Gas turbine pull rod thread service life and anti-loosening optimization method based on reverse technology

Abstract

The invention relates to the field of gas turbines, in particular to a gas turbine pull rod thread service life and anti-loosening optimization method based on a reverse technology, and the thread service life optimization method comprises the following steps: fitting a pull rod pre-tightening stretching amount by adopting normal distribution to obtain a cold-state stretching amount; measuring the main runner gas temperature under normal start-stop and quick start-stop working conditions, and calculating a convective heat transfer coefficient; a transient temperature field is calculated, and then a pull rod pre-tightening force transient change curve is solved; according to the stress and strain of the pull rod thread, respectively calculating the pull rod thread life and the pull rod thread total damage; an unloading groove is milled in the end face, making contact with a wheel disc, of the pull-rod nut, and the optimal solution of the unloading groove of the pull-rod nut is obtained through response face optimization. According to the anti-loosening optimization method, the response surface of the taper angle of the thread teeth of the pull rod thread is optimized on the basis. By solving the optimal solution of the unloading groove, the stress and strain of the tooth root part of the first thread are minimum, and the service life is prolonged; and the taper angle is added on the thread, so that the thread tooth load distribution is more uniform, and the anti-loosening effect is better.

Description

Technical Field

[0001] The present invention relates to the field of gas turbines, and in particular to a method for optimizing the life and anti-loosening of a gas turbine tie rod thread based on a reverse technology. Background Art

[0002] A gas turbine is a high-speed rotating impeller heat engine consisting of three main components: a compressor, a combustion chamber, and a turbine. The compressor draws air from the atmosphere and compresses it step by step through the axial flow compressor. The temperature and pressure increase step by step. The compressed air is then fed into the turbine to mix and burn with the fuel gas, generating high-temperature gas that expands and produces work. The main connection methods for the compressor and turbine rotors include circumferentially distributed tie rods, central tie rods, and welding. Tie rod rotors are widely used due to their light weight, ease of assembly, and cooling. To ensure the integrity of the rotor, the tie rod preload design is critical. It is necessary to provide sufficient preload to ensure the integrity of the turbine rotor while also taking into account the tie rod's own strength, lifespan, and anti-loosening requirements. In particular, the characteristics of the tie rod thread itself lead to uneven load distribution on the thread teeth. The stress at the root of the first thread tooth is concentrated and yields, making the tie rod's own lifespan even more serious.

[0003] Furthermore, due to their rapid start-up and shutdown characteristics, gas turbines are often responsible for peak load regulation in the power grid, and frequent starts and stops are unavoidable. During each start-up and shutdown process, the turbine rotor shortens due to centrifugal force due to the Poisson effect, reducing the tie rod contraction preload. Thermal resistance exists at the contact surface between the tie rod and the disc, causing the disc contact temperature to be slightly higher than the tie rod. If the disc thermal expansion coefficient is greater than that of the tie rod, the tie rod will be stretched, increasing its preload. The tie rod preload changes during the start-up and shutdown process, and the tie rod stress alternates. The tie rod thread life is reduced with each start-up and shutdown, so optimizing the tie rod thread structure to reduce stress and plastic strain and increase the tie rod thread life is essential.

[0004] During normal operation of the turbine, the tie rods are subjected to the wheel's gravity bending moment, airflow torque, and lateral vibration. Excessive loads can cause the tie rod nuts to loosen, reducing the tie rod preload and threatening the wheel's integrity. The primary methods for preventing tie rod nut loosening are to use flat washers, spring washers, or non-removable locking elements. However, data indicates that flat washers or spring washers do not provide significant locking effect, while non-removable locking elements offer significant reliability but come with the significant disadvantage of being non-reusable threaded fasteners. Therefore, locking the tie rod nuts is a crucial aspect of tie rod design.

[0005] Domestic gas turbine maintenance companies lack drawings, information and design guidelines for maintenance units. When there is a need for disassembly, maintenance and replacement, specifically for tie rod maintenance and thread optimization, it is first necessary to measure the elongation of the circumferentially distributed tie rods. Due to the long service time and the dispersion of installation, the elongation measurement data will have a certain dispersion, and a reverse data processing method is needed; secondly, there is a lack of original design guidelines, and active optimization of the tie rod thread structure requires reasonable methods and evaluation criteria; finally, in order to prevent the tie rod nut from loosening, the thread structure of the tie rod or tie rod nut is generally adjusted. The existing method of measuring anti-loosening threads has low accuracy, especially the thread taper angle. The measurement dispersion is large and has no reference value, and a forward design method is needed to solve it.

[0006] Based on the above problems and needs, the present invention proposes a method for optimizing the life and anti-loosening of gas turbine tie rod threads based on reverse technology. Summary of the Invention

[0007] In order to overcome the problems existing in the prior art, the present invention aims to provide a method for optimizing the life and anti-loosening of a gas turbine tie rod thread based on reverse technology.

[0008] To achieve the above object, the present invention provides the following technical solution: a method for optimizing the life of a gas turbine tie rod thread based on inverse technology, comprising the following steps:

[0009] S1: Use normal distribution to fit the pre-tension of the tie rod, and obtain the average value of the pre-tension of the tie rod as the cold stretch;

[0010] S2: Actual measurement of the gas temperature in the main flow channel of the gas turbine compressor under normal start-stop conditions and rapid start-stop conditions, and calculation of the convective heat transfer coefficient under normal start-stop conditions and rapid start-stop conditions;

[0011] S3: Build a three-dimensional model of the compressor wheel, tie rod, and tie rod nut. After importing it into finite element simulation software, apply the main flow channel gas temperature and convective heat transfer coefficient under normal start-stop conditions and rapid start-stop conditions, calculate the transient temperature field of the compressor wheel and tie rod under the two start-stop conditions, and then solve the transient change curve of the tie rod preload under the two start-stop conditions;

[0012] S4: Based on the stress and strain of the tie rod thread, the tie rod thread life under the two start-stop conditions is calculated according to the mean stress correction formula, and the total damage of the tie rod thread is calculated;

[0013] S5: Mill a relief groove on the end face where the tie rod nut contacts the wheel disc. Response surface optimization is used to obtain the optimal solution for the relief groove in the tie rod nut, thereby improving the life of the tie rod thread. The optimized tie rod thread life and total damage are compared with those before optimization in step S4 to verify the optimization effect.

[0014] The present invention is further configured as follows: Step S1 specifically includes recording the length of the gas turbine tie rod in the installed state as L 0i , the length of the tie rod in the disassembled state is recorded as L 1i ; Solve the preload stretch △L of each tie rod in the installed state i ,

[0015] △L i =L 0i -L 1i

[0016] Wherein i=1, 2, ... z; z is the total number of tie rods; the tie rod pre-tightening stretch is fitted using normal distribution, and the average value of the tie rod pre-tightening stretch is obtained as the cold stretch.

[0017] The present invention is further configured as follows: in step S2, the convection heat transfer coefficient is reversely calculated based on the empirical criterion relationship:

[0018] Nu=0.023Re 0.8 Pr 0.4 ;

[0019]

[0020] Where Nu is the Nusselt number, Re is the Reynolds number, Pr is the Prandtl number, h is the convective heat transfer coefficient, K is the thermal conductivity, and L is the characteristic length of the fluid flow.

[0021] The present invention is further configured as follows: after importing the three-dimensional model into finite element simulation software, transient convection heat transfer coefficients and temperatures under normal operating conditions and rapid start-stop operating conditions are applied to the main channel of the compressor wheel, and transient temperature fields of the compressor wheel and tie rod under the two operating conditions are calculated;

[0022] The same finite element model is then used, and the cold stretching amount is input into the finite element model as the load borne by the tie rod. The boundary conditions are respectively applied with the transient temperature field and rotation speed of the compressor wheel and the tie rod, radial and circumferential constraints are applied to the inner annular surface of the wheel, and axial constraints are applied to the upstream end face of the wheel. Static analysis of the compressor wheel and tie rod under normal operating conditions and rapid start-stop conditions is performed. After the calculation is completed, the transient preload of the tie rod under the two operating conditions is extracted respectively, and the transient change curve of the tie rod preload is drawn.

[0023] The present invention is further configured as follows: Step S4 specifically creates a simplified two-dimensional axisymmetric model of the tie rod and tie rod nut based on the three-dimensional model created in Step S3, applies the transient change curves of the tie rod preload under the two start-stop operating conditions in Step S3, performs elastic-plastic analysis of the tie rod and tie rod nut, and obtains the stress and strain of the tie rod thread under the two start-stop operating conditions;

[0024] The Manson-Coffin formula with mean stress correction is used to calculate the tie rod thread life under two start-stop conditions:

[0025]

[0026] Where ε a is the strain amplitude, σ f ′ is the fatigue strength coefficient, σ m is the mean stress, ε f ′ is the fatigue ductility coefficient, 2N is the life, b is the fatigue strength index, and c is the fatigue ductility index;

[0027] The linear damage fatigue accumulation equation is then used to calculate the total damage of the tie rod thread:

[0028]

[0029] Among them, j represents the start-stop condition, n j Indicates the number of starts and stops under the j start-stop condition, N j Indicates the life of the tie rod thread under start-stop conditions.

[0030] The present invention is further configured as follows: Step S5 specifically uses the unloading groove width a, depth h and fillet radius r as optimization variables, minimizes the total strain et at the root of the tie rod thread and minimizes the unloading groove stress σ as optimization objectives, and adopts response surface optimization to obtain the optimal solution of the unloading groove of the tie rod nut.

[0031] The present invention also provides a method for optimizing the anti-loosening of a gas turbine tie rod thread based on a reverse technology, which comprises the following steps after the steps of the above-mentioned method for optimizing the life of a gas turbine tie rod thread based on a reverse technology:

[0032] S6: Since a more uniform load distribution on the tie rod nut threads leads to a smaller thread load deviation, the tie rod nut's anti-loosening effect is better. The unloading groove structure makes the thread load distribution more uniform. Based on this, a response surface optimization of the thread taper angle was performed, with the thread taper angle as the optimization variable and the minimum thread load variance as the optimization objective. The tie rod nut taper was obtained after optimization.

[0033] In summary, the beneficial effects of the above technical solution of the present invention are as follows:

[0034] The present invention reversely solves the stress and strain of the tie rod thread through the pre-tightening elongation of the tie rod, performs linear cumulative damage calculation, and opens a unloading groove in the tie rod nut to reduce the stiffness of the tie rod nut, so that the load of the first thread tooth is reduced, resulting in reduced stress and strain at the root of the first thread tooth. Then, response surface optimization is used to obtain the optimal solution of the unloading groove to minimize the stress and strain at the root of the first thread tooth; based on the tie rod nut structure with a unloading groove, the thread increases the taper angle, so that the load distribution of the thread teeth is more uniform and the anti-loosening effect is better. Then, response surface optimization is used to obtain the optimal solution of the taper angle to ensure that the thread has the best anti-loosening effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing 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 creative work.

[0036] Figure 1 This is a schematic diagram of the normal distribution fitting of the tension rod preload;

[0037] Figure 2 It is a schematic diagram of the start-stop working condition;

[0038] Figure 3 3D model of compressor wheel and tie rod;

[0039] Figure 4 The transient temperature field of the tie rod under normal start-stop conditions and rapid start-stop conditions;

[0040] Figure 5 It is the transient change curve of the tie rod preload under normal start-stop conditions and rapid start-stop conditions;

[0041] Figure 6 It is the schematic diagram of the unloading tank;

[0042] Figure 7 Optimize the total strain at the root of the first thread of the front tie rod for the relief groove;

[0043] Figure 8 The total strain at the root of the first thread of the tie rod after optimizing the unloading groove;

[0044] Figure 9 is the load deviation of the tie rod nut thread;

[0045] Figure 10 Schematic diagram of the optimized tie rod nut in the embodiment. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings of the present invention. Based on the embodiments of the present invention, other similar embodiments obtained by ordinary technicians in this field without making any creative work should fall within the scope of protection of the present invention.

[0047] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0048] Example 1:

[0049] like Figure 1-8 As shown in FIG. 1 , which is a preferred embodiment of the present invention, a method for optimizing the life of a gas turbine tie rod thread based on inverse technology includes the following steps:

[0050] S1: Use normal distribution to fit the pre-tension of the tie rod, and obtain the average value of the pre-tension of the tie rod as the cold stretch;

[0051] The length of the gas turbine tie rod in the installed state is recorded as L 0i , the length of the tie rod in the disassembled state is recorded as L 1i ; Solve the preload stretch △L of each tie rod in the installed state i ,

[0052] △L i =L 0i -L 1i

[0053] Where i = 1, 2, ... z; z is the total number of tie rods; the normal distribution is used to fit the tie rod preload, such as Figure 1 As shown, the average value of the pre-tightening stretch of the tie rod is obtained as the cold stretch.

[0054] S2: Actual measurement of the gas temperature in the main flow channel of the gas turbine compressor under normal start-stop conditions and rapid start-stop conditions, and calculation of the convective heat transfer coefficient under normal start-stop conditions and rapid start-stop conditions;

[0055] It should be noted that different gas turbine units require different start-up and shutdown times. The time required for the normal start-up and shutdown conditions and the rapid start-up and shutdown conditions described in the present invention is determined according to the specifications of the gas turbine unit in actual application. Generally speaking, the larger the specifications, the longer the required start-up and shutdown time.

[0056] In this embodiment, the normal start-stop condition is to complete the gas turbine startup, reach the rated load and shut down within 20,000 seconds; the rapid start-stop condition is to complete the gas turbine startup, reach the rated load and shut down within 2,500 seconds. Figure 2 As shown, Figure 2 Figure a shows the normal start-stop condition. Figure 2 Figure b shows the fast start-stop condition.

[0057] The convective heat transfer coefficient is calculated in reverse based on the empirical formula:

[0058] Nu=0.023Re 0.8 Pr 0.4 ;

[0059]

[0060] Where Nu is the Nusselt number, Re is the Reynolds number, Pr is the Prandtl number, h is the convective heat transfer coefficient, K is the thermal conductivity, and L is the characteristic length of the fluid flow.

[0061] S3: Create a three-dimensional model of the compressor wheel, tie rod and tie rod nut, such as Figure 3 After the 3D model is imported into the finite element simulation software, the model is meshed and assigned material data. The transient convection heat transfer coefficient and temperature of the compressor wheel main channel under normal working conditions and rapid start-stop working conditions are applied respectively. The transient temperature field of the compressor wheel and tie rod under the two working conditions is calculated, as shown in the figure below. Figure 4 shown.

[0062] Using the same finite element model, the cold stretch amount is input into the finite element model as the load borne by the tie rod. The boundary conditions are respectively applied with the transient temperature field and speed of the compressor wheel and the tie rod, the radial and circumferential constraints are applied to the inner ring surface of the wheel, and the axial constraint is applied to the upstream end surface of the wheel. The static analysis of the compressor wheel and the tie rod under the two working conditions is performed. After the calculation is completed, the transient preload of the tie rod under the two working conditions is extracted and plotted into the transient preload curve of the tie rod, as shown in FIG. Figure 5 shown.

[0063] S4: Based on the stress and strain of the tie rod thread, the tie rod thread life under the two start-stop conditions is calculated according to the mean stress correction formula, and the total damage of the tie rod thread is calculated;

[0064] Based on the three-dimensional model created in step S3, a simplified two-dimensional axisymmetric model of the tie rod and tie rod nut is created, and the transient change curves of the tie rod preload under the two start-stop operating conditions in step S3 are applied respectively; an elastic-plastic analysis of the tie rod and tie rod nut is performed to obtain the stress and strain of the tie rod thread under the two start-stop operating conditions;

[0065] The Manson-Coffin formula with mean stress correction is used to calculate the tie rod thread life under two start-stop conditions:

[0066]

[0067] Where ε a is the strain amplitude, σ f ′ is the fatigue strength coefficient, σ m is the mean stress, εf ′ is the fatigue ductility coefficient, 2N is the life, b is the fatigue strength index, and c is the fatigue ductility index;

[0068] The linear damage fatigue accumulation equation is then used to calculate the total damage of the tie rod thread:

[0069]

[0070] Among them, j represents the start-stop condition, including normal start-stop and fast start-stop, n j Indicates the number of starts and stops under the j start-stop condition, N j Indicates the life of the tie rod thread under start-stop conditions.

[0071] S5: Mill a relief groove on the end face where the tie rod nut contacts the wheel disc, such as Figure 6 As shown in the figure, the response surface optimization is used to obtain the optimal solution of the tie rod nut unloading groove, thereby improving the life of the tie rod thread.

[0072] The response surface optimization method uses the Response Surface Optimization project in the general-purpose software ANSYS Workbench. The input parameters are the relief groove width a, depth h, and fillet radius r. The range of variation for each parameter is set. The output parameters are the total strain et at the root of the tie rod thread and the stress σ at the relief groove. A central composite design is selected as the experimental design type, and sample point calculations are performed. After the calculations are completed, the optimization goal is to minimize the total strain et at the root of the thread thread and the stress σ at the relief groove. The optimal solution for the relief groove is obtained through optimization.

[0073] Taking a gas turbine power plant as an example, during an overhaul cycle, normal start and stop times n1 = 1200, rapid start and stop times n2 = 50, the life of the tie rod thread under normal start and stop times n1 = 7400, and the life of the tie rod thread under rapid start and stop times n2 = 145. The total damage to the tie rod thread is:

[0074]

[0075] After optimization, the life of the tie rod thread under normal start and stop is 10 6 The life of the tie rod thread is 420 times under rapid start and stop. Substituting it into the total damage formula of the tie rod thread, D = 0.12, which is significantly less than the total damage of the original tie rod thread. The life of the tie rod thread is greatly improved.

[0076] The total strain at the root of the first thread tooth of the tie rod thread before optimization is as follows: Figure 7 As shown in the figure, the total strain at the root of the first thread tooth of the optimized tie rod thread is as follows: Figure 8 As shown in the figure, it can be clearly seen that the total strain distribution at the root of the first thread tooth of the optimized tie rod thread is more uniform.

[0077] Example 2:

[0078] The present invention also provides a method for optimizing the anti-loosening of a gas turbine tie rod thread based on a reverse technology, which comprises the following steps after the steps of the above-mentioned method for optimizing the life of a gas turbine tie rod thread based on a reverse technology:

[0079] S6: As the load distribution on the tie rod nut threads is more uniform and the thread load deviation is smaller, the anti-loosening effect of the tie rod nut is better. Figure 9 As shown, the unloading groove structure makes the thread load more uniform. Based on this, a response surface optimization of the thread taper angle was performed using the Response Surface Optimization project in the large-scale general-purpose software ANSYS Workbench. The input parameters were thread taper angle, the range of thread taper variation was set, and the output parameter was thread load variance. Central composite design was selected as the experimental design type, and sample point calculations were performed. After the calculations were completed, minimizing the thread load variance was set as the optimization goal, and the optimal solution for the thread taper angle was obtained.

[0080] In summary, the present invention reversely solves the stress and strain of the tie rod thread through the tie rod pre-tightening elongation, performs linear cumulative damage calculation, and opens a unloading groove in the tie rod nut to reduce the stiffness of the tie rod nut, so that the load of the first thread tooth is reduced, resulting in reduced stress and strain at the root of the first thread tooth. Then, the response surface optimization is used to obtain the optimal solution of the unloading groove to minimize the stress and strain at the root of the first thread tooth. Based on the tie rod nut structure with the unloading groove, the thread increases the taper angle, so that the thread tooth load distribution is more uniform and the anti-loosening effect is better. Then, the response surface optimization is used to obtain the optimal solution of the taper angle to ensure that the thread has the best anti-loosening effect. The final optimization results of the embodiment are as follows. Figure 10 As shown, the structural features are the unloading groove and the taper angle, wherein the unloading groove width a is 3.45mm, the depth h is 5.93mm, the fillet radius r is 1.35mm, and the taper angle is 0.2°

[0081] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for optimizing the life of a gas turbine tie rod thread based on reverse technology, characterized in that: The following steps are involved: S1: Use normal distribution to fit the pre-tension of the tie rod, and obtain the average value of the pre-tension of the tie rod as the cold stretch; S2: actually measure the gas temperature of the main flow channel of the gas turbine compressor under normal start-stop conditions and rapid start-stop conditions, and calculate the convective heat transfer coefficient under normal start-stop conditions and rapid start-stop conditions; S3: Establish a three-dimensional model of the compressor wheel, tie rod and tie rod nut, import it into the finite element simulation software, apply the mainstream gas temperature and convection heat transfer coefficient under normal start-stop conditions and rapid start-stop conditions, calculate the transient temperature field of the compressor wheel and tie rod under the two start-stop conditions, and then solve the transient change curve of the tie rod preload under the two start-stop conditions; S4: Based on the stress and strain of the tie rod thread, the tie rod thread life under two start-stop conditions is calculated according to the average stress correction formula, and the total damage of the tie rod thread is calculated; S5: A relief groove is milled on the end face where the tie rod nut contacts the wheel disc, and the optimal solution of the tie rod nut relief groove is obtained by response surface optimization. The optimized tie rod thread life and total damage are compared with those before optimization in step S4 to verify the optimization effect.

2. The method for optimizing the life of a gas turbine tie rod thread according to claim 1, characterized in that: Step S1 specifically includes recording the length of the gas turbine tie rod in the installed state as L 0i , the length of the tie rod in the disassembled state is recorded as L 1i ; Solve the preload stretch △L of each tie rod in the installed state i , △L i =L 0i -L 1i Wherein i=1, 2, ... z; z is the total number of tie rods; the pre-tensioning amount of the tie rods is fitted by normal distribution, and the average value of the pre-tensioning amount of the tie rods is obtained as the cold-state stretching amount.

3. The method for optimizing the life of a gas turbine tie rod thread according to claim 1, characterized in that: In step S2, the convective heat transfer coefficient is calculated inversely based on the empirical criterion relationship: Now=0.023Re 0.8 Per 0.4 ; Where Nu is the Nusselt number, Re is the Reynolds number, Pr is the Prandtl number, h is the convective heat transfer coefficient, K is the thermal conductivity, and L is the characteristic length of the fluid flow.

4. The method for optimizing the life of a gas turbine tie rod thread according to claim 1, characterized in that: After importing the 3D model into the finite element simulation software, the transient convection heat transfer coefficient and temperature of the compressor wheel main channel under normal working conditions and rapid start-stop working conditions are applied respectively, and the transient temperature fields of the compressor wheel and tie rod under the two working conditions are calculated. The same finite element model is then used, and the cold stretching amount is input into the finite element model as the load borne by the tie rod. The boundary conditions are respectively applied with the transient temperature field and rotation speed of the compressor impeller and the tie rod, radial and circumferential constraints are imposed on the inner annular surface of the impeller, and axial constraints are imposed on the upstream end surface of the impeller. Static analysis of the compressor impeller and tie rod under normal operating conditions and rapid start-stop conditions is performed. After the calculation is completed, the transient preload of the tie rod under the two conditions is extracted respectively, and the transient change curve of the tie rod preload is plotted.

5. The method for optimizing the life of a gas turbine tie rod thread according to claim 4, characterized in that: Step S4 specifically creates a simplified two-dimensional axisymmetric model of the tie rod and tie rod nut based on the three-dimensional model created in step S3, and applies the transient change curves of the tie rod preload force under the two start-stop conditions in step S3 respectively; performs elastic-plastic analysis on the tie rod and tie rod nut to obtain the stress and strain of the tie rod thread under the two start-stop conditions; The Manson-Coffin formula with mean stress correction is used to calculate the tie rod thread life 2N under two start-stop conditions: Where ε a is the strain amplitude, σ f ′ is the fatigue strength coefficient, σ m is the mean stress, ε f ′ is the fatigue ductility coefficient, 2N is the life, b is the fatigue strength index, c is the fatigue ductility index, and E is the elastic modulus; The linear damage fatigue accumulation equation is then used to calculate the total damage of the tie rod thread: Among them, j represents the start-stop condition, n j represents the number of starts and stops under the j start-stop condition, N j Indicates the life of the tie rod thread under start-stop conditions.

6. The method for optimizing the life of a gas turbine tie rod thread according to claim 1, characterized in that: Specifically, step S5 uses the relief groove width a, depth h and fillet radius r as optimization variables, minimizes the total strain et at the root of the tie rod thread and minimizes the relief groove stress σ as optimization objectives, and adopts response surface optimization to obtain the optimal solution of the relief groove of the tie rod nut.

7. A gas turbine tie rod thread anti-loosening optimization method based on reverse technology, characterized in that: After the steps of the method for optimizing the life of a gas turbine tie rod thread based on inverse technology as described in any one of claims 1 to 6, The following steps are involved: S6: The taper angle of the thread teeth of the tie rod thread is optimized by response surface method. The thread taper angle is taken as the optimization variable and the minimum variance of the thread tooth load is taken as the optimization target. After optimization, the taper of the tie rod nut is obtained.

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