A foreign body impact wear assessment method based on DEM solver

Abstract

The invention discloses a foreign object collision wear assessment method based on a DEM solver, wherein various contact collision simulation environments are set by the DEM solver, and contact collision detection is performed between an imported engine geometric model and FOD (Foreign Object Debris), that is, the engine geometric model and foreign object damage particles or particle clusters, FOD particles or FOD particle clusters, and contact collision numerical simulation and solution are performed in the subsequent calculation process, and then the wear assessment is performed on the engine geometric model where the contact collision occurs, so as to obtain the wear state of the collision position of the engine where the contact collision occurs. The method comprises the following steps: obtaining the engine geometric model and importing the engine geometric model into the DEM solver; setting the DEM solver contact collision simulation environment and initializing it; performing contact collision detection and calculation on the engine geometric model based on the contact collision simulation environment to obtain contact collision information; and performing wear assessment on the engine geometric model where the contact collision occurs based on the contact collision information.

Description

Technical Field

[0001] The invention relates to the field of foreign body impact on aircraft engines, and in particular to a foreign body impact wear assessment method based on a DEM solver. Background Art

[0002] During the takeoff or landing phase of an aircraft turbine engine, the high-speed rotating turbine blades need to withstand greater pressure, centrifugal and high-frequency vibration stresses under the action of the front flow. If the engine inhales hard FOD (Foreign Object Debris) during this phase, it is likely to cause notches, pits or cracks on the fan blades and the front blades of the compressor, accompanied by stress concentration and microstructural damage. Different types of damage states will affect the high-cycle fatigue (HCF) strength, and then accelerate the propagation of blade cracks under the action of fatigue loads, greatly reducing the blade life and inducing premature blade fracture failure.

[0003] FOD can be easily sucked into the engine, causing it to fail. According to conservative estimates, the global losses caused by FOD are at least $3-4 billion per year. FOD not only causes huge direct losses, but also causes indirect losses such as flight delays, aborted takeoffs, and runway closures.

[0004] However, the current domestic and foreign research on the impact of FOD on aircraft engines mainly uses experimental means to make FOD impact fan blades at high speed to conduct multi-parameter research on the characteristics of the impact damage area and the mechanism of crack initiation and expansion behavior, and uses numerical analysis methods based on nonlinear structural mechanics to numerically solve the process of FOD impacting fan blades. However, experimental methods are not only costly, but also cause substantial damage to the inside of the material, making it difficult to conduct multi-parameter and multi-environmental state research. When hard FOD such as coins, parts or stones are sucked into the engine, they are broken by the impact of rotating fan blades or low-pressure compressors, and impact high-pressure compressor blades under the action of high-speed carrier flow, which can easily cause blade deformation and cause engine vibration. Especially when large hard residues enter the combustion chamber, it is likely to cause serious accidents. Summary of the invention

[0005] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0006] The purpose of the present invention is to solve the above-mentioned problem and provide a foreign object collision wear assessment method based on a DEM solver. The method can meet the foreign object debris (FOD) collision wear assessment requirements, set various contact collision simulation environments through a DEM solver (Discrete Element Method), then perform contact collision detection on an engine geometric model, and perform wear assessment on the engine geometric model where contact collision occurs.

[0007] The technical solution of the present invention is:

[0008] The present invention provides a method for evaluating the impact wear of foreign matter based on a DEM solver, comprising the following steps:

[0009] Obtaining the engine geometry model and importing the engine geometry model into the DEM solver;

[0010] Set up the DEM solver contact collision simulation environment and initialize it;

[0011] Conduct contact collision detection on the engine geometry model based on the contact collision simulation environment;

[0012] Wear assessment of an engine geometry subject to contact collision.

[0013] According to an embodiment of the foreign object collision wear assessment method based on a DEM solver of the present invention, the foreign object collision wear assessment method based on a DEM solver uses a polyhedral grid to perform grid preprocessing on an engine geometric model to obtain a refined engine geometric model.

[0014] According to an embodiment of the foreign object collision wear assessment method based on the DEM solver of the present invention, the contact collision simulation environment includes an FOD particle cluster physical model, a calculation domain, model collision boundary conditions and a contact collision calculation physical model; wherein the FOD particle cluster physical model is a physical model of foreign objects that collide with various components of the engine geometric model, and the DEM solver first performs contact collision detection on the FOD particle cluster physical model in the calculation domain, and performs contact collision numerical simulation in the subsequent calculation process.

[0015] According to an embodiment of the foreign body collision wear assessment method based on the DEM solver of the present invention, the contact collision detection and calculation includes the following steps:

[0016] Start contact collision detection and calculation, perform neighborhood detection on the FOD particle cluster physical model in the calculation domain, and determine whether a contact collision scene occurs in the calculation domain; if so, perform contact calculation; if not, continue neighborhood detection;

[0017] According to the contact calculation results, it is judged whether the FOD particle cluster physical model is broken; if so, the neighborhood detection is re-performed on the FOD particle cluster physical model; if not, the motion calculation is performed on the FOD particle cluster physical model at the current time step;

[0018] Perform motion calculation on the FOD particle cluster physical model of the current time step, and update the position of the FOD particle cluster physical model according to the motion calculation result;

[0019] Determine whether the scheduled calculation time has not been reached and whether there is still a FOD particle cluster physical model in the calculation domain; if so, continue the neighborhood detection; if not, end the contact collision detection and calculation and obtain the contact collision information.

[0020] According to an embodiment of the foreign object collision wear assessment method based on the DEM solver of the present invention, the contact collision scenario includes particle-particle contact collision, particle-object surface contact collision and FOD particle cluster crushing; wherein, when the DEM solver detects the occurrence of a contact collision scenario, contact calculation is performed on the FOD particle cluster physical model-FOD particle cluster physical model or the FOD particle cluster physical model-engine geometric model where the contact collision occurs.

[0021] According to an embodiment of the foreign object collision wear assessment method based on the DEM solver of the present invention, the contact collision calculation physical model includes a contact collision physical model, through which the motion trajectory and contact collision of the FOD particle cluster physical model are numerically simulated to obtain simulated contact collision parameters, thereby performing contact collision calculation; wherein, the contact calculation includes contact force calculation, torque calculation and foreign object overlapping volume calculation.

[0022] According to an embodiment of the foreign body collision wear assessment method based on the DEM solver of the present invention, the contact collision model adopts a nonlinear spring-damper contact model based on the Hertz-Mindlin contact theory to obtain the contact force calculation parameters when the contact collision scene occurs, and the contact force is calculated by the following formula:

[0023] F contact =F n n+F t t;

[0024] Among them, F contact is the resultant contact force,

[0025] F n represents the normal component of the contact force,

[0026] F t represents the tangential component of the contact force,

[0027] n represents the normal vector,

[0028] t represents the tangent vector.

[0029] According to an embodiment of the foreign body collision wear assessment method based on the DEM solver of the present invention, the contact force normal component is an elastic normal component based on the Hertz contact theory, which is calculated by the following formula:

[0030] ;

[0031] Among them, S n represents the normal relative displacement at the contact point,

[0032] represents the normal vector of the relative velocity at the contact point,

[0033] represents the damping coefficient,

[0034] Represents the stiffness coefficient.

[0035] According to an embodiment of the foreign body collision wear evaluation method based on the DEM solver of the present invention, the stiffness coefficient The elastic deformation of the model used to describe the contact collision scenario is calculated using the following formula:

[0036] ;

[0037] Among them, E * represents Young's modulus, R * It represents the effective or equivalent radius of the FOD particle cluster physical model during the contact collision process.

[0038] According to an embodiment of the foreign body collision wear assessment method based on the DEM solver of the present invention, the Young's modulus E * The model's ability to resist deformation in contact collision scenarios is calculated using the following formula:

[0039] ;

[0040] in,

[0041] E1 and E2 represent the equivalent Young's modulus of the FOD particle cluster physical model-FOD particle cluster physical model or the FOD particle cluster physical model-engine geometry model in the contact collision scenario, respectively;

[0042] v1 and v2 represent the Poisson's ratio of the FOD particle cluster physical model-FOD particle cluster physical model or the FOD particle cluster physical model-engine geometric model in the contact collision scenario.

[0043] According to an embodiment of the foreign body collision wear assessment method based on the DEM solver of the present invention, the contact force tangential component is an energy dissipation tangential component based on the Mindlin-Deresiewic contact theory, and is calculated by the following formula:

[0044]

[0045] ;

[0046] Where μ represents the friction coefficient,

[0047] F n represents the normal component of the contact force,

[0048] S τ represents the tangential relative displacement of the contact part,

[0049] represents the tangential component of the relative velocity at the contact point,

[0050] S τ ,max represents the maximum relative displacement in the tangential direction when the FOD particle cluster physical model starts to slide,

[0051] m * represents the effective mass,

[0052] ητ represents the tangential damping ratio.

[0053] According to an embodiment of the foreign matter collision wear assessment method based on the DEM solver of the present invention, the tangential damping ratio ητ is calculated by the formula:

[0054] ;

[0055] Where ε represents the restitution coefficient of the interaction between the contacting objects.

[0056] According to an embodiment of the foreign object collision wear assessment method based on the DEM solver of the present invention, the contact collision detection also includes a time step calibration, and whether the time step calibration is needed is determined by calculating the critical time step of FOD particles of a specific size.

[0057] According to an embodiment of the foreign matter collision wear assessment method based on the DEM solver of the present invention, the FOD particles of a specific size are particles with a density of ρ P , shear modulus G, Poisson's ratio v, and radius R PThe critical time step is calculated by the following formula:

[0058]

[0059] x=0.163v+0.8766;

[0060] Among them, Δt critical It is the critical time step. When the time step in the DEM solver is higher than or equal to the critical time step, time step calibration is performed.

[0061] According to an embodiment of the foreign object collision wear assessment method based on the DEM solver of the present invention, the DEM solver constructs a plurality of different breakable FOD particle cluster physical models by setting different breakable bond parameters and the number of spherical particles.

[0062] According to an embodiment of the foreign object collision wear assessment method based on the DEM solver of the present invention, the breakable bond parameters include normal stress and tangential stress, and the strength of the breakable bond is set by calculating the normal stress and the tangential stress; wherein the DEM solver constructs a variety of different types of FOD particle cluster physical models by applying breakable bonds of different strengths to different numbers of spherical particles.

[0063] According to an embodiment of the foreign body collision wear assessment method based on the DEM solver of the present invention, the normal stress σ and the tangential stress τ of the breakable bond are calculated and set by the following formula:

[0064]

[0065] ;

[0066] in, represents the normal force that can break the bond,

[0067] represents the tangential force that can break the bond,

[0068] represents the normal torque,

[0069] is the tangential torque,

[0070] A b represents the cross-sectional area of ​​the breakable bond,

[0071] J is the polar moment of inertia,

[0072] R b Represents the radius of a breakable bond.

[0073] According to an embodiment of the foreign object collision wear assessment method based on the DEM solver of the present invention, the contact collision calculation physical model also includes a wear physical model, and the wear physical model is used to perform wear assessment on the engine geometric model where the contact collision occurs.

[0074] According to an embodiment of the foreign matter collision wear assessment method based on the DEM solver of the present invention, the DEM solver adopts the Archard wear model as the wear physics model, and performs wear assessment by calculating the total volume V of the surface wear material of the engine geometric model where the contact collision occurs, and the calculation formula is as follows:

[0075] ;

[0076] Among them, F τ represents the tangential force on the worn surface,

[0077] s τ Indicates the sliding distance of the worn surface;

[0078] H represents the hardness of the wear material;

[0079] k represents a dimensionless empirical constant.

[0080] Compared with the prior art, the present invention has the following beneficial effects: the present invention adopts the contact collision algorithm of the DEM solver, and the physical model of the FOD particle cluster-the physical model of the FOD particle cluster or the physical model of the FOD particle cluster-the engine geometric model where the contact collision occurs is used for contact collision detection and calculation, so as to obtain contact collision information, and then the wear assessment of the engine geometric model where the contact collision occurs is performed according to the obtained contact collision information. Through the DEM solver, the present invention can numerically solve the possible FOD collision accidents in production operation or research and teaching efficiently, quickly, at low cost and without number restrictions from the mechanism. In addition, in the present invention, the DEM solver has great scalability, and can set a variety of contact collision simulation environments according to the evaluation requirements, and by setting FOD of any scale and any shape, perform multi-physical model modeling and analysis under any external conditions, so as to obtain numerical model parameters that can accurately describe the physical state of FOD when it hits multiple parts of the engine. In addition, the present invention also uses a wear physics model to perform wear assessment on the engine geometric model where the collision occurs, and obtains the wear state of the collision position of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] The above features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or features may have the same or similar reference numerals.

[0082] Figure 1 It is a flow chart showing an embodiment of a method for evaluating foreign matter collision wear based on a DEM solver of the present invention.

[0083] Figure 2 is a flow chart showing an embodiment of the contact collision detection and calculation method of the present invention.

[0084] Figure 3 Schematic diagram showing an embodiment of a contact collision model of the present invention. DETAILED DESCRIPTION

[0085] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Note that the aspects described below in conjunction with the accompanying drawings and specific embodiments are only exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0086] Disclosed herein is an embodiment of a method for evaluating foreign matter collision wear based on a DEM solver. Figure 1 is a flow chart showing an embodiment of the foreign matter collision wear evaluation method based on the DEM solver of the present invention. Figure 1 ,The following is a detailed description of each step of the shared site ,selection method based on the hybrid clustering algorithm.

[0087] Step S1: Obtain an engine geometry model and import the engine geometry model into a DEM solver.

[0088] In this embodiment, a DEM solver is used to analyze the wear of an aircraft engine undergoing a collision simulation test. The engine model is a three-dimensional geometric model of the actual size of the aircraft engine, and the file format is usually iges, stp, stl, etc. Since the engine contains a large number of components that are unnecessary for the study of foreign body collision wear assessment and will cause additional consumption of computer resources, it is necessary to appropriately simplify the engine geometry model and perform fine processing before importing it into the DEM solver for collision analysis.

[0089] Specifically, after the engine model is imported into the DEM solver, the unnecessary parts of the engine model are first deleted, and only the parts that may be impacted by FOD, such as the fan, high-pressure compressor, low-pressure compressor, and bearings, are retained. Then, the engine geometry model is pre-meshed using polyhedral meshes, and the minimum surface mesh size is set to 1% of the basic size of the model to cover the initial engine geometry model with surface meshes, thereby obtaining a refined engine geometry model. This refined processing method can make the object-surface contact unit of the engine geometry model more refined, which is conducive to obtaining higher contact collision accuracy in the later calculation process.

[0090] In addition, in this embodiment, the FOD particle cluster physical model is a destructible particle cluster model composed of a plurality of rigid spherical particles with physical properties such as a determined physical radius and a contact radius. Among them, each FOD particle cluster physical model can change its size by increasing or reducing spherical particles according to actual needs, and the DEM solver forms a rigid sphere with physical attributes such as radius, Young's modulus and elastic coefficient by applying a breakable bonding bond of a specific strength to different numbers of spherical particles. In addition, in this embodiment, the overall number of FOD particle clusters can also be adjusted according to the actual wear assessment needs.

[0091] Specifically, in this embodiment, the DEM solver can construct multiple different breakable FOD particle cluster physical models by setting different breakable bond parameters and the number of spherical particles. Among them, the breakable bond parameters include normal stress and tangential stress, and the DEM solver sets the strength of the breakable bond by calculating the size of the normal stress and tangential stress. The calculation formulas for normal stress σ and tangential stress τ are as follows:

[0092]

[0093] ;

[0094] in, represents the normal force that can break the bond, represents the tangential force that can break the bond, represents the normal torque, Indicates the tangential torque, A b represents the cross-sectional area of ​​the breakable bond, J represents the polar moment of inertia, R b Represents the radius of a breakable bond.

[0095] Step S2: Setting the DEM solver contact collision simulation environment and initializing it.

[0096] In this embodiment, the DEM solver can determine the calculation domain boundary of this contact collision analysis and the object surface boundary that may collide with the FOD based on the refined engine geometry model in step S1, and assign the relevant contact collision numerical model.

[0097] Specifically, in this embodiment, before using the DEM solver for contact collision detection, the DEM solver contact collision simulation environment is set according to the refined engine geometry model in step S1, such as the FOD particle cluster physical model, calculation domain, model collision boundary conditions and contact collision calculation physical model that meet the collision analysis requirements, and these set parameters are initialized.

[0098] Step S3: performing contact collision detection and calculation on the engine geometric model based on the contact collision simulation environment to obtain contact collision information.

[0099] In this embodiment, the FOD particle cluster physical model is a physical model of foreign matter that impacts various components of the engine geometric model. The DEM solver performs contact collision detection and calculation on the FOD particle cluster physical model in the calculation domain to obtain contact collision information, thereby completing the contact collision simulation evaluation. FIG2 is a flow chart showing an embodiment of the contact collision detection and calculation method of the present invention, please refer to FIG2. Figure 2 ,The following is a detailed description of each step of the contact collision detection domain calculation method.

[0100] Step S31: Start contact collision detection and calculation, perform neighborhood detection on the FOD particle cluster physical model in the calculation domain, and determine whether a contact collision scene occurs in the calculation domain; if so, perform contact calculation; if not, continue neighborhood detection.

[0101] In the present embodiment, after DEM solver completes contact collision simulation environment setting and initialization, contact collision detection and calculation are started, and spatial positioning and boundary contact detection are carried out between FOD particle cluster physical models and between FOD particle cluster physical model and the object surface boundary of engine.Wherein, contact collision detection and calculation are constituted by two main stages, including neighborhood detection stage and contact calculation stage.In the first stage, DEM solver does not consider FOD actual geometric shape at this stage, and only carries out neighborhood detection, to save calculation time.And the second stage DEM solver can carry out detailed contact calculation to the particle pair and particle boundary in the neighborhood, to determine the geometry related parameters required for FOD particle cluster physical model.Wherein, the geometric parameters of FOD particle cluster physical model include particle and geometric radius, contact radius and geometric shape of particle cluster constituted by particle, as the variable of physical model in the next step DEM contact collision.These geometries are not directly related to FOD particle cluster physical model parameters, and are independent variable parameters.

[0102] Specifically, in this embodiment, the contact collision scene includes particle-particle contact collision, particle-object surface contact collision and FOD particle cluster crushing. After the DEM solver detects the contact collision scene, the motion trajectory and contact collision of the FOD particle cluster physical model that has contact collision are numerically simulated through the contact collision physical model, so as to obtain the simulated contact collision parameters and perform contact calculation. Among them, the contact calculation includes contact force calculation, moment calculation and foreign matter overlapping volume calculation, etc.

[0103] In one embodiment, the DEM solver uses a linear spring-damper contact model based on the Hertz-Mindlin contact theory as a contact collision model, and obtains the contact force calculation parameters when a contact collision scenario occurs through this model. Specifically, in this embodiment, the normal force in the DEM simulation needs to mainly consider two requirements: first, the force must be a repulsive force; second, since the granular medium is an extremely dissipative system, the normal force must allow significant energy dissipation. Since this contact force model is similar to the linear spring-buffer model, the main difference is that the elastic component and the damping component of the normal force are both nonlinear functions of the overlapping parts in the Hertzian model. Therefore, the linear spring-damper contact model based on the Hertz-Mindlin contact theory is used as the contact collision model. Figure 3 is a schematic diagram showing an embodiment of the contact collision model of the present invention, taking the contact collision scene of particle-particle contact collision as an example, combined with Figure 3 , further illustrating this embodiment.

[0104] like Figure 3 As shown, in this embodiment, when two spherical FOD particle cluster physical models come into contact and collide, a parallel linear spring-damper connected in series with a slider transverse to the contact point P is used to represent the tangential component of the contact force, and a parallel linear spring-damper connected in series to the longitudinal point P is used to represent the normal component of the contact force. The contact force resultant F when the contact and collision occur is calculated by the following formula: contact :

[0105] F contact =F n n+F t t;

[0106] Among them, F n represents the normal component of the contact force, F t represents the tangential component of the contact force, n represents the normal vector, and t represents the tangential vector.

[0107] In addition, in this embodiment, the nonlinear spring-damper contact model uses the elastic part of the spring response, and the normal component of the contact force is the elastic normal component based on the Hertz contact theory, which is calculated by the following formula:

[0108]

[0109] Among them, S n represents the normal relative displacement at the contact point, represents the normal vector of the relative velocity at the contact point, represents the damping coefficient, Represents the stiffness coefficient.

[0110] Specifically, in this embodiment, the stiffness coefficient It is used to describe the elastic deformation of the model in the contact collision scenario. The calculation formula is as follows:

[0111]

[0112] Among them, E * represents Young's modulus, R * It represents the effective or equivalent radius of the FOD particle cluster physical model during the contact collision process.

[0113] Young's modulus E * It is used to represent the model's ability to resist deformation in a contact collision scenario. The calculation formula is as follows:

[0114]

[0115] Wherein, E1 and E2 represent the equivalent Young's modulus of the FOD particle cluster physical model-FOD particle cluster physical model or the FOD particle cluster physical model-engine geometric model in the contact collision scenario, respectively. v1 and v2 represent the Poisson's ratio of the FOD particle cluster physical model-FOD particle cluster physical model or the FOD particle cluster physical model-engine geometric model in the contact collision scenario.

[0116] In addition, in this embodiment, the nonlinear spring-damper contact model uses a damper to consider the energy dissipation during the collision, and the tangential component of the contact force is the energy dissipation tangential component based on the Mindlin-Deresiewic contact theory, which is calculated by the following formula:

[0117]

[0118] ;

[0119] Where μ represents the friction coefficient, F n represents the normal component of the contact force, S τ represents the tangential relative displacement of the contact part, Represents the tangential component of the relative velocity at the contact point, S τ ,max represents the maximum relative displacement in the tangential direction when the FOD particle cluster physical model starts to slide, m * represents the effective mass, and ητ represents the tangential damping ratio. The tangential damping ratio ητ is calculated by the formula:

[0120]

[0121] ε represents the restitution coefficient of the interaction between the contacting objects.

[0122] Step S32: Determine whether the FOD particle cluster physical model is broken based on the contact calculation results; if so, re-perform field detection; if not, perform motion calculation on the FOD particle cluster physical model of the current time step.

[0123] In this embodiment, when the external stress acting on the FOD particle cluster physical model exceeds the strength of its internal bonding bonds, the FOD particle cluster physical model will break at the location where the internal stress threshold is first reached.

[0124] Specifically, in this embodiment, the strength of the breakable bonding bond between particles set by the FOD particle cluster physical model can be adjusted according to actual conditions. The internal stress threshold of each FOD particle cluster physical model is not necessarily the same. Therefore, after a contact collision occurs, the FOD particle cluster physical model may not be broken. Only when the strength of the calculated contact force exceeds the strength of the breakable bonding bond obtained by the FOD particle cluster physical model, it is possible for the contact point where the contact force occurs to be broken. If the FOD particle cluster physical model that has a contact collision breaks, return to the previous step and perform field detection again.

[0125] In addition, in this embodiment, contact collision detection also includes time step calibration, which determines whether time step calibration is required by calculating the critical time step of FOD particles of a specific size.

[0126] Specifically, in this embodiment, for a density of ρ P , shear modulus G, Poisson's ratio v, and radius R P The FOD particles are subjected to Rayleigh analysis to calculate the critical time step Δt critical Calibrate the time step in the DEM solver, and the calculation formula is as follows:

[0127]

[0128] x=0.163v+0.8766.

[0129] If the time step in the DEM solver is higher than this critical value, the numerical calculation results may be inaccurate. If the time step in the DEM solver is lower than this critical value, it will lead to excessive consumption of computing resources.

[0130] Step S33: Perform motion calculation on the FOD particle cluster physical model of the current time step, and update the position of the FOD particle cluster physical model according to the motion calculation result.

[0131] In this embodiment, if the FOD particle cluster physical model that has contact collision is not broken, the FOD position, velocity, time step and other information of the current time step are used to calculate the movement position of the FOD particle cluster physical model in the next time step, and update the position of the FOD particle cluster physical model.

[0132] In addition, in this embodiment, the DEM solver will record all the spatial coordinates of each FOD particle cluster physical model, and connect the spatial coordinates in all calculation domains in chronological order to form a polyline or Bezier curve as the motion trajectory of the FOD particle cluster physical model.

[0133] Step S34: Determine whether the predetermined calculation time has not been reached and whether there is still a FOD particle cluster physical model in the calculation domain; if so, continue the field detection; if not, end the contact collision detection and calculation and obtain the contact collision information.

[0134] In this embodiment, the DEM solver sets a calculation time according to the wear assessment requirements. After the motion calculation is completed, it is necessary to determine whether the contact collision detection of the current time step has not reached the predetermined calculation time and whether there is still a FOD particle cluster physical model in the calculation domain. If so, the contact collision detection is continued until all FOD particle clusters in the calculation domain are physically broken. Otherwise, the contact collision detection and calculation are terminated, the contact collision information is obtained, and then the wear assessment of the engine geometric model is performed based on the contact collision information. Among them, the contact collision information includes the contact force, motion trajectory, and contact position of the engine geometric model or the FOD particle cluster physical model where the contact collision occurs.

[0135] Step S4: performing wear assessment on the engine geometric model where contact collision occurs.

[0136] In this embodiment, the contact collision calculation physical model also includes a wear physical model. When the FOD particle cluster physical model contacts and collides with the wall of the engine geometric model, the wear condition of the collision position between the FOD particle cluster physical model and the engine geometric model, i.e., the aircraft engine, needs to be evaluated based on the set wear physical model.

[0137] In one embodiment, the DEM solver uses the Archard wear model as the wear physics model, and performs wear assessment on the collision position of the aircraft engine by calculating the total volume V of the surface wear material of the engine geometric model where the contact collision occurs. The calculation formula is as follows:

[0138]

[0139] Among them, F τ represents the tangential force on the worn surface, s τrepresents the sliding distance of the wear surface; H represents the hardness of the wear material; k represents a dimensionless empirical constant. The Archard wear model can effectively describe the wear state of the engine after being impacted by FOD from multiple perspectives based on the mechanism of FOD and the physical parameters of the surface.

[0140] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

[0141] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. The technician may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as resulting in a departure from the scope of the present invention.

[0142] The various illustrative logic blocks, modules, and circuits described in conjunction with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in cooperation with a DSP core, or any other such configuration.

[0143] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside in a user terminal as discrete components.

[0144] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented as a computer program product in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. Storage media may be any available medium accessed by a computer. As an example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of the medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wherein disk often reproduces data magnetically, while disc reproduces data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0145] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for evaluating the impact wear of foreign objects based on a DEM solver, characterized in that: The following steps are involved: Obtaining the engine geometry model and importing the engine geometry model into the DEM solver; Set up the DEM solver contact collision simulation environment and initialize it; Conduct contact collision detection and calculation on the engine geometry model based on the contact collision simulation environment to obtain contact collision information; Based on the contact collision information, the wear of the engine geometric model where the contact collision occurs is evaluated; wherein, The contact collision simulation environment includes a FOD particle cluster physical model, a computational domain, a model collision boundary condition, and a contact collision computational physical model; wherein the FOD particle cluster physical model is a physical model of foreign matter that collides with various components of an engine geometric model, and the DEM solver first performs contact collision detection on the FOD particle cluster physical model in the computational domain, and performs contact collision numerical simulation in a subsequent computational process; The contact collision detection and calculation comprises the following steps: Start contact collision detection and calculation, perform neighborhood detection on the FOD particle cluster physical model in the calculation domain, and determine whether a contact collision scene occurs in the calculation domain; if so, perform contact calculation; if not, continue neighborhood detection; According to the contact calculation results, it is judged whether the FOD particle cluster physical model is broken; if so, the neighborhood detection is re-performed on the FOD particle cluster physical model; if not, the motion calculation is performed on the FOD particle cluster physical model at the current time step; Perform motion calculation on the FOD particle cluster physical model of the current time step, and update the position of the FOD particle cluster physical model according to the motion calculation result; Determine whether the scheduled calculation time has not been reached and whether there is still a FOD particle cluster physical model in the calculation domain; if so, continue the neighborhood detection; if not, end the contact collision detection and calculation and obtain the contact collision information.

2. The method for evaluating the impact wear of foreign matter based on a DEM solver according to claim 1, characterized in that: The DEM solver-based foreign body collision wear assessment method uses polyhedral meshes to perform mesh preprocessing on the engine geometry model to obtain a refined engine geometry model.

3. The method for evaluating the impact wear of foreign matter based on a DEM solver according to claim 1, characterized in that: The contact collision scenarios include particle-particle contact collision, particle-object surface contact collision and FOD particle cluster crushing; wherein, when the DEM solver detects the occurrence of a contact collision scenario, contact calculation is performed on the FOD particle cluster physical model-FOD particle cluster physical model or the FOD particle cluster physical model-engine geometric model where the contact collision occurs.

4. The method for evaluating the impact wear of foreign matter based on a DEM solver according to claim 1, characterized in that: The contact collision calculation physical model includes a contact collision physical model, through which the motion trajectory and contact collision of the FOD particle cluster physical model are numerically simulated to obtain simulated contact collision parameters, thereby performing contact collision calculation; wherein, the contact calculation includes contact force calculation, torque calculation and foreign matter overlapping volume calculation.

5. The method for evaluating the impact wear of foreign matter based on a DEM solver according to claim 4 is characterized in that: The contact collision model uses a nonlinear spring-damper contact model based on the Hertz-Mindlin contact theory to obtain the contact force calculation parameters when a contact collision scenario occurs, and the contact force is calculated using the following formula: F contact =F n n+F t t; Among them, F contact is the resultant contact force, F n represents the normal component of the contact force, F t represents the tangential component of the contact force, n represents the normal vector, t represents the tangent vector.

6. The method for evaluating the impact wear of foreign matter based on a DEM solver according to claim 5 is characterized in that: The normal component of the contact force is an elastic normal component based on the Hertz contact theory and is calculated using the following formula: ； Among them, S n represents the normal relative displacement at the contact point, represents the normal vector of the relative velocity at the contact point, represents the damping coefficient, Represents the stiffness coefficient.

7. The method for evaluating the impact wear of foreign matter based on a DEM solver according to claim 6, characterized in that: The stiffness coefficient The elastic deformation of the model used to describe the contact collision scenario is calculated using the following formula: ； Among them, E * represents Young's modulus, R * It represents the effective or equivalent radius of the FOD particle cluster physical model during the contact collision process.

8. The method for evaluating the impact wear of foreign matter based on a DEM solver according to claim 7, characterized in that: The Young's modulus E * The model's ability to resist deformation in contact collision scenarios is calculated using the following formula: ； in, E1 and E2 represent the equivalent Young's modulus of the FOD particle cluster physical model-FOD particle cluster physical model or the FOD particle cluster physical model-engine geometry model in the contact collision scenario, respectively; v1 and v2 represent the Poisson's ratio of the FOD particle cluster physical model-FOD particle cluster physical model or the FOD particle cluster physical model-engine geometric model in the contact collision scenario.

9. The method for evaluating the impact wear of foreign matter based on a DEM solver according to claim 5, characterized in that: The contact force tangential component is an energy dissipation tangential component based on the Mindlin-Deresiewic contact theory and is calculated using the following formula: ； Where μ represents the friction coefficient, F n represents the normal component of the contact force, S τ represents the tangential relative displacement of the contact part, represents the tangential component of the relative velocity at the contact point, S τ ,max represents the maximum relative displacement in the tangential direction when the FOD particle cluster physical model starts to slide, m * represents the effective mass, ητ represents the tangential damping ratio.

10. The method for evaluating foreign matter collision wear based on DEM solver according to claim 9, characterized in that: The tangential damping ratio ητ is calculated by the formula: ； Where ε represents the restitution coefficient of the interaction between the contacting objects.

11. The method for evaluating foreign matter collision wear based on DEM solver according to claim 1, characterized in that: The contact collision detection also includes time step calibration, which determines whether time step calibration is needed by calculating the critical time step of FOD particles of a specific size.

12. The method for evaluating foreign matter collision wear based on DEM solver according to claim 11, characterized in that: The FOD particles of the specific size are of density ρ P , shear modulus G, Poisson's ratio v, and radius R P The critical time step is calculated by the following formula: x=0.163v+0.8766; Among them, Δt critical It is the critical time step. When the time step in the DEM solver is higher than or equal to the critical time step, time step calibration is performed.

13. The method for evaluating foreign matter collision wear based on DEM solver according to claim 1, characterized in that: The DEM solver constructs a plurality of different breakable FOD particle cluster physical models by setting different breakable bonding bond parameters and the number of spherical particles.

14. The method for evaluating foreign matter collision wear based on DEM solver according to claim 13, characterized in that: The breakable bond parameters include normal stress and tangential stress, and the strength of the breakable bond is set by calculating the normal stress and the tangential stress; wherein the DEM solver constructs a variety of different types of FOD particle cluster physical models by applying breakable bonds of different strengths to different numbers of spherical particles.

15. The method for evaluating foreign matter collision wear based on DEM solver according to claim 14, characterized in that: The normal stress σ and tangential stress τ of the breakable bond are calculated using the following formula: ； in, represents the normal force that can break the bond, represents the tangential force that can break the bond, represents the normal torque, is the tangential torque, A b represents the cross-sectional area of ​​the breakable bond, J is the polar moment of inertia, R b Represents the radius of a breakable bond.

16. The method for evaluating foreign matter collision wear based on DEM solver according to claim 1, characterized in that: The contact collision calculation physical model also includes a wear physical model, which is used to perform wear assessment on the engine geometric model where the contact collision occurs.

17. The method for evaluating foreign matter collision wear based on DEM solver according to claim 16, characterized in that: The DEM solver uses the Archard wear model as the wear physics model and performs wear evaluation by calculating the total volume V of the surface wear material of the engine geometric model where contact collision occurs. The calculation formula is as follows: ； Among them, F τ represents the tangential force on the worn surface, s τ Indicates the sliding distance of the worn surface; H represents the hardness of the wear material; k represents a dimensionless empirical constant.

Images