A method and device for constructing an equivalent mechanical model of an engine

Abstract

The application discloses an engine equivalent mechanical model construction method and device. The method comprises the following steps: firstly, obtaining the structural characteristics of an engine and establishing a preliminary equivalent mechanical model; then, optimizing the preliminary equivalent mechanical model and generating an equivalent mechanical model; next, testing the equivalent mechanical model, judging whether the equivalent mechanical model meets the equivalent accuracy requirement, and if yes, determining that the equivalent mechanical model construction is completed, and if not, re-establishing the equivalent mechanical model. The engine equivalent mechanical model construction method and device of the application embodiment specifically describe the construction process of the equivalent mechanical model, can quickly, conveniently, efficiently and accurately establish the equivalent mechanical model, make the equivalent mechanical model have higher credibility, and further guarantee the reliability of the equivalent mechanical model through the equivalent rationality test of the equivalent mechanical model.

Description

Technical Field

[0001] This application relates to the field of impact dynamics technology, and in particular to a method and apparatus for constructing an equivalent mechanical model of an engine. Background Technology

[0002] With the increasing risk of impacts to buildings and facilities, research on the impact resistance of critical structures such as dams and nuclear power plants has become a hot topic. This research primarily involves structural materials, structural forms, and design methods. During an impact, the overall stiffness of the aircraft, excluding the engine, is relatively low, resulting primarily in overall structural deformation. However, the aircraft engine has relatively high stiffness, and during an impact, it may cause significant localized penetration into the structure. Therefore, aircraft engine impact tests are necessary to study the response and damage of buildings or facilities to aircraft impacts, and to explore how to improve the impact resistance of buildings or facilities and protect personnel and property by modifying structural materials and design methods. However, conducting impact tests directly using prototype aircraft engines is extremely expensive; therefore, research on prototype aircraft engine impact tests is currently very limited both domestically and internationally.

[0003] Currently, Sugano et al. published "Local damage to reinforced concrete structures caused by impact of aircraft engine missiles." This paper, based on tests of fighter jet turbojet engines impacting reinforced concrete slabs, established a simplified model of the aircraft engine and conducted scaled-down tests. However, the article did not provide the process for establishing the simplified model, nor did it specify its applicable scope. Following this research, subsequent studies have directly used this simplified model to conduct impact tests on other types of structures. Patent CN106777490 discloses a method for calculating the impact resistance of a stern shaft sealing device based on the large-mass method. According to the geometric characteristics of the stern shaft sealing device, various components are simulated to establish a finite element analysis model. Then, a large-mass element M is set, i.e., a point is established in the finite element analysis model, and the mass of this point is assigned the mass of the ship. Based on the constraint relationship between the stern shaft sealing device and the ship, the constraint between the stern shaft sealing device and this point is established. Dynamic impact loads are applied to the large-mass point to simulate impact loads, and these impact loads are applied to the finite element analysis model of the stern shaft sealing device. The impact resistance calculation method for in-cabin equipment is then used for the calculation. However, the patent does not provide the specific process for determining the parameter values ​​in the finite element analysis model, nor does it discuss the correctness and applicability of the model. Summary of the Invention

[0004] This application aims to at least partially address one of the aforementioned technical problems.

[0005] Therefore, the first objective of this application is to propose a method for constructing an equivalent mechanical model of an engine, specifically describing the construction process of the equivalent mechanical model, so as to achieve the rapid, convenient, efficient and accurate establishment of the equivalent mechanical model, so that the equivalent mechanical model has high credibility, and further ensures the reliability of the equivalent mechanical model by passing the equivalence rationality test.

[0006] The second objective of this application is to propose an engine equivalent mechanical model construction device.

[0007] To achieve the above objectives, the first aspect of this application proposes a method for constructing an equivalent mechanical model of an engine, including:

[0008] Obtain the structural characteristics of the engine and establish a preliminary equivalent mechanical model;

[0009] The preliminary equivalent mechanical model is optimized to generate an equivalent mechanical model;

[0010] The equivalent mechanical model is tested to determine whether it meets the requirements for equivalent accuracy.

[0011] If the equivalent accuracy requirements are met, then the equivalent mechanical model is considered to have been successfully constructed.

[0012] If the equivalent accuracy requirement is not met, then the equivalent mechanical model should be reconstructed.

[0013] Optionally, a preliminary equivalent mechanical model may be established, including:

[0014] The concentrated and dispersed mass components in the engine are determined based on the mass distribution curve along the engine axis.

[0015] The mass concentration part is equivalent to the disk part of the preliminary equivalent mechanical model;

[0016] The mass dispersion portion is equivalent to the cylindrical shell portion of the preliminary equivalent mechanical model.

[0017] Optionally, the preliminary equivalent mechanical model is optimized to generate an equivalent mechanical model, including:

[0018] The thickness h of the disk portion can be calculated using Formula 1. n Formula 1: Among them, M n The mass d represents the mass of the disk portion. e ρ represents the diameter of the engine. n The density of the engine material is represented, and the disk portion of the preliminary equivalent mechanical model is optimized based on the thickness.

[0019] The length of the cylindrical shell section is determined based on the structural characteristics of the engine.

[0020] Based on the load-displacement curve of the engine, the crushing force of the cylindrical shell section is obtained;

[0021] The design value of the wall thickness of the cylindrical shell section is verified based on the crushing force.

[0022] The cylindrical shell portion of the preliminary equivalent mechanical model is optimized based on the design values ​​of length and wall thickness.

[0023] Optionally, the wall thickness design value of the cylindrical shell section can be verified based on the crushing force, including:

[0024] The stable bearing capacity F of the cylindrical shell section is calculated using Formula 2. u Formula 2: F u =A s ·σ u , where A s σ represents the cross-sectional area of ​​the cylindrical shell portion. u Indicates buckling stress;

[0025] The wall thickness design value is verified based on the stable bearing capacity and crushing force.

[0026] Optional, buckling stress σ u It is obtained through calculation using either Formula 3 or Formula 4. Formula 3: Formula 4: Where fy represents the yield stress of the engine material, σcl represents the elastic buckling stress, and α0 represents the reduction factor. γ represents the safety factor of the attachment. It represents the dimensionless slenderness ratio.

[0027] Optional, dimensionless slenderness ratio The result is obtained through calculation using Formula 5. Formula 5: Among them, f y σ represents the yield stress of the engine material. cl Indicates elastic buckling stress. α0 represents the reduction factor. or E represents the elastic modulus of the engine material, t represents the design wall thickness, and r = d. e / 2,d e This indicates the diameter of the engine.

[0028] Optionally, the design wall thickness value can be verified based on the stable bearing capacity and crushing force, including:

[0029] The absolute error in calculating the stable bearing capacity and crushing force;

[0030] Determine whether the absolute error is less than or equal to a preset threshold;

[0031] If the ratio is less than or equal to the preset threshold, then the wall thickness design value is determined to meet the design requirements;

[0032] If the ratio is greater than the preset threshold, the wall thickness design value is adjusted and recalculated.

[0033] Optionally, the equivalent mechanical model can be tested, including:

[0034] The approximation of static crushing stiffness, impact force curve, and equivalence of impacting real structures in the equivalent mechanical model are examined.

[0035] Optionally, the approximation of the static crushing stiffness of the equivalent mechanical model can be tested, including:

[0036] The first static crushing stiffness curve of the engine and the second static crushing stiffness curve of the equivalent mechanical model were obtained.

[0037] Calculate the first similarity between the first static crushing stiffness curve and the second static crushing stiffness curve, and verify the equivalent mechanical model based on the first similarity.

[0038] The crushing sequence of each component was verified during static crushing of the equivalent mechanical model.

[0039] Optionally, the approximation of the impact force curve of the equivalent mechanical model can be tested, including:

[0040] Obtain the time history curve of the first impact force of the engine and the time history curve of the second impact force of the equivalent mechanical model;

[0041] Calculate the second similarity between the time history curves of the first and second impact forces, and verify the equivalent mechanical model based on the second similarity.

[0042] The failure sequence of each component during an engine impact was verified using an equivalent mechanical model.

[0043] Optionally, the equivalence of the equivalent mechanical model to the impacted real structure can be tested, including:

[0044] The first failure mode of the engine and the second failure mode of the equivalent mechanical model were obtained;

[0045] Verify the consistency between the first and second failure modes;

[0046] The third similarity of the remaining height of the engine and the equivalent mechanical model after the impact test on the real structure is calculated, and the equivalent mechanical model is verified based on the third similarity.

[0047] The engine equivalent mechanical model construction method of this application first obtains the structural features of the engine and establishes a preliminary equivalent mechanical model; then, it optimizes the preliminary equivalent mechanical model and generates a new equivalent mechanical model; next, it verifies the equivalent mechanical model to determine whether it meets the equivalence accuracy requirements. If it meets the requirements, the equivalent mechanical model is considered complete; otherwise, it is reconstructed. Therefore, this method fully considers the structural features of the engine and specifically describes the construction process of the equivalent mechanical model. It can quickly, conveniently, efficiently, and accurately establish the equivalent mechanical model, giving it high reliability. Furthermore, by verifying the equivalence rationality of the equivalent mechanical model, its reliability is further guaranteed. This significantly reduces time costs when using the equivalent mechanical model for related experiments and simultaneously improves experimental accuracy.

[0048] To achieve the above objectives, a second aspect of this application provides an apparatus for constructing an equivalent mechanical model of an engine, comprising:

[0049] A module was established to obtain the structural features of the engine and to build a preliminary equivalent mechanical model.

[0050] The generation module is used to optimize the preliminary equivalent mechanical model and generate an equivalent mechanical model.

[0051] The verification module is used to verify the equivalent mechanical model and determine whether the equivalent mechanical model meets the equivalent accuracy requirements.

[0052] The determination module is used to confirm that the equivalent mechanical model has been constructed if the equivalent accuracy requirements are met.

[0053] The Rebuild module is used to rebuild the equivalent mechanical model if the equivalent accuracy requirements are not met.

[0054] Optionally, create modules for:

[0055] The concentrated and dispersed mass components in the engine are determined based on the mass distribution curve along the engine axis.

[0056] The mass concentration part is equivalent to the disk part of the preliminary equivalent mechanical model;

[0057] The mass dispersion portion is equivalent to the cylindrical shell portion of the preliminary equivalent mechanical model.

[0058] Optional, a generation module, used for:

[0059] The thickness h of the disk portion can be calculated using Formula 1. n Formula 1: Among them, Mn The mass d represents the mass of the disk portion. e ρ represents the diameter of the engine. n The density of the engine material is represented, and the disk portion of the preliminary equivalent mechanical model is optimized based on the thickness.

[0060] The length of the cylindrical shell section is determined based on the structural characteristics of the engine.

[0061] Based on the load-displacement curve of the engine, the crushing force of the cylindrical shell section is obtained;

[0062] The design value of the wall thickness of the cylindrical shell section is verified based on the crushing force.

[0063] The cylindrical shell portion of the preliminary equivalent mechanical model is optimized based on the design values ​​of length and wall thickness.

[0064] Optional, a generation module, used for:

[0065] The stable bearing capacity F of the cylindrical shell section is calculated using Formula 2. u Formula 2: F u =A s ·σ u , where A s σ represents the cross-sectional area of ​​the cylindrical shell portion. u Indicates buckling stress;

[0066] The wall thickness design value is verified based on the stable bearing capacity and crushing force.

[0067] Optional, a generation module, used for:

[0068] Buckling stress σ u It is obtained through calculation using either Formula 3 or Formula 4. Formula 3: Formula 4: Among them, f y σ represents the yield stress of the engine material. cl This represents the elastic buckling stress, and α0 represents the reduction factor. γ represents the safety factor of the attachment. It represents the dimensionless slenderness ratio.

[0069] Optional, a generation module, used for:

[0070] Dimensionless slenderness ratio The result is obtained through calculation using Formula 5. Formula 5: Among them, f y σ represents the yield stress of the engine material. cl Indicates elastic buckling stress. α0 represents the reduction factor. or E represents the elastic modulus of the engine material, t represents the design wall thickness, and r = d. e / 2,d e This indicates the diameter of the engine.

[0071] Optional, a generation module, used for:

[0072] The absolute error in calculating the stable bearing capacity and crushing force;

[0073] Determine whether the absolute error is less than or equal to a preset threshold;

[0074] If the ratio is less than or equal to the preset threshold, then the wall thickness design value is determined to meet the design requirements;

[0075] If the ratio is greater than the preset threshold, the wall thickness design value is adjusted and recalculated.

[0076] Optional, the inspection module is used for:

[0077] The approximation of static crushing stiffness, impact force curve, and equivalence of impacting real structures in the equivalent mechanical model are examined.

[0078] Optional, the inspection module is used for:

[0079] The first static crushing stiffness curve of the engine and the second static crushing stiffness curve of the equivalent mechanical model were obtained.

[0080] Calculate the first similarity between the first static crushing stiffness curve and the second static crushing stiffness curve, and verify the equivalent mechanical model based on the first similarity.

[0081] The crushing sequence of each component was verified during static crushing of the equivalent mechanical model.

[0082] Optional, the inspection module is used for:

[0083] Obtain the time history curve of the first impact force of the engine and the time history curve of the second impact force of the equivalent mechanical model;

[0084] Calculate the second similarity between the time history curves of the first and second impact forces, and verify the equivalent mechanical model based on the second similarity.

[0085] The failure sequence of each component during an engine impact was verified using an equivalent mechanical model.

[0086] Optional, the inspection module is used for:

[0087] The first failure mode of the engine and the second failure mode of the equivalent mechanical model were obtained;

[0088] Verify the consistency between the first and second failure modes;

[0089] The third similarity of the remaining height of the engine and the equivalent mechanical model after the impact test on the real structure is calculated, and the equivalent mechanical model is verified based on the third similarity.

[0090] The engine equivalent mechanical model construction apparatus of this application first acquires the structural features of the engine and establishes a preliminary equivalent mechanical model; then, it optimizes the preliminary equivalent mechanical model and generates a new equivalent mechanical model; next, it verifies the equivalent mechanical model to determine whether it meets the equivalence accuracy requirements. If it meets the requirements, the equivalent mechanical model is considered complete; otherwise, it is reconstructed. Therefore, this apparatus fully considers the structural features of the engine and specifically describes the construction process of the equivalent mechanical model, enabling the rapid, convenient, efficient, and accurate establishment of the equivalent mechanical model. This results in a high level of reliability for the equivalent mechanical model. Furthermore, the equivalence rationality verification of the equivalent mechanical model further ensures its reliability. Consequently, when applying this equivalent mechanical model to conduct related experiments, it significantly reduces time costs and simultaneously improves experimental accuracy.

[0091] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0092] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0093] Figure 1 A flowchart of an embodiment of an engine equivalent mechanical model construction method is presented;

[0094] Figure 2 An equivalent curve of the mass distribution of an engine along its axis according to an embodiment is presented;

[0095] Figure 3 A flowchart of a generative equivalent mechanical model of one embodiment is presented;

[0096] Figure 4 A load-displacement curve of an engine according to one embodiment is presented;

[0097] Figure 5 A flowchart of a static crushing stiffness approximation test according to an embodiment is presented;

[0098] Figure 6 A crushing stiffness curve of one embodiment is shown;

[0099] Figure 7 A schematic diagram of the crushing sequence of engine components according to one embodiment is provided;

[0100] Figure 8 A flowchart for an example of an impact force curve approximation test is provided;

[0101] Figure 9 An impact force time history graph of one embodiment is presented;

[0102] Figure 10 A schematic diagram illustrating the failure sequence of engine components according to one embodiment is provided;

[0103] Figure 11 A flowchart of an embodiment for testing the equivalence of impacting a real structure is presented;

[0104] Figure 12(a) shows a schematic diagram of the impact surface of a real structure in an engine according to an embodiment;

[0105] Figure 12(b) shows a schematic diagram of the non-impact surface of a real structure in an engine according to an embodiment;

[0106] Figure 12(c) shows a cross-sectional view of an actual structure in an engine according to an embodiment after being impacted;

[0107] Figure 13(a) shows a schematic diagram of the frontal surface of a real structure in an equivalent mechanical model of an embodiment;

[0108] Figure 13(b) shows a schematic diagram of the non-impact surface of a real structure in an equivalent mechanical model of an embodiment;

[0109] Figure 13(c) shows a cross-sectional schematic diagram of the real structure after being impacted in an equivalent mechanical model of an embodiment;

[0110] Figure 14(a) shows a schematic diagram of the remaining engine height in one embodiment;

[0111] Figure 14(b) shows a schematic diagram of the remaining height of the equivalent mechanical model in one embodiment;

[0112] Figure 15 A comparison diagram of the external structure of an engine and its equivalent model in a specific embodiment is presented;

[0113] Figure 16 A flowchart of a method for constructing an equivalent mechanical model of an engine according to a specific embodiment is presented;

[0114] Figure 17 A flowchart for determining the design value of the cylindrical shell wall thickness according to a specific embodiment is provided;

[0115] Figure 18 A comparison diagram of the internal structure of an engine in a specific embodiment and its equivalent model is presented;

[0116] Figure 19 A schematic diagram of an engine equivalent mechanical model construction device according to an embodiment is shown.

[0117] Figure descriptions: 1. Intake device; 2. Front casing; 3. Front section of compressor casing; 4. Rear section of compressor casing; 5. Combustion chamber; 6. Turbine; 7. Afterburner; 8. Disc section; 9. Rigid plate. Detailed Implementation

[0118] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0119] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0120] The method and apparatus for constructing an equivalent mechanical model of an engine according to embodiments of this application are described below with reference to the accompanying drawings.

[0121] Figure 1 This is a flowchart of the engine equivalent mechanical model construction method according to an embodiment of this application, which specifically includes the following steps:

[0122] S1. Obtain the structural characteristics of the engine and establish a preliminary equivalent mechanical model.

[0123] In one embodiment, firstly, based on the mass distribution curve of the engine along the axis (e.g. Figure 2 (As shown by the dashed line) Identify the concentrated and dispersed mass portions in the engine. Then, the concentrated mass portion is equivalent to the disk portion of the preliminary equivalent mechanical model, and the dispersed mass portion is equivalent to the cylindrical shell portion of the preliminary equivalent mechanical model.

[0124] Specifically, when performing preliminary equivalent design based on the engine's structural characteristics, the mass per unit length m of the engine component can be used as a reference. n To determine the concentrated and dispersed mass components in the engine. For example... Figure 2 As shown by the dashed line, if m n If the mass density is >400 kg / m, it is determined to be a concentrated mass portion and is equivalent to a disk portion; if m n If the mass is ≤400kg / m, it is determined to be the mass-dispersed part and is equivalent to the cylindrical shell part.

[0125] The above-described process simplifies the engine into an equivalent mechanical model, enabling a more convenient, rapid, and efficient creation of a model suitable for subsequent research. This avoids the complex process of constructing a real engine model, thus saving time and costs. Furthermore, the process comprehensively considers the engine's internal structural characteristics and mass distribution, effectively enhancing the accuracy and equivalence of the preliminary equivalent mechanical model, thereby increasing its credibility.

[0126] S2 optimizes the preliminary equivalent mechanical model to generate an equivalent mechanical model.

[0127] In one embodiment, such as Figure 3 As shown, the specific steps include:

[0128] S21, calculate the thickness h of the disk portion using Formula 1. n The disk portion of the preliminary equivalent mechanical model was optimized based on the thickness.

[0129] Specifically, Formula 1: Among them, M n The mass d represents the mass of the disk portion. e ρ represents the diameter of the engine. n This represents the density of the engine material. Therefore, based on the engine's structural characteristics and mass distribution features, the disk portion in the preliminary equivalent mechanical model can be accurately optimized, thus achieving mass distribution equivalence between the disk portion and engine components, and enhancing the reliability of the equivalent mechanical model.

[0130] S22, determine the length of the cylindrical shell section based on the structural characteristics of the engine.

[0131] Specifically, based on the structural characteristics of the engine, the length l of the cylindrical shell section is... n The length of the engine component equivalent to the cylindrical shell portion in S1, perpendicular to the bottom surface of the engine, is determined.

[0132] S23, based on the load-displacement curve of the engine, obtains the crushing force of the cylindrical shell section.

[0133] Based on such Figure 4 The load-displacement curve of the engine shown defines the crushing force of the engine component equivalent to the cylindrical shell portion as the crushing force F of the cylindrical shell portion. nTherefore, the crushing force of the cylindrical shell section can be obtained quickly, conveniently, and accurately. Specifically, the load-displacement curve of the engine can be obtained by static compression along the engine's axial direction and combined with the engine's axial crushing process. It should be understood that the engine mentioned here can be a real engine or an engine finite element model, which can be established based on the structure of a real engine.

[0134] S24, verifying the wall thickness design value of the cylindrical shell section based on crushing force.

[0135] Specifically, the stable bearing capacity F of the cylindrical shell section is first calculated using Formula 2. u Formula 2: F u =A s ·σ u , where A s σ represents the cross-sectional area of ​​the cylindrical shell portion. u This represents the buckling stress. Then, based on the steady bearing capacity F... u The crushing force F obtained from S23 n Verify the wall thickness design value.

[0136] Among them, the buckling stress σ in Formula 1 u It is obtained through calculation using formula three or formula four. Specifically, when Elastic buckling occurs, and the buckling stress σ can be calculated using Formula 3. u Formula 3: when Plastic buckling occurs, and the buckling stress σ can be calculated using Formula 4. u Formula 4: Among them, f y σ represents the yield stress of the engine material. cl This represents the elastic buckling stress, and α0 represents the reduction factor. γ represents the safety factor of the attachment. It represents the dimensionless slenderness ratio.

[0137] Among them, the dimensionless slenderness ratio in Formulas 3 and 4 The result is obtained through calculation using Formula 5. Formula 5: Among them, f y σ represents the yield stress of the engine material. cl Indicates elastic buckling stress. α0 represents the reduction factor. or E represents the elastic modulus of the engine material, t represents the design wall thickness, and r = d. e / 2,d e This indicates the diameter of the engine. Specifically, when... hour, when hour,

[0138] In one specific embodiment, the stable bearing capacity F can be calculated. u and crushing force F n The absolute error is then measured, and the wall thickness design value is verified by determining whether the absolute error is less than or equal to a preset threshold. This preset threshold is determined based on the stability requirements of the subsequent application scenarios of the equivalent mechanical model. If the ratio is less than or equal to the preset threshold, the wall thickness design value is determined to meet the design requirements; if the ratio is greater than the preset threshold, the wall thickness design value is adjusted and recalculated.

[0139] Therefore, based on the structural and mechanical characteristics of the engine, the wall thickness design value can be verified, thereby accurately determining the wall thickness design value of the cylindrical shell section.

[0140] S25, optimize the cylindrical shell portion of the preliminary equivalent mechanical model based on the design values ​​of length and wall thickness.

[0141] Therefore, by integrating the design values ​​of the length and wall thickness of the cylindrical shell section, the optimization of the cylindrical shell section in the preliminary equivalent mechanical model was completed, thereby achieving equivalence of mass distribution and static crushing stiffness between the cylindrical shell section and the engine components, thus making the equivalent mechanical model more reliable.

[0142] The above process, based on numerical simulation, fully considers the engine's structural characteristics, mass distribution features, and mechanical properties. It details the construction process of the equivalent mechanical model, enabling rapid, convenient, accurate, and efficient determination of the optimized parameters for the disk and cylindrical shell sections, thereby generating the equivalent mechanical model and achieving equivalence between the equivalent mechanical model and the engine's mass distribution (e.g., Figure 2 As shown in the figure, the static crushing stiffness is equivalent to that of the equivalent mechanical model, thus giving the equivalent mechanical model a high degree of credibility.

[0143] S3. Verify the equivalent mechanical model to determine whether it meets the requirements for equivalent accuracy.

[0144] Specifically, the approximation of the static crushing stiffness, the approximation of the impact force curve, and the equivalence of the impact on the real structure of the equivalent mechanical model are tested.

[0145] In one embodiment, such as Figure 5 As shown, the specific steps for verifying the approximation of the static crushing stiffness of the equivalent mechanical model include:

[0146] S501, obtain the first static crushing stiffness curve of the engine and the second static crushing stiffness curve of the equivalent mechanical model.

[0147] In one specific embodiment, rigid plates covering the engine cross-section are constructed at the head and tail of the engine and equivalent mechanical model. Then, static crushing stiffness tests are performed on the engine and equivalent mechanical model respectively. Specifically, the rigid plate located at the head of the engine and equivalent mechanical model is fixed, and a displacement condition is applied to the rigid plate located at the tail of the engine and equivalent mechanical model, continuously compressing the engine along the engine axis. Next, the contact force between the rigid plate and the engine and equivalent mechanical model is extracted as the applied load, and coupled with the displacement condition to obtain... Figure 6 The diagram shows the first static crushing stiffness curve of the engine and the second static crushing stiffness curve of its equivalent mechanical model. It should be understood that the engine referred to here can be a real engine or a finite element model of an engine, which can be established based on the structure of a real engine. Figure 6 As shown, the engine prototype refers to the engine, and the equivalent model refers to the equivalent mechanical model.

[0148] S502, calculate the first similarity between the first static crushing stiffness curve and the second static crushing stiffness curve, and verify the equivalent mechanical model based on the first similarity.

[0149] Specifically, the verification condition for S502 is that the first similarity meets the first similarity value range, thereby ensuring that the equivalent mechanical model and the engine achieve stiffness equivalence. The first similarity value range is determined by the staff based on the subsequent application scenario requirements of the equivalent mechanical model. In this embodiment, if the error between the first static crushing stiffness curve and the second static crushing stiffness curve at any horizontal axis (i.e., the same displacement) and their corresponding vertical axis (i.e., load) is between 0 and 0.2, it indicates that the first similarity between the first and second static crushing stiffness curves is within the preset range, meaning that the S502 verification is successful.

[0150] S503 verifies the crushing sequence of each component during static crushing of the equivalent mechanical model.

[0151] Specifically, the verification condition for S503 is that the crushing sequence of each component is consistent during static crushing of the engine and the equivalent mechanical model.

[0152] In one specific embodiment, such as Figure 7 The diagram shows the crushing sequence of each component during static crushing of the engine and its equivalent mechanical model.

[0153] If both S502 and S503 verifications pass, it means that the equivalent mechanical model verification is successful.

[0154] In another embodiment, such as Figure 8 As shown, the specific steps for verifying the approximation of the impact force curve of the equivalent mechanical model include:

[0155] S801, obtain the first impact force time history curve of the engine and the second impact force time history curve of the equivalent mechanical model.

[0156] In one specific embodiment, rigid plates are established at the head of both the engine and the equivalent mechanical model, and then engine impact force tests are performed on both the engine and the equivalent mechanical model. Specifically, the engine and the equivalent mechanical model are given the same initial velocity. Then, the contact force time history curves between the rigid plate and the engine and the equivalent mechanical model are extracted respectively to obtain... Figure 9 The time history curves for the first and second impact forces are shown. It should be understood that the engine referred to here can be a real engine or a finite element model of an engine, which can be established based on the structure of a real engine. For example... Figure 9 As shown, the engine prototype refers to the real engine or the engine finite element model, and the equivalent model refers to the equivalent mechanical model.

[0157] S802, calculate the second similarity between the time history curve of the first impact force and the time history curve of the second impact force, and verify the equivalent mechanical model based on the second similarity.

[0158] Specifically, the verification condition for S802 is that the second similarity meets the range of values ​​for the second similarity, thereby ensuring that the time-varying laws of the forces experienced by the equivalent mechanical model and the engine during the collision are equivalent. The range of values ​​for the second similarity is determined by the staff based on the subsequent application requirements of the equivalent mechanical model. In this embodiment, if the area enclosed by the first impact force time history curve and the time axis (i.e., impact energy) is between 0 and 0.2 compared to the area enclosed by the second impact force time history curve and the time axis, it indicates that the second similarity between the first and second impact force time history curves is within the preset range, meaning that the S802 verification is successful.

[0159] S803 verifies the failure sequence of each component during an engine impact using an equivalent mechanical model.

[0160] Specifically, the verification condition for S803 is that the crushing order of each component is consistent when the engine and the equivalent mechanical model are subjected to engine impact.

[0161] In one specific embodiment, such as Figure 10 The diagram shows the order of failure of each component during an engine impact and the equivalent mechanical model of the engine.

[0162] If both S802 and S803 verifications pass, it means that the equivalent mechanical model verification is successful.

[0163] In yet another embodiment, such as Figure 11As shown, the equivalence test of the equivalent mechanical model for impacting real structures specifically includes the following steps:

[0164] S1101, obtain the first failure mode of the engine and the second failure mode of the equivalent mechanical model.

[0165] In one specific embodiment, impact tests on a real structural structure were conducted on the engine and the equivalent mechanical model, respectively, and the results were obtained as follows: Figures 12(a)-12(c) The first failure mode of the engine shown and as Figures 13(a)-13(c) The second failure mode of the equivalent mechanical model shown. Failure modes may include intrusion failure, back collapse failure, and penetration failure. It should be understood that the engine mentioned here can be a real engine or a finite element model of an engine, which can be established based on the structure of a real engine.

[0166] S1102, verify the consistency between the first failure mode and the second failure mode.

[0167] Specifically, the verification condition for S1102 is that the first failure mode and the second failure mode are consistent, thereby ensuring that the equivalent mechanical model is equivalent to the damage to the real structure caused by the engine after impact.

[0168] S1103 calculates the third similarity of the remaining height of the engine and the equivalent mechanical model after completing the impact test on the real structure, and verifies the equivalent mechanical model based on the third similarity.

[0169] Specifically, the verification condition for S1103 is that the third similarity meets the range of values ​​for the third similarity. This range is determined by the staff based on the subsequent application requirements of the equivalent mechanical model. In this embodiment, if the error in the remaining height after the engine and equivalent mechanical model complete the impact test on a real structure is between 0 and 0.2, it indicates that the third similarity of the remaining height after the impact test is within the preset range, meaning that verification for S1103 is successful.

[0170] In one specific embodiment, such as Figure 14(a) and 14(b) The figure shows the remaining height after the engine and equivalent mechanical model were impacted into the real structure.

[0171] If both S1102 and S1103 pass the verification, it means that the equivalent mechanical model has passed the verification.

[0172] The above verification process, based on numerical simulation, accurately verifies the equivalence rationality by comparing the equivalent mechanical model with the engine, thus determining the applicability of the equivalent mechanical model and ensuring its reliability.

[0173] S4. If the equivalent accuracy requirement is met, then the equivalent mechanical model is considered to have been successfully constructed.

[0174] Specifically, based on the subsequent application scenarios of the equivalent mechanical model, the verification content in S3 is determined. If the equivalent mechanical model passes all verification conditions in S3, then the construction of the equivalent mechanical model is considered complete. This ensures the rationality and reliability of the equivalent mechanical model and provides it with high accuracy.

[0175] S5. If the equivalent accuracy requirement is not met, then the equivalent mechanical model is reconstructed.

[0176] For example, if the second static crushing stiffness curve of the equivalent mechanical model exceeds the range of the first similarity value compared to the first static crushing stiffness curve of the engine, the stiffness of the cylindrical shell part can be reduced by decreasing the wall thickness design value of the cylindrical shell part; if the second impact force time history curve of the equivalent mechanical model exceeds the range of the second similarity value compared to the first impact force time history curve of the engine, it is advisable to replace the disk part with the cylindrical shell part and reconstruct the model.

[0177] Therefore, when the equivalent mechanical model does not meet the S3 verification requirements, the optimization and adjustment of the equivalent mechanical model can be completed quickly and conveniently, making the equivalent mechanical model more reasonable and reliable.

[0178] The engine equivalent mechanical model construction method of this application first obtains the structural features of the engine and establishes a preliminary equivalent mechanical model; then, it optimizes the preliminary equivalent mechanical model and generates a new equivalent mechanical model; next, it verifies the equivalent mechanical model to determine whether it meets the equivalence accuracy requirements. If it meets the requirements, the equivalent mechanical model is considered complete; otherwise, it is reconstructed. Therefore, this method fully considers the structural features of the engine and specifically describes the construction process of the equivalent mechanical model. It can quickly, conveniently, efficiently, and accurately establish the equivalent mechanical model, giving it high reliability. Furthermore, by verifying the equivalence rationality of the equivalent mechanical model, its reliability is further guaranteed. This significantly reduces time costs when using the equivalent mechanical model for related experiments and simultaneously improves experimental accuracy.

[0179] In one specific embodiment, such as Figure 15 As shown, the components of a real engine may include: intake device 1, front casing 2, front section of compressor casing 3, rear section of compressor casing 4, combustion chamber 5, turbine 6, and afterburner 7.

[0180] like Figure 16As shown, this embodiment specifically includes the following steps:

[0181] S161, based on the engine's structural geometric features, complete the preliminary construction of the equivalent model.

[0182] Specifically, such as Figure 15 As shown, the equivalent model, in its initial construction, satisfies the requirement that its main geometric dimensions are approximately equal to those of the engine, i.e.: l o ≈l e d o ≈d e , where l o l represents the length of the equivalent model. e d represents the length of the engine. o d represents the width of the equivalent model. e This indicates the width of the engine. Furthermore, based on the engine's internal structure, a preliminary equivalent design is performed, equating the concentrated mass distribution to a solid disk (disk thickness h). n The mass dispersion is equivalent to a cylindrical shell (the length and wall thickness of the cylindrical shell are l). n t n ).

[0183] Specifically, it can be based on the mass per unit length of the engine (e.g. Figure 2 (As shown by the dashed line) Determine the equivalent method, if m n If the mass is greater than 400 kg / m, it is simplified to a disk; if m n If the mass is ≤400kg / m, it simplifies to a cylindrical shell. For example, the mass concentration of the front casing 2 and turbine 6 can be equivalently represented as a disc section 8 (e.g., Figure 15 As shown), the mass distribution of the compressor casing front section 3, compressor casing rear section 4, combustion chamber 5 and afterburner chamber 7 can be equivalent to a cylindrical shell section.

[0184] Thus, the above steps completed the initial construction of the equivalent model.

[0185] S162, based on the refined finite element model of the engine, determine the detailed parameters of the equivalent model.

[0186] First, extract the mass distribution curve along the axis of the engine finite element model (e.g., Figure 2 (As shown by the dashed line in the middle), the thickness h, which is equivalent to the disk portion, is calculated using the following formula. n (h1, h2, h3…): Among them, M n (M1, M2, M3…) represent the component masses equivalent to the disk portion, d e ρ is the diameter of the engine. n The density of the engine material is used to calculate the geometric parameters of the equivalent disk portion.

[0187] Secondly, the length of the components in the engine finite element model is equivalent to the length l of a cylindrical shell. n (like Figure 15 As shown), and complete the static compression process along the axial direction of the engine finite element model, extracting the load-displacement curve (as shown). Figure 4 As shown in the figure, and combined with the crushing process along the axis of the engine finite element model, the crushing force F of each component is obtained by fitting. n (F1, F2, F3…) and assign them to the corresponding crushing forces of the equivalent cylindrical shell. Then, based on the formula for calculating the axial stability bearing capacity of a cylindrical shell, the design value t of the cylindrical shell wall thickness is obtained through trial calculations. n (t1, t2, t3...), thus completing the determination of the geometric parameters of the equivalent cylindrical shell part.

[0188] Among them, such as Figure 17 As shown, the design wall thickness t n The trial calculation process specifically includes the following steps:

[0189] S171, assume the design value of the wall thickness of the cylindrical shell.

[0190] Specifically, based on the engine's structural characteristics, and combined with staff experience and past data, the wall thickness design value is assumed to be t. n .

[0191] S172, Calculate the dimensionless slenderness ratio of a cylindrical shell.

[0192] Specifically, the dimensionless slenderness ratio of the cylindrical shell is calculated according to the following formula. Among them, f y σ represents the yield stress of the engine material. cl This represents the elastic buckling stress of an ideal cylindrical shell under axial compression, where α0 represents the reduction factor considering the effects of defects. Specifically, Where E represents the elastic modulus of the engine material, and t represents the design wall thickness t n , r = d e / 2,d e This indicates the diameter of the engine. Also, when hour, when hour,

[0193] S173, calculate the buckling stress of a cylindrical shell.

[0194] Specifically, the buckling stress σ of the cylindrical shell is calculated according to the following formula. u :when Elastic buckling occurs at this time. when Plastic buckling occurs at this time.

[0195] Among them, f y σ represents the yield stress of the engine material. cl This represents the elastic buckling stress, and α0 represents the reduction factor. γ represents the safety factor of the attachment. It represents the dimensionless slenderness ratio.

[0196] S174, determine the axial stable bearing capacity of the cylindrical shell.

[0197] Calculate the axial stability bearing capacity F of the cylindrical shell using the following formula. u :F u =A s ·σ u , where A s σ represents the cross-sectional area of ​​the cylindrical shell portion. u This indicates buckling stress.

[0198] S175, verify whether the equivalence holds.

[0199] Specifically, if Then determine the design value of wall thickness t n The verification is satisfied; if Then adjust the wall thickness design value t n Then, recalculate.

[0200] Therefore, through the above steps, the geometric parameters of the equivalent model were determined, and the following was completed: Figure 18 The construction of the equivalent engine model shown.

[0201] S163, finite element calculation is used to verify the equivalence of the equivalent model.

[0202] Specifically, verifying the equivalence of the equivalent model may include: verifying and analyzing the equivalence of the static crushing process, the impact on the rigid plate process, and the impact on the real structure process of the equivalent model.

[0203] 1. The equivalence of the static crushing process of the equivalent model is verified by numerical simulation.

[0204] Specifically, first, a finite element model of a real engine is established, and shell elements are used to mesh the equivalent model. Then, as... Figure 15As shown, rigid plates 9 covering the engine cross-section are established at the head and tail sections of the engine finite element model and equivalent mechanical model, respectively. The rigid plate at the head is fixed, and displacement conditions are applied to the rigid plate at the tail section to continuously compress the engine along the engine axis. A static crushing process finite element analysis is then performed. Next, after the calculation, the contact force between the rigid plate and the engine finite element model and equivalent mechanical model is extracted as the applied load, and coupled with the displacement conditions to establish a load-displacement curve, as shown below. Figure 6 The static crushing stiffness curves of the engine finite element model and the equivalent model are shown for approximation verification. It is necessary to ensure the similarity between the static crushing stiffness curves of the equivalent model and the engine finite element model, so as to ensure that the equivalent model achieves stiffness equivalence with the real engine.

[0205] In addition, after the calculation is completed, the following information is obtained simultaneously: Figure 7 The crushing order of each component in the finite element model and equivalent model of the engine shown is required, and the consistency of the crushing order of each component in the finite element model and equivalent model must be ensured.

[0206] 2. The equivalence of the impact on the rigid plate process of the equivalent model is verified and analyzed by numerical simulation.

[0207] Specifically, first, a finite element model of the real engine is established, and shell elements are used to mesh the equivalent model. Then, a rigid plate is created at the head of both the engine finite element model and the equivalent model, and both are given the same initial velocity for finite element analysis of the impact process. Next, the contact force time history curves between the engine finite element model, the equivalent model, and the rigid plate are extracted after the analysis to obtain... Figure 9 The impact force curves of the engine finite element model and the equivalent model shown are used for approximation verification. It is necessary to ensure the similarity of the impact force time history curves of the equivalent model and the engine finite element model, so as to ensure that the force change law of the equivalent model and the prototype engine during the collision is equivalent in time.

[0208] In addition, after the calculation is completed, the following information is obtained simultaneously: Figure 10 The failure order of each component in the finite element model and equivalent model of the engine is shown, and the consistency of the failure order of each component in the finite element model and equivalent model of the engine must be ensured.

[0209] 3. The equivalence of the equivalent model to the impact on the real structure is verified and analyzed by numerical simulation.

[0210] Specifically, firstly, a finite element model of the real engine is established, and shell elements are used to mesh the equivalent model. Then, a real structural model is created within both the engine finite element model and the equivalent model based on the actual structural conditions, and both are given the same initial velocity. Finite element analysis of the impact on the real structure is then performed. Next, after the analysis, the damage to the impacted real structure in both the engine finite element model and the equivalent model is extracted. It is necessary to ensure that the damage modes of the real structure in the equivalent model and the engine finite element model are consistent, thus ensuring that the precise equivalent model and the prototype engine achieve equivalence in the damage to the real structure after impact. The damage modes may include intrusion damage, back collapse damage, and penetration. In this embodiment, a reinforced concrete target plate is selected as the real structure. The damage characteristics of the engine finite element model are as follows: Figures 12(a)-12(c) As shown, the destruction status of the equivalent model is as follows: Figures 13(a)-13(c) As shown.

[0211] In addition, after the calculation is completed, the remaining height of the engine finite element model and equivalent model after impacting the real structure should be obtained simultaneously, as shown in Figure 14(a) and Figure 14(b), and it should be ensured that the remaining height of the engine finite element model and equivalent model are similar.

[0212] S164. If the calculation results show that the equivalent model can meet the equivalent accuracy requirements, then the equivalent model can be used in subsequent experimental research.

[0213] If the accuracy requirements are not met, an equivalent model needs to be reconstructed based on the characteristics of the prototype engine.

[0214] For example, if the static crushing load-displacement curve of the equivalent model is locally greater than that of the prototype engine, the stiffness of the cylindrical shell can be reduced by decreasing the thickness of the cylindrical shell wall; if the impact force of the equivalent model is greater than that of the prototype engine, the solid disk can be replaced with a cylindrical shell to rebuild the model.

[0215] This specific embodiment describes a construction process for an equivalent mechanical model of an engine, fully considering the engine's internal characteristics, mass distribution, and mechanical features. Numerical simulation is applied to the construction of the equivalent mechanical model, ensuring its high reliability. The embodiment also outlines the optimization process for the equivalent model: after construction, an equivalence rationality check is performed. If the required accuracy is not met, the model must be adjusted and reconstructed to guarantee its reliability. Therefore, based on this equivalent mechanical model, research and experiments related to the protective performance of structures can be conducted, significantly reducing experimental time and improving efficiency, providing crucial technical support for research on the protective performance of important structures.

[0216] To implement the above embodiments, this application also proposes an apparatus for constructing an equivalent mechanical model of an engine.

[0217] Figure 19 This is a schematic diagram of the structure of an engine equivalent mechanical model construction device according to an embodiment of this application.

[0218] like Figure 19 As shown, the engine equivalent mechanical model construction device includes a building module 110, a generation module 120, a verification module 130, a determination module 140, and a reconstruction module 150.

[0219] Module 110 is established to obtain the structural features of the engine and to establish a preliminary equivalent mechanical model.

[0220] Module 110 is established specifically for: First, determining the concentrated and dispersed mass portions in the engine based on the mass distribution curve along the engine axis. Then, the concentrated mass portion is equivalent to the disk portion of the preliminary equivalent mechanical model, and the dispersed mass portion is equivalent to the cylindrical shell portion of the preliminary equivalent mechanical model.

[0221] The generation module 120 is used to optimize the preliminary equivalent mechanical model and generate an equivalent mechanical model.

[0222] Module 120 is specifically used for: First, calculating the thickness h of the disk portion using Formula 1. n Formula 1: Among them, M n The mass d represents the mass of the disk portion. e ρ represents the diameter of the engine. n The density of the engine material is represented, and the disk portion of the preliminary equivalent mechanical model is optimized based on its thickness. Next, the length of the cylindrical shell portion is determined according to the engine's structural characteristics. Then, the crushing force of the cylindrical shell portion is obtained based on the engine's load-displacement curve. Next, the design wall thickness of the cylindrical shell portion is verified based on the crushing force. Finally, the cylindrical shell portion of the preliminary equivalent mechanical model is optimized based on its length and wall thickness design values.

[0223] Module 120 is specifically used for: First, calculating the dimensionless slenderness ratio λ using Formula 5, Formula 5: Among them, f y σ represents the yield stress of the engine material. cl Indicates elastic buckling stress. α0 represents the reduction factor. or E represents the elastic modulus of the engine material, t represents the design wall thickness, and r = d. e / 2,d eThis represents the diameter of the engine. Then, the buckling stress σ is calculated using either Formula 3 or Formula 4. u Formula 3: Formula 4: Among them, f y σ represents the yield stress of the engine material. cl This represents the elastic buckling stress, and α0 represents the reduction factor. γ represents the safety factor of the attachment. This represents the dimensionless slenderness ratio. Next, we use Formula 2 to calculate the stable bearing capacity F of the cylindrical shell section. u Formula 2: F u =A s σ u , where A s σ represents the cross-sectional area of ​​the cylindrical shell portion. u The buckling stress is represented, and the design wall thickness is then verified based on the stable bearing capacity and crushing force.

[0224] The generation module 120 is specifically used for: calculating the absolute error of the stable bearing capacity and the crushing force; and determining whether the absolute error is less than or equal to a preset threshold. If the ratio is less than or equal to the preset threshold, the wall thickness design value is determined to meet the design requirements; if the ratio is greater than the preset threshold, the wall thickness design value is adjusted and recalculated.

[0225] The verification module 130 is used to verify the equivalent mechanical model and determine whether the equivalent mechanical model meets the equivalent accuracy requirements.

[0226] The verification module 130 is specifically used to verify the approximation of the static crushing stiffness, the approximation of the impact force curve, and the equivalence of the impacted real structure in the equivalent mechanical model.

[0227] The verification module 130 is specifically used for: First, obtaining the first static crushing stiffness curve of the engine and the second static crushing stiffness curve of the equivalent mechanical model. Then, calculating the first similarity between the first and second static crushing stiffness curves, and verifying the equivalent mechanical model based on the first similarity verification. Simultaneously, verifying the crushing sequence of each component during static crushing of the equivalent mechanical model.

[0228] The verification module 130 is specifically used for: First, obtaining the first impact force time history curve of the engine and the second impact force time history curve of the equivalent mechanical model. Then, calculating the second similarity between the first and second impact force time history curves, and verifying the equivalent mechanical model based on the second similarity. Simultaneously, verifying the failure sequence of each component of the equivalent mechanical model during engine impact.

[0229] The verification module 130 is specifically used for: First, obtaining the first failure mode of the engine and the second failure mode of the equivalent mechanical model. Then, verifying the consistency between the first and second failure modes. Simultaneously, calculating the third similarity between the remaining height of the engine and the equivalent mechanical model after completing the impact test on a real structure, and verifying the equivalent mechanical model based on the third similarity.

[0230] Module 140 is used to determine that the equivalent mechanical model has been constructed if the equivalent accuracy requirements are met.

[0231] Rebuild module 150 to rebuild the equivalent mechanical model if the equivalent accuracy requirements are not met.

[0232] It should be understood that the description of the engine equivalent mechanical model construction device and its corresponding engine equivalent mechanical model construction method is consistent, so it will not be repeated in this embodiment.

[0233] The engine equivalent mechanical model construction apparatus of this application first acquires the structural features of the engine and establishes a preliminary equivalent mechanical model; then, it optimizes the preliminary equivalent mechanical model and generates a new equivalent mechanical model; next, it verifies the equivalent mechanical model to determine whether it meets the equivalence accuracy requirements. If it meets the requirements, the equivalent mechanical model is considered complete; otherwise, it is reconstructed. Therefore, this apparatus fully considers the structural features of the engine and specifically describes the construction process of the equivalent mechanical model, enabling the rapid, convenient, efficient, and accurate establishment of the equivalent mechanical model. This results in a high level of reliability for the equivalent mechanical model. Furthermore, the equivalence rationality verification of the equivalent mechanical model further ensures its reliability. Consequently, when applying this equivalent mechanical model to conduct related experiments, it significantly reduces time costs and simultaneously improves experimental accuracy.

[0234] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0235] It should be noted that, in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A method for constructing an equivalent mechanical model of an engine, characterized in that, include: Obtain the structural characteristics of the engine and establish a preliminary equivalent mechanical model, including: The concentrated and dispersed mass portions of the engine are determined based on the mass distribution curve along the engine axis. The mass concentration portion is equivalent to the disk portion of the preliminary equivalent mechanical model; The mass dispersion portion is equivalent to the cylindrical shell portion of the preliminary equivalent mechanical model; The preliminary equivalent mechanical model is optimized to generate an equivalent mechanical model, including: The thickness of the disk portion can be calculated using Formula 1. Formula 1: ,in, This refers to the mass of the disk portion. This indicates the diameter of the engine. The density of the engine material is represented, and the disk portion of the preliminary equivalent mechanical model is optimized based on the thickness. The length of the cylindrical shell portion is determined based on the structural characteristics of the engine. Based on the load-displacement curve of the engine, the crushing force of the cylindrical shell portion is obtained; The design value of the wall thickness of the cylindrical shell portion is verified based on the crushing force. The cylindrical shell portion of the preliminary equivalent mechanical model is optimized based on the length and the wall thickness design values. The equivalent mechanical model is tested to determine whether it meets the equivalent accuracy requirements. If the equivalent accuracy requirement is met, then the equivalent mechanical model is considered to have been successfully constructed. If the equivalent accuracy requirement is not met, the equivalent mechanical model is reconstructed.

2. The method according to claim 1, characterized in that, Verifying the wall thickness design value of the cylindrical shell portion based on the crushing force includes: The stable bearing capacity of the cylindrical shell section is calculated using Formula 2. Formula 2: ,in, This represents the cross-sectional area of ​​the cylindrical shell portion. Indicates buckling stress; The wall thickness design value is verified based on the stable bearing capacity and the crushing force.

3. The method according to claim 2, characterized in that, The buckling stress It is obtained through calculation using either Formula 3 or Formula 4. Formula 3: Formula 4: ,in, This represents the yield stress of the engine material. Indicates elastic buckling stress. This represents the reduction factor. , Indicates the safety factor of the attachment. It represents the dimensionless slenderness ratio.

4. The method according to claim 3, characterized in that, The dimensionless slenderness ratio The result is obtained through calculation using Formula 5. Formula 5: ,in, This represents the yield stress of the engine material. Indicates elastic buckling stress. , This represents the reduction factor. or , This represents the elastic modulus of the engine material. t This represents the design value for the wall thickness. , This indicates the diameter of the engine.

5. The method according to claim 2, characterized in that, Verifying the wall thickness design value based on the stable bearing capacity and the crushing force includes: Calculate the absolute error of the stable bearing capacity and the crushing force; Determine whether the ratio of the absolute error to the crushing force is less than or equal to a preset threshold. like If so, then the wall thickness design value is determined to meet the design requirements; If the ratio is greater than the preset threshold, the wall thickness design value is adjusted and recalculated.

6. The method according to claim 1, characterized in that, The equivalent mechanical model is tested, including: The approximation of the static crushing stiffness, the approximation of the impact force curve, and the equivalence of the equivalent mechanical model to the actual impact structure are verified.

7. The method according to claim 6, characterized in that, The approximation of the static crushing stiffness of the equivalent mechanical model is tested, including: Obtain the first static crushing stiffness curve of the engine and the second static crushing stiffness curve of the equivalent mechanical model; Calculate the first similarity between the first static crushing stiffness curve and the second static crushing stiffness curve, and verify the equivalent mechanical model based on the first similarity verification. The crushing sequence of each component was verified when the equivalent mechanical model was subjected to static crushing.

8. The method according to claim 6, characterized in that, The approximation of the impact force curve of the equivalent mechanical model is verified, including: Obtain the first impact force time history curve of the engine and the second impact force time history curve of the equivalent mechanical model; Calculate the second similarity between the first impact force time history curve and the second impact force time history curve, and verify the equivalent mechanical model based on the second similarity; The equivalent mechanical model was used to verify the failure sequence of each component during an engine impact.

9. The method according to claim 6, characterized in that, The equivalence of the aforementioned equivalent mechanical model to the impacted real structure is verified, including: Obtain the first failure mode of the engine and the second failure mode of the equivalent mechanical model; Verify the consistency between the first and second destruction modes; Calculate the third similarity of the remaining height of the engine and the equivalent mechanical model after they have completed the impact test on a real structure, and verify the equivalent mechanical model based on the third similarity.

10. An apparatus for constructing an equivalent mechanical model of an engine, characterized in that, include: A module is established to acquire the structural features of the engine and to build a preliminary equivalent mechanical model, including: The concentrated and dispersed mass portions of the engine are determined based on the mass distribution curve along the engine axis. The mass concentration portion is equivalent to the disk portion of the preliminary equivalent mechanical model; The mass dispersion portion is equivalent to the cylindrical shell portion of the preliminary equivalent mechanical model; The generation module is used to optimize the preliminary equivalent mechanical model and generate an equivalent mechanical model, including: The thickness of the disk portion can be calculated using Formula 1. Formula 1: ,in, This refers to the mass of the disk portion. This indicates the diameter of the engine. The density of the engine material is represented, and the disk portion of the preliminary equivalent mechanical model is optimized based on the thickness. The length of the cylindrical shell portion is determined based on the structural characteristics of the engine. Based on the load-displacement curve of the engine, the crushing force of the cylindrical shell portion is obtained; The design value of the wall thickness of the cylindrical shell portion is verified based on the crushing force. The cylindrical shell portion of the preliminary equivalent mechanical model is optimized based on the length and the wall thickness design values. The verification module is used to verify the equivalent mechanical model and determine whether the equivalent mechanical model meets the equivalent accuracy requirements. A determination module is used to determine that the equivalent mechanical model has been successfully constructed if the equivalent accuracy requirement is met. A reconstruction module is used to reconstruct the equivalent mechanical model if the equivalent accuracy requirement is not met.

11. The apparatus according to claim 10, characterized in that, The generation module is used for: The stable bearing capacity of the cylindrical shell section is calculated using Formula 2. Formula 2: ,in, This represents the cross-sectional area of ​​the cylindrical shell portion. Indicates buckling stress; The wall thickness design value is verified based on the stable bearing capacity and the crushing force.

12. The apparatus according to claim 11, characterized in that, The generation module is used for: The buckling stress It is obtained through calculation using either Formula 3 or Formula 4. Formula 3: Formula 4: ,in, This represents the yield stress of the engine material. Indicates elastic buckling stress. This represents the reduction factor. , Indicates the safety factor of the attachment. It represents the dimensionless slenderness ratio.

13. The apparatus according to claim 12, characterized in that, The generation module is used for: The dimensionless slenderness ratio The result is obtained through calculation using Formula 5. Formula 5: ,in, This represents the yield stress of the engine material. Indicates elastic buckling stress. , This represents the reduction factor. or , This represents the elastic modulus of the engine material. t This represents the design value for the wall thickness. , This indicates the diameter of the engine.

14. The apparatus according to claim 11, characterized in that, The generation module is used for: Calculate the absolute error of the stable bearing capacity and the crushing force; Determine whether the ratio of the absolute error to the crushing force is less than or equal to a preset threshold. like If so, then the wall thickness design value is determined to meet the design requirements; If the ratio is greater than the preset threshold, the wall thickness design value is adjusted and recalculated.

15. The apparatus according to claim 10, characterized in that, The inspection module is used for: The approximation of the static crushing stiffness, the approximation of the impact force curve, and the equivalence of the equivalent mechanical model to the actual impact structure are verified.

16. The apparatus according to claim 15, characterized in that, The inspection module is used for: Obtain the first static crushing stiffness curve of the engine and the second static crushing stiffness curve of the equivalent mechanical model; Calculate the first similarity between the first static crushing stiffness curve and the second static crushing stiffness curve, and verify the equivalent mechanical model based on the first similarity verification. The crushing sequence of each component was verified when the equivalent mechanical model was subjected to static crushing.

17. The apparatus according to claim 15, characterized in that, The inspection module is used for: Obtain the first impact force time history curve of the engine and the second impact force time history curve of the equivalent mechanical model; Calculate the second similarity between the first impact force time history curve and the second impact force time history curve, and verify the equivalent mechanical model based on the second similarity; The equivalent mechanical model was used to verify the failure sequence of each component during an engine impact.

18. The apparatus according to claim 15, characterized in that, The inspection module is used for: Obtain the first failure mode of the engine and the second failure mode of the equivalent mechanical model; Verify the consistency between the first and second destruction modes; Calculate the third similarity of the remaining height of the engine and the equivalent mechanical model after they have completed the impact test on a real structure, and verify the equivalent mechanical model based on the third similarity.

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