A method for optimizing design of a top cross beam of a ROPS framework and an engineering machinery cab

Abstract

The application discloses a ROPS framework top cross beam optimization design method and an engineering machinery cab, and the design method comprises the following steps: by analyzing the bending stress value of a portal hyperstatic structure mechanical model, the inertia moment I ratio of the top cross beam and the stand column when the maximum bending stress of the top cross beam and the stand column is equal is obtained, that is, the optimal cross section inertia moment ratio relationship of the top cross beam and the stand column, and the lightweight design of the ROPS framework is realized.

Description

Technical Field

[0001] This invention belongs to the technical field of engineering machinery cabs, and relates to an optimized design method for the top crossbeam of the ROPS frame and an engineering machinery cab. Background Technology

[0002] Engineering vehicles operate in harsh environments with complex and varied road surfaces, making rollover accidents frequent. Due to their large size, rollover accidents have an extremely high fatality rate, primarily caused by the extreme deformation of the cab after an accident. While rollover accidents are unavoidable, the most effective and simplest method to reduce the loss of life and property is passive protection, namely, installing rollover protection structures (ROPS) on the vehicle to provide a degree of safety.

[0003] Construction machinery operates in harsh environments, making Rollover Protection Structures (ROPS) frames a standard feature in cabs. Testing requires ROPS frames to meet loading requirements for lateral, vertical, and longitudinal loads, as well as lateral load energy. Under lateral loading, the cab is in a state of elastoplastic deformation, and plastic hinges appear in the frame at points of maximum bending moment or structural weakness. These plastic hinges allow for significant lateral deformation and displacement of the frame, facilitating the absorption of lateral impact load energy. Properly planning the location and sequence of these plastic hinge formations is crucial for achieving lightweight and high-quality design of the ROPS frame.

[0004] Currently, the industry's experience-based design of top crossbeams has problems of being either excessive or insufficient. When the top crossbeam design is insufficient, plastic hinges are formed on the top crossbeam too early, resulting in insufficient support force of the top crossbeam for the column. When the top crossbeam design is excessive, plastic hinges are formed on the column, resulting in large deformation of the column itself. Both of these situations are not conducive to the lightweight design of ROPS frames. Summary of the Invention

[0005] Objective: In order to overcome the shortcomings of the existing technology, the present invention provides an optimized design method for the top crossbeam of the ROPS frame and a cab for engineering machinery.

[0006] This invention provides a design method for the optimal ratio of the moments of inertia of the top crossbeam and the column sections of the ROPS skeleton; a reasonable design of the top crossbeam should enable both the top crossbeam and the root of the column to enter the plastic deformation zone simultaneously, thereby achieving effective absorption of impact load energy.

[0007] This invention analyzes the loading characteristics of ROPS experiments and proposes an optimized ROPS skeleton structure.

[0008] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0009] Firstly, a centrally symmetrical ROPS framework is provided, including columns, crossbeams, and longitudinal beams;

[0010] The columns include columns A, B, and D; the crossbeams include a top crossbeam and a bottom crossbeam; the longitudinal beams include a top longitudinal beam and a bottom longitudinal beam.

[0011] The two A-pillars are connected by the first top crossbeam and the first bottom crossbeam to form a closed rectangular A-ring;

[0012] The two B-pillars are connected by the second top crossbeam and the second bottom crossbeam to form a closed rectangular B-ring;

[0013] The two D-pillars are connected by the third top crossbeam and the third bottom crossbeam to form a closed rectangular D-ring;

[0014] The four corner positions corresponding to ring A and ring B are connected by the first top longitudinal beam and the first bottom longitudinal beam, and the four corner positions corresponding to ring B and ring D are connected by the second top longitudinal beam and the second bottom longitudinal beam, forming a closed space frame structure.

[0015] In some embodiments, the ratio of the moment of inertia I of the first top beam to that of column A is n, where n is 0.6 to 0.7.

[0016] In some embodiments, the ratio of the moment of inertia I of the second top beam to that of the B-column is n, where n is 0.6 to 0.7.

[0017] In some embodiments, the ratio of the moment of inertia I of the third top beam to that of column D is n, where n is 0.6 to 0.7.

[0018] Secondly, the method for optimizing the design of the top crossbeam of the central axis symmetric ROPS skeleton is provided, including:

[0019] S1 Create a mechanical model: Based on the ROPS skeleton structure, extract the length dimension W of the top beam and the length dimension L of the column to form a portal frame statically indeterminate structural mechanical model. Based on the portal frame statically indeterminate structural mechanical model, analyze the relationship between the bending moment distribution of the top beam and the column.

[0020] S2 Selected Design Parameters: Based on the fact that the moment of inertia I of the profile section is the key factor determining the bending moment distribution in the mechanical model, the moment of inertia I of the profile section is selected as the design parameter of the profile.

[0021] S3 Structural Mechanics Analysis: The bending moment and stress values ​​of the portal frame statically indeterminate structural mechanical model are analyzed using structural mechanics analysis software to obtain the ratio of the moments of inertia I of the top beam and the column when the maximum bending moment and stress of the top beam and the column are equal.

[0022] S4 Create Relationship: Based on the ratio of the moments of inertia I of the top beam and the column, the optimal design relationship of the top beam is obtained;

[0023] The profiles of the top crossbeam and the corresponding column are selected based on the optimized design formula of the top crossbeam.

[0024] In some embodiments, the length W of the top crossbeam is 1.45m to 1.6m; the length L of the column is 1.65m to 1.9m.

[0025] In some embodiments, the relationship between the bending moment distribution of the top beam and the column is: M 立柱 >M 顶_横梁 .

[0026] In some embodiments, the optimal design formula for the top crossbeam is: I 顶_横梁 =nI 立柱 The ratio of the moment of inertia I of the top beam and the column, n, is 0.6 to 0.7.

[0027] Thirdly, the present invention also provides a cab for engineering machinery, including the aforementioned axisymmetric ROPS frame.

[0028] Beneficial Effects: The ROPS frame top crossbeam optimization design method and engineering machinery cab provided by this invention, through analytical structural mechanics modeling, obtain the optimal proportional relationship of the cross-sectional moments of inertia of the top crossbeam and columns, realizing a lightweight and high-quality design method for the ROPS frame. This method can significantly shorten the ROPS frame design time and improve design quality. It has the following advantages:

[0029] (1) This invention provides a design method for the optimal ratio of the moments of inertia of the top crossbeam and column sections of the ROPS skeleton;

[0030] (2) The present invention provides a closed “ring” ROPS skeleton structure that facilitates force transmission;

[0031] (3) The design method of the present invention can be embedded into the intelligent design software database. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating the optimized design method for the top crossbeam of the ROPS skeleton in this embodiment.

[0033] Figure 2 In this embodiment, the ROPS skeleton has a closed "ring" structure.

[0034] Figure 3 This is a schematic diagram of the ROPS skeleton gantry-type statically indeterminate structural mechanical model in the embodiment. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0036] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0037] In the description of this disclosure, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this disclosure.

[0038] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the present invention.

[0039] Definition of technical terms:

[0040] ROPS – Rollover Protection Structures – are a series of structural components that reduce the likelihood of a seatbelt-wearing driver being crushed when a machine rolls over.

[0041] ROPS skeleton – a spatial frame structure constructed to meet the design requirements of ROPS;

[0042] Column – A component or part that provides vertical support;

[0043] A beam is a horizontally arranged structural member.

[0044] Top beam – the beam component at the top of the frame;

[0045] The moment of inertia I of a cross section is the integral of the product of the area of ​​each infinitesimal element of the cross section and the square of the distance from each infinitesimal element to a specified axis on the cross section. It is a geometric parameter that measures the bending resistance of a member's cross section. Unless otherwise specified in this article, the axis of the moment of inertia of the cross section passes through the centroid of the cross section.

[0046] Plastic hinge – In a ROPS skeleton under bending moment, a point in the local area of ​​the member where the opposite surface yields but does not fail, and the member can rotate about a finite angle, can be called a plastic hinge.

[0047] Plastic deformation zone – Under lateral loading, multiple plastic hinges appear in the ROPS skeleton, causing the ROPS skeleton to be unable to continue to maintain a statically determinate structure. This state is called the plastic deformation zone.

[0048] The design method of this invention is based on the characteristic that the most stringent requirement in ROPS testing is the lateral loading test. To facilitate the transfer of lateral loads, a method is created... Figure 2 The closed "ring" skeleton structure shown is Figure 3 The gantry-type statically indeterminate structural mechanics model shown is analyzed using structural mechanics software to determine the design objective of the top beam and columns simultaneously entering the plastic deformation zone. The ratio of the bending geometric parameters of the top beam and columns is obtained, and this ratio is used to guide the selection of ROPS frame profiles.

[0049] Example 1

[0050] The central axis symmetrical closed "ring" skeleton structure includes columns, top beams and bottom beams; one end of the top beam is connected to the top of one of the two columns, and the other end is connected to the top of the other of the two columns; one end of the bottom beam is connected to the bottom of one of the two columns, and the other end is connected to the bottom of the other of the two columns, forming a closed "ring" skeleton structure.

[0051] A centrally symmetrical cab ROPS frame includes multiple closed "ring" frame structures, which are connected sequentially by longitudinal beams.

[0052] In some embodiments, a corner brace is provided at the connection between the column and the top crossbeam, and a limit device is provided at the bottom of the cab ROPS frame.

[0053] In some embodiments, such as Figure 2 As shown, a ROPS frame for a centrally symmetrical cab includes columns, crossbeams, and longitudinal beams;

[0054] The columns include column A10, column B20, and column D30; the crossbeams include a top crossbeam and a bottom crossbeam; the longitudinal beams include a top longitudinal beam and a bottom longitudinal beam.

[0055] The two A-pillars 10 are connected by the first top crossbeam 11 and the first bottom crossbeam 12 to form a closed rectangular A-ring;

[0056] The two B-pillars 20 are connected by the second top crossbeam 21 and the second bottom crossbeam 22 to form a closed rectangular B-ring;

[0057] The two D-pillars 30 are connected by the third top crossbeam 31 and the third bottom crossbeam 32 to form a closed rectangular D-ring;

[0058] The four corner positions corresponding to ring A and ring B are connected by the first top longitudinal beam 41 and the first bottom longitudinal beam 42, and the four corner positions corresponding to ring B and ring D are connected by the second top longitudinal beam 51 and the second bottom longitudinal beam 52, forming a closed space frame structure.

[0059] The A ring, B ring, and D ring are all rectangular structures, and the entire ROPS skeleton has a central axis symmetry structure.

[0060] The longitudinal beams include the top longitudinal beam and the bottom longitudinal beam. To ensure the flatness of the bottom of the entire ROPS frame, the bottom longitudinal beam is basically set on the same plane as the bottom cross beam (e.g., horizontally). However, the lengths of the A, B, and D columns are not necessarily equal, so the top longitudinal beam and the top cross beam are not necessarily on the same plane.

[0061] In some embodiments, the ratio of the moment of inertia I of the first top beam to that of column A is n, where n is 0.6 to 0.7.

[0062] In some embodiments, the ratio of the moment of inertia I of the second top beam to that of the B-column is n, where n is 0.6 to 0.7.

[0063] In some embodiments, the ratio of the moment of inertia I of the third top beam to that of column D is n, where n is 0.6 to 0.7.

[0064] The ROPS skeleton was designed using the design method described in Example 2.

[0065] Example 2

[0066] like Figure 1 As shown, an optimization design method for the top crossbeam of a centrally symmetric ROPS skeleton includes:

[0067] S1 creates a mechanical model: based on, for example Figure 2 The ROPS skeleton structure shown is illustrated by extracting the length dimension W of the top crossbeam and the length dimension L of the column, and simplifying the column and crossbeam into a single structure. Figure 3The portal frame statically indeterminate structural mechanics model shown is used to analyze the bending moment distribution relationship between the top beam and the column, which is then obtained as follows: Column bending moment M 立柱 > Bending moment M of the top crossbeam 顶_横梁 The design principle of "strong column, weak beam" is derived.

[0068] S2 Selected Design Parameters: Based on the fact that the moment of inertia I of the profile section is the key factor determining the bending moment distribution in the mechanical model, the moment of inertia I of the profile section is selected as the design parameter of the profile.

[0069] S3 Structural Mechanics Analysis: Using structural mechanics analysis software (such as a structural mechanics solver), the bending moment and stress values ​​of the portal frame statically indeterminate structural mechanics model are analyzed to obtain the ratio of the moments of inertia I of the top beam and the column when the maximum bending moment and stress of the top beam and the column are equal; the value of n is 0.6 to 0.7.

[0070] S4 Create the relationship: Based on the ratio of the moments of inertia I of the top beam and the column, n, the optimal design relationship of the top beam is obtained: I 顶_横梁 =nI 立柱 ;

[0071] The profiles of the top crossbeam and the corresponding column are selected based on the optimized design formula of the top crossbeam.

[0072] The top crossbeam optimization design relationship I 顶_横梁 = (0.6~0.7)·I 立柱 Related to the external dimensions of the ROPS frame, this is an inherent property of the ROPS frame and is used to guide the optimized design of the top crossbeam of this ROPS frame type. Based on the design method of this invention, the external dimensions of common aircraft models can be statistically summarized to create a relational database for the optimized design of a full-coverage cab ROPS frame.

[0073] Example 3

[0074] An engineering machinery cab includes the ROPS frame described in Example 1, which is designed using the ROPS frame top crossbeam optimization design method described in Example 2.

[0075] The construction machinery can be a hydraulic excavator, loader, road roller, grader, etc., and has the advantages of the ROPS frame provided in the embodiments of this disclosure.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for optimizing the design of the top crossbeam of a centrally symmetrical ROPS (Reinforced Optical Frame) skeleton, characterized in that, The ROPS (Reinforced Optical Structure) framework comprises columns, crossbeams, and longitudinal beams; the columns include A-columns, B-columns, and D-columns; the crossbeams include top and bottom crossbeams; the longitudinal beams include top and bottom longitudinal beams; two A-columns are connected by a first top and bottom crossbeam to form a closed rectangular A-ring; two B-columns are connected by a second top and bottom crossbeam to form a closed rectangular B-ring; two D-columns are connected by a third top and bottom crossbeam to form a closed rectangular D-ring; the four corners of the A-ring and B-ring are connected by a first top and bottom longitudinal beam, and the four corners of the B-ring and D-ring are connected by a second top and bottom longitudinal beam, forming a closed spatial frame structure; the method includes: Based on the ROPS skeleton structure, the length dimension W of the top beam and the length dimension L of the column are extracted to form a portal frame statically indeterminate structural mechanical model. The bending moment distribution relationship between the top beam and the column is obtained by analyzing the portal frame statically indeterminate structural mechanical model. Since the moment of inertia I of the profile section is the key factor determining the bending moment distribution in the mechanical model, the moment of inertia I of the profile section is selected as the design parameter of the profile. The bending moment and stress values ​​of the portal frame statically indeterminate structural mechanical model were analyzed using structural mechanics analysis software, and the ratio of the moments of inertia I of the top beam and the column when the maximum bending moment and stress of the top beam and the column are equal was obtained. Based on the ratio of the moments of inertia I of the top beam and the column to n, the optimal design formula for the top beam is obtained. The profiles of the top crossbeam and the corresponding column are selected based on the optimized design formula of the top crossbeam.

2. The ROPS skeleton top crossbeam optimization design method according to claim 1, characterized in that, The length W of the top crossbeam is 1.45m to 1.6m; the length L of the column is 1.65m to 1.9m.

3. The ROPS skeleton top crossbeam optimization design method according to claim 1, characterized in that, The relationship between the bending moment distribution of the top beam and the column is: Column bending moment M 立柱 > Bending moment M of the top crossbeam 顶_横梁 .

4. The ROPS skeleton top crossbeam optimization design method according to claim 1, characterized in that, The optimal design formula for the top crossbeam is: I 顶_横梁 =nI 立柱 .

5. The ROPS skeleton top crossbeam optimization design method according to claim 1 or 4, characterized in that, The ratio of the moment of inertia I of the top beam and the column is 0.6 to 0.

7.

6. The method for optimizing the design of the top crossbeam of the ROPS skeleton according to claim 1, characterized in that, The ratio of the moment of inertia I of the first top beam to column A is n, where n ranges from 0.6 to 0.

7.

7. The method for optimizing the design of the top crossbeam of the ROPS skeleton according to claim 1, characterized in that, The ratio of the moment of inertia I between the second top beam and column B is n, where n ranges from 0.6 to 0.

7.

8. The method for optimizing the design of the top crossbeam of the ROPS skeleton according to claim 1, characterized in that, The ratio of the moment of inertia I of the third top beam to that of column D is n, where n ranges from 0.6 to 0.7.

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