A design method for thermo-mechanical coupling equivalent simulation parts at characteristic positions of cylinder head

Abstract

The present invention provides a design method for a thermo-mechanical coupling equivalent simulation part at a characteristic position of a cylinder head, and relates to the technical field of cylinder head simulation part preparation. The method comprises: determining the structural features of the cylinder head to be simulated and obtaining the stress-strain distribution under the thermo-mechanical coupling of the cylinder head to be simulated; simplifying the model of the cylinder head to be simulated using a regional suppression method according to the structural features to obtain a final simplified model; establishing a corresponding initial equivalent simulation part model according to the structural dimension parameters of the structural features and the final simplified model; optimizing the stress-strain mean of the initial equivalent simulation part model using the stress-strain mean of the final simplified model to obtain the optimal key structural parameters of the initial equivalent simulation part model; and designing the final equivalent simulation part model according to the optimal key structural parameters. The present invention solves the problems in the prior art of excessive complexity of the test part model and insufficient consideration of the cooling water channel structure.

Description

Technical Field

[0001] The present invention relates to the technical field of cylinder head simulation part preparation, in particular to a design method for a thermo-mechanical coupling equivalent simulation part at a characteristic position of a cylinder head. Background Art

[0002] The cylinder head is one of the key structural components of an internal combustion engine. It is used to seal the upper part of the cylinder and, together with the piston top and cylinder wall, form the combustion chamber. The cylinder head has an extremely complex structure, with intake and exhaust valves, valve guide holes, etc. machined on it, and internally cast cooling water channels, intake and exhaust pipes, and parts of the combustion chamber. When the internal combustion engine is operating, the cylinder head works in a very harsh environment and is subjected to very complex stress conditions. It not only needs to withstand mechanical loads such as the bolt preload generated during the internal combustion engine assembly process, but also the thermal load generated by gas combustion and the gas explosion pressure load. At the same time, due to the presence of cooling water channels, factors such as the uneven distribution of the coolant flow path can also lead to complex distributions of temperature and stress fields inside the cylinder head.

[0003] During service, cylinder heads face complex multi-physics coupling, including thermal, fluid-solid interaction. However, traditional testing methods have inherent limitations in addressing these challenges, including high costs, lengthy test cycles, complex operational procedures, and limitations in accuracy and precision.

[0004] The prior art closest to the present invention is the "A Cylinder Head Simulator Fatigue Test Method" disclosed in CN104792632A [2015-07-22]. This method uses a pure mechanical fatigue test instead of a thermal-mechanical coupling fatigue test, which reduces the test cycle and ensures the test accuracy to a certain extent. The specific steps are: calculating the three principal stress-strain values ​​of different dangerous positions of the solid cylinder head by finite element simulation method; establishing a test piece model; setting the maximum cyclic load value required to be applied on the unidirectional tension and compression test bench; calculating the three principal stress-strain values ​​of the dangerous positions of the test piece model; comparing the three principal stress-strain values ​​of the dangerous positions of the test piece model with those of the solid cylinder head to determine the final test piece model; processing the final test piece model into shape, and then conducting a fatigue test on the unidirectional tension and compression test bench. The structure of the test piece model is first preliminarily determined based on the external shape characteristics of the cylinder head fire surface. Since the traditional fatigue test bench cannot mount a large and complex solid cylinder head, and the fatigue test bench is difficult to achieve high-precision measurement of the dangerous position - the cylinder head fire surface, this invention designs a test piece that is easy to mount and measure and can reflect the stress-strain characteristics of the dangerous position, that is, the test piece model of the cylinder head.

[0005] However, this test specimen model suffers from a significant flaw: it fails to fully incorporate the geometry of the cooling channels. Cooling channel design is crucial for regulating the cylinder head's temperature distribution, reducing thermal stress concentration, and improving structural integrity. In actual operation, the shape and layout of the cooling channels directly affect the cylinder head's temperature field and thermal stress state, and thus its fatigue life. Therefore, a test specimen model lacking cooling channel structure may not fully simulate the thermomechanical coupling behavior of an actual cylinder head under operating conditions, which could negatively impact the accuracy and reliability of test results.

[0006] Another prior art that is relatively similar to the present invention is the "A method for predicting the thermal-fluid-solid coupling fatigue life of a diesel engine cylinder head considering machining residual stress" disclosed in CN118350318A [2024-07-16]. This patent proposes a method for predicting the thermal-fluid-solid coupling fatigue life of a diesel engine cylinder head considering machining residual stress. It comprehensively considers the influence of machining residual stress on the fatigue life of the cylinder head, and considers the uneven hot and cold structure caused by high-temperature gas and coolant in the cylinder head when calculating the temperature field, as well as the thermal engine fatigue life of the cylinder head under multiple working conditions such as high pressure and high temperature. The specific steps are: constructing the final simplified model of the diesel engine cylinder head; presetting the birth and death unit layer, using the birth and death unit technology to perform multi-process cutting simulation analysis on the diesel engine cylinder head to obtain the cutting residual stress of the cylinder head; using flow field analysis to obtain the cylinder head surface temperature parameters; calculating the temperature field distribution of the cylinder head based on the surface temperature parameters; performing stress field analysis based on the residual stress obtained after the cylinder head cutting and the temperature field of the cylinder head, and applying mechanical loads and thermal stress loads to calculate the mechanical stress and thermal stress of the cylinder head; predicting the thermal fatigue life of the diesel engine cylinder head based on the cylinder head temperature field, cylinder head thermal stress, mechanical stress and material properties to obtain the fatigue life cloud map of the diesel engine cylinder head.

[0007] This patent constructs a final simplified model of the cylinder head. This simplification removes minor features from various components that don't affect the calculation results, and simplifies the cylinder head base into a rectangular block. While this model incorporates various structural features, such as cooling channels, valve holes, and bolt holes, this highly detailed model also increases computational complexity, time, and cost. Summary of the Invention

[0008] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a design method for a thermo-mechanical coupling equivalent simulation part at a characteristic position of a cylinder head. The present invention solves the problems in the prior art of overly complex test piece models and insufficient consideration of cooling water channel structures.

[0009] To achieve the above object, the present invention provides the following solutions:

[0010] A design method for a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head, comprising:

[0011] Determining the structural characteristics of the cylinder head to be simulated and obtaining the stress and strain distribution of the cylinder head to be simulated under thermal-mechanical coupling;

[0012] According to the structural characteristics, a regional suppression method is used to simplify the model of the cylinder head to be simulated to obtain a final simplified model;

[0013] Determining the stress and strain mean value of the final simplified model according to the stress and strain distribution under the thermal-mechanical coupling of the cylinder head to be simulated;

[0014] Establishing a corresponding initial equivalent simulation component model according to the structural dimension parameters of the structural features and the final simplified model;

[0015] Determining the stress and strain distribution of the initial equivalent simulation component model to obtain the stress and strain mean of the initial equivalent simulation component model;

[0016] Optimizing the stress and strain mean values ​​of the initial equivalent simulation model using the stress and strain mean values ​​of the final simplified model to obtain optimal key structural parameters of the initial equivalent simulation model, wherein the key structural parameters include: width parameter, height parameter, and thickness parameter;

[0017] The final equivalent simulation component model is designed based on the optimal key structural parameters.

[0018] Preferably, determining the structural features of the cylinder head to be simulated and obtaining the stress and strain distribution of the cylinder head to be simulated under thermal-mechanical coupling includes:

[0019] determining a nose bridge region as a structural feature of the simulated cylinder head;

[0020] Performing finite element network division on the cylinder head to be simulated, wherein the structural feature area adopts high-density network division;

[0021] Apply corresponding thermal boundary conditions to each area of ​​the cylinder head to be simulated after dividing the network units to obtain the temperature field distribution of the cylinder head;

[0022] The thermal stress field is obtained according to the temperature field distribution

[0023] The maximum alternating working load and assembly load are superimposed to obtain the coupled stress field;

[0024] The stress and strain distribution is determined according to the thermal stress field and the coupled stress field.

[0025] Preferably, the model of the cylinder head to be simulated is simplified by adopting a regional suppression method according to the structural characteristics to obtain a final simplified model, including:

[0026] Simplifying the intake and exhaust valves of the cylinder head model to obtain a first simplified model;

[0027] Simplifying the bolt holes, pin holes, and ribs of the first simplified model to obtain a second simplified model;

[0028] The concave and convex portions of the second simplified model are simplified to obtain a final simplified model.

[0029] Preferably, the cross-section of the equivalent simulation component model is a T-shaped cross-section.

[0030] Preferably, the method for obtaining the optimal key structural parameters is:

[0031] determining a first set of key structural parameters according to the stress function;

[0032] determining a second set of key structural parameters based on the strain function;

[0033] Determine the minimum value of the parameters corresponding to the first key structural parameter set and the second key structural parameter set to obtain the optimal key structural parameters.

[0034] Preferably, the stress function is expressed as:

[0035] ;

[0036] Among them, the is the stress function, x is the design variable, is the mean stress of the initial simulation model, is the mean stress of the final simplified model.

[0037] Preferably, the strain function is expressed as:

[0038] ;

[0039] Among them, the is the strain function, is the mean strain of the initial simulation model, is the mean strain of the final simplified model.

[0040] Preferably, the expression of the design variable is:

[0041] ;

[0042] Wherein, W1 and W2 are respectively the first width parameter and the second width parameter, H1 and H2 are respectively the first height parameter and the second height parameter, and T is the thickness parameter.

[0043] The present invention discloses the following technical effects:

[0044] The present invention provides a design method for a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head, comprising:

[0045] Determine the structural features of the cylinder head to be simulated and obtain the stress and strain distribution of the cylinder head to be simulated under thermal-mechanical coupling; based on the structural features, simplify the model of the cylinder head to be simulated using the regional suppression method to obtain a final simplified model; determine the stress and strain mean of the final simplified model based on the stress and strain distribution of the cylinder head to be simulated under thermal-mechanical coupling; establish a corresponding initial equivalent simulation component model based on the structural dimension parameters of the structural features and the final simplified model; determine the stress and strain distribution of the initial equivalent simulation component model to obtain the stress and strain mean of the initial equivalent simulation component model; use the stress and strain mean of the final simplified model to optimize the stress and strain mean of the initial equivalent simulation component model to obtain the optimal key structural parameters of the initial equivalent simulation component model, wherein the key structural parameters include: width parameter, height parameter and thickness parameter; design the final equivalent simulation component model based on the optimal key structural parameters. Focus on the key structural feature of the cylinder head nose bridge area, and construct a corresponding small test piece around this feature. This design approach enables more accurate and efficient fatigue performance analysis of the cylinder head while maintaining consistency in key structural parameters and shapes. During the thermal-mechanical coupling simulation, an equivalent load application method was employed to simulate the complex thermodynamic and mechanical loads experienced by the cylinder head during actual operation, improving the accuracy of the simulation results. To ensure that the simulated component's structure closely resembles the actual cylinder head, the influence of the cooling channels was specifically considered, and the actual cross-sectional shape of the channels was accurately reproduced. This sophisticated design approach enables a more accurate capture of the temperature distribution and thermal stress state of the cylinder head under actual operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0047] Figure 1 A flow chart of a design method for a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head provided by an embodiment of the present invention;

[0048] Figure 2 A cross-sectional view of the nose bridge area of ​​a cylinder head provided in an embodiment of the present invention;

[0049] Figure 3A schematic diagram of structural parameters of an equivalent simulation component in the nose bridge area of ​​a cylinder head provided by an embodiment of the present invention;

[0050] Figure 4 A schematic diagram of the structure of an equivalent simulation component of the nose bridge area of ​​a cylinder head provided by an embodiment of the present invention;

[0051] Figure 5 Detailed design diagram of the equivalent simulation part of the cylinder head nose bridge area provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] like Figure 1 As shown, the present invention provides a design method for a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head, comprising:

[0055] Step 100: determining the structural characteristics of the cylinder head to be simulated and obtaining the stress and strain distribution of the cylinder head to be simulated under thermal-mechanical coupling;

[0056] Step 200: simplifying the model of the cylinder head to be simulated using a region suppression method according to the structural features to obtain a final simplified model;

[0057] Step 300: determining the stress and strain mean of the final simplified model according to the stress and strain distribution under the thermal-mechanical coupling of the cylinder head to be simulated;

[0058] Step 400: establishing a corresponding initial equivalent simulation component model according to the structural dimension parameters of the structural feature and the final simplified model;

[0059] Step 500: determining the stress and strain distribution of the initial equivalent simulation component model, and obtaining the stress and strain mean of the initial equivalent simulation component model;

[0060] Step 600: Optimizing the stress and strain mean values ​​of the initial equivalent simulation model using the stress and strain mean values ​​of the final simplified model to obtain optimal key structural parameters of the initial equivalent simulation model, wherein the key structural parameters include: width parameter, height parameter, and thickness parameter;

[0061] Step 700: Designing a final equivalent simulation component model according to the optimal key structural parameters.

[0062] Furthermore, the determining of the structural features of the cylinder head to be simulated and obtaining the stress and strain distribution of the cylinder head to be simulated under thermal-mechanical coupling includes:

[0063] determining a nose bridge region as a structural feature of the simulated cylinder head;

[0064] Performing finite element network division on the cylinder head to be simulated, wherein the structural feature area adopts high-density network division;

[0065] Apply corresponding thermal boundary conditions to each area of ​​the cylinder head to be simulated after dividing the network units to obtain the temperature field distribution of the cylinder head;

[0066] The thermal stress field is obtained according to the temperature field distribution

[0067] The maximum alternating working load and assembly load are superimposed to obtain the coupled stress field;

[0068] The stress and strain distribution is determined according to the thermal stress field and the coupled stress field.

[0069] Specifically, the structural characteristics of the cylinder head to be simulated are extracted and the stress and strain distribution under thermal-mechanical coupling is obtained:

[0070] The nose bridge area is a key feature of the internal combustion engine cylinder head. During engine operation, it is subjected to the direct impact of high-temperature combustion gases and the complex flow of coolant. This makes it a primary area of ​​thermal and mechanical stress concentration within the cylinder head, making it prone to fatigue failure. Related research, using fluid-structure interaction analysis of a single-sided cylinder head and water jacket, revealed that the exhaust valve nose bridge area and the intake and exhaust valve nose bridge areas exhibit the highest temperature and thermal stress levels within the cylinder head, confirming the significant influence of this area on cylinder head fatigue failure. Therefore, this paper extracts the nose bridge area from the overall cylinder head structure as a characteristic location.

[0071] For the complex structure of the cylinder head, a detailed finite element meshing of the cylinder head model was first performed using pre-processing software such as Hypermesh. A tetrahedral mesh was selected, with increased mesh density in the characteristic nose bridge area. A relatively sparse mesh was used in other areas to optimize computational resource allocation. Next, using finite element simulation software such as Abaqus, appropriate thermal boundary conditions were applied to different regions of the cylinder head to determine the temperature distribution and further calculate the thermal stress field. Finally, the coupled stress field of the cylinder head was calculated by superimposing assembly loads such as the maximum alternating working load and bolt preload on the thermal stress field while maintaining consistency in the boundary constraints. The calculated results focused on the maximum stress-strain level and the average stress-strain level experienced in the structurally significant regions, which served as the basis for the equivalent simulation component.

[0072] Furthermore, the model of the cylinder head to be simulated is simplified by adopting a regional suppression method according to the structural characteristics to obtain a final simplified model, including:

[0073] Simplifying the intake and exhaust valves of the cylinder head model to obtain a first simplified model;

[0074] Simplifying the bolt holes, pin holes, and ribs of the first simplified model to obtain a second simplified model;

[0075] The concave and convex portions of the second simplified model are simplified to obtain a final simplified model.

[0076] Specifically, the model simplification of the cylinder head to be simulated: This paper primarily studies the stress and strain in the characteristic nose bridge area, so the simplification is primarily focused on the structure away from the nose bridge area and the load application location. A model simplification method using regional suppression is used to simplify each region, suppressing each complex and unnecessary region in the model to generate a simplified version of the original model while retaining the rough shape of the original model. The details are as follows:

[0077] Simplified intake and exhaust valves. Due to their different structures and functions, in actual cylinder head structures, the intake valves are larger in diameter than the exhaust valves to reduce intake difficulty and increase intake volume. This invention simplifies these valves by unifying their diameters.

[0078] Simplification of bolt holes, pin holes, and ribs. Bolt holes, pin holes, and ribs that are located away from the load application location and have little effect on the temperature and stress field distribution are simplified.

[0079] Simplification of concave and convex surfaces. The concave surfaces are simplified by filling them according to the outer contour of the cylinder head, and the convex structures are simplified by flattening them and constructing new model surfaces.

[0080] Further, such as Figure 2-5 As shown, the cross section of the equivalent simulation part model is a T-shaped cross section.

[0081] Specifically, record the structural dimension parameters of the characteristic position, establish the dimension relationship, and design the initial equivalent simulation model: Figure 2 The schematic diagram of the structure of the flow channel in the water cavity of the actual nose bridge area of ​​the intake and exhaust valves is shown. The T-shaped cross-section part is the nose bridge area. Starting from the flow channel, the present invention abstracts a simplified nose bridge area structure with a T-shaped water cavity cross-section. By extracting the structural dimension parameters of the characteristic position and corresponding them with the dimension parameters of the subsequent equivalent simulation parts, a clear dimensional relationship is established. The specific corresponding relationship is as follows: the distance between the intake and exhaust channels is W1, which corresponds to the total width of the equivalent simulation part; the distance between the intake and exhaust valve seats is W2, which corresponds to the width of the lower half of the T-shaped equivalent simulation part; the thickness of the cylinder head is H1, which corresponds to the total height of the equivalent simulation part; the length of the intake and exhaust channels is H2, which corresponds to the height of the upper half of the T-shaped equivalent simulation part; assuming that the distance between the cooling water channel and the intake and exhaust channels, the intake and exhaust valve seats, the top surface of the cylinder head and the bottom surface of the cylinder head is the same, it is uniformly corresponded to the thickness T of the equivalent simulation part; the total length L of the equivalent simulation part is consistent with the diameter of the intake and exhaust valve seats.

[0082] According to the size correspondence, the initial equivalent simulation model is designed and the following three principles are followed:

[0083] Key structural parameters are identical to the shape. Using a simulated component with integrated cooling channels allows for a more accurate structural simulation of the actual cylinder head. The simulated component's T-shaped cross-section is designed to closely mimic the actual cooling channels in the nose area. This simplification is applicable to nearly all direct-injection diesel engine cylinder head nose cooling channels. Key structural parameters are width parameters W1 and W2, height parameters H1 and H2, thickness parameter T, and length parameter L.

[0084] Same material properties. The cylinder head material is an important factor affecting its fatigue performance and should be the same as the real cylinder head.

[0085] Identical boundary conditions. The boundary conditions in the cylinder head nose directly affect the magnitude of static and alternating stresses, and thus their fatigue performance. By ensuring that the boundary conditions of the simulated component are identical to those of the actual cylinder head, the simulated component's stress state and fatigue characteristics are similar to those of the actual cylinder head, thereby improving the reliability and practicality of the simulation results.

[0086] Furthermore, the stress and strain distribution of the equivalent simulation part is obtained by thermal-mechanical coupling simulation: based on the equivalent simulation part model, Abaqus and other software are used to perform thermal-mechanical coupling simulation analysis. The meshing method, operating parameters, material selection, load constraints and boundary conditions are consistent with step two. The stress and strain gradient distribution of the equivalent simulation part is obtained, and the average stress and strain level is selected as the main evaluation indicator.

[0087] Furthermore, the method for obtaining the optimal key structural parameters is:

[0088] determining a first set of key structural parameters according to the stress function;

[0089] determining a second set of key structural parameters based on the strain function;

[0090] Determine the minimum value of the parameters corresponding to the first key structural parameter set and the second key structural parameter set to obtain the optimal key structural parameters.

[0091] Furthermore, the stress function is expressed as:

[0092] ;

[0093] Among them, the is the stress function, x is the design variable, is the mean stress of the initial simulation model, is the mean stress of the final simplified model.

[0094] Furthermore, the strain function is expressed as:

[0095] ;

[0096] Among them, the is the strain function, is the mean strain of the initial simulation model, is the mean strain of the final simplified model.

[0097] Furthermore, the expression of the design variable is:

[0098] ;

[0099] Wherein, W1 and W2 are respectively the first width parameter and the second width parameter, H1 and H2 are respectively the first height parameter and the second height parameter, and T is the thickness parameter.

[0100] Specifically, the structural parameter optimization design of equivalent simulation parts:

[0101] According to the stress and strain mean values ​​of the cylinder head structural characteristics to be simulated, the optimization design method is used to design the equivalent simulation part structure of the cylinder head nose bridge area.

[0102] The key structural parameters of the equivalent simulation parts are used as design variables; the objective function of the optimization design is determined. The average stress and strain σ of the structural characteristics is used as the m , ε m As the optimization target, the average stress and strain σ' of the equivalent simulation part is m 、ε' m and σ m , ε m Equal or similar; for multi-objective optimization problems, a hierarchical sequence method can be used to solve them. The main objective function is the stress function F1(x), and the secondary objective function is the strain function F2(x). Each objective function is solved in turn to obtain the optimal structural parameters.

[0103] Based on the optimal structural parameter combination corresponding to the minimum stress and strain function, the optimal equivalent simulation component is constructed. After the design is completed, test components are precisely manufactured based on the simulation component model. These test components will be used in subsequent thermal-mechanical coupled fatigue tests.

[0104] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0105] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A design method for a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head, characterized in that: include: Determining the structural characteristics of the cylinder head to be simulated and obtaining the stress and strain distribution of the cylinder head to be simulated under thermal-mechanical coupling; According to the structural characteristics, a regional suppression method is used to simplify the model of the cylinder head to be simulated to obtain a final simplified model; Determining the stress and strain mean value of the final simplified model according to the stress and strain distribution of the cylinder head to be simulated under the thermal-mechanical coupling; Establishing a corresponding initial equivalent simulation component model according to the structural dimension parameters of the structural features and the final simplified model; Determining the stress and strain distribution of the initial equivalent simulation component model to obtain the stress and strain mean of the initial equivalent simulation component model; Optimizing the stress and strain mean values ​​of the initial equivalent simulation model using the stress and strain mean values ​​of the final simplified model to obtain optimal key structural parameters of the initial equivalent simulation model, wherein the key structural parameters include: a width parameter, a height parameter, and a thickness parameter; The final equivalent simulation component model is designed based on the optimal key structural parameters.

2. The design method of a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head according to claim 1, characterized in that: The determining of the structural characteristics of the cylinder head to be simulated and obtaining the stress and strain distribution of the cylinder head to be simulated under thermal-mechanical coupling includes: determining a nose bridge region as a structural feature of the simulated cylinder head; Performing finite element network division on the cylinder head to be simulated, wherein the structural feature area is divided into high-density networks; Apply corresponding thermal boundary conditions to each area of ​​the cylinder head to be simulated after dividing the network units to obtain the temperature field distribution of the cylinder head; The thermal stress field is obtained according to the temperature field distribution The maximum alternating working load and assembly load are superimposed to obtain the coupled stress field; The stress and strain distribution is determined according to the thermal stress field and the coupled stress field.

3. The design method of a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head according to claim 1, characterized in that: The model of the cylinder head to be simulated is simplified by adopting a regional suppression method according to the structural characteristics to obtain a final simplified model, including: Simplifying the intake and exhaust valves of the cylinder head model to obtain a first simplified model; Simplifying the bolt holes, pin holes, and ribs of the first simplified model to obtain a second simplified model; The concave and convex portions of the second simplified model are simplified to obtain a final simplified model.

4. The design method of a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head according to claim 1, characterized in that: The cross section of the equivalent simulation part model is a T-shaped cross section.

5. The design method of a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head according to claim 1, characterized in that: The method for obtaining the optimal key structural parameters is: determining a first set of key structural parameters according to the stress function; determining a second set of key structural parameters based on the strain function; Determine the minimum value of the parameters corresponding to the first key structural parameter set and the second key structural parameter set to obtain the optimal key structural parameters.

6. The design method of a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head according to claim 5, characterized in that: The expression of the stress function is: ； Among them, the is the stress function, x is the design variable, is the mean stress of the initial simulation model, is the mean stress of the final simplified model.

7. The design method of a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head according to claim 5, characterized in that: The expression of the strain function is: ； Among them, the is the strain function, is the mean strain of the initial simulation model, is the mean strain of the final simplified model.

8. The design method of a thermo-mechanical coupling equivalent simulation component at a characteristic position of a cylinder head according to claim 6, characterized in that: The expressions of the design variables are: ； Wherein, W1 and W2 are respectively the first width parameter and the second width parameter, H1 and H2 are respectively the first height parameter and the second height parameter, and T is the thickness parameter.

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