit to complete the assignment of structural dimension labels. Extract all material parameters from the material standard corresponding to the smallest calculation unit, bind each material parameter to the corresponding smallest calculation unit, and complete the assignment of material property labels. Then, extract the environmental parameters that each smallest calculation unit in the initial design drawings of the condenser is in contact with, and assign a medium environment label to each smallest calculation unit. Extract the connection methods between the smallest calculation unit in the condenser installation design drawings and adjacent components, steam turbine, and ship foundation, define the constraint types according to the connection methods, and complete the assignment of boundary constraint labels.

3. The condenser key component strength analysis system according to claim 1, characterized in that, The topology matching mapping module divides the loads on key components of the condenser into steady-state pressure loads, thermal loads, dynamic loads, and environmental loads. Each type of load is mapped to the corresponding sub-component, specifically: the throat expansion joint and the shell expansion joint are mapped to thermal load, steady-state pressure load, and dynamic impact load; The shell body is mapped to steady-state internal pressure and / or external pressure loads, thermal loads, impact loads, and external pressure stability loads; Map the tube sheet to the shell-and-tube pressure differential load, thermal expansion differential load, and heat exchange tube loading load; Map all flange components to steady-state pressure loads, bolt preload torque loads, and pipe reaction loads; The supporting structure is mapped to equipment weight load, impact inertial load, and hull sway load; The heat exchanger tube bundle is mapped to flow-induced vibration load, turbine rotation frequency alternating load, and thermal expansion difference load. Then, the sub-components are topologically associated and matched with the constraint boundaries, specifically as follows: The constraint boundaries between the throat expansion joint and the bottom rigid support are set as the displacement boundary between the throat expansion joint and the turbine interface, and the fixed constraint boundary between the bottom rigid support and the hull foundation, and the three-dimensional thermal expansion displacement release boundary is synchronously mapped. The constraint boundaries of the throat fixed structure and the bottom spring support are set as the fixed constraint boundary of the throat and the turbine interface, the elastic constraint boundary of the bottom spring support, and the triaxial displacement release boundary of the spring deformation are synchronously mapped. The constraint boundaries of the throat suspension structure and the bottom suspended structure are set as the suspension constraint boundary of the throat suspension structure and the turbine interface, the free displacement boundary of the bottom without constraint, and the inertial constraint boundary of the impact load is synchronously mapped. The topology matching and mapping module sorts all the smallest computational units bound with attribute labels, load mappings, and constraint boundaries according to a three-level decomposition framework to form a structured dataset framework. It then organizes all the parameters of each smallest computational unit into a one-to-one corresponding parameter group, generating the final topology mapping dataset for the entire condenser component.

4. The condenser key component strength analysis system according to claim 1, characterized in that, The coupling strength quantification calculation module extracts the three-dimensional geometric models of all the smallest computing units from the topology mapping dataset and splices them together into a geometric model of the entire condenser structure computing domain according to the connection relationship of the sub-components. Clean up the computational domain geometry model by removing features including chamfers, fillets, internal threads of bolt holes, and non-pressure bearing markings that are less than 1 mm in diameter. Then, perform topology repair on the cleaned geometry model to fix free edges, overlapping surfaces, gaps, and discontinuous entities in the computational domain geometry model. The basic mesh size and stress concentration region of each minimum computational unit are determined, and the geometric model of the computational domain is divided into structured topological blocks according to the structural characteristics of each minimum computational unit. Each topological block corresponds to a regular hexahedral structure. For each divided topological block, a structured hexahedral mesh is generated according to the determined basic mesh size. The edges of the structured hexahedral mesh are fully aligned with the edges of the topological block. The mesh nodes of adjacent topological blocks are fully shared. In the topological blocks in the stress concentration region, a finer size is set, and a transition processing is performed between the mesh in the finer region and the unfiner region. The structural dimension label, material property label, constraint boundary, and mapping load parameters of each smallest computational unit in the topology mapping dataset are mapped to the corresponding mesh element, thus completing the hexahedral structured mesh discretization of the geometric model of the entire computational domain.

5. The condenser key component strength analysis system according to claim 4, characterized in that, The coupling strength quantification calculation module extracts the material property parameters and medium environment parameters corresponding to each grid cell, sets the initial crack statistical parameters for each grid cell, and uses the Monte Carlo random generation method to randomly generate the center point position of the crack in the three-dimensional space of the grid cell, and then randomly generates the direction and dip angle of the crack to complete the generation of the initial crack in each grid cell, and constructs a discrete crack network model of the entire computational domain. Based on the material parameters of each grid cell in the topological mapping dataset, the total volume of all initial cracks in the corresponding grid cell is statistically analyzed through the discrete crack network model corresponding to each grid cell. Then, the ratio of the total volume of the initial cracks to the total volume of the grid cell is calculated to obtain the initial crack damage variables. After that, the initial equivalent macroscopic mechanical parameters of each grid cell are calculated. The initial crack damage variables and initial equivalent macroscopic mechanical parameters of each grid cell are mapped to the corresponding grid cell to form the initial damage field of the entire computational domain.

6. The condenser key component strength analysis system according to claim 1, characterized in that, The coupling strength quantification calculation module extracts all loads mapped by each grid cell based on the topology mapping dataset and classifies them into low-cycle fatigue loads and high-cycle fatigue loads. The low-cycle fatigue loads are discretized in the time domain to generate a low-cycle load time series that matches the design life of the equipment. The time step corresponds to one start-stop cycle of the equipment. The high-cycle fatigue loads are discretized in the time domain to generate a high-cycle load time series that is completely synchronized with the low-cycle load time series. Each low-cycle time step contains a complete high-cycle load cycle sequence. For each grid cell, the ratio of macroscopic stress generated by low-cycle load to the material yield limit is extracted as the load interaction coefficient. The corresponding low-cycle load amplitude and high-cycle load amplitude are synchronously superimposed at the same time point. After performing synchronous superposition operation on all time points, the high-low cycle composite fatigue load spectrum in the whole time domain is generated. The generated high- and low-cycle composite fatigue load spectrum is mapped onto the corresponding grid cells of the entire computational domain, and the boundary correction of the high- and low-cycle composite fatigue load spectrum is performed according to the constraint boundary in the topology mapping dataset, thus completing the construction of the full computational domain driving load field.

7. The condenser key component strength analysis system according to claim 6, characterized in that, The coupling strength quantification calculation module divides the discrete fracture network model of the entire computational domain into three mutually coupled subsystems according to the connection relationship of the primary component groups, specifically: The support and constraint subsystem includes all support structures, suspension structures, spring supports, and rigid supports. It is responsible for transferring equipment loads to the ship's foundation and serves as the constraint boundary for the entire equipment. The shell subsystem includes the shell body, shell expansion joints, shell flanges, shell openings and nozzles, shell manholes and handholes, and heat exchange tube bundles. It is the pressure-bearing structure for the shell-side medium, coupled to the tube-side subsystem through the tube sheet, and coupled to the support and constraint subsystem through the support structure. The tube-side tube bundle subsystem includes the water chamber shell, water chamber flange, water chamber nozzle, tube sheet, and heat exchange tubes. It is the pressure-bearing structure for the tube-side medium, coupled to the shell subsystem through the tube sheet, and coupled to the turbine through the throat interface. Extract the initial equivalent macroscopic mechanical parameters, structural dimension parameters, and grid node coordinates of all grid elements in each coupled subsystem. Multiply the volume of each grid element by the density of the material to obtain the mass of each element. Then, distribute the mass of each element to the grid nodes of that element to obtain the mass of each node. Arrange the masses of all nodes in the order of the node coordinates to form the mass matrix of each coupled subsystem. Based on the equivalent elastic modulus, Poisson's ratio, and element shape of each mesh element, the element stiffness matrix of each mesh element is calculated, and the damping matrix of each subsystem is also calculated. Based on the mass matrix, stiffness matrix, and damping matrix, the initial dynamic stiffness matrix of each subsystem is constructed. For each coupled connection interface, the dynamic stiffness of all mesh nodes on the interface is extracted, and the equivalent dynamic stiffness of the corresponding interface is calculated.

8. The condenser key component strength analysis system according to claim 7, characterized in that, The coupling strength quantification calculation module uses the ratio of the equivalent dynamic stiffness of the two coupled subsystems as the stiffness matching degree for the connection interface of each group of adjacent coupled subsystems, and divides 1 by the stiffness matching degree as the load amplification factor of the corresponding connection interface. For each connection interface, the calculated load amplification factor is mapped to all mesh elements on the corresponding interface. The constraint boundaries and load amplification factors of each subsystem are mapped onto the grid cells of the entire computational domain to construct a coupled constraint field of the entire computational domain. The coupling strength quantification calculation module sets the calculation step size for damage evolution by observing the discrete crack network model. After the calculation step size is fully aligned with the time step size of the low-cycle fatigue load, the total number of calculation steps is set. For the current calculation step, extract the high and low cycle composite fatigue load amplitude corresponding to the calculation step and the load amplification factor corresponding to the calculation step. Multiply the load amplitude by the load amplification factor to obtain the total load amplitude actually applied at the calculation step. Apply the total load amplitude to the discrete crack network model of the entire computational domain according to the load direction and the mesh element on which it is applied, and apply the constraint conditions of the coupled constraint field at the same time. The linear elastic finite element method is used to calculate the macroscopic stress field and strain field of each grid element in the entire computational domain, thus obtaining the stress field and strain field of the entire computational domain. By using the macroscopic stress and strain field of each grid cell, the propagation length, propagation direction, and aperture change of each crack in the current step size discrete crack network model are calculated, and the discrete crack network model of the entire computational domain is updated. The initial equivalent macroscopic mechanical parameters of each grid element and the dynamic stiffness matrix of the three coupled subsystems are recalculated using the discrete fracture network model of the entire computational domain. After the final iteration converges, the result set of multi-field coupling calculations for all components of the condenser is output.

9. The condenser key component strength analysis system according to claim 1, characterized in that, The verification and status identification module performs strength verification of the throat expansion joint and shell expansion joint, shell main body strength and external pressure stability, shell and / or water chamber flange and pipe flange, shell and tube side opening reinforcement verification, heat exchange tube vibration verification, support structure strength verification, tube sheet strength verification based on the calculation parameters in the full computation domain quantization results, and outputs the strength verification results. It also performs secondary verification based on damage field and composite fatigue life data to obtain the location of secondary failure points with insufficient fatigue life, and obtains the corresponding sub-components through location.

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