Engineering calculation method, system and device for emergency disconnect pin disconnect load and storage medium

Abstract

This invention discloses an engineering calculation method, system, device, and storage medium for the breakage load of an emergency breakage pin, relating to the field of aircraft structural strength design technology. The method includes: establishing a simplified calculation diagram of the breakage pin's stress based on beam theory to obtain the axial variation functions of shear force and bending moment; establishing expressions for cross-sectional area and bending modulus based on the cross-sectional geometry; calculating the shear stress, bending stress, and equivalent stress based on the fourth strength theory for each vertical section; determining the location of the most critical section by analyzing the equivalent stress distribution; calculating the first and second load values ​​based on the axial interval where the most critical section is located, using the material's shear strength and tensile strength as boundary conditions; comparing the two and taking the smaller value as the final breakage load. This invention achieves scientific quantitative selection of the breakage section and accurate calculation of the breakage load, with advantages such as low computational load, high efficiency, and a visually intuitive and verifiable process.

Description

Technical Field

[0001] This invention belongs to the field of aircraft structural strength design technology, and in particular relates to an engineering calculation method, system, device and storage medium for emergency disconnection pin disconnection load. Background Technology

[0002] The emergency landing gear disconnection is a crucial safety feature for civil aircraft. In the event of an emergency landing or other unforeseen circumstances, the landing gear separates from the fuselage by prematurely breaking the emergency disconnection pin, thus protecting the fuselage structure. The disconnection load of the disconnection pin is a core design parameter that directly determines whether this function can be reliably triggered.

[0003] Currently, the strength analysis of landing gear structures mainly employs the finite element method and engineering calculation methods. Compared with the finite element method, the engineering calculation method has the advantages of less computation, shorter cycle time, and more intuitive process. Its calculation steps are easy to compile into reports, facilitating verification, review, and long-term storage. Therefore, the engineering algorithm for emergency disconnection loads has irreplaceable engineering value.

[0004] However, current research on landing gear emergency disconnection mainly focuses on airworthiness regulations, structural design, simulation analysis, and experimental verification, while research on engineering algorithms for disconnection pin disconnection loads is almost non-existent. Relevant literature is as follows:

[0005] Regarding the literature concerning structural design and manufacturing process: Patent document CN117450151A discloses an emergency disconnect safety pin and its design method, which discloses a disconnect pin for engine suspension connection. However, its structure is limited to single and double lug connection, and it only assumes a double-sided shear form based on experience. It lacks a scientific method for selecting the disconnect cross section and a specific calculation process for the disconnect load. Patent documents CN118833386A (An emergency disconnect safety pin for aircraft main landing gear and its processing method) and CN118723067A (An emergency disconnect safety device for main landing gear) mainly focus on the structural form of the disconnect pin, material heat treatment and installation fit method, and do not involve load calculation.

[0006] Patents involving testing and verification, such as CN113800005A (an emergency disconnection test bench and test method for aircraft main landing gear), CN115824550A (a test bench and test method for the fallability test pin of civil aircraft), and CN116588352A (a static load verification device for emergency disconnection of landing gear), all disclose test devices and testing methods, and do not provide theoretical calculation methods for disconnection loads.

[0007] In summary, existing technologies primarily focus on the structural implementation and experimental verification of the break-off pin, lacking an engineering method based on mechanical theory that can systematically determine the break-off location and accurately calculate the break-off load. This gap makes it difficult to quickly assess break-off performance in the early stages of design, failing to meet the urgent need for efficient and verifiable calculation methods in aerospace engineering design. Summary of the Invention

[0008] To address the aforementioned deficiencies in the existing technology, the present invention aims to provide an engineering calculation method, system, device, and storage medium for emergency disconnection pin disconnection load, thereby solving the following technical problems:

[0009] To address the lack of a systematic method for selecting the break-off section in existing technologies: Overcoming the blind reliance on empirical assumptions about the break-off section (such as selecting only the smallest section), this paper provides a scientific method based on mechanical analysis to accurately determine the location of the most dangerous section on the break-off pin.

[0010] This addresses the lack of existing methods for calculating break-off load systems: filling the current gap in break-off pin engineering algorithms, changing the current situation where existing patents only focus on structure, process, or test equipment without providing load values, and providing a complete and quantifiable break-off load calculation process.

[0011] To address the issues of high computational load, long design cycle, and difficulty in rapid iteration in engineering applications of the finite element method, this paper proposes an explicit engineering algorithm based on beam theory and strength theory. This algorithm significantly reduces computational workload, shortens the design cycle, and facilitates multi-scheme comparison and rapid optimization in the early stages of design.

[0012] To address the lack of repeatability and ease of long-term preservation in existing methods, this paper provides a calculation method with clear calculation steps and an intuitive process. The results can be compiled into standardized paper or electronic documents, facilitating verification, review, and long-term preservation throughout the entire aircraft lifecycle.

[0013] In short, the present invention aims to provide a systematic, efficient, accurate and verifiable engineering calculation method for the breakage load of emergency disconnect pins, so as to guide the structural design of disconnect pins and ensure the reliable realization of emergency disconnection function.

[0014] This invention solves the above-mentioned technical problems through the following technical solution: an engineering calculation method for the breakage load of an emergency disconnection pin, comprising:

[0015] Based on the installation structure and stress characteristics of the break pin, a simplified calculation diagram of the break pin's stress is established based on beam theory, and the variation functions of shear force and bending moment along the break pin's axis are obtained.

[0016] Based on the cross-sectional geometry of the break pin, establish the calculation expressions for the cross-sectional area and bending modulus of the break pin;

[0017] Based on the shear force, bending moment, cross-sectional area, and flexural modulus, the shear stress and bending stress of each vertical section of the break pin are calculated, and the equivalent stress of each vertical section of the break pin is calculated based on the fourth strength theory. By analyzing the distribution law of the equivalent stress along the axial direction, the vertical section corresponding to the maximum equivalent stress is determined as the most dangerous section, and its axial position is recorded as the position of the most dangerous section.

[0018] Based on the axial interval where the most dangerous section is located, the breakup load is calculated using both shear strength theory and bending strength theory:

[0019] The first load value is calculated using the shear strength of the material as the boundary condition for maximum shear stress.

[0020] The second load value was calculated using the tensile strength of the material as the boundary condition for the maximum bending stress.

[0021] Compare the first load value and the second load value, and take the smaller value as the final break-off load of the break-off pin.

[0022] This invention establishes a stress model for a fracture pin based on beam theory, obtaining the axial distribution functions of shear force and bending moment. It then calculates the shear stress and bending stress at each section by combining cross-sectional geometric parameters. Furthermore, it calculates the equivalent stress based on the fourth strength theory (von Mises theory). By analyzing the axial distribution of the equivalent stress, the location of the most dangerous section on the fracture pin can be scientifically and quantitatively determined. This overcomes the blind assumption in existing technologies that the fracture section is the "minimum section" based solely on experience, providing a clear mechanical basis for the selection of the fracture section and improving the scientific rigor and accuracy of fracture pin design.

[0023] This invention calculates the breakage load based on the determined most dangerous section location, using both shear strength theory and bending strength theory. This fills the gap in the engineering calculation of breakage load in existing technologies and changes the current situation where existing technologies only focus on the structural form, material process, or test equipment of the breakage pin without providing load values. It provides a complete and quantifiable means of load calculation for breakage pin design.

[0024] This invention employs an explicit engineering algorithm, based on beam theory and mechanics of materials formulas for derivation and calculation, eliminating the need for complex finite element models. Compared to the finite element method, it significantly reduces computational workload, shortens the design cycle, and facilitates multi-scheme comparison and rapid iterative optimization in the early design stages. Furthermore, the calculation steps are clear and the process is intuitive, allowing for the creation of standardized paper or electronic documents that facilitate proofreading, review, and long-term preservation throughout the aircraft's lifespan, thus solving the problem of long-term archiving and review inherent in the finite element method.

[0025] This invention compares the load values ​​under shear failure and bending failure modes, taking the smaller value as the final breakage load. Based on the comparison result, the actual failure mode and failure initiation location of the breakage pin can be determined. This ensures that the breakage pin can reliably break under the expected operating conditions, avoids design deviations caused by incorrect failure mode determination, improves the reliability of the emergency breakage function, and provides technical support for the safety design of aircraft landing gear.

[0026] The method of this invention is based on the general stress characteristics of breakable pins, is not dependent on a specific structural form, and can be applied to different types of breakable pin designs. Furthermore, by analyzing the distribution of equivalent stress along the axial direction, the geometric dimensions of the breakable pin (such as inner and outer diameters) can be adjusted according to design needs, ensuring that the most critical section is located at a preset position. This method is highly versatile and has a wide range of applications; it also offers good design controllability, allowing engineers to optimize the breakable pin structure according to actual requirements.

[0027] Furthermore, the mounting structure of the break-off pin includes a landing gear end lug and a fuselage end spherical bearing. A coordinate system is established with the intersection of the vertical symmetry plane of the fuselage end spherical bearing and the axis of the break-off pin as the origin, and the direction of the break-off pin axis pointing towards the landing gear end as the positive X-axis. The variation functions of the shear force and bending moment along the axial direction of the break-off pin are as follows:

[0028] ;

[0029] ;

[0030] Where Q represents the shear force on the vertical section of the break pin; P represents the load on the vertical symmetry plane of the fuselage end spherical bearing; L1 represents the distance between the origin of the coordinate system and the near side of the landing gear end lug, where the near side refers to the side of the landing gear end lug closest to the origin of the coordinate system; L2 represents the width of the landing gear end lug; M represents the bending moment on the vertical section of the break pin; and x represents the axial position coordinate of any point on the break pin along the axis.

[0031] This invention provides a precise geometric benchmark and mechanical boundary for the stress analysis of the break-off pin by clearly defining the installation structure and coordinate system, giving the piecewise functions of shear force and bending moment a clear physical meaning and mathematical form. The introduction of piecewise functions reveals the differences in the stress characteristics of the break-off pin in different axial intervals, laying an accurate mechanical foundation for subsequent stress calculations and the location of critical sections. Simultaneously, the clear definition of the coordinate system ensures the consistency and repeatability of the method across different design applications.

[0032] Furthermore, the calculation expressions for the cross-sectional area and flexural modulus of the break pin are as follows:

[0033] ;

[0034] ;

[0035] Where A represents the cross-sectional area of ​​the break pin; D represents the outer diameter of the vertical section of the break pin; d represents the inner diameter of the vertical section of the break pin; and W represents the bending modulus of the break pin.

[0036] This invention provides a standardized calculation basis for the geometric properties of the cross-section of a breakable pin, directly linking the design parameters (outer diameter D, inner diameter d) of the breakable pin to the mechanical properties of the cross-section. These two formulas are standard expressions for the geometric properties of a circular cross-section in mechanics of materials, ensuring the accuracy and universality of the calculation results. By incorporating the cross-sectional geometry into the calculation system, designers can adjust D and d to change the load-bearing characteristics of the breakable pin, providing a mathematical tool for the parametric design and optimization of breakable pins.

[0037] Furthermore, the formulas for calculating the shear stress, bending stress, and equivalent stress are as follows:

[0038] , ;

[0039] ;

[0040] in, Q represents the shear stress in the vertical section of the break pin; Q represents the shear force in the vertical section of the break pin; A represents the cross-sectional area of ​​the break pin. M represents the bending stress in the vertical section of the broken pin; W represents the bending moment in the vertical section of the broken pin; W represents the bending modulus of the broken pin. This represents the equivalent stress at the vertical section of the broken pin.

[0041] This invention clarifies the complete transformation relationship from internal forces (Q, M) and cross-sectional properties (A, W) to stress states, making the stress calculation process transparent and standardized. In particular, the use of the fourth strength theory (von Mises) to calculate equivalent stress can comprehensively consider the coupling effect of shear and bending stress components, more accurately reflecting the actual stress level of the fracture pin under complex stress conditions, and providing a reliable mechanical criterion for the scientific determination of critical sections.

[0042] Furthermore, based on the axial interval where the most dangerous section location is located, the first load value and the second load value are calculated as follows:

[0043] when hour, , ;

[0044] when hour, , ;

[0045] in, L1 represents the location of the most dangerous section; L1 represents the distance between the coordinate origin and the near side of the landing gear end lug. The coordinate origin is the intersection of the vertical symmetry plane of the fuselage end joint bearing and the axis of the breakage pin. The near side refers to the side of the landing gear end lug closest to the coordinate origin; L2 represents the width of the landing gear end lug. This represents the first load value, i.e., the breakage load value of the breakage pin under shear failure conditions; The shear strength of the material is represented by D; the outer diameter of the vertical section of the broken pin is represented by d; the inner diameter of the vertical section of the broken pin is represented by d. This represents the second load value, i.e., the breakage load value of the broken pin under bending failure conditions; This indicates the tensile strength of the material.

[0046] The introduction of the segmented load formula reflects the differences in the force mechanism of the broken pin in different axial intervals, enabling the load calculation to accurately match the actual location of the most critical section. Specifically:

[0047] For the shear failure mode, the formula for calculating the first load value directly reflects the relationship between shear stress and cross-sectional area. When the second interval is located, L2 is introduced to reflect the influence of the ear width on the shear load.

[0048] For the bending failure mode, the formula for calculating the second load value reflects the relationship between the bending moment and the section bending modulus, where the denominator contains... or The introduction of this precisely reflects the influence of the moment arm length.

[0049] These segmented formulas fully encapsulate the mechanical model of the broken pin, ensuring high accuracy and reliability in load calculation results.

[0050] Furthermore, the method also includes determining the failure mode and failure initiation location of the broken pin based on the comparison result of the first load value and the second load value:

[0051] When the first load value is greater than the second load value, the failure mode of the broken pin is bending stress failure, and the failure initiation point is the vertex and bottom point of the vertical symmetry plane of the broken pin.

[0052] When the first load value is less than the second load value, the failure mode of the break pin is shear failure, and the failure initiation point is the neutral axis of the break pin.

[0053] When the first load value equals the second load value, the failure mode of the break pin is a combined bending and shear failure, where the shear stress and bending stress simultaneously reach the ultimate strength. The failure initiation points include the neutral axis of the break pin, the vertex of the vertical symmetry plane, and the bottom point of the vertical symmetry plane.

[0054] This invention directly links load calculation results with failure mechanisms, revealing the failure modes of fracture pins and providing deeper guidance for their structural design. Specifically: the determination of failure modes allows designers to predict the actual failure mode of fracture pins, facilitating targeted optimization of cross-sectional shape or material selection; the explicit identification of the failure initiation location clearly indicates the weakest link on the fracture pin, providing a basis for local reinforcement design or damage monitoring; and the handling of equivalent cases ensures the logical integrity of the method under boundary conditions, avoiding theoretical blind spots.

[0055] This feature expands the output of the present invention from a single "load value" to a complete set of failure information including failure modes and locations, significantly enhancing the engineering practical value of the method.

[0056] Based on the same concept, the present invention also provides an engineering calculation system for emergency disconnection pin disconnection load, the system comprising:

[0057] The first module is used to establish a simplified calculation diagram of the stress on the disconnect pin based on beam theory, according to the installation structure and stress characteristics of the disconnect pin, and to obtain the variation functions of shear force and bending moment along the axis of the disconnect pin.

[0058] The second module is used to establish calculation expressions for the cross-sectional area and bending modulus of the break pin based on its cross-sectional geometry.

[0059] The first calculation module is used to calculate the shear stress and bending stress of each vertical section of the break pin based on the shear force, bending moment, cross-sectional area and bending modulus, and to calculate the equivalent stress of each vertical section of the break pin based on the fourth strength theory.

[0060] The analysis and determination module is used to determine the vertical section corresponding to the maximum equivalent stress as the most dangerous section by analyzing the distribution law of the equivalent stress along the axial direction, and its axial position is recorded as the position of the most dangerous section.

[0061] The second calculation module is used to back-calculate the breakup load based on the shear strength theory and bending strength theory, respectively, according to the axial interval where the most dangerous section is located:

[0062] The first load value is calculated using the shear strength of the material as the boundary condition for maximum shear stress.

[0063] The second load value was calculated using the tensile strength of the material as the boundary condition for the maximum bending stress.

[0064] The comparison module is used to compare the first load value and the second load value, and take the smaller value as the final break-off load of the break-off pin.

[0065] The first module transforms the physical disconnected pin installation structure into a quantifiable and calculable mechanical model, automatically outputting the distribution functions of shear force and bending moment along the axial direction. This modular approach standardizes and reusables the complex mechanical modeling process. Users no longer need to perform repeated mechanical derivations; they only need to input the installation structure parameters to obtain accurate shear force and bending moment distributions, providing precise mechanical input for subsequent stress calculations.

[0066] The second module automatically converts the geometric design parameters (outer diameter D, inner diameter d) of the break-off pin into expressions for the mechanical properties of the cross section, realizing a direct mapping from geometric design to mechanical properties. This feature allows designers to instantly obtain the corresponding cross-sectional characteristics by adjusting the geometric parameters, providing tool support for the parametric design and rapid iteration of break-off pins.

[0067] The first calculation module automatically synthesizes internal forces and section properties into complete stress state information, especially by comprehensively considering the coupling effect of shear and bending stresses through the fourth strength theory. This modular processing allows stress distributions that previously required manual point-by-point calculations to be automatically generated in batches, significantly improving calculation efficiency while ensuring the accuracy and consistency of stress calculations.

[0068] The analysis and determination module enables the automatic identification and location of the critical section of the breakage pin. By analyzing the equivalent stress distribution pattern, the system can objectively and quantitatively determine the location of the breakage, rather than relying on experience-based judgment. This feature algorithmizes and automates the selection process of the breakage section, avoiding the subjectivity and uncertainty of manual judgment, and providing accurate location input for subsequent load back-calculation.

[0069] The second calculation module fully encapsulates the core back-calculation algorithm of this invention. It can automatically match the corresponding calculation formula based on the actual location of the most dangerous section, and simultaneously calculate two load values ​​in parallel based on two different failure theories (shear and bending). This modular design makes the complex load back-calculation process transparent and traceable, allowing users to obtain accurate load calculation results without manually handling piecewise functions and formula selection.

[0070] The comparison module automatically performs logical comparisons and outputs decisions for the two load values. By taking the smaller value as the final break-off load, the system ensures that the design results are conservative and reliable, conforming to the mechanical principle that "structural failure is determined by the first ultimate limit state reached." This feature automates and standardizes the final engineering decision, avoiding oversights that may occur with manual comparisons, and directly outputs the final break-off load value that can be used for design.

[0071] Based on the same concept, the present invention also provides an electronic device, including a memory, a processor, and a computer program or instructions stored in the memory, wherein the processor executes the computer program or instructions to implement the engineering calculation method for the emergency disconnection pin disconnection load as described above.

[0072] Based on the same concept, the present invention also provides a computer-readable storage medium having a computer program or instructions stored thereon, which, when executed by a processor, implements the engineering calculation method for the emergency disconnection pin disconnection load as described above.

[0073] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0074] This invention systematically solves the problems existing in the prior art, such as blind selection of the break-off section, lack of break-off load calculation, low efficiency of the finite element method, and difficulty in verifying calculation results, through a complete technical path of "modeling → stress analysis → critical section location → dual-mode load back calculation → minimum value output". It realizes scientific, efficient, accurate and verifiable engineering calculation of break-off load of break-off pin, and has significant technical progress and engineering practical value. Attached Figure Description

[0075] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0076] Figure 1 This is a flowchart of the engineering calculation method for the emergency disconnection pin disconnection load in an embodiment of the present invention;

[0077] Figure 2 This is a schematic diagram of the installation structure of the disconnect pin in an embodiment of the present invention;

[0078] Figure 3 This is a simplified diagram of the stress calculation of the broken pin based on beam theory in an embodiment of the present invention;

[0079] Figure 4 This is a schematic diagram showing the distribution of equivalent stress along the axial direction of a vertical cross section of a broken pin in an embodiment of the present invention.

[0080] Explanation of reference numerals in the attached diagram: 1-Disconnect pin, 2-Landing gear end lug, 3-Fuselage end spherical bearing, 4-Vertex of vertical symmetry plane, 5-Bottom point of vertical symmetry plane. Detailed Implementation

[0081] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0082] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0083] Example 1

[0084] Reference Figure 1 The engineering calculation method for the emergency disconnection load provided in this embodiment of the invention includes the following steps:

[0085] Step 1: Based on the installation structure and stress characteristics of the break pin, establish a simplified calculation diagram of the break pin's stress based on beam theory, and obtain the variation functions of shear force and bending moment along the break pin's axial direction.

[0086] like Figure 2 As shown, the mounting structure of the breakaway pin 1 includes a landing gear end lug 2 and a fuselage end spherical bearing 3. The fuselage end spherical bearing 3 is mounted and connected to the breakaway pin 1 (i.e., the fuselage end is connected to the breakaway pin 1 via the spherical bearing), and the landing gear end lug 2 is connected to the breakaway pin 1 via a hole-shaft fit. The load that the breakaway pin 1 bears in the vertical plane of symmetry of the fuselage end spherical bearing 3 is P. The load value that causes the breakaway pin 1 to fail is the breakaway load of the breakaway pin 1.

[0087] by Figure 2 Taking the installation structure shown as an example, with the intersection point O of the vertical symmetry plane of the fuselage end joint bearing 3 and the axis of the break pin 1 as the origin of the coordinate system, and with the axis of the break pin 1 pointing towards the landing gear end as the positive X-axis, a coordinate system is established with the X-axis as the axial position reference. The Y-axis of the coordinate system is positive when it is vertically downward, and the Z-axis follows the right-hand rule. Figure 2 In the diagram, point A is the intersection of the landing gear end lug 2 (near the origin) and the axis of the break pin 1; point B is the intersection of the landing gear end lug 2 (far from the fuselage) and the axis of the break pin 1. L1 represents the distance between the origin and the near side of the landing gear end lug 2; L2 represents the width of the landing gear end lug 2. A three-dimensional coordinate system is established with point O as the origin. The x-axis is positive, pointing towards the landing gear end along the axis of the break pin 1; the y-axis is positive, pointing vertically downwards; and the z-axis follows the right-hand rule.

[0088] Figure 3 This diagram illustrates a simplified calculation of the stress on the break pin based on beam theory, where P represents the load borne by the break pin in the vertical plane of symmetry of the fuselage end spherical bearing, and F...A To disengage the load on the near-side of the landing gear end lug, F B Let Q be the load borne by the break pin on the distal side of the landing gear end lug, and M be the shear force on the vertical section of the break pin. Combined with... Figure 2 and Figure 3 The shear force and bending moment acting on the vertical section of the detached pin are piecewise functions along the X-axis (i.e., the axial direction):

[0089] (1)

[0090] (2)

[0091] Where x represents the axial position coordinate of any point on the break pin along the axis.

[0092] Step 2: Based on the cross-sectional geometry of the break pin, establish the calculation expressions for the cross-sectional area and bending modulus of the break pin.

[0093] For a common annular cross-section, let the outer diameter of the vertical cross-section of the broken pin be D and the inner diameter be d, then we have:

[0094] (3)

[0095] (4)

[0096] Where A represents the cross-sectional area of ​​the break pin; W represents the bending modulus of the break pin.

[0097] Step 3: Based on shear force, bending moment, cross-sectional area, and flexural modulus, calculate the shear stress and bending stress of each vertical section of the break pin, and calculate the equivalent stress of each vertical section of the break pin based on the fourth strength theory.

[0098] The formulas for calculating shear stress, bending stress, and equivalent stress are as follows:

[0099] (5)

[0100] (6)

[0101] (7)

[0102] in, This represents the shear stress in the vertical section of the break pin; This represents the bending stress in the vertical section of the broken pin; This represents the equivalent stress at the vertical section of the broken pin.

[0103] Step 4: By analyzing the distribution law of equivalent stress along the axial direction, the vertical section corresponding to the maximum equivalent stress is determined as the most dangerous section, and its axial position is recorded as the position of the most dangerous section.

[0104] Equivalent stress was plotted using data processing software. The curve showing the change in axial direction is used to determine the vertical section corresponding to the maximum equivalent stress as the most critical section, and its axial position (i.e., the X-axis coordinate position) is recorded as the location of the most critical section. . Figure 4 The curve showing the equivalent stress versus axial force at the vertical section of a broken pin is presented. From this curve, the X-axis coordinate corresponding to the point of maximum equivalent stress can be visually identified (i.e.,...). If the most dangerous section is not in the expected position, the inner diameter d or outer diameter D of the break pin can be adjusted to place it in the expected position.

[0105] Step 5: Based on the axial interval where the most dangerous section is located, calculate the break-off load using both shear strength theory and bending strength theory: calculate the first load value using the shear strength of the material as the maximum shear stress boundary condition; calculate the second load value using the tensile strength of the material as the maximum bending stress boundary condition.

[0106] Let the location of the most dangerous section be... Let the shear stress of this section be , Calculate the load value (first load value) borne by the breakage pin in the vertical symmetry plane of the fuselage end spherical bearing under this condition, based on the shear strength of the material. That is, the breaking load value of the breaking pin under shear failure conditions:

[0107] when hour:

[0108] (8)

[0109] when hour:

[0110] (9)

[0111] Let the bending stress at the most dangerous section be , Indicates the tensile strength of the material. Calculate the load value (second load value) borne by the breakage pin in the vertical symmetry plane of the fuselage end spherical bearing under this condition. That is, the breaking load value of the broken pin under bending failure conditions:

[0112] when hour:

[0113] (10)

[0114] when hour:

[0115] (11)

[0116] Step 6: Compare the first load value and the second load value, and take the smaller value as the final break-off load of the break-off pin.

[0117] when > At that time, take The final break-off load of the break-off pin;

[0118] when < At that time, take The final break-off load of the break-off pin;

[0119] when = At that time, take or This is the final break-off load of the break-off pin.

[0120] Step 7: Based on the comparison between the first load value and the second load value, determine the failure mode and failure initiation position of the broken pin.

[0121] when > When the broken pin fails, the failure mode is bending stress failure, and the failure initiation point is the vertex 4 and the bottom point 5 of the vertical symmetry plane of the broken pin.

[0122] when < When the break pin breaks, the failure mode is shear failure, and the failure initiation point is the neutral axis of the break pin;

[0123] when = When the fracture pin breaks, the failure mode is a combination of bending and shear failure, where the shear stress and bending stress simultaneously reach the ultimate strength. The failure initiation points include the neutral axis of the fracture pin, the vertex 4 of the vertical symmetry plane, and the bottom point 5 of the vertical symmetry plane.

[0124] Example 2

[0125] This invention provides an engineering calculation system for the breakage load of an emergency disconnection pin, the system comprising the following modules:

[0126] The first module establishes a simplified calculation diagram of the stress on the break pin based on beam theory, taking into account its installation structure and stress characteristics, and derives the variation functions of shear force and bending moment along the axial direction of the break pin. This module receives user-inputted break pin installation parameters, including the position of the landing gear end lugs, the position of the fuselage end spherical bearing, and the load application point. It automatically establishes a coordinate system with the intersection of the vertical symmetry plane of the fuselage end spherical bearing and the break pin axis as the origin, and derives piecewise function expressions of shear force and bending moment along the axial direction based on a simply supported beam model. For example, for... Figure 2 The typical installation structure shown shows that the shear force and bending moment output by this module are represented by formulas (1) and (2) in Example 1.

[0127] The second module is used to establish calculation expressions for the cross-sectional area and bending modulus of the break pin based on its cross-sectional geometry. This module receives geometric parameters such as the outer diameter D and inner diameter d of the break pin and automatically calculates the cross-sectional area and bending modulus according to the standard formula for annular sections in mechanics of materials, as shown in formulas (3) and (4) in Example 1.

[0128] The first calculation module is used to calculate the shear stress and bending stress of each vertical section of the break pin based on the shear force and bending moment obtained from the first establishment module and the cross-sectional area and bending modulus obtained from the second establishment module, and to calculate the equivalent stress of each vertical section based on the fourth strength theory. The specific calculation formulas are shown in formulas (5) to (7) in Example 1.

[0129] The analysis and determination module is used to determine the vertical section corresponding to the maximum equivalent stress as the most critical section by analyzing the distribution pattern of equivalent stress along the axial direction. Its axial position is denoted as the location of the most critical section. This module can use a numerical search algorithm to find the maximum point of equivalent stress within the axial interval, or it can do so by plotting stress distribution curves (such as...). Figure 4 (As shown in the image) and automatically identifies the peak point to determine the location of the most dangerous section. If it is necessary to adjust the most dangerous section to the expected location, the module can also suggest to the user to adjust the value of the inner diameter d or outer diameter D of the break pin based on the calculation results.

[0130] The second calculation module is used to back-calculate the breakage load based on the shear strength theory and bending strength theory respectively, according to the axial interval where the most dangerous section is located, to obtain the first load value and the second load value. The specific back-calculation formulas are shown in formulas (8) to (11) in Example 1.

[0131] The comparison module compares the first load value and the second load value, takes the smaller value as the final breakage load of the breakage pin, and outputs the result. This module can further determine the failure mode and failure initiation location of the breakage pin based on the comparison result: when the first load value > the second load value, it is determined to be bending stress failure, with the initiation point being the vertex and trough of the vertical symmetry plane; when the first load value < the second load value, it is determined to be shear failure, with the initiation point being the neutral axis; when the first load value = the second load value, it is determined to be combined bending and shear failure, with the initiation points including the neutral axis, the vertex and trough of the vertical symmetry plane.

[0132] The system in this embodiment can be deployed in a computer, workstation, or embedded device. Each module is implemented by a software program and stored in memory, and is executed by the processor. The system provides a user interface for inputting the structural parameters of the break pin (such as L1, L2, D, d) and material strength parameters (…). , The system provides information on load conditions and automatically calculates and displays the location of the most dangerous section, the final break-off load, and the failure mode. This system achieves modular and automated break-off load calculation, significantly improving design efficiency and accuracy.

[0133] Example 3

[0134] This invention also provides an electronic device, which includes: a memory, a processor, and a computer program or instructions stored in the memory. The processor executes the computer program or instructions to implement the engineering calculation method for the emergency disconnection pin disconnection load in this invention.

[0135] Although not shown, the electronic device includes a processor that can perform various appropriate operations and processes based on programs and / or data stored in read-only memory (ROM) or loaded from a storage portion into random access memory (RAM). The processor can be a multi-core processor or may contain multiple processors. In some embodiments, the processor may include a general-purpose main processor and one or more specialized coprocessors, such as a central processing unit, graphics processing unit (GPU), neural network processor (NPU), digital signal processor (DSP), etc. Various programs and data required for device operation are also stored in RAM. The processor, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0136] The processor and memory described above are used together to execute programs / instructions stored in the memory. When the program / instructions are executed by the computer, they can implement the methods, steps, or functions described in the above embodiments.

[0137] Although not shown, embodiments of the present invention also provide a computer-readable storage medium having a computer program or instructions stored thereon, which, when executed by a processor, implements the engineering calculation method for the emergency disconnection pin disconnection load in embodiments of the present invention.

[0138] Readable storage media include both permanent and non-permanent, removable and non-removable media that can store information by any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0139] The above description only discloses specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An engineering calculation method for the breakage load of an emergency disconnection pin, characterized in that, The calculation method includes: Based on the installation structure and stress characteristics of the break pin, a simplified calculation diagram of the break pin's stress is established based on beam theory, and the variation functions of shear force and bending moment along the break pin's axis are obtained. Based on the cross-sectional geometry of the break pin, establish the calculation expressions for the cross-sectional area and bending modulus of the break pin; Based on the shear force, bending moment, cross-sectional area, and flexural modulus, the shear stress and bending stress of each vertical section of the break pin are calculated, and the equivalent stress of each vertical section of the break pin is calculated based on the fourth strength theory. By analyzing the distribution law of the equivalent stress along the axial direction, the vertical section corresponding to the maximum equivalent stress is determined as the most dangerous section, and its axial position is recorded as the position of the most dangerous section. Based on the axial interval where the most dangerous section is located, the breakup load is calculated using both shear strength theory and bending strength theory: The first load value is calculated using the shear strength of the material as the boundary condition for maximum shear stress. The second load value was calculated using the tensile strength of the material as the boundary condition for the maximum bending stress. Compare the first load value and the second load value, and take the smaller value as the final break-off load of the break-off pin.

2. The engineering calculation method for the emergency disconnection pin disconnection load according to claim 1, characterized in that, The mounting structure of the breakaway pin includes landing gear end lugs and fuselage end spherical bearings. A coordinate system is established with the intersection of the vertical symmetry plane of the fuselage end spherical bearing and the axis of the breakaway pin as the origin, and the direction of the breakaway pin axis pointing towards the landing gear end as the positive X-axis. The variation functions of the shear force and bending moment along the axial direction of the breakaway pin are as follows: ； ； Where Q represents the shear force on the vertical section of the break pin; P represents the load on the vertical symmetry plane of the fuselage end spherical bearing; L1 represents the distance between the origin of the coordinate system and the near side of the landing gear end lug, where the near side refers to the side of the landing gear end lug closest to the origin of the coordinate system; L2 represents the width of the landing gear end lug; M represents the bending moment on the vertical section of the break pin; and x represents the axial position coordinate of any point on the break pin along the axis.

3. The engineering calculation method for the emergency disconnection pin disconnection load according to claim 1, characterized in that, The calculation expressions for the cross-sectional area and flexural modulus of the break pin are as follows: ； ； Where A represents the cross-sectional area of ​​the break pin; D represents the outer diameter of the vertical section of the break pin; d represents the inner diameter of the vertical section of the break pin; and W represents the bending modulus of the break pin.

4. The engineering calculation method for the emergency disconnection pin disconnection load according to claim 1, characterized in that, The formulas for calculating shear stress, bending stress, and equivalent stress are as follows: ， ； ； in, Q represents the shear stress in the vertical section of the break pin; Q represents the shear force in the vertical section of the break pin; A represents the cross-sectional area of ​​the break pin. M represents the bending stress in the vertical section of the broken pin; W represents the bending moment in the vertical section of the broken pin; W represents the bending modulus of the broken pin. This represents the equivalent stress at the vertical section of the broken pin.

5. The engineering calculation method for the emergency disconnection pin disconnection load according to claim 1, characterized in that, Based on the axial interval where the most dangerous section is located, the first load value and the second load value are calculated as follows: when hour, , ; when hour, , ; in, L1 represents the location of the most dangerous section; L1 represents the distance between the coordinate origin and the near side of the landing gear end lug. The coordinate origin is the intersection of the vertical symmetry plane of the fuselage end joint bearing and the axis of the breakage pin. The near side refers to the side of the landing gear end lug closest to the coordinate origin; L2 represents the width of the landing gear end lug. This represents the first load value, i.e., the breakage load value of the breakage pin under shear failure conditions; The shear strength of the material is represented by D; the outer diameter of the vertical section of the broken pin is represented by d; the inner diameter of the vertical section of the broken pin is represented by d. This represents the second load value, i.e., the breakage load value of the broken pin under bending failure conditions; This indicates the tensile strength of the material.

6. The engineering calculation method for the emergency disconnection pin disconnection load according to any one of claims 1 to 5, characterized in that, The method further includes determining the failure mode and failure initiation location of the break pin based on a comparison between the first load value and the second load value: When the first load value is greater than the second load value, the failure mode of the broken pin is bending stress failure, and the failure initiation point is the vertex and bottom point of the vertical symmetry plane of the broken pin. When the first load value is less than the second load value, the failure mode of the break pin is shear failure, and the failure initiation point is the neutral axis of the break pin. When the first load value equals the second load value, the failure mode of the break pin is a combined bending and shear failure, where the shear stress and bending stress simultaneously reach the ultimate strength. The failure initiation points include the neutral axis of the break pin, the vertex of the vertical symmetry plane, and the bottom point of the vertical symmetry plane.

7. An engineering calculation system for emergency disconnection pin disconnection load, characterized in that, The system includes: The first module is used to establish a simplified calculation diagram of the stress on the disconnect pin based on beam theory, according to the installation structure and stress characteristics of the disconnect pin, and to obtain the variation functions of shear force and bending moment along the axis of the disconnect pin. The second module is used to establish calculation expressions for the cross-sectional area and bending modulus of the break pin based on its cross-sectional geometry. The first calculation module is used to calculate the shear stress and bending stress of each vertical section of the break pin based on the shear force, bending moment, cross-sectional area and bending modulus, and to calculate the equivalent stress of each vertical section of the break pin based on the fourth strength theory. The analysis and determination module is used to determine the vertical section corresponding to the maximum equivalent stress as the most dangerous section by analyzing the distribution law of the equivalent stress along the axial direction, and its axial position is recorded as the position of the most dangerous section. The second calculation module is used to back-calculate the breakup load based on the shear strength theory and bending strength theory, respectively, according to the axial interval where the most dangerous section is located: The first load value is calculated using the shear strength of the material as the boundary condition for maximum shear stress. The second load value was calculated using the tensile strength of the material as the boundary condition for the maximum bending stress. The comparison module is used to compare the first load value and the second load value, and take the smaller value as the final break-off load of the break-off pin.

8. An electronic device comprising a memory, a processor, and a computer program or instructions stored in the memory, characterized in that, The processor executes the computer program or instructions to implement the engineering calculation method for the emergency disconnection pin disconnection load as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, When the computer program or instructions are executed by the processor, they implement the engineering calculation method for the emergency disconnection pin disconnection load as described in any one of claims 1 to 6.

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