Finite element simplified simulation method for luffing mechanism steel wire rope winding

Abstract

The invention discloses a finite element simplified simulation method for luffing mechanism steel wire rope winding, and the method comprises the steps: constructing a modeling plane coordinate system defined by a pulley sleeve shaft, and releasing the normal rotation degree of freedom of a luffing pulley and the axis rotation degree of freedom of a guide pulley in a customized manner; establishing a rod unit force transmission chain formed by rigid unit nodes to simulate a steel wire winding path; a dynamic coupling node position adjusting mechanism is innovatively adopted, and the problem of tension equivalent transmission of multi-layer winding is solved; and in combination with a real-time updating technology of a boom rotation accompanying modeling plane, rapid adaptation of different pitching working conditions is realized. According to the method, the precision limitation of a traditional empirical formula is broken through, overall modeling nodes are reduced, the solving speed is increased, the tension output error of the steel wire rope is reduced, working condition spectrum tension data can be directly generated, and a reliable analysis basis is provided for the design of a luffing mechanism of large hoisting equipment.

Description

Technical Field

[0001] In the field of engineering machinery data processing technology, specifically, this relates to a simplified finite element simulation method for the wire rope winding of a variable amplitude mechanism during linear analysis of complex structures. Background Technology

[0002] The luffing mechanism is a crucial component of complex lifting equipment, and its safety and reliability directly affect the overall performance of the lifting equipment. Currently, lifting equipment is continuously developing towards larger sizes and heavier loads, which places higher demands on the wire rope winding design of the luffing mechanism. With the increasing development of simulation methods, the finite element analysis method is widely used in the engineering analysis and calculation of lifting equipment. To improve computational accuracy and efficiency, an overall modeling approach is increasingly being adopted. How to simplify the simulation of the luffing wire rope winding system, realize the transmission of luffing force from the wire rope to the structure, and thus complete the overall modeling of the lifting equipment is a problem that urgently needs to be solved.

[0003] Existing literature on wire ropes for luffing mechanisms has the following main drawbacks: 1. The main focus is on the winding design of the wire rope to solve the problems of tangled ropes or insufficient load-bearing capacity that often occur; 2. The selection and calculation of wire ropes are mainly based on traditional theories or empirical formulas, resulting in a large error in the calculation of wire rope tension. 3. Currently, there is no detailed finite element modeling method for the wire rope winding of the luffing mechanism of lifting equipment. Summary of the Invention

[0004] To address the aforementioned technical issues, existing technologies lack effective finite element modeling methods for variable amplitude wire rope winding, suffer from large errors in wire rope tension calculation, and are unable to achieve whole-machine modeling. Therefore, this paper proposes a physically equivalent modeling framework based on three-dimensional degree-of-freedom decoupling. This framework constructs a modeling plane coordinate system defined by the pulley sleeve shaft, customizes the release of the normal rotational degree of freedom of the variable amplitude pulley and the rotational degree of freedom of the guide pulley axis, establishes a rigid force transmission chain for the rod unit, and dynamically adjusts the positions of the multi-layer winding coupling nodes to achieve accurate transmission of variable amplitude force, efficient linear modeling of the whole machine, and a simplified simulation method for real-time output of tension data under multiple working conditions.

[0005] The technical means employed in this invention are as follows: A simplified finite element simulation method for wire rope winding in a variable amplitude mechanism. A finite element model of the main steel structure of the lifting equipment is established. The main steel structure includes the A-frame and the boom. The A-frame and the main body of the boom are modeled using beam elements. The pulley shaft is simulated by beam elements, and the pulley shaft and the ear plate shaft hole are connected by a rigid element with the first node positioned at the center of the shaft hole. The modeling plane is determined based on the pulley sleeve axle of the crossbeam and boom head of the A-frame; The wire rope is simplified as a two-force member element simulation, and the pulley is simplified as a rigid element simulation. For variable amplitude pulleys, the rotational degree of freedom in the normal direction of the modeling plane is released by coupling coincident nodes; For guide pulleys and balance pulleys, the rotational degree of freedom of the pulley's own axis is released by coupling coincident nodes; The rigid element nodes simulating the pulley are connected sequentially through rod elements according to the wire rope winding path; After rotating the boom to the target pitch angle, update the local coordinate system of the modeling plane.

[0006] Furthermore, the local coordinate system update operation of the modeling plane occurs after the boom pitch angle changes, and the origin of the coordinate system is fixed at the intersection of the A-frame and the boom pulley sleeve axis.

[0007] Furthermore, when the wire rope is wound in a multi-layered manner, the total tension output by the rod unit is made equal to the actual total tension of the wire rope by moving the coupling node position of the pulley shaft.

[0008] Furthermore, the connection method of the rod unit satisfies the ratio of the pulley sleeve tension between the A-frame side and the boom side, wherein the tension ratio between the inner pulley sleeve and the outer pulley sleeve of the A-frame is 8:7, and the tension unit of the pulley sleeve at the boom head is 8.

[0009] Furthermore, the connection point between the rigid unit and the ear plate is precisely located at the center of the ear plate shaft hole, and the length extension direction of the rigid unit matches the radius direction of the pulley.

[0010] Furthermore, under different pitch conditions, only the physical tangent point between the guide pulley and the wire rope is adjusted.

[0011] The core concept of this invention, employing the above technical solution, lies in solving the engineering challenge of simulating wire rope winding in complex crane luffing mechanisms through innovative finite element modeling structural design. Specifically, it utilizes a three-dimensional geometric relationship reconstruction and degree-of-freedom decoupling mechanism to achieve a physically equivalent substitution of the force transmission path: using the modeling plane determined by the pulley sleeve shaft as the reference coordinate system, a rigid element connects the center of the ear plate shaft hole to the pulley shaft, releasing the normal rotational degree of freedom of the modeling plane for the luffing pulley and the axial rotational degree of freedom for the guide / balance pulley, forming a core structure with precise decoupling of rotational constraints; the wire rope is simplified into a rod element and rigidly connected to the pulley nodes according to the actual winding path, combined with an adjustable coupling node position mechanism during multi-layer winding to achieve physically equivalent transmission of total tension rather than numerical calculation; and a mechanism for dynamic updating of the modeling plane accompanied by boom rotation enables rapid adaptation to multiple working conditions.

[0012] This technical solution has the following advantages: 1. The modeling approach is clear and simple, and the model is easy to modify: Based on the simple lever arm balance principle, the transmission of wire rope tension in the luffing winding system is realized. The size of the lever arm on both sides of the coupling point can be adjusted according to the requirements to reduce the number of rod units and thus reduce the modeling complexity. For working conditions with different pitch angles, it is only necessary to rotate the boom model around its root axis by a certain angle and adjust the tangent position of some guide pulleys and wire ropes appropriately, without making any other modifications.

[0013] 2. High simulation efficiency: By ignoring the nonlinear effects of the wire rope itself and simplifying it into linear units, the model solution speed is improved when the equipment is analyzed as a whole.

[0014] 3. Reasonable calculation accuracy and convenient and quick reading of wire rope tension and structural stress results: The simplified simulation of wire rope winding reflects the transmission of structural amplitude force well, and the calculation accuracy can well meet the actual needs of engineering; the post-processing module of the finite element software can quickly read the wire rope tension and related stress data under different working conditions. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the overall structure of the simulated floating crane device.

[0017] Figure 2 for Figure 1 A schematic diagram of the pulley layout between the boom head and the crossbeam of the A-frame of the floating crane device.

[0018] Figure 3 for Figure 1 A schematic diagram of the luffing pulley block assembly for the floating crane device.

[0019] Figure 4 for Figure 1 A schematic diagram of the assembly of the balance pulleys on the back of the crossbeam of the A-frame of the floating crane.

[0020] Figure 5 for Figure 1 A schematic diagram of the assembly of the guide pulleys at the top of the crossbeam of the A-frame of the floating crane device.

[0021] Figure 6 for Figure 1 A schematic diagram of the guide pulley assembly at the front end of the crossbeam on the A-frame of the floating crane.

[0022] Figure 7 To utilize the simulation method of this invention Figure 1 The diagram shows a simulation of the wire rope winding of the luffing mechanism of the floating crane device.

[0023] Figure 8 This is a schematic diagram of the assembly and connection of the A-frame pulley sleeve and the guide pulley model of the present invention.

[0024] Figure 9 This is a schematic diagram of the assembly and connection of the A-frame balance wheel model of the present invention.

[0025] Figure 10 This is a schematic diagram of the assembly and connection of the boom head pulley sleeve model of the present invention.

[0026] Figure 11 This is a schematic diagram of the pulley sleeve node layout between the boom head and the upper crossbeam of the A-frame of the present invention.

[0027] Figure 12 for Figure 1 Finite element model of the overall structure of the floating crane device.

[0028] Figure 13 This is a schematic diagram of the complete modeling of the wire rope winding of the luffing mechanism of the present invention (the beam unit simulating the pulley shaft is hidden for ease of display). Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. 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 drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0033] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this application. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0034] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0035] Furthermore, it should be noted 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 cannot be construed as limiting the scope of protection of this application.

[0036] A simplified finite element simulation method for wire rope winding in a luffing mechanism includes the following steps: 1. Modeling the main steel structure of the lifting equipment.

[0037] The main steel structure (such as A-frames and booms) is mostly modeled using beam elements, while local details can be modeled using plate and shell elements according to complexity and needs, thereby reducing the amount of modeling work.

[0038] 2. Connection between the pulley shaft and the ear plate.

[0039] The pulley shaft is simulated using beam elements, and the connection between it and the lug plate is simulated using rigid elements.

[0040] 3. Modeling plane of luffing pulley and wire rope.

[0041] To facilitate model modification and modeling feasibility under different boom pitching conditions, the modeling planes for the luffing pulley and wire rope were artificially defined as needed.

[0042] 4. Connections between pulleys, shafts, and wire ropes.

[0043] The wire rope is simplified as a two-force member for simulation, and the pulleys are simulated using rigid elements. The connection between the luffing pulley and its axle is achieved by coupling the degrees of freedom of the coincident nodes about the normal direction of the modeling plane, while the connections between other pulleys and their axles, such as the guide pulley and the balance pulley, are achieved by coupling the degrees of freedom of the coincident nodes about the axis. The rigid element nodes simulating the pulleys are then sequentially connected using rod elements to achieve the transmission of the wire rope tension.

[0044] 5. Selection of the coupling node position between the variable amplitude pulley and the shaft, and adjustment of the tension of the rod unit.

[0045] As can be seen from the lever torque balance, the length (i.e., lever arm) of the rigid unit on both sides of the coupling node determines the ratio of the tensile output of the rod units at both ends. For a single layer of wire rope winding, the coupling point can be intuitively selected at the actual position of the pulley shaft, and the model can be modeled in a one-to-one correspondence between the rod unit and the wire rope, that is, each rod unit outputs the actual tensile force of a single wire rope; however, for multi-layer winding of wire rope, considering the convenience of modeling, it is not possible to achieve a one-to-one correspondence between the number of rod units and the number of wire ropes. It is only necessary to ensure that the total tensile force of the rod unit acting on the crossbeam and the boom head of the A-frame matches the actual force.

[0046] 6. Obtaining finite element models under different amplitude variations.

[0047] Rotate the boom model to the specified pitch angle and update the local coordinate system determined by the previously defined modeling plane.

[0048] 7. Output of wire rope tension.

[0049] By extracting the internal forces of the rod elements in the post-processing module of the finite element software, the tension of the wire rope under different amplitude conditions can be obtained.

[0050] Example 1 This embodiment is based on the simulation calculation of the luffing mechanism wire rope winding system of a 3500-ton floating crane. The implementation process of the simplified wire rope winding model under the maximum load condition and the tensile force calculation method are as follows: from Figure 1 As shown in the overall layout diagram of the floating crane, it mainly consists of four parts: an A-frame, a boom, a luffing wire rope system, and a hoisting wire rope system. To meet the need for high lifting capacity, the luffing pulley block adopts a pulley sleeve design, with each sleeve containing two rows of pulleys to increase the number of wire ropes that can be wound around it. (See...) Figure 2 For details on the assembly of pulleys related to the luffing mechanism, please refer to [link / reference]. Figure 3-6 The outer large pulley of the pulley sleeve has a diameter of 1400mm, the inner small pulley has a diameter of 1120mm, the wire rope diameter is 52mm, and the distance between the ear plates on both sides of the pulley sleeve is 1400mm. There are 16 large pulleys and 16 small pulleys on both the A-frame upper beam and the boom head. The luffing wire rope originates from the No. 1 luffing mechanism on the ship's deck, passes through a guide pulley on one side of the front end of the A-frame upper beam, and is transmitted to the inner side of the corresponding pulley on the boom head. It begins winding from the outer large pulley of the A-frame and boom pulley sleeve, then from the inner small pulley, and then through the top guide pulley and the back balance pulley of the A-frame upper beam to the other side, continuing winding in the same way. Finally, it returns to the No. 2 luffing mechanism via the other guide pulley at the front end of the A-frame upper beam. This luffing mechanism has a winding system ratio of 32, 2 rope systems, and 68 pulleys. See [link to details]. Figure 7 In this embodiment, after completing the finite element modeling of the A-frame structure, boom structure, and luffing mechanism wire rope winding system, the finite element solution is performed in the whole machine model.

[0051] The standard boom section is modeled using beam elements. The A-frame, boom root section, and head section are modeled using shell elements based on their complexity. The pulley axle is simulated using beam elements. The pin and the lug hole are directly connected using rigid elements to simulate the pulley-lug connection. The first node of the rigid element is set at the center of the lug hole. See [link to details]. Figure 8-10 .

[0052] The specific modeling of the winding method between the wire rope and the pulley is as follows: To reduce computational complexity, the geometric nonlinearity caused by the wire rope's own deflection and the effect of the pulley system efficiency are ignored, and the wire rope is simplified into a two-force member (LinkElement) for simulation. Since the boom needs to operate at different pitch angles, considering the feasibility of modeling and the convenience of model modification under different pitch conditions, the plane defined by the crossbeam on the A-frame and the pulley sleeve axis at the boom head is artificially used as the modeling plane for the pulley and wire rope on the pulley sleeve. The pulley of the pulley sleeve is simulated using rigid elements. The rotation of the pulley around its axis is achieved by coupling the degrees of freedom of the coincident node: that is, rotating the coincident node to the local coordinate system defined by the modeling plane, only releasing the rotational degree of freedom about the normal direction of the modeling plane, and coupling the translational degrees of freedom in three directions and the rotational degrees of freedom in the other two directions. For pulleys in other positions, such as guide pulleys and balance pulleys, rigid units of equal length are established from the pulley's center of rotation based on the pulley's radius (the position of the other end node of the rigid unit is determined by the tangent point between the wire rope and the pulley), and their corresponding rotational degrees of freedom are released according to the actual direction of rotation. Finally, the rigid unit nodes of the crossbeam on the A-frame and the simulated pulley at the boom head are connected sequentially with rod units to achieve the transmission of wire rope tension.

[0053] As can be seen from the lever moment balance, the lengths (i.e., lever arms) of the rigid elements on both sides of the coupling node determine the ratio of the tensile force outputs of the rod elements at both ends. For a single-layer winding of wire rope, the coupling point can be intuitively selected at the actual position of the pulley axis, and the model can be built in a one-to-one correspondence between rod elements and wire ropes, that is, each rod element outputs the actual tensile force of a single wire rope. However, for multi-layer winding of wire rope, considering the operability and convenience of modeling, it is not possible to achieve a one-to-one correspondence between the number of rod elements and the number of wire ropes. In this case, it is only necessary to ensure that the total tensile force of the rod elements acting on the crossbeam and boom head of the A-frame is equal to the actual force. This requires manually adjusting the position of the coupling node and the lengths of the rigid elements on both sides (i.e., to adjust the lever arm ratio), changing the ratio of the internal force outputs of the rod elements at both ends, and reducing the number of rod elements to reduce the complexity of modeling. The spacing of the rigid element nodes and the number of rod elements in the simulated pulley can be flexibly adjusted according to the actual distance between the two side lugs and the multiplier of the wire rope winding system. This may result in different angles between the rod elements and the rigid elements on both sides of the coupling node. However, the distance between the boom head and the upper crossbeam of the A-frame is very large. Therefore, the impact of this modeling defect on the calculation accuracy is negligible. (See...) Figure 11Since the wire ropes on both sides of the floating crane's center of symmetry are wound in the same way, the modeling of the winding connection on one side is only shown in the figure. In this embodiment, each set of pulleys at the boom head has 8 pulleys, and the total resultant force exerted on the end plates is the tension of 8 × 2 wire ropes. The inner pulley set of the crossbeam on the A-frame also has 8 pulleys, and the total resultant force exerted on the end plates is also the tension of 8 × 2 wire ropes. The outer pulley set has 7 pulleys, and the total resultant force exerted on the end plates is the tension of 7 × 2 wire ropes. The other wire rope acts on the guide pulley in the middle. Therefore, the total amplitude force acting on the boom head and the crossbeam on the A-frame is the tension of 8 × 2 × 2 × 2 = 64 wire ropes. It is important to pay attention to the selection of the coupling node position to avoid excessive eccentric loading of the pulley group on the end plates. The overall finite element model of the floating crane structure is shown in [reference needed]. Figure 12 The modeling details of its luffing mechanism wire rope winding system can be found in [link to model]. Figure 13 For working models with different luffing angles, it is only necessary to rotate the relevant nodes on the boom model with the pin at the base of the boom as the rotation center, and update the local coordinate system determined by the luffing wire rope modeling plane.

[0054] The tension of a single wire rope and the total amplitude force on the structure were evaluated by reading the internal forces of each rod element in the post-processing module of the finite element software, as shown in Table 1. The minimum internal force output by the rod element is approximately 569.3 kN, which is the tension of a single wire rope. The ratios of other larger internal force output values ​​to this minimum value are 2.0 or 3.0. Figure 11 The tensile force output multiple of the rod element in the model is very consistent, indirectly proving the rationality of simplifying the model by wrapping the wire rope around the luffing pulley. The total luffing force on the structure is approximately 569.3 × 64 = 36435.2 kN.

[0055]

[0056] Table 1 Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A simplified finite element simulation method for wire rope winding in a luffing mechanism, characterized in that: A finite element model of the main steel structure of the lifting equipment is established. The main steel structure includes the A-frame and the boom. The A-frame and the main body of the boom are modeled using beam elements. The pulley shaft is simulated by beam elements, and the pulley shaft and the ear plate shaft hole are connected by a rigid element with the first node positioned at the center of the shaft hole. The modeling plane is determined based on the pulley sleeve axle of the crossbeam and boom head of the A-frame; The wire rope is simplified as a two-force member element simulation, and the pulley is simplified as a rigid element simulation. For variable amplitude pulleys, the rotational degree of freedom in the normal direction of the modeling plane is released by coupling coincident nodes; For guide pulleys and balance pulleys, the rotational degree of freedom of the pulley's own axis is released by coupling coincident nodes; The rigid element nodes simulating the pulley are connected sequentially through rod elements according to the wire rope winding path; After rotating the boom to the target pitch angle, update the local coordinate system of the modeling plane.

2. The simplified finite element simulation method for wire rope winding of a luffing mechanism according to claim 1, characterized in that: The local coordinate system update operation of the modeling plane occurs after the boom pitch angle changes, and the origin of the coordinate system is fixed at the intersection of the A-frame and the boom pulley sleeve axis.

3. The simplified finite element simulation method for wire rope winding of a luffing mechanism according to claim 1, characterized in that: When the wire rope is wound in a multi-layered manner, the total tension output by the rod unit is made equal to the actual total tension of the wire rope by moving the coupling node position of the pulley shaft.

4. The simplified finite element simulation method for wire rope winding of a luffing mechanism according to claim 1, characterized in that: The connection method of the rod unit satisfies the ratio of the pulley sleeve tension on the A-frame side and the boom side, wherein the tension ratio of the inner pulley sleeve to the outer pulley sleeve of the A-frame is 8:7, and the tension unit of the pulley sleeve at the boom head is 8.

5. The simplified finite element simulation method for wire rope winding of a luffing mechanism according to claim 1, characterized in that: The connection point between the rigid unit and the ear plate is precisely located at the center of the ear plate shaft hole, and the length extension direction of the rigid unit matches the radius direction of the pulley.

6. The simplified finite element simulation method for wire rope winding of a luffing mechanism according to claim 1, characterized in that: Under different pitch conditions, only the physical tangent point between the guide pulley and the wire rope is adjusted.

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