Blisk linear friction welding fatigue crack propagation numerical simulation method

Abstract

The invention discloses a blisk linear friction welding fatigue crack propagation numerical simulation method, and belongs to the technical field of linear friction welding. The method comprises the following specific steps: establishing a three-dimensional solid model of the blisk; performing grid division on the three-dimensional solid model of the blisk by adopting a non-uniform grid; setting load and boundary conditions; acquiring temperature field and stress field distribution of the joint; importing the welding residual stress field into the sub-model through node interpolation; grid division is carried out again based on a fracture mechanics M integral criterion; applying a multi-axis coupling load in the sub-model according to an actual service condition to obtain stress distribution of the blade, and implanting an initial crack with a preset size and orientation into a stress concentration area; the expansion behavior of the crack under the coupling action of the residual stress and the multi-axial load is simulated; and in combination with a fatigue crack propagation rate model of the material, establishing a quantitative relationship between a crack propagation path and fatigue life, and realizing life prediction. The problem that traditional heat input calculation is not accurate is solved.

Description

Technical Field

[0001] This invention belongs to the field of linear friction welding technology, specifically relating to a numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks. Background Technology

[0002] Linear friction welding, as a highly efficient solid-state joining technology, has been widely used in the manufacturing and repair of integral bladed disks for aero-engines. This process generates heat through high-frequency reciprocating friction between workpieces, achieving metallurgical bonding in a thermoplastic state, which is crucial for ensuring the reliability of welded components. However, due to the complex coupling between the reciprocating frictional motion of the interface and the plastic flow of the material under high strain rates, it is difficult to achieve real-time observation of key physical quantities such as the temperature and stress fields at the weld interface. The intense thermo-mechanical coupling during welding leads to complex residual stress fields and microstructure gradients in the joint area, significantly affecting the fatigue performance of the integral bladed disk under high temperature, high centrifugal loads, and aerodynamic load coupling.

[0003] Currently, numerical simulation studies on linear friction welding processes mainly focus on temperature and stress field analysis and welding process parameter optimization. For example, the Arbitrary Lagrange-Euler (ALE) method is used to simulate the large deformation behavior of materials, or the Johnson-Cook constitutive model is used to describe the material response under high temperature and high strain rate. However, such studies often overlook a key issue: the integral bladed disk has a special geometric structure of "disk-sloping surface-boob," and the traditional heat input model derived from planar butt joints cannot accurately reflect the loss effect during the pressure transmission process on the inclined surface of the disk, resulting in a systematic bias in the calculation of the welding heat source, which directly affects the prediction accuracy of the residual stress field.

[0004] On the other hand, the fatigue crack propagation behavior in the post-weld joint region has a decisive impact on the bladed disk's lifespan. Conventional uniform meshes or single-element types are insufficient to accurately capture the stress intensity factor distribution at the crack tip, and there is a particular lack of high-precision mesh transition strategies and element configuration schemes suitable for crack propagation on curved surfaces. Furthermore, the coupling mechanism between welding residual stress and in-service multiaxial loads (centrifugal force, aerodynamic loads, and thermal loads) remains unclear, leading to significant deviations between fatigue life predictions and actual conditions.

[0005] Therefore, there is an urgent need to develop a method that can accurately characterize the overall bladed disk structural features, correct the heat input model, achieve high-precision simulation of surface cracks, and comprehensively consider the fatigue cracking effect of the coupling effect of welding residual stress and multiaxial service loads. A numerical simulation method for ripple extension is used to improve the accuracy of life prediction and support welding process optimization and bladed disk reliability design. Summary of the Invention

[0006] The technical problem to be solved: To overcome the shortcomings of existing technologies, this invention provides a numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks. This method first establishes a three-dimensional thermo-mechanical coupling model of the linear friction welding process of integral bladed disks using ABAQUS finite element analysis software, based on the Arbitrary Lagrangian-Eulerian method, to investigate the temperature field distribution and stress field evolution of the joint during the linear friction welding process. For the special structure of linear friction welding of integral bladed disks (disk body with inclined surfaces and bosses), a pressure transmission correction model is proposed, solving the problem of inaccurate traditional heat input calculations. Simultaneously, a high-precision sub-model mesh strategy (M-integral + hybrid elements) is used to simulate the crack propagation on curved surfaces.

[0007] The technical solution of this invention is: a numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks, the specific steps of which are as follows: Establish a three-dimensional solid model of the integral bladed disk and set the temperature-related material thermophysical parameters and mechanical property parameters; A non-uniform mesh was used to mesh the three-dimensional solid model of the integral bladed disk; By setting loads and boundary conditions, and based on the geometry of the integral bladed disk "disk-boss-sloping surface", the welding heat input power is corrected to accurately reflect the pressure transmission loss of the disk-sloping surface. A three-dimensional thermo-mechanical coupled finite element analysis was performed on the linear friction welding process to obtain the temperature field and stress field distribution of the joint. Extract key areas of the bladed disk to establish a blade sub-model, and import the welding residual stress field into the sub-model through node interpolation; Based on the geometric characteristics of the blade surface, the mesh was re-divided according to the fracture mechanics M-integral criterion, and a three-ring unit loop and a layered transition unit structure were set. Multiaxial coupled loads are applied to the sub-model according to the actual service conditions to obtain the stress distribution of the blade, and initial cracks of preset size and orientation are implanted in the stress concentration area. Based on three-dimensional crack propagation technology, the propagation behavior of cracks under the coupled action of residual stress and multiaxial load is simulated. By combining the fatigue crack propagation rate model of materials, a quantitative relationship between crack propagation path and fatigue life is established to achieve life prediction.

[0008] A further technical solution of the present invention is: the specific method for correcting the welding heat input power is as follows: Welding pressure P Based on the inclined plane angle of the disk, the height of the welding interface, and the parameters of the disk height and radius, a coupled correction is performed. The correction formula is as follows:

[0009] in, h 0 represents the height of the welding interface. w For the width of the welding boss, h 1 represents the height of the disk. θ 1 represents the angle of the inclined plane. P 0 represents the nominal welding pressure; The corrected expression for heat input power is:

[0010] in, μ The coefficient of friction, f Let A be the vibration frequency and A be the amplitude.

[0011] A further technical solution of the present invention is: the non-uniform mesh division specifically comprises: The weld and near-weld area use C3D8RT elements with local mesh refinement, and the mesh size is 1mm×1mm×1mm; the area away from the weld uses a gradually increasing mesh size.

[0012] A further technical solution of the present invention is: the method of re-meshing based on the fracture mechanics M-integral criterion includes: Three rings of elements are arranged at the crack leading edge. The closest ring uses eight 15-node C3D15 wedge elements, the outer ring uses 20-node C3D20 hexahedral elements, and the remaining area uses 10-node C3D10 tetrahedral elements. The mesh continuity and displacement coordination are achieved between the various types of elements through transition elements. A further technical solution of the present invention is that the multi-axis coupled load includes centrifugal load, aerodynamic load and thermal load, and the load application takes into account the phase and amplitude coupling relationship in actual working conditions. A further technical solution of the present invention is: the method of importing welding residual stress into the sub-model through node interpolation is achieved by using the data interaction interface between Abaqus and FRANC3D software to realize stress mapping from the overall model to the sub-model.

[0013] A further technical solution of the present invention is: before implanting the initial crack, stress field verification is required to ensure that the boundary response of the sub-model is consistent with that of the overall model in the corresponding region. A further technical solution of the present invention is to calculate the crack propagation rate by using the Paris formula or the Forman formula in combination with the stress intensity factor amplitude, and to obtain the fatigue life by integration. A further technical solution of the present invention is to use ALE adaptive mesh technology in thermo-mechanical coupling analysis, with the mesh update frequency set to 50 times per increment step, in order to balance computational efficiency and simulation accuracy.

[0014] A numerical simulation system for fatigue crack propagation in linear friction welding of an integral bladed disk includes: a processor; and a memory storing an instruction program executable by the processor; the instruction program executes the numerical simulation method for fatigue crack propagation in linear friction welding of an integral bladed disk.

[0015] Beneficial effects The beneficial effects of this invention are as follows: This invention provides a numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks. This method first establishes a three-dimensional thermo-mechanical coupling model of the linear friction welding process of integral bladed disks using Abaqus finite element analysis software, based on the arbitrary Lagrange-Euler method. By dividing the model into sub-models, cracks are implanted at stress concentration locations. The influence of the temperature field, stress field, and fatigue cracks on crack propagation and fatigue life of the blades during the linear friction welding process is predicted. A quantitative relationship between the crack propagation path and the remaining life of the integral bladed disk is established, thereby achieving high-quality forming control, process optimization, and fatigue life prediction of the linear friction welded joint of integral bladed disks. This numerical simulation method has a simple modeling process and high computational efficiency and accuracy. Specific effects are analyzed as follows: 1. This invention significantly improves the accuracy and reliability of fatigue life prediction for integral bladed disk welded joints. By establishing a modified heat input model for the special geometry of the "disk-bore-sloping surface", the loss effect in the pressure transmission process is accurately considered, which improves the accuracy of the thermo-mechanical coupling simulation of the welding process from the source, and provides a more realistic residual stress field and temperature field data foundation for subsequent crack propagation analysis.

[0016] 2. This invention achieves high-fidelity simulation of crack propagation in complex curved surface structures. It innovatively employs a mesh re-division strategy based on the M-integral criterion of fracture mechanics, and carefully arranges three-ring element loops and layered transition elements (such as a hybrid topology of C3D15 wedge elements, C3D20 hexahedral elements, and C3D10 tetrahedral elements) at the crack front. This effectively overcomes the insufficient accuracy of traditional uniform meshes in capturing complex stress-strain fields at the crack front of curved surfaces, significantly improving the calculation accuracy of key parameters such as the stress intensity factor.

[0017] 3. This invention overcomes the technical challenge of simulating fatigue crack propagation under multi-physics field and multi-axial load coupling. The system considers the multi-axial coupling effect of welding residual stress and centrifugal force, aerodynamic load, and thermal load in actual service. Through sub-model technology and nodal interpolation methods, it achieves seamless data transfer from macroscopic welding simulation to local crack propagation analysis, realistically simulating crack propagation behavior in complex service environments, and making life prediction results closer to engineering reality.

[0018] 4. This invention forms a set of efficient and universal numerical simulation system solutions. This method integrates modeling, heat source correction, mesh generation, load application, crack implantation, and extended life prediction into a complete process. It boasts a high degree of automation, avoids reliance on expensive and time-consuming physical experiments, and has significant engineering application value and promising prospects in overall bladed disk welding process optimization, in-service life assessment, and reliability design. Attached Figure Description

[0019] Figure 1 This is a flowchart of a numerical simulation method for fatigue crack propagation in linear friction welding of an integral bladed disk according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the three-dimensional solid model of the overall bladed disk in an embodiment of the present invention; Figure 3 This is a diagram illustrating the evolution of the axial temperature field of the integral bladed disk in an embodiment of the present invention. Figure 4 This is a diagram showing the evolution of heat flux density at the friction interface in an embodiment of the present invention; Figure 5 The following are the initial crack location and crack mesh division of the crack propagation model in this embodiment of the invention: (a) crack location, (b) mesh division; Figure 6 This is a stress field distribution diagram of a single blade in an embodiment of the present invention; Figure 7 The following are stress cloud diagrams and fatigue crack propagation paths at the trailing edge of the blade in this embodiment of the invention: (a) initial crack, (b) fracture crack; Figure 8 Comparison of leading and trailing edge crack stress and life in embodiments of the present invention: (a) equivalent stress intensity factor distribution, (b) crack propagation. aN curve. Detailed Implementation The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0020] Currently, integral bladed disks (IBs) in compressors typically face high temperatures, high pressures, and complex mechanical load coupling during operation. Residual stress in the welded joint area can promote crack initiation and propagation, thus significantly impacting the fatigue life of the component. Given the presence of residual stress in the welded joint and the randomness of the initial crack size and angle, predicting the fatigue performance of the joint becomes difficult. This invention provides a numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks, with specific steps including: A three-dimensional solid model of linear friction welding of the integral bladed disk was established, and temperature-related material thermophysical parameters and mechanical property parameters were set. A non-uniform mesh was used to mesh the three-dimensional solid model of the integral bladed disk; By setting loads and boundary conditions, and considering the unique structural features of the integral bladed disk ("disk-bore-sloping surface"), pressure transmission losses are taken into account, and the load, i.e., the heat input power, is corrected to accurately match the heat generation calculation at the disk friction interface. Boundary conditions include: displacement boundary conditions, initial temperature, workpiece air heat dissipation coefficient, and the coefficient for converting frictional heat into plastic deformation heat. Finite element analysis was performed on a three-dimensional thermo-mechanical coupling model of the linear friction welding process to obtain the temperature field and stress field distribution characteristics of the joint.

[0021] The entire bladed disk is divided, and key areas are extracted to obtain blade sub-models. Welding residual stress is imported into the sub-models through node interpolation. For the case of complex blade surfaces, the sub-model mesh is re-divided according to fracture mechanics M-integral, setting three-ring element loops and layered transition elements.

[0022] The blades are subjected to multiaxial loads under actual operating conditions to obtain the stress field distribution during service. Initial cracks of preset size and orientation are then implanted at stress concentration locations. Finite element analysis of blade crack propagation was performed using three-dimensional crack propagation technology to obtain the impact of crack propagation on blade fatigue life.

[0023] In one embodiment, the thermophysical material parameters include: thermal conductivity, density, modulus, Poisson's ratio, plasticity, and specific heat capacity.

[0024] In one embodiment, the non-uniform mesh division includes: Small-sized meshes (C3D8RT type) are used for the weld seams and near-weld areas of the overall bladed disk, while large-sized meshes are used for areas far from the weld seams.

[0025] In one embodiment, the specific process for correcting the load is as follows: The pressure P on the bladed disk body and the welding pressure P0 of the welded joint are shown in the following formula:

[0026] In the formula, F0 is the welding boss pressure, F is the pressure borne by the disc body; S0 is the welding area; and is the arc angle of the pressure applied to the disc. 1 represents the slope angle; h0 is the welding interface height; h1 is the disk height; w is the welding boss width; and r is the inner radius of the disk's inner circle. Therefore, the applied welding pressure P can be obtained as follows:

[0027] The corrected average heat input power expression for the linear friction welding process of bladed disks is:

[0028] In the formula, q is the frictional heat generation, μ is the friction interface coefficient, f is the vibration frequency, P is the welding pressure, and A is the amplitude.

[0029] The displacement boundary conditions stipulate that both the blades and the disk have free deformation zones within the welding area. The disk is fully constrained in the X and Y axes, with only a Z-axis degree of freedom. The blades have only a X-axis degree of freedom. The defined field temperature is set to 25 °C, and the initial temperature is uniform throughout. The air heat dissipation coefficient of the workpiece is 100 W / (m²). 2 The coefficient for converting frictional heat into plastic deformation heat (°C) is set to 0.9.

[0030] In one embodiment, the key regions of the bladed disk are extracted using FRANC3D software to obtain the blade sub-model. Welding residual stress is then imported into the sub-model in Abaqus via node interpolation. For crack propagation on the blade surface, the blade mesh is regenerated based on the fracture mechanics M-integral. The mesh at the crack leading edge is divided into three rings of elements, with eight 15-node C3D15 wedge elements using quarter-node technology. These elements are surrounded by two layers of 20-node C3D20 hexahedral elements. The remaining area uses 10-node C3D10 tetrahedral elements, with the tetrahedral and hexahedral elements connected by 10-node C3D10 transition elements. This topology precisely matches the accuracy and adaptability of crack propagation on the curved surface.

[0031] In one embodiment, the blade is subjected to multiaxial coupled loads, including aerodynamic loads, temperature loads, and centrifugal force, according to actual service conditions. The stress field distribution of the blade during service is obtained, and initial cracks are implanted into the sub-model at stress concentration locations.

[0032] In one embodiment, by combining the fatigue crack propagation rate model of the material, the fatigue life loss corresponding to different crack parameters is calculated, and a quantitative relationship between the crack propagation path and the remaining life of the overall bladed disk is established.

[0033] This invention divides individual blade sub-models and uses a method combining ABAQUS and FRANC3D to predict the fatigue crack propagation behavior and fatigue life of the integral bladed disk, so as to achieve high-quality forming control, process optimization and fatigue life prediction of the integral bladed disk welded joint.

[0034] The above technical solution will be further explained below with reference to the accompanying drawings and examples: In one embodiment, refer to Figure 1 As shown in the figure, this embodiment presents a numerical simulation method for fatigue crack propagation in linear friction welding of an integral bladed disk. The specific steps include: S1. Construct a three-dimensional solid model and set material parameters; Specifically, a three-dimensional solid model of the integral bladed disk linear friction welding was established, and temperature-related material parameters were set. These material parameters include thermal conductivity, density, elastic modulus, Poisson's ratio, and specific heat capacity.

[0035] For simulating the plastic deformation of materials under high temperature and high strain rate conditions in linear friction welding, the Johnson-Cook model can effectively capture the complex plastic deformation behavior of materials under these conditions. Furthermore, by introducing temperature softening and strain rate strengthening terms, the Johnson-Cook model can accurately describe the strength decrease at high temperatures and the strength increase at high strain rates. The Johnson-Cook model expresses stress as a function of strain, strain rate, and temperature. The JC constitutive equation is shown below: (1) (2) In the formula, It is rheological stress. It is equivalent plastic strain. It is the strain rate. It is the normalized temperature, where T r It is a temperature change. It is room temperature. It is the melting point of the material. A, B, C, n and m It is a constant of the material. m It is an index of the temperature effect.

[0036] S2, Mesh Generation 40mm×18mm×15mm bosses were set at both the end of the integral bladed disk and on each blade as free deformation zones. These free deformation zones are the welding areas, with a mesh size of 1mm×1mm×1mm. Larger mesh sizes were used further away from the weld zone. The mesh type selected was C3D8RT element. This element configuration exhibits excellent deformation compatibility and stress field analytical performance. Its mesh demonstrates excellent anti-distortion stability under large deformation conditions, and the computational accuracy is significantly reduced by geometric nonlinearity. Therefore, it can achieve high accuracy and computational speed when analyzing the severe plastic deformation of linear friction welding.

[0037] In the model, the welding region is divided into a fine mesh and defined as the ALE domain using the "Adaptive Mesh Domain" function. The ALE method effectively controls the mesh quality of the welding region through mesh smoothing and re-meshing mechanisms, making it particularly suitable for scenarios involving high temperatures, high stress concentrations, and rapid material flow in linear friction welding processes. By combining appropriate explicit dynamic analysis steps, elastoplastic or viscoplastic material models, and a reasonable mesh update frequency, ALE technology can achieve accurate simulation of the welding dynamic process. To improve computational accuracy, the ALE sweep frequency is set to 1, with 50 mesh checks and re-meshing operations performed each time.

[0038] S3, Load and Boundary Condition Settings (1) Load parameters The average heat input power during linear friction welding can be calculated using the following formula:

[0039] In the formula, q Heat is generated by friction, where μ is the frictional interface coefficient. f The vibration frequency, P For welding pressure, A This represents the welding amplitude.

[0040] The uneven pressure distribution on the contact surface is caused by the angle between the applied pressure direction and the blade vibration direction. Simultaneously, the instantaneous loading of the welding pressure induces localized mesh stress concentration and instability. By adjusting the load increment and setting a smooth analysis step, a smooth transition during the loading process can be achieved, thereby effectively improving the frictional characteristics of the contact surface and suppressing excessive deformation. (2) Boundary condition settings Both the blades and the disk have their welding areas designed as free deformation zones. The disk is fully constrained in the X and Y axes, retaining only the Z-axis degree of freedom to simulate the actual welding pressure loading path; the blade assembly is limited to displacement only in the X-axis direction. The motion of the linear friction welding is set as a sinusoidal function variation. Temperature loads and heat transfer are simulated by setting a pre-temperature field and boundary conditions during the simulation. The initial temperature is set to 25 °C, and the temperature is uniform at all points at the initial moment. The air heat dissipation coefficient of the workpiece is 100 W / (m²). 2 The coefficient for converting frictional heat into plastic deformation heat (°C) is set to 0.9.

[0041] S4. Obtain the temperature field and stress field distribution characteristics of the joint.

[0042] The Explicit solver, combined with a hexahedral mesh, was used for calculations. The model defined the material's physical and mechanical properties, as well as the coefficient of friction, as they varied with temperature, and the Johnson-Cook constitutive model was selected to describe the material behavior. Simultaneously, thermal boundary conditions were set to simulate the temperature field distribution characteristics at the joint interface.

[0043] S5. Divide the model into sub-models and load them, then insert cracks at stress concentration locations.

[0044] Using FRANC3D software, key areas of the bladed disk were extracted, and the entire bladed disk was divided into sub-models of individual blades. In Abaqus, the stress field generated by welding was imported into the sub-models via node interpolation. The sub-model mesh was regenerated based on the M-integral for subsequent crack propagation calculations. Multiaxial coupled loads were applied to the blades according to actual service conditions. During service, the blades primarily bear periodic loads caused by airflow pressure (aerodynamic loads) and inertial forces generated by high-speed rotation (centrifugal force). They also bear thermal stress (temperature loads). Therefore, the stress field distribution of a single blade under coupled loads was obtained. Since stress concentration points are prone to crack initiation and propagation, cracks were implanted at stress concentration points to simulate fatigue crack propagation.

[0045] S6. The Influence of Crack Propagation on Blade Fatigue Life Since the blades in this paper are mainly subjected to centrifugal force and aerodynamic loads during service, primarily generating tensile stress, this paper focuses on open-type cracks. The crack tip stress intensity factor (SIF) is one of the most important parameters in fracture mechanics, closely related to crack propagation, material fracture toughness, load conditions, and geometry. Combining residual stress distribution, extended fracture mechanics methods (such as Paris's rule) are used to simulate the fatigue crack initiation and propagation process in the welded joint region. By combining the material's fatigue crack propagation rate model, the fatigue life loss corresponding to different crack parameters is calculated, establishing a quantitative relationship between the crack propagation path and the remaining life of the overall bladed disk, and evaluating the fatigue life of the welded joint.

[0046] In one embodiment, the integral bladed disk of the compressor is used as a welded component, made of GH4169 material. A three-dimensional solid model is created in Abaqus / CAE software, and its three-dimensional solid model is as follows: Figure 2As shown, the integral bladed disk can be divided into two parts. The bladed disk end height is 60 mm, the inner radius is 40 mm, and the outer radius is 120 mm. A 15 mm boss is set on the inclined surface as the welding area. The length and width of the friction surface are 40 mm and 18 mm, respectively. The blade, as the vibrating component, has a height of 70 mm. The welding bosses of the blade and the bladed disk are set as a uniform cross-section joint, and the welding areas are all set as free deformation areas. The blade part is constrained to have only the X-direction degree of freedom, and the motion mode of linear friction welding changes according to a sine function law.

[0047] Figure 3 The evolution of the temperature field perpendicular to the friction interface of the weld joint is shown. In the initial friction stage, the friction interface begins to heat up due to frictional heat generation. After entering the transition stage, the temperature continues to rise to a peak of 1300°C. At this time, the temperature field expands axially, but since no flash has formed, the heat is mainly dissipated through air convection. In this stage, frictional heat generation dominates the temperature change, the interface temperature field gradually becomes homogenized, and the vertical heat conduction effect is significantly enhanced. When entering the stable friction stage (>2 s), the highest temperature at the weld center stabilizes at 1300°C. At this time, the heat generated by plastic deformation due to adhesive friction becomes the main heat source, while the continuous extrusion of flash removes some heat, so that the heat generation and dissipation at the friction interface reach a dynamic balance, and the axial temperature distribution remains stable.

[0048] Figure 4 The dynamic evolution of heat flux density in the joint region at different time points during the welding process is shown. After 1 second of friction, the heat flux density at the interface center decreases significantly as heat gradually transfers into the workpiece. The heat flux density at the friction interface exhibits a rounded rectangular characteristic. During the transition to the steady-state phase, although the overall heat flux density decreases, the interface temperature gradually increases. In the stable friction phase, heat is generated by plastic deformation. This becomes the dominant heat generation mechanism, with the friction interface temperature continuously rising and the heat flux density gradually stabilizing. This is mainly because the friction interface temperature is high at this stage, but has not reached the melting point; the interface is primarily composed of ductile metal, and the friction mechanism changes from dry friction to adhesive friction.

[0049] Figure 5 This diagram illustrates the stress field distribution of a single blade. A single blade sub-model was cut from the overall bladed disk, and the blade was loaded with loads as experienced during actual service in ABAQUS. Simultaneously, the stress field generated in the linear friction welding simulation was imported into the single blade sub-model. Then, a static analysis simulation was performed in ABAQUS to obtain the stress field distribution of the single blade sub-model. It can be seen that significant stress concentration occurs at the leading and trailing edges of the blade.

[0050] Figure 6To establish the initial crack location and mesh generation for the crack propagation model, the single-blade mesh was regenerated using the M-integral criterion. Cracks were implanted in the stress concentration regions, namely the leading and trailing edges of the blade. A hybrid element topology strategy was adopted for the global mesh. The mesh at the crack leading edge was divided into element loops with a radius approximately one-tenth of the crack's minor axis. Eight 15-node C3D15 wedge elements were arranged at the crack leading edge. The wedge elements were surrounded by 20-node C3D20 hexahedral elements, while the remaining areas were divided using 10-node C3D10 tetrahedral elements. This mesh generation not only effectively improved computational accuracy but also significantly reduced the number of elements.

[0051] Figure 7 The diagram shows the stress distribution cloud map and fatigue crack propagation schematic at the trailing edge of the blade. In the initial stage, the stress value at the crack tip is relatively small, and the driving force for crack propagation is relatively small. However, in the fracture stage, the stress at the crack tip rapidly increases to 915.7 MPa and 1033.8 MPa. Cracks in the trailing edge region of the blade will face the risk of failure in the later stage of propagation due to the high stress state that appears locally.

[0052] Figure 8 SIF in the trailing edge region of the blade and aN Curve. From Figure 7 As can be seen from (a), the Type I stress intensity factor has a relatively uniform distribution and a high amplitude, making it the main driving force for crack propagation. From... Figure 7 (b) shows that the crack propagation rate of the leading edge of the blade is relatively slow in the early stage. However, as the number of cycles gradually increases, the crack propagation rate accelerates significantly, eventually leading to failure in a short period of time. The crack propagation rate of the trailing edge of the blade is significantly lower than that of the leading edge. This is mainly because the trailing edge region of the blade experiences lower loads and stress concentrations during service, resulting in a lower crack propagation rate.

[0053] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks, characterized in that... The specific steps are as follows: Establish a three-dimensional solid model of the integral bladed disk and set the temperature-related material thermophysical parameters and mechanical property parameters; A non-uniform mesh was used to mesh the three-dimensional solid model of the integral bladed disk; By setting loads and boundary conditions, and based on the geometry of the integral bladed disk "disk-boss-sloping surface", the welding heat input power is corrected to accurately reflect the pressure transmission loss of the disk-sloping surface. A three-dimensional thermo-mechanical coupled finite element analysis was performed on the linear friction welding process to obtain the temperature field and stress field distribution of the joint. Extract key areas of the bladed disk to establish a blade sub-model, and import the welding residual stress field into the sub-model through node interpolation; Based on the geometric characteristics of the blade surface, the mesh was re-divided according to the fracture mechanics M-integral criterion, and a three-ring unit loop and a layered transition unit structure were set. Multiaxial coupled loads are applied to the sub-model according to the actual service conditions to obtain the stress distribution of the blade, and initial cracks of preset size and orientation are implanted in the stress concentration area. Based on three-dimensional crack propagation technology, the propagation behavior of cracks under the coupled action of residual stress and multiaxial load is simulated. By combining the fatigue crack propagation rate model of materials, a quantitative relationship between crack propagation path and fatigue life is established to achieve life prediction.

2. The numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks according to claim 1, characterized in that: The specific method for correcting the welding heat input power is as follows: Welding pressure P Based on the inclined plane angle of the disk, the height of the welding interface, and the parameters of the disk height and radius, a coupled correction is performed. The correction formula is as follows: in, h 0 represents the height of the welding interface. w For the width of the welding boss, h 1 represents the height of the disk. θ 1 represents the angle of the inclined plane. P 0 represents the nominal welding pressure; The corrected expression for heat input power is: in, μ The coefficient of friction, f Let A be the vibration frequency and A be the amplitude.

3. The numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks according to claim 1, characterized in that: The non-uniform mesh division is specifically as follows: The weld and near-weld area use C3D8RT elements with local mesh refinement, and the mesh size is 1mm×1mm×1mm; the area away from the weld uses a gradually increasing mesh size.

4. The numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks according to claim 1, characterized in that: The method of re-meshing based on the fracture mechanics M-integral criterion includes: Three rings of elements are arranged at the crack leading edge. The closest ring uses eight 15-node C3D15 wedge elements, the outer ring uses 20-node C3D20 hexahedral elements, and the remaining area uses 10-node C3D10 tetrahedral elements. The mesh continuity and displacement coordination are achieved between the various types of elements through transition elements.

5. The numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks according to claim 1, characterized in that: The multi-axis coupled load includes centrifugal load, aerodynamic load and thermal load, and the load application takes into account the phase and amplitude coupling relationship in actual working conditions.

6. The numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks according to claim 1, characterized in that: The method of importing welding residual stress into the sub-model through node interpolation is achieved by using the data interaction interface between Abaqus and FRANC3D software to realize stress mapping from the overall model to the sub-model.

7. The numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks according to claim 1, characterized in that: Before implanting the initial crack, stress field verification is required to ensure that the boundary response of the sub-model is consistent with that of the overall model in the corresponding region.

8. The numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks according to claim 1, characterized in that: The crack propagation rate is calculated by combining the Paris formula or Forman formula with the stress intensity factor amplitude, and the fatigue life is obtained by integration.

9. The numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks according to claim 1, characterized in that: In the thermo-mechanical coupling analysis, the ALE adaptive mesh technique was adopted, and the mesh update frequency was set to 50 times per increment step to balance computational efficiency and simulation accuracy.

10. A numerical simulation system for fatigue crack propagation in linear friction welding of integral bladed disks, characterized in that, include: processor; And a memory having an instruction program that can be executed by a processor; the instruction program executes the numerical simulation method for fatigue crack propagation in linear friction welding of integral bladed disks as described in any one of claims 1-9.

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