A multi-mode failure assessment method for a turboshaft engine combustion turbine bladed disk assembly

Abstract

The present application belongs to the technical field of aerospace engine, and particularly relates to a multi-mode failure evaluation method for a turbine disc assembly of a turboshaft engine gas generator, comprising: obtaining initial assembly parameters; obtaining working conditions; obtaining a mechanical model of the turbine disc assembly; determining the contact interface damage of a plurality of components; determining the influence of the contact interface damage on the initial assembly parameters; determining the influence of the contact interface damage on the sealing function; determining whether at least one of the contact interface damage reaches the damage tolerance, if none of the contact interface damage reaches the damage tolerance, the mechanical model is corrected; if at least one of the contact interface damage reaches the damage tolerance, the turbine disc assembly fails, and the failure life of the turbine disc assembly is obtained. The present application solves the problem that the single-component or single-interface damage life evaluation method for the failure evaluation of the turbine disc assembly of the turboshaft engine gas generator is not accurate enough, and improves the accuracy of the life evaluation of the turbine disc assembly.

Description

Technical Field

[0001] This invention belongs to the field of aerospace engine technology, specifically relating to a multi-mode failure assessment method for turbine disk assemblies in turboshaft engines. Background Technology

[0002] Driven by the need for high structural efficiency, modern advanced aero-engine turbine disk assemblies often employ a boltless baffle design. This means that multiple components, including the turbine disk, blades, and integrated sealing disk-baffle, utilize their own elastic pre-deformation to mutually compress and constrain each other, forming a structural system with relatively independent functions. During operation, multiple contact interfaces between these tandemly compressed components experience multi-mode damage, including interface slippage, wear, and fatigue. This affects the assembly parameters and sealing function, thus influencing the damage rates of multiple interfaces and exhibiting a multi-interface, multi-mode failure interaction. Currently, failure analysis of turbine disk assemblies primarily focuses on single components or single interfaces. Stress / strain distributions of components or interfaces are obtained through experiments or finite element analysis. Then, appropriate damage-failure empirical formulas are used to calculate the lifespan of components or contact interfaces under complex loads.

[0003] The Archard formula is the most widely used method for quantitative characterization of wear at metal interfaces. Essentially, the Archard formula establishes a quantitative relationship between wear volume and frictional work by introducing a wear proportionality coefficient related to material properties and the coefficient of friction. The frictional work is related to two parameters: the frictional force between the contact surfaces and the relative displacement. In wear damage analysis of the contact interface, the interfacial frictional work is obtained through simulation analysis, the wear proportionality coefficient is determined based on experiments or experience, the wear volume is calculated, and then the wear depth is finally determined by the wear area. The degree of wear can be described by the ratio of the wear depth to the allowable wear depth; when the ratio reaches 1, wear failure is considered to have occurred.

[0004] For contact fatigue damage analysis, stress / strain fatigue life models are commonly used. Among them, the Smith-Watson-Topper fatigue damage model (SWT model) is the most widely used. The SWT model quantitatively provides the relationship between contact fatigue life and contact stress, strain, and material properties. Furthermore, by introducing the concept of a critical plane, the SWT model can be used for multiaxial fatigue life analysis. When performing contact fatigue damage analysis on a contact interface, the contact stress, strain, and related material parameters are obtained through simulation or experimentation, and the fatigue life of the contact interface can be calculated. The degree of contact fatigue damage can be described by the ratio of the number of load cycles to the fatigue life; when the ratio reaches 1, fatigue failure is considered to have occurred. In addition, for the cumulative calculation of fatigue damage across different load cycles, the most common method is the Miner criterion, i.e., the linear superposition criterion.

[0005] However, the aforementioned interface damage analysis methods cannot consider the multi-interface, multi-mode failure interaction during the operation of the turbine disk assembly of the turboshaft engine gas generator. Therefore, when applied to the failure analysis of the turbine disk assembly, they cannot reflect the actual damage situation, reduce the accuracy of mechanical part life assessment, and seriously restrict the development of high-precision equipment.

[0006] Therefore, how to provide a multi-mode failure assessment method for the combustion turbine disk assembly of a turboshaft engine is an urgent problem to be solved in this field. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a multi-mode failure assessment method for turbine disk assemblies in turboshaft engines.

[0008] This invention is implemented as follows: a multi-mode failure assessment method for a turboshaft engine combustion turbine bladed disk assembly, comprising the following steps: Step 1: Obtain the initial assembly parameters of the turbine disk assembly, including the initial assembly preload, the initial interference fit of the cylindrical mating surface, and the mating parameters of the tenon connection interface. Step 2: Obtain the operating conditions of the turbine bladed disk assembly; Step 3: Obtain the mechanical model of the turbine bladed disk assembly under operating conditions; Step 4: Determine the contact interface damage of multiple components in the turbine disk assembly during the entire working cycle after the complete machine assembly, including the wear of the contact end face of the multi-stage series clamping components, the wear of the cylindrical mating surface of the multi-stage series clamping components, and the contact fatigue damage of the tenon connection interface. Step 5: Determine the effect of wear on the contact end face of the multi-stage series clamping components on the initial assembly preload and the effect of wear on the cylindrical mating surface of the multi-stage series clamping components on the initial cylindrical mating surface interference. Step 6: Determine the impact of damage to the contact interface of multiple components on the sealing function. If it causes the sealing function to fail, obtain the temperature distribution; if it does not cause the sealing function to fail, keep the temperature distribution unchanged. Step 7: Determine whether at least one of the contact interface damages of multiple components has reached the damage tolerance. If none of them have reached the damage tolerance, then use the results in Step 5 and Step 6 to correct the mechanical model in Step 3, and repeat Step 4-7. If at least one has reached the damage tolerance, then the turbine bladed disk assembly fails, the failure life of the turbine bladed disk assembly is obtained, and the cycle is terminated.

[0009] Preferably, step 3 includes the following steps: Step 3.1: Obtain the finite element model of the turbine disk assembly with interface contact units based on the initial assembly parameters in Step 1; Step 3.2: Based on the operating conditions in Step 2 and the finite element model of the turbine bladed disk assembly, calculate the normal load stress-strain state and tangential load stress-strain state of the turbine bladed disk assembly under the operating conditions, respectively. Step 3.3: Linearly superimpose the stress-strain state of the normal load and the stress-strain state of the tangential load to establish a stress-strain state model under the combined action of the normal load stress and the tangential load stress, which is the mechanical model of the turbine disk assembly under the working conditions.

[0010] Preferably, step 4 includes the following steps: Step 4.1: Determine the contact parameters and wear coefficient of the contact end faces and cylindrical mating surfaces of the multi-stage tandem clamping components; Step 4.2: Based on the contact parameters, wear coefficient, and working time, obtain the wear of the contact end face of the multi-stage series clamping component and the wear of the cylindrical mating surface of the multi-stage series clamping component; Step 4.3: Select a fatigue damage model based on the mechanical model of the turbine bladed disk assembly in Step 3, and determine the fatigue life. Step 4.4: Determine the proportion of contact fatigue damage based on the fatigue life and working time; Step 4.5: Obtain the fatigue failure crack length as the fatigue damage tolerance; Step 4.6: Obtain the contact fatigue damage at the tenon joint interface based on the fatigue damage tolerance and the contact fatigue damage ratio.

[0011] More preferably, step 4.3 includes the following steps: Step 4.3.1: Using the mechanical model of the turbine disk assembly in Step 3, obtain the stress and strain values ​​at any contact point of the tenon connection interface in the turbine disk assembly, and determine the candidate point most prone to failure. Step 4.3.2: Determine the critical plane of the most likely failure candidate point by using the stress-strain values ​​of the most likely failure candidate point; Step 4.3.3: Obtain the fatigue life by using the stress-strain values ​​of the critical plane of the most likely failure candidate point and the material constant of the tenon joint interface.

[0012] More preferably, step 5 includes the following steps: Step 5.1: Obtain the axial stiffness of the multi-stage cascaded clamping components; Step 5.2: Based on the wear of the contact end faces of the multi-stage series clamping components and the axial stiffness of the multi-stage series clamping components determined in Step 4.2, obtain the reduction in assembly preload. Step 5.3: Based on the initial assembly preload in Step 1 and the reduction in assembly preload, obtain the remaining assembly preload, which is defined as the equivalent assembly preload. Step 5.4: Based on the initial cylindrical mating surface interference in Step 1 and the wear of the cylindrical mating surface of the multi-stage series clamping components determined in Step 4.2, obtain the remaining cylindrical mating surface interference, which is defined as the equivalent cylindrical mating surface interference.

[0013] More preferably, step 5.1 includes the following steps: Step 5.1.1: Obtain the axial compression of the multi-stage series clamping components under the initial assembly preload using the mechanical model of the turbine disk assembly in Step 3; Step 5.1.2: Obtain the axial stiffness of the multi-stage series clamping components based on the initial assembly preload and axial compression.

[0014] More preferably, step 6 includes the following steps: Step 6.1: Based on the mechanical model of the turbine disk assembly in Step 3 and the contact interface damage of multiple components in Step 4, obtain the clamping force of the integrated sealing disk-baffle on the turbine disk. Step 6.2: When the clamping force is greater than 0, it is considered that the sealing function has not failed and the temperature distribution remains unchanged; when the clamping force is equal to 0, it is considered that the sealing function has failed and a new temperature distribution is obtained.

[0015] More preferably, step 7 includes the following steps: Step 7.1: Determine the total permissible wear depth at the contact interfaces of multiple components in the turbine disk assembly as the wear damage tolerance; Step 7.2: Wear failure is considered to have occurred when at least one of the wear on the contact end face of the multi-stage series clamping component in step 4.2 or the wear on the cylindrical mating surface of the multi-stage series clamping component exceeds the wear damage tolerance; otherwise, wear failure is considered not to have occurred. Step 7.3: When the contact fatigue damage at the tenon joint interface in Step 4.6 is greater than or equal to the fatigue damage tolerance in Step 4.5, contact fatigue failure is considered to have occurred; otherwise, contact fatigue failure is considered not to have occurred. Step 7.4: If neither wear failure nor contact fatigue failure occurs, modify the mechanical model of the turbine disk assembly in Step 3 according to the equivalent assembly preload in Step 5.3, the equivalent cylindrical mating surface interference in Step 5.4, and the temperature distribution in Step 6.2, respectively, and replace the assembly preload, cylindrical mating surface interference, and temperature distribution in the original model, and repeat Steps 4-7; otherwise, the turbine disk assembly is considered to have failed, and the life of the turbine disk assembly is obtained.

[0016] Compared with the prior art, the advantages of the present invention are as follows: This invention addresses the problem that damage life assessment methods based on single components or single interfaces are not accurate enough when assessing the failure of turbine disk assemblies in turboshaft engine gas generators. By iteratively refining the mechanical model, the accuracy of turbine disk assembly life assessment is improved. Attached Figure Description

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments: Figure 1 A simplified flowchart of a multi-mode failure assessment method for a turboshaft engine combustion turbine disk assembly provided by the present invention; Figure 2 A schematic diagram of a typical turboshaft engine gas generator turbine disk assembly; Figure 3 This is a schematic diagram of the contact end face and cylindrical mating surface of a typical turboshaft engine gas generator turbine bladed disk assembly. The components are: 1. End face clamping nut; 2. Grate sealing ring; 3. Integrated sealing disc-baffle; 4. Turbine disc; 5. Turbine blade; 6. Tenon connection interface; 7. First end face; 8. Second end face; 9. Third end face; 10. Fourth end face; 11. First mating cylindrical surface; 12. Second mating cylindrical surface; 13. Third mating cylindrical surface; 14. Fourth mating cylindrical surface. Detailed Implementation

[0018] Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is not intended to limit the invention or its application or use in any way. The invention can be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that the invention will be thorough and complete, and will fully express the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, the composition of materials, numerical expressions, and values ​​set forth in these embodiments should be interpreted as merely exemplary and not as limiting.

[0019] refer to Figures 1-3 This invention provides a multi-mode failure assessment method for turbine disk assemblies in turboshaft engines, comprising the following steps: Step 1: Obtain the initial assembly parameters of the turbine disk assembly, including the initial assembly preload, the initial interference fit of the cylindrical mating surface, and the mating parameters of the tenon connection interface, etc. In one specific embodiment, the turbine disk assembly is assembled from an end face clamping nut 1, a toothed sealing ring 2, an integrated sealing disk-baffle 3, a turbine disk 4, and turbine blades 5. The initial assembly preload is the assembly preload generated by the end face clamping nut 1 in the initial assembly state; the initial cylindrical mating surface interference is the mating parameters of the first mating cylindrical surface 11, the second mating cylindrical surface 12, the third mating cylindrical surface 13, and the fourth mating cylindrical surface 14 in the initial assembly state; the tenon connection interface mating parameters are the mating parameters of the tenon connection interface 6 in the initial assembly state. Step 2: Obtain the operating conditions of the turbine disk assembly. These operating conditions refer to the mechanical and thermal loads at various locations within the turbine disk assembly, determined by the turbine disk assembly's design operating speed, operating temperature distribution, and external load spectrum. The specific design operating temperature distribution is denoted as... ; Step 3: Obtain the mechanical model of the turbine bladed disk assembly under operating conditions; specifically including the following steps: Step 3.1: Based on the initial assembly parameters in Step 1, obtain the finite element model of the turbine disk assembly with interface contact units; specifically, the assembly preload in the model is the initial assembly preload, the interference of the cylindrical mating surface is the initial cylindrical mating surface interference, and the tenon connection interface mating parameters are the initial tenon connection interface mating parameters. Step 3.2: Based on the operating conditions in Step 2 and the finite element model of the turbine disk assembly, calculate the normal load stress-strain state and tangential load stress-strain state of the turbine disk assembly under the operating conditions; specifically, the temperature distribution under the operating conditions adopts the temperature distribution under the design operating conditions. ; Step 3.3: Linearly superimpose the stress-strain state of the normal load and the stress-strain state of the tangential load to establish a stress-strain state model under the combined action of the normal load stress and the tangential load stress, which is the mechanical model of the turbine blade disk assembly during operation. Step 4: Determine the contact interface damage of multiple components in the turbine disk assembly throughout the entire working cycle after assembly, including wear on the contact end faces of multi-stage tandem clamping components, wear on the cylindrical mating surfaces of multi-stage tandem clamping components, and fatigue damage at the tenon joint interface; including the following steps: Step 4.1: Determine the contact parameters and wear coefficient of the contact end faces and cylindrical mating surfaces of the multi-stage tandem clamping components; In one specific embodiment, the contact end faces of the multi-stage series clamping member are the first end face 7, the second end face 8, the third end face 9 and the fourth end face 10, and the cylindrical mating surfaces of the multi-stage series clamping member are the first mating cylindrical surface 11, the second mating cylindrical surface 12, the third mating cylindrical surface 13 and the fourth mating cylindrical surface 14. Step 4.2: Based on the contact parameters, wear coefficient, and working time, obtain the wear of the contact end face of the multi-stage series clamping component and the wear of the cylindrical mating surface of the multi-stage series clamping component; Specifically, the wear depth is recorded as ; Step 4.3: Select a fatigue damage model based on the turbine bladed disk assembly mechanical model in Step 3, and determine the fatigue life; specifically, this includes the following steps: Step 4.3.1: Using the mechanical model of the turbine disk assembly in Step 3, obtain the stress and strain values ​​at any contact point of the tenon connection interface in the turbine disk assembly, and determine the candidate point most prone to failure. Step 4.3.2: Determine the critical plane of the most likely failure candidate point by using the stress-strain values ​​of the most likely failure candidate point; Step 4.3.3: Obtain the fatigue life by using the stress-strain values ​​of the critical plane of the most likely failure candidate point and the material constant of the tenon joint interface; Step 4.4: Determine the proportion of contact fatigue damage based on the fatigue life and working time; Step 4.5: Obtain the fatigue failure crack length, which is generally the lower limit of conventional crack detection, as the fatigue damage tolerance; specifically, determine the fatigue failure crack length through the lower limit of conventional crack detection, which is generally 0.2 mm; Step 4.6: Obtain the contact fatigue damage at the tenon joint interface based on the fatigue damage tolerance and the contact fatigue damage ratio. Specifically: Working hours recorded ; Fatigue life recording ; The length of the fatigue failure crack is denoted as ; The proportion of contact fatigue damage is expressed as ; The contact fatigue damage at the tenon joint interface is expressed as: ; Step 5: Determine the impact of contact interface damage of the multi-stage tandem clamping components on assembly parameters, including the impact of wear on the contact end faces of the multi-stage tandem clamping components on the assembly preload and the impact of wear on the cylindrical mating surfaces of the multi-stage tandem clamping components on the interference fit of the cylindrical mating surfaces; specifically including the following steps: Step 5.1: Obtain the axial stiffness of the multi-stage tandem clamping component; specifically including the following steps: Step 5.1.1: Obtain the axial compression of the multi-stage series clamping components under the initial assembly preload using the mechanical model of the turbine disk assembly in Step 3; Step 5.1.2: Based on the initial assembly preload and axial compression, obtain the axial stiffness of the multi-stage tandem clamping component. Specifically: Initial assembly preload is denoted as ; When not assembled, the sum of the axial lengths of the toothed sealing ring 2 and the integrated sealing disc-baffle 3, that is, the axial length from the first end face 7 to the fourth end face 10, is called the axial length when not assembled, denoted as . ; In the initial assembly state, the sum of the axial lengths of the toothed sealing ring 2 and the integrated sealing disc-baffle 3, that is, the axial length from the first end face 7 to the fourth end face 10, is called the axial length in the initial assembly state, denoted as . ; Axial compression is expressed as ; The axial stiffness of a multi-stage tandem clamping member is expressed as: ; Step 5.2: Based on the wear of the contact end faces of the multi-stage tandem clamping components determined in Step 4.2 and the axial stiffness of the multi-stage tandem clamping components, obtain the reduction in assembly preload; specifically, No. The wear depth of the contact end face is denoted as ; The sum of the wear depths of the first end face 7, the second end face 8, and the fourth end face 10 is expressed as: ; The reduction in assembly preload is expressed as ; Step 5.3: Based on the initial assembly preload from Step 1 and the reduction in assembly preload, obtain the remaining assembly preload, which is defined as the equivalent assembly preload; specifically, The equivalent assembly preload is expressed as: ; Step 5.4: Based on the initial interference fit of the cylindrical mating surfaces in Step 1, and the wear of the cylindrical mating surfaces of the multi-stage tandem clamping components determined in Step 4.2, obtain the remaining interference fit of the cylindrical mating surfaces, which is defined as the equivalent cylindrical mating surface interference fit; specifically, No. The initial assembly interference of the cylindrical mating surfaces is denoted as... ; No. The wear depth of the cylindrical mating surface is denoted as... ; The equivalent cylindrical mating surface interference is expressed as: ; Step 6: Determine the impact of damage to the contact interfaces of multiple components on the sealing function. If it causes sealing failure, obtain the temperature distribution; if it does not cause sealing failure, keep the temperature distribution unchanged. This includes the following steps: Step 6.1: Based on the mechanical model in Step 3 and the contact interface damage of multiple components in Step 4, obtain the clamping force of the integrated sealing disc-baffle on the turbine disk; specifically, the clamping force of the integrated sealing disc-baffle on the turbine disk refers to the clamping force of the fourth end face 10 under working conditions, denoted as... This can be obtained through simulation calculations or experiments; Step 6.2: When the clamping force is greater than 0, it is considered that the sealing function has not failed, and the temperature distribution remains unchanged; when the clamping force is equal to 0, it is considered that the sealing function has failed, and a new temperature distribution is obtained; specifically: Temperature distribution is represented as ; At that time, it was considered that the sealing function had not failed and the temperature distribution remained unchanged. ; When the sealing function is considered to have failed, a new temperature distribution is obtained through experimentation or simulation, denoted as... ; Step 7: Determine whether at least one of the contact interface damages of multiple components has reached the damage tolerance limit. If none of them have reached the damage tolerance limit, then use the calculation results from Steps 5 and 6, including assembly preload, interference fit of cylindrical mating surfaces, and temperature distribution, to correct the mechanical model of the turbine disk assembly in Step 3, and repeat Steps 4-7. If at least one component has reached the damage tolerance limit, the turbine disk assembly fails, the failure life of the turbine disk assembly is obtained, and the cycle terminates. Specifically, this includes the following steps: Step 7.1: Determine the total permissible wear depth at the contact interfaces of multiple components in the assembly, as the wear damage tolerance; specifically, determine the total permissible wear depth based on experiments or experience, denoted as... ; Step 7.2: Wear failure is considered to have occurred when at least one of the contact end faces of the multi-stage tandem clamping components in Step 4.2, or the cylindrical mating surfaces of the multi-stage tandem clamping components, wears beyond the wear tolerance; otherwise, wear failure is considered not to have occurred. Specifically, wear failure occurs when the wear depth of any one of the contact interfaces of the first end face 7, the second end face 8, the third end face 9, and the fourth end face 10, as well as the first mating cylindrical surface 11, the second mating cylindrical surface 12, the third mating cylindrical surface 13, and the fourth mating cylindrical surface 14, exceeds the total allowable wear depth. or any At that time, it is considered that wear failure has occurred; Step 7.3: When the fatigue damage at the tenon joint interface in Step 4.6 is greater than or equal to the fatigue damage tolerance in Step 4.5, contact fatigue failure is considered to have occurred; otherwise, contact fatigue failure is considered not to have occurred. Specifically, when the fatigue damage at the tenon joint interface is greater than or equal to the fatigue failure crack length, i.e. If the failure occurs, it is considered that contact fatigue failure has occurred; otherwise, it is considered that contact fatigue failure has not occurred. Step 7.4: When neither wear failure nor contact fatigue failure occurs, apply the equivalent assembly preload force from Step 5.3. Interference of the equivalent cylindrical mating surface in step 5.4 and the temperature distribution in step 6.2. The mechanical model of the turbine disk assembly in step 3 is modified by replacing the assembly preload, interference fit of the cylindrical mating surface, and temperature distribution in the original model, and steps 4-7 are repeated; otherwise, the turbine disk assembly is considered to have failed, and the turbine disk assembly life is obtained, which is equal to the operating time at the time of failure, denoted as . .

[0020] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A multi-mode failure assessment method for a turboshaft engine combustion turbine disk assembly, characterized in that, Includes the following steps: Step 1: Obtain the initial assembly parameters of the turbine disk assembly, including the initial assembly preload, the initial interference fit of the cylindrical mating surface, and the mating parameters of the tenon connection interface. Step 2: Obtain the operating conditions of the turbine bladed disk assembly; Step 3: Obtain the mechanical model of the turbine bladed disk assembly under operating conditions; Step 4: Determine the contact interface damage of multiple components in the turbine disk assembly during the entire working cycle after the complete machine assembly, including the wear of the contact end face of the multi-stage series clamping components, the wear of the cylindrical mating surface of the multi-stage series clamping components, and the contact fatigue damage of the tenon connection interface. Step 5: Determine the effect of wear on the contact end face of the multi-stage series clamping components on the initial assembly preload and the effect of wear on the cylindrical mating surface of the multi-stage series clamping components on the initial cylindrical mating surface interference. Step 6: Determine the impact of damage to the contact interface of multiple components on the sealing function. If it causes the sealing function to fail, obtain the temperature distribution; if it does not cause the sealing function to fail, keep the temperature distribution unchanged. Step 7: Determine whether at least one of the contact interface damages of multiple components has reached the damage tolerance. If none of them have reached the damage tolerance, then use the results in Step 5 and Step 6 to correct the mechanical model in Step 3, and repeat Step 4-7. If at least one has reached the damage tolerance, then the turbine bladed disk assembly fails, the failure life of the turbine bladed disk assembly is obtained, and the cycle is terminated.

2. The multi-mode failure assessment method for the turbine disk assembly of a turboshaft engine according to claim 1, characterized in that, Step 3 includes the following steps: Step 3.1: Obtain the finite element model of the turbine disk assembly with interface contact units based on the initial assembly parameters in Step 1; Step 3.2: Based on the operating conditions in Step 2 and the finite element model of the turbine bladed disk assembly, calculate the normal load stress-strain state and tangential load stress-strain state of the turbine bladed disk assembly under the operating conditions, respectively. Step 3.3: Linearly superimpose the stress-strain state of the normal load and the stress-strain state of the tangential load to establish a stress-strain state model under the combined action of the normal load stress and the tangential load stress, which is the mechanical model of the turbine disk assembly under the working conditions.

3. The multi-mode failure assessment method for the turbine disk assembly of a turboshaft engine according to claim 1, characterized in that, Step 4 includes the following steps: Step 4.1: Determine the contact parameters and wear coefficient of the contact end faces and cylindrical mating surfaces of the multi-stage tandem clamping components; Step 4.2: Based on the contact parameters, wear coefficient, and working time, obtain the wear of the contact end face of the multi-stage series clamping component and the wear of the cylindrical mating surface of the multi-stage series clamping component; Step 4.3: Select a fatigue damage model based on the mechanical model of the turbine bladed disk assembly in Step 3, and determine the fatigue life. Step 4.4: Determine the proportion of contact fatigue damage based on the fatigue life and working time; Step 4.5: Obtain the fatigue failure crack length as the fatigue damage tolerance; Step 4.6: Obtain the contact fatigue damage at the tenon joint interface based on the fatigue damage tolerance and the contact fatigue damage ratio.

4. The multi-mode failure assessment method for the turbine disk assembly of a turboshaft engine according to claim 3, characterized in that, Step 4.3 includes the following steps: Step 4.3.1: Using the mechanical model of the turbine disk assembly in Step 3, obtain the stress and strain values ​​at any contact point of the tenon connection interface in the turbine disk assembly, and determine the candidate point most prone to failure. Step 4.3.2: Determine the critical plane of the most likely failure candidate point by using the stress-strain values ​​of the most likely failure candidate point; Step 4.3.3: Obtain the fatigue life by using the stress-strain values ​​of the critical plane of the most likely failure candidate point and the material constant of the tenon joint interface.

5. The multi-mode failure assessment method for the turbine disk assembly of a turboshaft engine according to claim 3, characterized in that, Step 5 includes the following steps: Step 5.1: Obtain the axial stiffness of the multi-stage cascaded clamping components; Step 5.2: Based on the wear of the contact end faces of the multi-stage series clamping components and the axial stiffness of the multi-stage series clamping components determined in Step 4.2, obtain the reduction in assembly preload. Step 5.3: Based on the initial assembly preload in Step 1 and the reduction in assembly preload, obtain the remaining assembly preload, which is defined as the equivalent assembly preload. Step 5.4: Based on the initial cylindrical mating surface interference in Step 1 and the wear of the cylindrical mating surface of the multi-stage series clamping components determined in Step 4.2, obtain the remaining cylindrical mating surface interference, which is defined as the equivalent cylindrical mating surface interference.

6. The multi-mode failure assessment method for the turbine disk assembly of a turboshaft engine according to claim 5, characterized in that, Step 5.1 includes the following steps: Step 5.1.1: Obtain the axial compression of the multi-stage series clamping components under the initial assembly preload using the mechanical model of the turbine disk assembly in Step 3; Step 5.1.2: Obtain the axial stiffness of the multi-stage series clamping components based on the initial assembly preload and axial compression.

7. The multi-mode failure assessment method for the turbine disk assembly of a turboshaft engine according to claim 6, characterized in that, Step 6 includes the following steps: Step 6.1: Based on the mechanical model of the turbine disk assembly in Step 3 and the contact interface damage of multiple components in Step 4, obtain the clamping force of the integrated sealing disk-baffle on the turbine disk. Step 6.2: When the clamping force is greater than 0, it is considered that the sealing function has not failed and the temperature distribution remains unchanged; when the clamping force is equal to 0, it is considered that the sealing function has failed and a new temperature distribution is obtained.

8. The multi-mode failure assessment method for the turbine disk assembly of a turboshaft engine according to claim 7, characterized in that, Step 7 includes the following steps: Step 7.1: Determine the total permissible wear depth at the contact interfaces of multiple components in the turbine disk assembly as the wear damage tolerance; Step 7.2: Wear failure is considered to have occurred when at least one of the wear on the contact end face of the multi-stage series clamping component in step 4.2 or the wear on the cylindrical mating surface of the multi-stage series clamping component exceeds the wear damage tolerance; otherwise, wear failure is considered not to have occurred. Step 7.3: When the contact fatigue damage at the tenon joint interface in Step 4.6 is greater than or equal to the fatigue damage tolerance in Step 4.5, contact fatigue failure is considered to have occurred; otherwise, contact fatigue failure is considered not to have occurred. Step 7.4: If neither wear failure nor contact fatigue failure occurs, modify the mechanical model of the turbine disk assembly in Step 3 according to the equivalent assembly preload in Step 5.3, the equivalent cylindrical mating surface interference in Step 5.4, and the temperature distribution in Step 6.2, respectively, and replace the assembly preload, cylindrical mating surface interference, and temperature distribution in the original model, and repeat Steps 4-7; otherwise, the turbine disk assembly is considered to have failed, and the life of the turbine disk assembly is obtained.

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