Complex pipeline system multi-physics field collaborative fatigue analysis method

Abstract

The application provides a complex pipeline system multi-physical field cooperative fatigue analysis method and relates to the technical field of engine power system simulation.The physical field in the method comprises a fluid field, a temperature field and a structure field, specifically, a complex pipeline system basic model, temperature field and pressure field analysis, structure analysis, harmonic response analysis and fatigue life analysis.Through the establishment of a fluid-solid-thermal multi-physical field coupling model and the simulation of the actual working state of the pipeline, the fatigue failure analysis of the engine pipeline system under complex working conditions is realized, the problems of the traditional fatigue failure analysis, such as the neglect of the multi-physical field coupling effect and poor adaptability, are solved, a reference is provided for the vibration characteristic analysis and structure optimization design of the pipeline, and the method is suitable for scenes such as the fatigue failure analysis of the engine complex pipeline system.

Description

Technical Field

[0001] This invention relates to the technical field of aerospace propulsion system simulation, and in particular to a multi-physics field collaborative fatigue analysis method for complex pipeline systems. Background Technology

[0002] As a key component of the engine power unit system, the pipeline's core function is to transport fuel. During rocket launch, the pipeline system operates in a complex fluid-structure-thermal multiphysics coupled environment, and is affected by the flow of liquid fuel and engine vibration.

[0003] Traditional fatigue failure analysis of engine piping systems often employs single-physics field analysis methods, neglecting the coupling effects between fluid, temperature, and structural fields, and failing to consider the influence of fluid pressure and temperature on the stiffness of the piping structure. To address these issues, this patent proposes a multi-physics field collaborative fatigue analysis method for complex piping systems. This method comprehensively considers the fluid-structure-thermal coupling effects during engine piping operation, making it suitable for complex operating environments and providing a reference for vibration characteristic analysis and structural optimization design of engine piping systems. Summary of the Invention

[0004] The purpose of this invention is to establish a multi-physics coupling model of engine pipelines and simulate the actual working state of the pipelines to realize the vibration characteristics analysis of engine pipelines under complex working conditions. Therefore, a multi-physics synergistic fatigue analysis method for complex pipeline systems is proposed.

[0005] A multi-physics collaborative fatigue analysis method for complex pipeline systems, the method comprising the following:

[0006] A multi-physics field synergistic fatigue analysis method for complex pipeline systems is characterized by the following main steps: S1 Basic model of the complex pipeline system; S5 Temperature and pressure field analysis of the complex pipeline system; S10 Structural analysis of the complex pipeline system; S16 Harmonic response analysis of the complex pipeline system; S21 Fatigue life analysis of the complex pipeline system.

[0007] The method for multi-physics field collaborative fatigue analysis of complex pipeline systems according to claim 1 is characterized in that: in S1, the basic model of the pipeline system is constructed. In order to meet the working conditions of different types of engine pipeline structures, pipeline structure parameters, fuel fluid medium parameters and temperature environment parameters are collected to establish a parameterized model including fluid field, temperature field and structural field.

[0008] In S2, S3, and S4, a fluid computation domain matching the actual pipeline structure is constructed. The structural region is divided using Boolean operations to construct a fluid domain consistent with the pipeline's nominal diameter, wall thickness, bending angle, and other structural features. The key boundaries of the pipeline fluid domain are standardized and named, such as inlet, outlet, and wall. For the pipeline structure, an appropriate mesh generation algorithm is adopted, and local mesh refinement is performed in high-gradient regions to increase the unit density in local areas.

[0009] The method for multi-physics field collaborative fatigue analysis of complex pipeline systems according to claim 1 is characterized in that: in S5, the analysis of the temperature field and pressure field of the pipeline system is involved, a turbulence model adapted to the flow characteristics of the pipeline is selected, boundary conditions are set for the pipeline inlet interface, and numerical simulation of the flow field of the pipeline system is carried out to obtain the global temperature field and pressure field distribution of the pipeline system, and the fluid temperature and pressure load data are extracted.

[0010] In S6 and S7, the selected turbulence model is matched with the fluid flow state in the pipeline. Parameters such as fluid density and viscosity are defined, and dynamic fitting is performed based on the working temperature state of the pipeline. Boundary conditions such as working pressure and temperature at the inlet interface of the fluid domain, as well as boundary conditions at the outlet interface, are defined.

[0011] In S8 and S9, the simulation involves the fluid field and temperature field of the engine pipeline. It simulates the flow state of the fluid in the pipeline, such as turbulent vortices and sudden velocity changes at bends. At the same time, the fluid field and temperature field are solved to achieve collaborative calculation and analysis. This yields data such as the pressure distribution and temperature distribution of the pipeline, which are used as input loads for subsequent structural analysis.

[0012] The method for multi-physics field collaborative fatigue analysis of complex pipeline systems according to claim 1 is characterized in that: in S10, the pipeline system structural analysis is involved, temperature and pressure load data are imported into the calculation model, a fluid-structure coupling model is constructed, structural strength analysis such as pipeline deformation and stress is carried out, as well as static modal and prestressed modal analysis of the pipeline, and the resonance risk of the pipeline system is assessed.

[0013] In S11 and S12, engine pipeline structure simulation is involved. Data such as pipeline pressure and temperature are used as load inputs to the pipeline structure analysis model to calculate the deformation and stress distribution of the pipeline under the combined action of fluid pressure and temperature, identify stress concentration areas, and evaluate whether the pipeline meets the strength requirements.

[0014] In S13, S14, and S15, the prestressed modal natural frequencies and mode shapes of the pipeline under working loads (pressure and temperature) are solved, as well as the static modal natural frequencies and mode shapes of the pipeline without working loads. The results of S13 and S14 are compared to analyze the influence mechanism of working loads on the pipeline vibration characteristics. The vibration spectrum of the external excitation source and the natural frequency of the pipeline are compared to assess the resonance risk of the engine pipeline and avoid instantaneous failure or fatigue damage caused by structural resonance.

[0015] The multi-physics field synergistic fatigue analysis method for complex pipeline systems according to claim 1 is characterized in that: in S16, harmonic response analysis of the pipeline system is involved, a periodic harmonic excitation is applied to the pipeline system, the frequency sweep range and damping coefficient are set, and the frequency domain numerical solution is carried out using the modal superposition algorithm to obtain the frequency response function of physical quantities such as displacement and stress as a function of the excitation frequency, thereby characterizing the dynamic response characteristics of the pipeline system under harmonic excitation.

[0016] In S17, S18, S19, and S20, periodic harmonic excitation is applied to the complex pipeline system. Based on the actual working conditions, the sweep frequency range and damping coefficient are set. The modal superposition algorithm is used to obtain the frequency response curves of physical quantities such as displacement and stress as a function of the excitation frequency, and the frequency response function and finite element simulation results of the pipeline system are obtained.

[0017] The multi-physics field collaborative fatigue analysis method for complex pipeline systems according to claim 1 is characterized in that: in S21, fatigue life analysis of complex pipeline systems is involved, which combines material fatigue performance parameters and introduces random vibration excitation power spectral density load conditions to solve for stress response power spectral density, and performs fatigue damage and failure analysis on key locations of the pipeline system.

[0018] Fatigue failure analysis was conducted on complex pipelines, using the finite element simulation results of the aforementioned harmonic response analysis as input data. In step S22, fatigue performance parameters corresponding to the component materials were selected, including the material's SN curve and fatigue strength correction coefficient. In step S23, the power spectral density of random vibration excitation under actual operating conditions was input to simulate the actual random vibration load environment of the pipeline. Subsequently, in steps S24 and S25, the stress response power spectral density at different locations was obtained by combining the aforementioned frequency response function, identifying the critical areas for accumulated fatigue damage in the pipeline.

[0019] The core value of the systematic analysis of simulation results of complex engine piping systems lies in the multi-physics field collaborative fatigue analysis technology for complex piping systems, which provides a methodological reference for vibration characteristic analysis and structural optimization design of engine piping systems. Attached Figure Description

[0020] Figure 1This is a flowchart of a multi-physics field collaborative fatigue analysis method for complex pipeline systems.

[0021] Figure 2 , 3 This is a technical flowchart of a multi-physics field collaborative fatigue analysis method for complex pipeline systems. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings and examples. However, the scope of protection of the present invention is not limited to the specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0023] like Figure 1 The flowchart shown below illustrates the method, which includes the following steps: S1 Basic model of the complex piping system; S5 Temperature and pressure field analysis of the complex piping system; S10 Structural analysis of the complex piping system; S16 Harmonic response analysis of the complex piping system; S21 Fatigue life analysis of the complex piping system. The specific flow of each module is as follows: Figure 2 , 3 As shown.

[0024] This example uses a space-based dual-pipeline system in a rocket engine as the analysis object. The two pipes have bends in three-dimensional space that are not on the same plane and are fixed together by pipe clamps. Liquid fuel flows inside the pipes, generating loads such as temperature and pressure on the pipe walls. This invention is used to perform synergistic fatigue analysis of this example under fluid-structure-thermal multiphysics fields.

[0025] The first pipe has a nominal outer diameter of 12mm, a wall thickness of 1.5mm, and is made of stainless steel. It includes two 90° spatial bends and has a total length of 750mm. The second pipe has a nominal outer diameter of 10mm, a wall thickness of 1.2mm, and is also made of stainless steel. It includes one 45° bend and one 90° bend and has a total length of 860mm.

[0026] The pipeline structure was simplified, and the internal fluid computational domain was extracted. A hexahedral structured mesh was used, with local mesh refinement at bends. The pipeline inlet and outlet names were named, and parameters such as fuel temperature and pressure at the inlet were defined. A k-ε turbulence model was selected to accommodate high Reynolds number turbulent flow within the pipeline. Fluid flow field simulations were conducted to obtain fluid temperature and pressure load data.

[0027] Structural strength analysis was performed on the pipeline by applying mapped temperature and pressure loads to the structural model, taking into account actual boundary conditions. Two sets of modes were solved separately: static modes and prestressed modes, and the resonance risk zone was analyzed by comparison.

[0028] Harmonic response analysis was performed based on prestressed modal analysis. A frequency sweep interval was set, and the modal superposition method was used to apply simple harmonic acceleration excitation at the bolt constraint locations to simulate periodic vibrations input to the pipeline under actual working conditions. The frequency response curves at key locations in the pipeline were obtained, and the system frequency response function was derived.

[0029] Random vibration fatigue failure analysis is carried out. The frequency response function obtained above is used as the basis for fatigue analysis. The SN curve of the pipeline material is input, and fatigue strength correction coefficients for surface processing, welded joints, etc. are introduced. The actual measured random vibration power spectral density is input, and the stress response power spectral density of each critical node is calculated. Then, the fatigue life of the pipeline structure is analyzed.

[0030] This example demonstrates that bends and welded joints in pipelines can affect fatigue life. Increasing the pipeline wall thickness, adding intermediate support points, and reducing the stress level at welded joints can improve the fatigue resistance of the pipeline system.

[0031] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that some local modifications or changes can still be made without departing from the principles and basic characteristics of this invention; all of these fall within the scope of protection of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is determined by the appended claims. Parts not covered in this invention are the same as or can be implemented using existing technology.

Claims

1. A multi-physics field synergistic fatigue analysis method for complex pipeline systems, characterized in that, The method mainly includes the following steps: S1 Basic model of complex pipeline system; S5 Temperature and pressure field analysis of complex pipeline system; S10 Structural analysis of complex pipeline system; S16 Harmonic response analysis of complex pipeline system; S21 Fatigue life analysis of complex pipeline system.

2. The multi-physics field synergistic fatigue analysis method for complex pipeline systems according to claim 1, characterized in that: In S1, the basic model of the pipeline system is constructed. In order to meet the working conditions of different types of engine pipeline structures, pipeline structure parameters, fuel fluid medium parameters and temperature environment parameters are collected to establish a parameterized model that includes fluid field, temperature field and structural field.

3. The multi-physics field synergistic fatigue analysis method for complex pipeline systems according to claim 1, characterized in that: In S5, the analysis of the temperature and pressure fields of the pipeline system is involved. A turbulence model suitable for the pipeline flow characteristics is selected, boundary conditions are set for the pipeline inlet interface, and numerical simulation of the flow field of the pipeline system is carried out to obtain the global temperature and pressure field distribution of the pipeline system, and the fluid temperature and pressure load data are extracted.

4. The multi-physics field synergistic fatigue analysis method for complex pipeline systems according to claim 1, characterized in that: In S10, the structural analysis of the pipeline system is involved. Temperature and pressure load data are imported into the calculation model to build a fluid-structure coupling model. Structural strength analysis such as pipeline deformation and stress is carried out, as well as static modal and prestressed modal analysis of the pipeline, and the resonance risk of the pipeline system is assessed.

5. The multi-physics field synergistic fatigue analysis method for complex pipeline systems according to claim 1, characterized in that: S16 involves harmonic response analysis of the pipeline system. Periodic harmonic excitation is applied to the pipeline system, the frequency sweep range and damping coefficient are set, and the modal superposition algorithm is used to carry out frequency domain numerical solution to obtain the frequency response functions of physical quantities such as displacement and stress as a function of excitation frequency, thus characterizing the dynamic response characteristics of the pipeline system under harmonic excitation.

6. The multi-physics field synergistic fatigue analysis method for complex pipeline systems according to claim 1, characterized in that: S16 involves fatigue life analysis of complex pipeline systems. Combining material fatigue performance parameters and introducing random vibration excitation power spectral density load conditions, the stress response power spectral density is obtained by solving, and fatigue damage and failure analysis is performed on key locations of the pipeline system.

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