Numerical simulation method and system for aero-engine blade impacted by large pieces of sand

Abstract

The application relates to an aviation engine blade numerical simulation method and system for large-grit impact in the technical field of aviation, and the method comprises the following steps: establishing a deformation motion equation of large grit and an engine blade structure and performing discrete calculation by adopting an FEM method to obtain an FEM equation; in the case that the blade is impacted by large grit, a contact algorithm between FEM and FEM is adopted, and in the case that damage occurs, an SPDH method is adopted to calculate a damaged unit; a geometric model of large grit and the engine blade structure is established and is discretized to obtain a grid discrete model; the FEM equation is simulated and calculated based on the grid discrete model; and data processing is performed on the calculation result to obtain damage morphology, damage fragment motion conditions and the like of the engine blade under the action of large-grit impact. The application realizes complete reproduction of the process of high-speed large-grit impact on the aviation engine blade damage and secondary impact damage of other structures.

Description

Technical Field

[0001] This invention belongs to the field of aerospace technology, specifically relating to a numerical simulation method and system for aero-engine blades subjected to impact from large pieces of gravel. Background Technology

[0002] When operating in harsh environments, aero-engines inevitably ingest particulate contaminants of varying properties, such as large-hardness and large-particle-size gravel, sand, and hail. Once ingested, these large particles are carried by the high-speed airflow, causing impact damage to the engine blades. Gravel impact damage within aero-engines can lead to decreased aerodynamic performance, structural performance, and operational efficiency, and may even result in serious problems such as flight accidents. Therefore, predicting and assessing the structural impact damage caused by large particles within aero-engines is essential.

[0003] Current research methods for studying the damage to aero-engine blades from impacts with large, hard gravel mainly include experimental and numerical simulation methods. Experimental methods primarily involve constructing high-speed impact test rigs, setting up optical measurement equipment, and performing high-speed photography and post-impact micro-CT scans to obtain the impact process and post-impact characteristics. Numerical simulation mainly utilizes high-performance computers, relying on physical models and numerical calculation methods to simulate the dynamic process and obtain details of the impact. Commonly used methods include the finite element method (FEM), smoothed particle hydrodynamics (SPH), and material point method (MPM).

[0004] Although the experimental method can obtain the true impact damage morphology, the experimental results are random, the experimental setup is time-consuming and labor-intensive, and it cannot capture the complete dynamic process of the impact damage and movement of damage fragments on the aero-engine blade structure.

[0005] Therefore, conducting in-depth research on the particle impact damage process of aero-engine blades using numerical simulation technology is of great significance for revealing the laws governing structural impact damage and predicting the dynamic process of damage. However, current numerical simulation methods include two main approaches: one is the finite element method (FEM) to simulate the impact process. This method relies on mesh elements, which can lead to computational crashes due to mesh distortion and entanglement during damage calculations. Furthermore, this method deletes damaged elements, failing to capture the continued motion of damaged elements and the secondary impact damage process on other blades. The other approach is meshless particle methods, such as SPH and MPM. While these methods have significant advantages in simulating large structural deformations and damage, they suffer from drawbacks such as tensile instability, low computational efficiency, and poor accuracy in static calculations.

[0006] Therefore, we need to further develop a more comprehensive method for simulating and predicting the high-speed damage of large gravel to aero-engine blades. Summary of the Invention

[0007] To address the aforementioned technical problems, embodiments of the present invention provide a numerical simulation method and system for aero-engine blades subjected to impacts from large pieces of gravel, thereby resolving the issues raised in the prior art.

[0008] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0009] One embodiment of the present invention provides a numerical simulation method for aero-engine blades subjected to impact from large pieces of gravel, the method comprising:

[0010] Step 1: Establish the deformation motion equations for the large gravel and engine blade structure;

[0011] Step 2: Discretize the deformation motion equations using the finite element method (FEM) to obtain the FEM equations;

[0012] Step 3: Under the condition that the engine blade structure is impacted by large pieces of gravel, the contact algorithm between FEMs is used to simulate and calculate the deformation and damage of the large pieces of gravel and the engine blade structure.

[0013] Step 4: When the engine blade structure is damaged by the impact of large pieces of gravel, the FEM-SDPH transformation algorithm that considers the transformation of elements in the structural damage and the smooth discrete particle fluid dynamics SDPH method that simulates the motion of damaged fragments are used for simulation calculation.

[0014] Step 5: Establish a geometric model of the large gravel and engine blade structure and perform mesh discretization to obtain a mesh discretized model;

[0015] Step 6: Simulate and calculate the FEM equations based on the grid discretization model to obtain the calculation results;

[0016] Step 7: Process the calculation results to obtain the damage morphology of the engine blades under the impact of large gravel, the movement of damaged fragments, and the secondary impact process on other structures.

[0017] Optionally, step 3 includes:

[0018] A local search method was used to determine whether contact forces were generated between large pieces of gravel and the engine blade structure.

[0019] If it is determined that a contact force is generated, the contact force is calculated using a penalty function;

[0020] The contact force is incorporated as an external force into the FEM equation.

[0021] Optionally, the method for calculating the contact force using a penalty function includes: calculating the contact force using the following formula.

[0022]

[0023] Among them, f s Indicates contact force. L Indicates the depth of intrusion. k i Indicates the penalty factor. n i This represents the unit vector of the outward normal to the element surface.

[0024] Optionally, step 4 includes:

[0025] Calculate the damage value of engine blade structure caused by impact from large pieces of sand and gravel;

[0026] Determine whether the damage value has reached a predetermined value;

[0027] If the predetermined value is reached, the FEM-SDPH conversion algorithm is used to convert the damage unit into SDPH particles, and the SDPF method is used to simulate the trajectory of the damage fragments.

[0028] Optionally, the step of calculating the damage value of the engine blade structure subjected to impact from large pieces of gravel includes: calculating the damage value using the following formula:

[0029] ,

[0030] in, for The damage increment caused by equivalent plastic strain over time. Let D be the damage plastic strain under constant pressure, and D be the damage value.

[0031] Optionally, the step of simulating the trajectory of damaged fragments using the SDPF method includes:

[0032] The location information can be obtained by calculating the velocity and density of the damaged fragments using the following formula.

[0033] ,

[0034] ,

[0035] , This represents two SDPH particles. , They represent particles respectively The density and total stress tensor, , They represent particles respectively The density and total stress tensor, Represents particles exist The velocity component in the direction, Represents particles exist Displacement components in the direction, Represents particles exist External force components in the direction, Represents particles exist Displacement components in the direction, For particles and particles Artificial adhesion between them Represents particles quality Represents particles exist The velocity component in the direction, For particles Supports the total number of SDPH particles within the domain. For particles For particles The smooth kernel function of the influence, where t represents time.

[0036] Optionally, the data processing of the calculation results includes:

[0037] The calculation results are input into the specified software, which graphically displays the damage morphology of the engine blades under the impact of large gravel, the movement of damaged fragments, and the secondary impact process on other structures.

[0038] Optionally, the time step for simulating the FEM equation based on the grid discrete model is 0.00000001 seconds.

[0039] Optionally, the method further includes:

[0040] Output a calculation result every 1000 steps.

[0041] Another embodiment of the present invention provides a numerical simulation system for aero-engine blades subjected to impact from large pieces of gravel, the system comprising:

[0042] The first unit is used to establish the deformation motion equations for large gravel and engine blade structures.

[0043] The second unit is used to discretize the deformation motion equations using the finite element method (FEM) to obtain the FEM equations.

[0044] The third unit is used to simulate and calculate the deformation and damage of the large sand and gravel and the engine blade structure under the condition that the engine blade structure is impacted by large sand and gravel.

[0045] The fourth unit is used to simulate the damage to engine blades caused by impacts from large pieces of gravel. It employs the FEM-SDPH transformation algorithm, which considers element transformation in structural damage, and the SDPH method, which simulates the motion of damaged fragments, for simulation calculations.

[0046] The fifth unit is used to establish a geometric model of the large gravel and engine blade structure and to perform mesh discretization to obtain a mesh discretized model;

[0047] The sixth unit is used to perform simulation calculations on the FEM equations based on the grid discretization model and obtain the calculation results;

[0048] The seventh unit is used to process the calculation results to obtain the damage morphology of the engine blades under the impact of large gravel, the movement of damaged fragments, and the secondary impact process on other structures.

[0049] The embodiments of the present invention have the following beneficial effects:

[0050] This invention effectively combines the advantages of traditional mesh methods and meshless methods. It combines the two methods by using the FEM method before damage occurs, which has high calculation accuracy and efficiency. After damage occurs, it switches to the SDPH method to continue tracking the movement of damaged fragments and their secondary damage process to other structures. This invention achieves a complete reproduction of the damage to aero-engine blades caused by high-speed impact of large pieces of gravel and its secondary impact damage process to other structures. It is an effective tool for the design of aero-engine anti-gravel impact structures.

[0051] Of course, implementing any product or method of the present invention does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 A flowchart of a numerical simulation method for an aero-engine blade subjected to impact from large pieces of gravel, according to an embodiment of this application;

[0054] Figure 2This is a schematic diagram of a large piece of gravel impacting an aero-engine blade according to an embodiment of this application;

[0055] Figure 3 This is a schematic diagram illustrating the physical process of pit formation according to an embodiment of this application;

[0056] Figure 4 The images show the morphology of blade dents at different impact velocities according to an embodiment of this application.

[0057] Figure 5 This is a graph showing the variation of dent depth with impact velocity according to an embodiment of this application;

[0058] Figure 6 This is a schematic diagram of a numerical simulation system for an aero-engine blade subjected to impact from large pieces of gravel, according to an embodiment of this application. Detailed Implementation

[0059] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can also be combined with each other.

[0060] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of the invention, the terms "first," "second," "third," "fourth," etc., are used only to distinguish descriptions and should not be construed as merely or implying relative importance.

[0061] This invention proposes a numerical method for fluid dynamics of smooth particles using the finite element method. The finite element method is used to calculate the material of the blade before damage, while the smooth particles are used to track and simulate the material after damage. This method obtains the morphology of the aero-engine blade surface after being damaged by large pieces of gravel, providing a reference for preventing aero-engine blades from being damaged by particle impact.

[0062] like Figure 1 The diagram shows a flowchart of a numerical simulation method for aero-engine blades subjected to impact from large pieces of gravel, provided by an embodiment of the present invention. The method includes the following steps:

[0063] Step 1: Establish the deformation motion equations for the large gravel and engine blade structure;

[0064] Step 2: Discretize the deformation motion equations using the FEM method to obtain the FEM equations;

[0065] Step 3: Under the condition that the engine blade structure is impacted by large pieces of gravel, the contact algorithm between FEMs is used to simulate and calculate the deformation and damage of the large pieces of gravel and the engine blade structure.

[0066] Step 4: When the engine blade structure is damaged by the impact of large pieces of gravel, the FEM-SDPH transformation algorithm that considers the transformation of elements in the structural damage and the smooth discrete particle hydrodynamics (SDPH) method that simulates the motion of damaged fragments are used for simulation calculation.

[0067] Step 5: Establish a geometric model of the large gravel and engine blade structure and perform mesh discretization to obtain a mesh discretized model;

[0068] Step 6: Simulate and calculate the FEM equations based on the grid discretization model to obtain the calculation results;

[0069] Step 7: Process the calculation results to obtain the damage morphology of the engine blades under the impact of large gravel, the movement of damaged fragments, and the secondary impact process on other structures.

[0070] To further understand the present invention, the above steps will be described in more detail below.

[0071] The deformation motion of the large gravel and engine blade structure in step 1 can be described by the following basic dynamic equations:

[0072] (1)

[0073] In the formula: i =1,2,3; j =1,2,3 σ Represents the stress tensor. f i Force per unit volume A This represents the differential operator with respect to coordinates.

[0074] The motion velocity of large gravel and engine blade structural units can be obtained using the above formula (1). However, the stress tensor in this equation is an unknown quantity. In order to close the motion equation of a single gravel and engine blade structure, this invention adopts a Johnson-Cook constitutive model with damage. This model describes the dynamic mechanical characteristics of solid materials, such as large deformation and high strain rate, through flow stress and failure strain. Its flow stress σ eq The expression is:

[0075] (2)

[0076] in It is a material constant. As a damage variable, This indicates that the material is undamaged. This indicates that the material has completely failed. It is cumulative damage plastic strain, , , The cumulative damage plastic strain rate ratio factor, It is cumulative plastic strain. It is a user-defined reference strain rate. Dimensionless temperature. T is the current temperature of the material. It is room temperature. It refers to the material's melting point. In reality, when a material develops a macrocrack, the critical value of the damage variable is less than 1, and the failure criterion can be described as... ,in This is the critical value for the damage variable. Damage variable It is the cumulative plastic strain The function can be described as follows:

[0077] (3)

[0078] The rate of change of damage, To accumulate plastic strain rate, It is the damage threshold. It is the fracture plastic strain, which is related to the material's stress triaxiality, strain rate, and temperature, as shown in the following formula.

[0079] (4)

[0080] in For material constants, For stress triaxiality, The average normal stress. Principal stresses in three directions. σ x , σ y , σ z Computational paradigm equivalent stress (von Mises) J :

[0081] (5)

[0082] In the formula: if J ≤ σ eq but σ ij Remain unchanged; if J > σ eqThe stress then returns to the yield surface proportionally, that is... σ ij = σ ij σ eq / J .

[0083] For normal stress, the Grüneisen equation of state is used for calculation:

[0084] (6)

[0085] in,

[0086] (7)

[0087] P H The specific formula for the reference pressure value is as follows: ρ For the density of the material, e Energy of materials

[0088] (8)

[0089] (9)

[0090] The density of steel is The coefficients in the formula are , , .

[0091] By superimposing formulas (2) and (6) and substituting them into formula (1), the motion velocity of the large gravel and engine blade structural unit can be obtained. Then, by combining the velocity-displacement relationship, the displacement of the large gravel and engine blade structural unit can be updated.

[0092] Step 2 involves discretizing the deformation motion equations using the FEM method. Since equation (1) is a partial differential equation, it cannot be directly calculated analytically and requires a numerical method for discretization. This invention uses the finite element method to simulate the deformation motion process of the engine blade structure. In the finite element method, the weighting function is selected as a trial function for approximate solution. , W i Let N be the weight function. i For trial functions. Substituting the dynamic equation (1) into the equivalent integral form, we get

[0093] (10)

[0094] Ω represents the integration region. T iRepresents surface force. This represents the direction cosine of the slope normal in the principal coordinate system. i The values ​​are 1, 2, and 3, representing the three directions in the Cartesian coordinate system. This is obtained through integration by parts.

[0095] (11)

[0096] Substituting equation (11) into equation (10) yields

[0097] (12)

[0098] In elasticity, constitutive relations can be used to obtain...

[0099] (13)

[0100] in Represents the elasticity matrix. Represents the strain matrix. Indicates strain, This represents the displacement vector of a point. It can be obtained from geometric relationships.

[0101] (14)

[0102] Substituting equations (13) and (14) into equation (12) yields the following result.

[0103] (15)

[0104] From this, we can obtain the finite element equation.

[0105] (16)

[0106] in Represents the overall stiffness matrix. This represents a known structural load vector.

[0107] The above discretization process transforms equation (1) into a numerically discretized equation that can be directly calculated, thus obtaining the FEM equation.

[0108] Step 3 involves establishing a contact algorithm between FEMs (Front End Mechanisms) impacted by large sand and gravel on the engine blade structure. This specifically includes:

[0109] Since the calculation using the above formula (16) involves the contact problem between large pieces of gravel and the engine blade structure, a contact algorithm is needed to calculate the contact force. This invention uses the penalty function method to calculate the contact force. A local search is used to determine whether a contact force is generated between the large pieces of gravel and the engine blade structure. If the large pieces of gravel intrude into the unit surface of the engine blade structure, that is, a contact force is generated, then the contact force needs to be calculated; otherwise, no processing is required. The contact force of the intruding unit node is calculated according to the penalty function method as follows:

[0110] (17)

[0111] In the formula, f s Indicates contact force. L Indicates the depth of intrusion. k i Indicates the penalty factor. n i This represents the unit vector of the outward normal to the element surface.

[0112] Unit penalty function k i The calculation method is as follows

[0113] (18)

[0114] In the formula, f Indicates the scaling factor. K i Bulk modulus A i For the unit surface area, V i The unit volume is denoted as .

[0115] bulk modulus of unit K i The specific calculation method is as follows:

[0116] (19)

[0117] in, E For elastic modulus, v It is Poisson's ratio.

[0118] The contact force acting on the finite element is equal in magnitude and opposite in direction to the contact force acting on the node of the intruding element. The contact force f at the contact point... s Interpolate the contact force f at the four nodes of the surface mesh. sn The contact force is then incorporated as an external force into the FEM dynamic equations for further solution.

[0119] M a ¨( t ) + Ca ˙( t ) + K a ( t ) = f sn (20)

[0120] , , and f sn These represent the system's mass matrix, damping matrix, stiffness matrix, and nodal load vector, respectively. a ¨( t ), a ˙( t ), a ( t ) represent the acceleration, velocity, and displacement of the node, respectively.

[0121] The deformation and damage process of each unit under the contact between the large gravel and the engine blade structure can be calculated using formula (20).

[0122] Step 4 involves establishing the FEM-SDPH transformation algorithm that considers element transformation during structural damage and the SDPH method that simulates the motion of damage fragments.

[0123] In step 3, if the material element deformation is very severe and exceeds a certain limit, it indicates that the object structure has been damaged. This can be achieved by calculating the damage value of the engine blade structure under the impact of large pieces of gravel; determining whether the damage value has reached a predetermined value; if it has reached the predetermined value, an error will occur if the calculation is continued using formula (20). In this case, the FEM needs to be converted into particles for further calculation. This invention uses a novel FEM-SDPH conversion algorithm to describe the process of the engine blade structure being converted into damaged fragments. The Johnson-Cook constitutive model with damage mentioned in step 1 is added to the finite element calculation method of the blade structure, and whether the material has completely yielded and failed is used as the element conversion criterion:

[0124] (twenty two)

[0125] for The damage increment caused by equivalent plastic strain over time. The damage plastic strain is defined as the damage strain under constant pressure. When the damage value D satisfies equation (22), that is, when the damage value is 1, the FEM is converted into SDPH free particles, making the conversion condition more reasonable. When the FEM reaches the damage condition, the background particles set at its nodes will be converted into SDPH particles. The position, velocity, mass, and stress of the SDPH particles are inherited from the corresponding background particles and no longer have the properties of the background particles. The calculation is performed according to the SDPH particles.

[0126] The motion control equations for simulating the trajectory of damaged debris using the SDPF method are as follows:

[0127] (twenty three)

[0128] (twenty four)

[0129] in, , This represents two SDPH particles. , They represent particles respectively The density and total stress tensor, , They represent particles respectively The density and total stress tensor, Represents particles exist The velocity component in the direction, Represents particles exist Displacement components in the direction, Represents particles exist External force components in the direction, Represents particles exist Displacement components in the direction, For particles and particles Artificial adhesion between them Represents particles quality Represents particles exist The velocity component in the direction, For particles Supports the total number of SDPH particles within the domain. For particles A smoothing kernel function for the influence of particles. This invention uses a modified kernel function to improve the unit decomposition characteristics of particles near the boundary or irregularly distributed particles, achieving approximate zero-order and first-order uniformity of particles. Let h be the particle's spatial position vector, and h be the smooth length of the region of influence of the kernel function. The velocity and density of the fragments are calculated using formulas (23) and (24), thereby obtaining their position information.

[0130] Step 5 involves establishing a geometric model of the large gravel and the aero-engine blades and performing mesh discretization.

[0131] This invention uses NASA Rotor 37 compressor blades for numerical simulation studies of gravel impact. A schematic diagram of the geometric models of the large gravel pieces and the engine blades is shown below. Figure 2 As shown. Gravel at 30 ◦ The impact surface of the engine blades is simulated to represent the impact of the compressor against gravel during rotation. Both the engine blades and the gravel meshes utilize structured hexahedral meshes. Constraints are applied to the bottom of the engine blades to ensure structural stability during particle impact and to facilitate obtaining the impact morphology of the blades. The parameter settings for the calculations are shown in Table 1.

[0132] Table 1

[0133]

[0134] Step 6 describes the numerical simulation calculation process, which includes:

[0135] Using the model established in step 5 as the geometric boundary condition, the specific calculation process is as follows: First, the initial velocity of the large gravel and the engine blade structure is given. Based on each element of the large gravel and the engine blade structure obtained by discretization in step (6), the position of each element of the large gravel and the engine blade structure at each moment is calculated and updated using the velocity-displacement relationship. It is then determined whether the position of the large gravel and the engine blade structure is in contact. If they are in contact, it indicates that the large gravel is impacting the engine blade structure. At this time, the contact force can be calculated according to formula (17), and then the contact force is added to the large gravel and the engine blade structure. On the corresponding contact unit, the motion velocity of each unit of the large gravel and engine blade structure is calculated using formula (20), and then the position of each unit of the large gravel and engine blade structure is obtained using the velocity-displacement relationship. At the same time, based on the stress and strain of each unit of the large gravel and engine blade structure, it is determined whether the finite element of the engine blade structure is in a damaged and failed state according to formula (22). Formula (22) can be used to determine whether it is in a damaged and failed state. If it is determined to be in a damaged and failed state, it is converted into SDPH particles, and the velocity, density and position of the failed unit are calculated and updated using formulas (23) and (24). In this way, the effective simulation of the impact of large gravel on the aero-engine blade structure is realized. The calculation time step is set to 0.00000001s, and a data file (in .dat format) is output every 1000 steps for subsequent calculation result processing. The termination time is 0.3ms.

[0136] The method for processing the calculation results in step 7 can be as follows: input the calculation results into a designated software program to graphically display the damage morphology of the engine blades under the impact of large gravel, the movement of damaged fragments, and the secondary impact process on other structures, revealing the causes of different damage morphologies such as dents, small notches, tears, and large notches. The designated software program can be, for example, Tecplot.

[0137] like Figure 3 The diagram illustrates the process of a compressor blade's pressure surface being impacted by gravel, resulting in a dent. To more clearly demonstrate the blade deformation, the gravel model is omitted, and only the blade model is shown. Figure 3 As can be seen, at t=0.08ms, the gravel has already impacted the blade's pressure surface, and slight wrinkles have appeared on the leading edge of the blade. This is due to the deformation of the blade caused by the impact force of the gravel. At t=0.16ms, as the gravel continues to move forward, compared to t=0.08ms, the blade surface has changed from wrinkles to more obvious small pits. This is because the continuous impact of the gravel on the blade's pressure surface leads to more severe deformation. At t=0.24ms, compared to t=0.16ms, with the continuous impact of the gravel, the small pits on the blade's pressure surface have developed into larger pits. In summary, as the gravel continuously impacts the blade's pressure surface, the deformation of the blade surface goes through the stages of wrinkles, small pits, and finally large pits. This demonstrates that the structural impact algorithm proposed in this invention can obtain the complete dynamic process of gravel impact on the blade structure, resulting in pit damage.

[0138] This invention, while keeping other conditions constant, obtained the morphology of the pits on the blade surface under different gravel impact velocities, such as... Figure 4 As shown. The dent depth varies with impact velocity as follows. Figure 5 As shown. By Figure 4 It can be seen that as the speed at which gravel impacts the blades increases, the dents develop more severely; from Figure 5 It can be seen that when the particle impact velocity is 100 m / s, the pit depth is 2 mm. As the velocity increases to 120 m / s, the pit depth is 2.8 mm. When the velocity reaches 140 m / s, the pit depth increases to 3.6 mm. This is because as the velocity increases, the interaction force between the gravel and the blade increases, and the blade deformation becomes more severe, resulting in a deeper pit at the leading edge of the blade at the same time.

[0139] Based on this, we can further obtain the formation process of damage morphologies such as small notches, tears, and large notches, reveal the formation mechanism of different damage morphologies of blades, and provide an effective tool for future large-scale engineering applications.

[0140] This invention effectively combines the advantages of traditional mesh methods and meshless methods. It combines the two methods by using the FEM method before damage occurs, which has high calculation accuracy and efficiency. After damage occurs, it switches to the SDPH method to continue tracking the movement of damaged fragments and their secondary damage process to other structures. This invention achieves a complete reproduction of the damage to aero-engine blades caused by high-speed impact of large pieces of gravel and its secondary impact damage process to other structures. It is an effective tool for the design of aero-engine anti-gravel impact structures.

[0141] In addition, compared with traditional experimental methods, the present invention has at least the following advantages: numerical simulation can complete process prediction with only electronic computers, without the need for experimental platforms and sites required for physical experiments, which greatly reduces the consumption of manpower, material resources and financial resources. At the same time, it is easy to perform repeated calculations, eliminates the randomness of experiments, and can clearly capture every detail of the damage process of aero-engine blades, providing an effective tool for the protective design of aero-engine blades.

[0142] This invention has at least the following advantages over other methods for simulating impact damage to aero-engine blades:

[0143] It overcomes the problems of mesh distortion and entanglement in the traditional mesh numerical method during damage calculation. It automatically converts the mesh after damage into particles for tracking calculation and has the characteristics of adaptability, meshlessness and Lagrangian.

[0144] It overcomes the problems of traditional single-particle methods in calculating small deformations and undamaged structures, such as tensile instability, large computational load, and low numerical accuracy.

[0145] The finite element method is used to calculate the undamaged parts, which has the advantages of good stability and high numerical accuracy.

[0146] It fully combines the advantages of traditional meshing and meshless methods while effectively avoiding the disadvantages of both, making it a technology with great practical value and application prospects.

[0147] This invention also provides a numerical simulation system for aero-engine blades subjected to impact from large pieces of gravel, such as... Figure 6 The diagram shown illustrates the system structure, which includes:

[0148] Unit 1, Section 61, is used to establish the deformation motion equations for large gravel and engine blade structures.

[0149] Unit 62 is used to discretize the deformation motion equations using the finite element method (FEM) to obtain the FEM equations.

[0150] Unit 3, 63, is used to simulate and calculate the deformation and damage of large sand and gravel and engine blade structure under the condition that the engine blade structure is impacted by large sand and gravel.

[0151] Unit 4, 64, is used to simulate the damage to engine blades caused by impact from large pieces of gravel, employing the FEM-SDPH transformation algorithm that considers element transformation in structural damage and the SDPH method that simulates the movement of damage fragments.

[0152] Unit 5, item 65, is used to establish a geometric model of large gravel and engine blade structure and to perform mesh discretization to obtain a mesh discretized model.

[0153] Unit 66 is used to perform numerical simulation calculations of the FEM equations based on the grid discretization model, and obtain the calculation results;

[0154] Unit 7, 67, is used to process the calculation results to obtain the damage morphology of the engine blades under the impact of large gravel, the movement of damaged fragments, and the secondary impact process on other structures.

[0155] Regarding the system in the above embodiments, the specific manner in which each unit performs operations has been described in detail in the embodiments related to the method, and will not be elaborated here.

[0156] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0157] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0158] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A numerical simulation method for aero-engine blades subjected to impact from large pieces of gravel, characterized in that, The method includes: Step 1: Establish the deformation motion equations for the large gravel and engine blade structure; Step 2: Discretize the deformation motion equations using the finite element method (FEM) to obtain the FEM equations; Step 3: Under the condition that the engine blade structure is impacted by large pieces of gravel, the contact algorithm between FEMs is used to simulate and calculate the deformation and damage of the large pieces of gravel and the engine blade structure. Step 4: When the engine blade structure is damaged by the impact of large pieces of gravel, the FEM-SDPH transformation algorithm that considers the transformation of elements in the structural damage and the smooth discrete particle fluid dynamics SDPH method that simulates the motion of damaged fragments are used for simulation calculation. Step 5: Establish a geometric model of the large gravel and engine blade structure and perform mesh discretization to obtain a mesh discretized model; Step 6: Simulate and calculate the FEM equations based on the grid discretization model to obtain the calculation results; Step 7: Process the calculation results to obtain the damage morphology of the engine blades under the impact of large gravel, the movement of damaged fragments, and the secondary impact process on other structures.

2. The method according to claim 1, characterized in that, Step 3 includes: A local search method was used to determine whether contact forces were generated between large pieces of gravel and the engine blade structure. If it is determined that a contact force is generated, the contact force is calculated using a penalty function; The contact force is incorporated as an external force into the FEM equation.

3. The method according to claim 2, characterized in that, The method for calculating contact force using a penalty function includes: calculating the contact force using the following formula. ， Among them, f s Indicates contact force. L Indicates the depth of intrusion. k i Indicates the penalty factor. n i This represents the unit vector of the outward normal to the element surface.

4. The method according to claim 1, characterized in that, Step 4 includes: Calculate the damage value of engine blade structure caused by impact from large pieces of sand and gravel; Determine whether the damage value has reached a predetermined value; If the predetermined value is reached, the FEM-SDPH conversion algorithm is used to convert the damage unit into SDPH particles, and the SDPF method is used to simulate the trajectory of the damage fragments.

5. The method according to claim 4, characterized in that, The step of calculating the damage value of the engine blade structure caused by the impact of large pieces of sand and gravel includes: calculating the damage value using the following formula: ， in, for The damage increment caused by equivalent plastic strain over time. Let D be the damage plastic strain under constant pressure, and D be the damage value.

6. The method according to claim 4, characterized in that, The steps for simulating the trajectory of damaged debris using the SDPF method include: The location information can be obtained by calculating the velocity and density of the damaged fragments using the following formula. ， ， , This represents two SDPH particles. , They represent particles respectively The density and total stress tensor, , They represent particles respectively The density and total stress tensor, Represents particles exist The velocity component in the direction, Represents particles exist Displacement components in the direction, Represents particles exist External force components in the direction, Represents particles exist Displacement components in the direction, For particles and particles Artificial adhesion between them Represents particles quality Represents particles exist The velocity component in the direction, For particles Supports the total number of SDPH particles within the domain. For particles For particles The smooth kernel function of the influence, where t represents time.

7. The method according to claim 1, characterized in that, The data processing of the calculation results includes: The calculation results are input into the specified software, which graphically displays the damage morphology of the engine blade structure under the impact of large sand and gravel, the movement of damaged fragments, and the secondary impact process on other structures.

8. The method according to claim 1, characterized in that, The time step for simulating the FEM equation based on the grid discrete model is 0.00000001 seconds.

9. The method according to claim 1 or 8, characterized in that, The method further includes: Output a calculation result every 1000 steps.

10. A numerical simulation system for the impact of large sand and gravel on aero-engine blades, characterized in that, The system includes: The first unit is used to establish the deformation motion equations for large gravel and engine blade structures. The second unit is used to discretize the deformation motion equations using the finite element method (FEM) to obtain the FEM equations. The third unit is used to simulate and calculate the deformation and damage of the large sand and gravel and the engine blade structure under the condition that the engine blade structure is impacted by large sand and gravel. The fourth unit is used to simulate the damage to engine blades caused by impacts from large pieces of gravel. It employs the FEM-SDPH transformation algorithm, which considers element transformation in structural damage, and the SDPH method, which simulates the motion of damaged fragments, for simulation calculations. The fifth unit is used to establish a geometric model of the large gravel and engine blade structure and to perform mesh discretization to obtain a mesh discretized model; The sixth unit is used to perform simulation calculations on the FEM equations based on the grid discretization model and obtain the calculation results; The seventh unit is used to process the calculation results to obtain the damage morphology of the engine blades under the impact of large gravel, the movement of damaged fragments, and the secondary impact process on other structures.

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