A stiffness matching method and structure of a frequency-variable stiffness swing arm joint

Abstract

The application discloses a stiffness matching method of a frequency-variable stiffness rotary arm joint, which comprises adding different structures in the longitudinal and vertical directions of a liquid rubber composite joint shaft, so that different longitudinal, vertical and transverse stiffnesses and a lower longitudinal-transverse stiffness ratio are obtained, and relates to the technical field of locomotive component manufacturing. The application provides a stiffness matching method and structure of a frequency-variable stiffness rotary arm joint, different main body structures are formed by means of twice adding materials, longitudinal, transverse and vertical stiffnesses are quickly adjusted, and project research and development cost is saved and product development period is shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of locomotive component manufacturing technology, in particular to a stiffness matching method and structure of a frequency-variable stiffness swing arm node. BACKGROUND

[0002] China standard EMU: referred to as standard EMU, refers to the China standard system dominant EMU (in 254 important standards, various Chinese standards account for 84%), its function standard and supporting track construction standard are higher than European standard and Japanese standard, have distinct and comprehensive Chinese characteristics; this also refers to the standardization (unification) design of Chinese EMU in the face of diversified CRH environment (including four types of imported CRH and Chinese self-designed CRH6), so as to realize interconnection. This newly developed new type of EMU increases compatibility, no derailment and other characteristics, thus forming distinct and comprehensive Chinese characteristics, and is named as EMU China standard (Huabiao), representing the advanced standard system of the world EMU technology; according to the China patent document with publication number CN106627640B, a method for preventing shaft box bearing wear by changing the mode of swing arm type shaft box positioning is disclosed, which is a method for preventing shaft box bearing wear by adjusting the slope structure of the rubber layer of the swing arm node, adopts a two-section conical inner hole swing arm node combined structure, and the rubber layers of the two-section swing arm nodes are arranged in opposite directions, characterized in that: the matching of the radial stiffness and the axial stiffness of the swing arm node is adjusted by changing the angle of the slope of the rubber layer of the swing arm node, so that the longitudinal stiffness and the deflection stiffness of the swing arm node are reduced, and the torsional stiffness is avoided from being reduced by increasing the axial stiffness, thereby effectively reducing the wear of the axle bearing.

[0003] Based on the above patent search, and combined with the existing equipment in the prior art, the above-mentioned equipment adopts different structure design of rubber body in the main body structure design to realize different stiffness adjustment, which needs to design different vulcanization forming molds and process different metal parts, and has high cost and long period. SUMMARY

[0004] The purpose of the present application is to provide a stiffness matching method and structure of a frequency-variable stiffness swing arm node to solve the problems raised in the background art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a stiffness matching method of a frequency-variable stiffness swing arm node, including adding different structures in the longitudinal and vertical directions of a liquid rubber composite node core shaft to obtain different longitudinal, vertical and horizontal stiffness and a lower longitudinal to horizontal stiffness ratio; including the following steps:

[0006] S1: establishing a mechanical model: according to the actual geometric shape, material properties and connection form of the swing arm node, a precise mechanical model is established by using theoretical mechanics, material mechanics and structural dynamics;

[0007] S2: modal analysis: modal analysis is performed on the established model to determine its natural frequency and mode shape. By solving the eigenvalue problem, the natural frequency of different orders and the corresponding vibration mode are obtained;

[0008] S3: determine the stiffness matching: based on the analysis in S1 and S2 and the expected frequency variable stiffness target, the stiffness matching strategy is formulated, and the entity structure is added;

[0009] S4: structure addition: standard mandrel sample is used, and then secondary addition is used around the mandrel to obtain different mandrel outer shape structure, wherein the mandrel outer shape structure can be realized by adjusting the height, width size and angle of the secondary addition structure in longitudinal and vertical directions;

[0010] S5: experimental verification: the steps of experimental verification include:

[0011] S5.1: experimental sample preparation;

[0012] S5.2: experimental equipment building;

[0013] S5.3: static characteristic test;

[0014] S5.4: data analysis;

[0015] S5.5: reliability and repeatability verification.

[0016] As a further scheme of the application: the stiffness matching strategy in S3 adopts variable stiffness elements, and the parameter adjustment law of the variable stiffness elements is set according to different frequency ranges.

[0017] As a further scheme of the application: the secondary addition method in S4 includes injection molding, secondary vulcanization, welding, bonding and the like.

[0018] As a further scheme of the application: the injection molding secondary forming puts raw materials into an injection molding mold, injects a plastic forming process, and adopts an injection molding method to add polymer materials in the longitudinal and vertical directions of the standard mandrel to form different outer shape structures, realize the adjustment of different longitudinal and transverse stiffness, secondary vulcanization: in the longitudinal and transverse directions of the standard mandrel, a simple vulcanization mold is used to vulcanize rubber materials onto the mandrel, different internal structures are formed, thereby realizing the adjustment of different longitudinal and transverse stiffness; welding: in the longitudinal and transverse directions of the standard mandrel, a welding method is used to weld metal materials of the same material to the mandrel, which can quickly complete different structure adjustment and stiffness verification; bonding: in the longitudinal and transverse directions of the standard mandrel, a glue bonding method is used to bond parts of different materials and shapes to the mandrel to form different mandrel results, and realize the rapid adjustment of different longitudinal and transverse stiffness.

[0019] As a further scheme of the present application: the secondary addition structure mode in S4 is specifically as follows:

[0020] By adjusting the size of A and ensuring the encapsulation size C as a fixed value, generally 1-4mm, the longitudinal direction can realize the hard stop function of different gaps H;

[0021] The longitudinal stiffness of the product can be adjusted by the size of A, when the size A increases, the longitudinal hard stop gap H decreases, and vice versa;

[0022] The vertical stiffness can be adjusted by the size of B, when the size B increases, the vertical stiffness also increases, and vice versa;

[0023] The axial stiffness can be adjusted by adjusting the sizes of E, F and G, when the size E increases and the sizes of F and angle G decrease, the transverse stiffness increases, and vice versa.

[0024] As a further scheme of the present application: the experimental steps of S5 are specifically as follows: according to the designed frequency-variable stiffness slewing node structure, the slewing node physical sample is accurately processed and manufactured, to ensure that the size precision, surface quality and the like meet the design requirements, to ensure that the installation positions of these elements are accurate, the connection is reliable, and the performance of the slewing node is stable, the quality detection and size checking of the conventional components in the slewing node are strictly carried out, to avoid that the processing error affects the accuracy of the experimental results;

[0025] A suitable vibration table or exciter is selected to apply excitation forces of different frequencies, the frequency range should be able to cover the expected working frequency range of the slewing node, and the excitation force size can be accurately adjusted and controlled, with sufficient precision and stability, the displacement sensor is installed at the key position of the slewing node, to measure the displacement response of the slewing node under different frequency excitations, the measurement precision should meet the experimental requirements, to accurately capture the small displacement change, to ensure the accuracy of the force value measurement, the error is controlled within a small range, like the general precision can reach within 0.5% of the full scale;

[0026] By slowly applying static force to the slewing node, the force sensor and the displacement sensor are used to measure the corresponding displacement under different static forces, to calculate the stiffness value of the slewing node under static state, as the basic data for subsequent dynamic experiment comparison and analysis;

[0027] In order to ensure the reliability of the experimental results, after completing the above experiments, some experimental conditions can be changed or new slewing node samples of the same specification are replaced, the above experimental process is repeated, to observe whether the frequency-variable stiffness curve and the related experimental conclusions are consistent, if the experimental results have good repeatability and stability, then the effectiveness and reliability of the adopted stiffness matching method and the slewing node design can be more powerfully proved.

[0028] The stiffness matching structure of the frequency-variable stiffness rotating arm node comprises symmetrically arranged left rotating joint arm outer sleeves and right rotating joint arm outer sleeves and symmetrically arranged left rotating joint arm inner sleeves and right rotating joint arm inner sleeves, the left rotating joint arm inner sleeves and the right rotating joint arm inner sleeves are internally sleeved with a mandrel, liquid rubber is arranged between the mandrel and the inner walls of the left rotating joint arm inner sleeves and the right rotating joint arm inner sleeves, the outer surface of the mandrel is provided with a bevel structure in abutment with the left rotating joint arm inner sleeves and the right rotating joint arm inner sleeves, and the thickness of the liquid rubber on the left and right sides of the mandrel is smaller than the thickness of the liquid rubber on the upper and lower sides

[0029] Compared with the prior art, the beneficial effects of the present application are:

[0030] 1. The present application provides a stiffness matching method and structure of a frequency-variable stiffness rotating arm node, which adopts a secondary material adding mode to form different main body structures, can quickly adjust the longitudinal, vertical and horizontal stiffness of the liquid composite node in a large range, and thus obtain ideal stiffness parameters.

[0031] 2. The present application can reduce the difficulty in processing the mandrel, reduce the product cost, shorten the processing cycle of the mandrel and the product development cycle.

[0032] 3. The present application can be applied to conventional rubber nodes of the solid and hollow structure, realize three-way stiffness matching, and obtain a lower longitudinal and horizontal stiffness ratio. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a sectional view of the stiffness structure of the frequency-variable stiffness rotating arm node in the embodiment of the present application;

[0034] Figure 2 It is another view of the sectional view of the stiffness structure of the frequency-variable stiffness rotating arm node in the embodiment of the present application;

[0035] Figure 3 It is a sectional view of the stiffness structure of the frequency-variable stiffness rotating arm node in the embodiment of the present application;

[0036] Figure 4 It is a flowchart of the stiffness matching method in the embodiment of the present application.

[0037] In the figure: 1, left rotating joint arm outer sleeve; 2, right rotating joint arm outer sleeve; 3, left rotating joint arm inner sleeve; 4, right rotating joint arm inner sleeve; 5, mandrel; 6, liquid rubber; 7, bevel structure. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings.

[0039] Reference Figures 1-4As shown, the stiffness matching method and structure of the frequency-variable stiffness rotating arm node shown in the embodiment of the present application is obtained by adding different structures in the longitudinal and vertical directions of the liquid rubber composite node core shaft twice, and different longitudinal, vertical and horizontal stiffnesses and a lower longitudinal-to-horizontal stiffness ratio are obtained; wherein the rotating joint arm includes symmetrically arranged left rotating joint arm outer sleeve 1 and right rotating joint arm outer sleeve 2, and symmetrically arranged left rotating joint arm inner sleeve 3 and right rotating joint arm inner sleeve 4, the core shaft 5 is sleeved in the left rotating joint arm inner sleeve 3 and the right rotating joint arm inner sleeve 4, the liquid rubber 6 is arranged between the core shaft 5 and the inner wall of the left rotating joint arm inner sleeve 3 and the right rotating joint arm inner sleeve 4, the inclined surface structure 7 is arranged on the outer surface of the core shaft 5 and the left rotating joint arm inner sleeve 3 and the right rotating joint arm inner sleeve 4, and the thickness of the liquid rubber 6 on the left and right sides of the core shaft 4 is less than the thickness of the liquid rubber 6 on the upper and lower sides;

[0040] The stiffness matching method includes the following steps:

[0041] S1: Establishing a mechanical model: according to the actual geometric shape, material properties and connection form of the rotating arm node, a precise mechanical model is established by using theoretical mechanics, material mechanics and structural dynamics; a concentrated parameter model or a finite element model is used to construct, embodiment: for a relatively simple rotating arm node, the key parts are simplified as a combination of spring-mass-damper system to simulate its dynamic behavior; for a complex structure, a grid is divided by using finite element software to accurately describe its mechanical characteristics;

[0042] S2: Modal analysis: modal analysis is performed on the established model to determine its natural frequency and mode shape. By solving the eigenvalue problem, the natural frequency of different orders and the corresponding vibration mode are obtained; this step can help understand the natural vibration characteristics of the rotating arm node itself under no external complex excitation, and can lay the foundation for subsequent analysis of its response under different frequency external loads; it is found that the vibration mode under certain key frequencies may have a greater impact on the stability or function of the overall structure, so attention should be paid to the adjustment of the stiffness near these frequencies;

[0043] S3: Determine the stiffness matching: based on the analysis in S1 and S2 and the expected frequency-variable stiffness target, a stiffness matching strategy is developed to add the entity structure; wherein the stiffness matching strategy uses variable stiffness elements, and the parameter adjustment law of these variable stiffness elements is set according to different frequency ranges; when the node stiffness is larger in the low frequency band to ensure the stability of the structure, it is realized through appropriate control means; when vibration isolation and force transmission reduction are required in the high frequency band, the stiffness is correspondingly reduced;

[0044] S4: Structure addition: standard mandrel sample is adopted, and then different mandrel outer shape structures are obtained by using secondary addition method around the mandrel, wherein the mandrel outer shape structure can be realized by adjusting the height, width size and angle of the secondary addition structure in the longitudinal and vertical directions; wherein the secondary addition method includes injection molding, secondary vulcanization, welding, bonding and the like;

[0045] Further, injection molding: injection molding secondary forming is a molding process of putting a certain raw material into an injection molding mold and injecting a plastic, and different outer shape structures are formed by using injection molding method to add polymer materials (such as nylon, polytetrafluoroethylene, etc.) in the longitudinal and vertical directions of the standard mandrel, so as to realize the adjustment of different longitudinal and transverse stiffnesses;

[0046] Secondary vulcanization: simple vulcanization mold is used in the longitudinal and transverse directions of the standard mandrel, and rubber material is vulcanized to the mandrel, so as to realize the adjustment of different longitudinal and transverse stiffnesses;

[0047] Welding: in the longitudinal and transverse directions of the standard mandrel, the same kind of metal material is welded to the mandrel, so as to quickly complete the adjustment of different structures and the verification of stiffness;

[0048] Bonding: in the longitudinal and transverse directions of the standard mandrel, adhesive (AB glue, Loctite glue, etc.) bonding method is used to bond different materials and different shapes of parts to the mandrel, so as to form different mandrel results and realize the quick adjustment of different longitudinal and transverse stiffnesses;

[0049] Further, the secondary addition structure method is as follows:

[0050] By adjusting the size A and ensuring that the glue covering size C is a fixed value, usually 1-4 mm, the longitudinal direction can realize the hard stop function of different gaps H;

[0051] The longitudinal stiffness of the product can be adjusted by the size A, when the size A increases, the longitudinal hard stop gap H decreases, and vice versa;

[0052] The vertical stiffness can be adjusted by the size B, when the size B increases, the vertical stiffness also increases, and vice versa;

[0053] The axial stiffness can be adjusted by adjusting the sizes E, F and G, when the size E increases and the sizes F and angle G decrease, the transverse stiffness increases, and vice versa;

[0054] S5: Experimental verification: the steps of experimental verification include:

[0055] S5.1: Experimental sample preparation;

[0056] S5.2: Experimental equipment setup;

[0057] S5.3: Static characteristic test;

[0058] S5.4: Data analysis;

[0059] S5.5: Reliability and repeatability verification;

[0060] The experimental steps are as follows: according to the designed frequency-variable stiffness rotary arm node structure, the rotary arm node physical sample is accurately processed and manufactured, the size precision, surface quality and the like are ensured to meet the design requirements, the installation position of the components is ensured to be accurate and the connection is ensured to be reliable, and the performance of the components is ensured to be stable, the quality detection and size checking of the conventional components in the rotary arm node are strictly performed, and the influence of the processing error on the accuracy of the experimental results is avoided;

[0061] A suitable vibration table or exciter is selected to apply excitation forces of different frequencies, the frequency range of the excitation forces should cover the expected working frequency range of the rotary arm node, and the size of the excitation forces can be accurately adjusted and controlled, and the excitation forces have sufficient precision and stability, the displacement sensor is installed at the key position of the rotary arm node, and is used to measure the displacement response of the rotary arm under different frequency excitations, the measurement precision of the displacement sensor should meet the experimental requirements, so as to accurately capture the small displacement change and ensure the accuracy of the force value measurement, and the error is controlled within a small range, for example, the general precision can be within 0.5% of the full scale;

[0062] The static force is slowly applied to the rotary arm node, the force sensor and the displacement sensor are used to measure the corresponding displacement under different static forces, and the stiffness value of the rotary arm node under static state is calculated, which is used as the basic data for subsequent dynamic experiment comparison and analysis;

[0063] In order to ensure the reliability of the experimental results, after the above experiments are completed, some experimental conditions can be changed or a new rotary arm node sample of the same specification can be manufactured, the above experimental process is repeated, and whether the frequency-variable stiffness curve and the related experimental conclusions obtained are consistent is observed, if the experimental results have good repeatability and stability, the effectiveness and reliability of the stiffness matching method and the rotary arm node design can be more effectively proved.

[0064] The above only describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A stiffness matching method for a frequency-varying stiffness swing arm joint, wherein different structures are added twice in the longitudinal and vertical directions of the liquid rubber composite joint mandrel to obtain different longitudinal, vertical, and lateral stiffnesses and a lower longitudinal-to-lateral stiffness ratio; characterized in that, Includes the following steps: S1: Establish a mechanical model: Based on the actual geometry, material properties, and connection form of the swing arm node, establish an accurate mechanical model using theoretical mechanics, mechanics of materials, and structural dynamics. S2: Modal analysis: Perform modal analysis on the established model to determine its natural frequencies and mode shapes. By solving the eigenvalue problem, obtain the natural frequencies of different orders and the corresponding vibration modes. S3: Determine stiffness matching: Based on the analysis in S1 and S2 and the desired frequency-varying stiffness target, formulate a stiffness matching strategy before adding the solid structure; S4: Structural Addition: Using a standard mandrel sample, different mandrel shapes are obtained by secondary addition around the mandrel. The mandrel shape is achieved by adjusting the height, width, and angle of the secondary added structure in the longitudinal and vertical directions. S5: Experimental Verification: The steps for experimental verification include: S5.1: Preparation of experimental samples; S5.2: Setup of experimental equipment; S5.3: Static characteristic test; S5.4: Data Analysis; S5.5: Reliability and repeatability verification.

2. The stiffness matching method for a frequency-varying stiffness swing arm node according to claim 1, characterized in that, The stiffness matching strategy in S3 uses variable stiffness elements, and the parameter adjustment rules of these variable stiffness elements are set according to different frequency ranges.

3. The stiffness matching method for a frequency-varying stiffness swing arm node according to claim 1, characterized in that, The secondary addition methods in S4 include injection molding, secondary vulcanization, welding, and bonding.

4. The stiffness matching method for a frequency-varying stiffness swing arm node according to claim 3, characterized in that, Injection molding involves placing raw materials into an injection mold and injecting a type of plastic. Polymer materials are then added secondaryly in the longitudinal and vertical directions of a standard mandrel to create different shapes and structures, allowing for adjustments to longitudinal and lateral stiffness. Secondary vulcanization uses a simple vulcanization mold in the longitudinal and lateral directions of the standard mandrel to vulcanize rubber material onto the mandrel, creating different internal structures and thus adjusting longitudinal and lateral stiffness. Welding involves welding metal materials of the same type onto the mandrel in the longitudinal and lateral directions, quickly completing different structural adjustments and verifying stiffness. Adhesion involves using adhesive to bond components of different materials and shapes onto the mandrel in the longitudinal and lateral directions, creating different mandrel designs and enabling rapid adjustments to longitudinal and lateral stiffness.

5. The stiffness matching method for a frequency-varying stiffness swing arm node according to claim 4, characterized in that, The specific method of secondary addition structure in S4 is as follows: By adjusting dimension A and ensuring that the overlay dimension C is a fixed value of 1~4mm, the hard stop function of different gaps H can be achieved in the longitudinal direction; The longitudinal stiffness of the product can be adjusted by dimension A. When dimension A increases, the longitudinal hard stop clearance H decreases, and vice versa. The vertical stiffness can be adjusted by the dimension B. When the dimension B increases, the vertical stiffness also increases, and vice versa. The axial stiffness can be adjusted by changing the dimensions E, F, and G. Increasing dimension E and decreasing dimension F and angle G will increase the lateral stiffness, and vice versa.

6. The stiffness matching method for a frequency-varying stiffness swing arm node according to claim 1, characterized in that, The experimental steps of S5 are as follows: Based on the designed frequency-varying stiffness swing arm node structure, accurately process and manufacture physical samples of the swing arm node to ensure that its dimensional accuracy and surface quality meet the design requirements, ensure that the installation position of these components is accurate and the connection is reliable, and ensure that their own performance is stable. Strict quality inspection and dimensional verification are carried out on the conventional components in the swing arm node to avoid the impact of processing errors on the accuracy of experimental results. Select a suitable vibration table or exciter to apply excitation forces of different frequencies. The frequency range should be able to cover the expected working frequency range of the swing arm node, and the magnitude of the excitation force should be precisely adjustable and controllable, with sufficient accuracy and stability. Install displacement sensors at key parts of the swing arm node to measure the displacement response of the swing arm under different frequency excitations. The measurement accuracy should meet the experimental requirements to accurately capture minute displacement changes, ensure the accuracy of force measurement, and control the error within a small range. By slowly applying static force to the swing arm node, force sensors and displacement sensors are used to measure the displacement under different static forces, and the stiffness value of the swing arm node under static conditions is calculated, which serves as the basis for subsequent dynamic experimental comparative analysis. To ensure the reliability of the experimental results, after completing the above experiment, the experimental conditions were changed or a new sample of the same specification of swing arm node was manufactured, and the above experimental process was repeated to observe whether the obtained frequency-varying stiffness curve and related experimental conclusions were consistent.

7. A stiffness matching structure formed by the stiffness matching method of the frequency-varying stiffness swing arm node according to claim 1, characterized in that, The device includes a symmetrically arranged left slewing arm outer sleeve (1) and a right slewing arm outer sleeve (2), as well as a symmetrically arranged left slewing arm inner sleeve (3) and a right slewing arm inner sleeve (4). A mandrel (5) is fitted inside the left slewing arm inner sleeve (3) and the right slewing arm inner sleeve (4). Liquid rubber (6) is provided between the mandrel (5) and the inner wall of the left slewing arm inner sleeve (3) and the right slewing arm inner sleeve (4). The outer surface of the mandrel (5) and the inner wall of the left slewing arm inner sleeve (3) and the right slewing arm inner sleeve (4) are provided with abutting inclined structure (7). The thickness of the liquid rubber (6) on the left and right sides of the mandrel (5) is less than the thickness of the liquid rubber (6) on the upper and lower sides.

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