Transformer air cushion vehicle tray and design method thereof

Abstract

The present application relates to a kind of transformer air cushion vehicle tray and its design method, comprising the following steps: the overall structure of tray is regarded as continuum, and continuum is decomposed into discretization structure;For each unit in discretization structure, stress analysis is carried out, and all units in discretization structure are fused, and then the stress deformation result of the overall structure of tray is obtained;According to the stress analysis of each unit and the stress deformation result of the overall structure of tray, discretization structure is optimized, and the optimized tray structure is obtained.The present application optimizes structure, improves stress mode, avoids fatigue failure between the components of tray caused by excessive bending moment;Computer simulation method is used instead of test verification, problems are found in simulation process, and then optimization design is carried out, to improve the efficiency and quality of design.The present application optimizes the problem of unreasonable material use in actual structure design, and reduces material use cost.

Description

Technical Field

[0001] This invention relates to the field of transformer manufacturing technology. Specifically, it relates to a transformer air cushion vehicle tray and its design method. Addressing the problems of deformation and cracking that occur during the use of air cushion vehicle trays in transformer production, this invention proposes a design method for an air cushion vehicle tray and designs a transformer air cushion vehicle tray. Background Technology

[0002] Currently, in the field of ultra-high voltage transformer manufacturing, after the transformer body is assembled and during the overall assembly process, air cushion vehicles are needed to move the transformer body and the entire unit. A key component transporting the transformer along with the air cushion vehicle is the air cushion vehicle pallet, which bears the transformer throughout the transportation process. Because hundreds of tons of transformer weight are constantly pressing on the pallet, improper design or repeated use can easily lead to deformation and cracking failures, posing a significant safety hazard to transformer production, manufacturing, transportation, and storage.

[0003] Current air cushion vehicle pallet designs rely mainly on experience, lacking clear diagnosis of vulnerable areas. This leads to structural damage issues such as pallet deformation and cracking during production, posing significant safety hazards. Design often focuses solely on the fit between the structure and the air cushion vehicle, neglecting areas requiring reinforcement. The load-bearing capacity is often increased by adding more material, resulting in low material utilization and an unreasonable material distribution. Summary of the Invention

[0004] This invention provides a transformer air cushion vehicle pallet and its design method. The pallet structure is an improvement based on existing structural defects and actual fatigue failure phenomena, and a method for designing the pallet is proposed.

[0005] The technical solution adopted by the present invention to achieve the above objectives is: a design method for a transformer air cushion vehicle tray, comprising the following steps:

[0006] The overall structure of the pallet is treated as a continuum, and the continuum is decomposed into a discretized structure.

[0007] For each element in the discretized structure, a stress analysis is performed, and all elements in the discretized structure are merged to obtain the stress and deformation results of the overall pallet structure.

[0008] Based on the stress analysis of each unit and the stress deformation results of the overall pallet structure, the discretized structure is optimized to obtain the optimized pallet structure.

[0009] The process of transforming the continuum into a discretized structure specifically involves dividing the continuum into a finite number of elements and a finite number of nodes, and then dividing the mesh according to the structural characteristics of each component.

[0010] The upper panel, lower panel, and support beam are divided into hexahedral meshes, while the two legs are divided into tetrahedral meshes, thus achieving discretization of the pallet sorting structure.

[0011] The force analysis for each element in the discretized structure is specifically as follows:

[0012] For each hexahedral element of the top panel, bottom panel, and supporting beam, the nodal force relationships in any plane are as follows:

[0013]

[0014] in, , , , These represent the nodal forces at planar nodes a, b, c, and d of the hexahedral element, respectively. The submatrix representing the stiffness matrix of a hexahedral element is specifically represented as numbered... The node along or When there is a unit displacement in the direction, the stiffness of the hexahedral element will cause stress at the nodes. of or Nodal forces caused by direction; , , , These represent the displacements of nodes numbered i, j, k, and m, respectively.

[0015] Based on the principle of static equivalence, the element load is distributed to each node of the element, which is the planar nodal force; according to the planar nodal force... , , , By combining the element stiffness matrix, the nodal displacements can be obtained. , , , .

[0016] The force analysis for each element in the discretized structure is specifically as follows:

[0017] For each tetrahedral element of the two legs, the nodal force relationships in any plane are as follows:

[0018]

[0019] in, , , Let a, b, and c represent the nodal forces at planar nodes of the tetrahedral element, respectively. The submatrix representing the stiffness matrix of the tetrahedral element is specifically represented as numbered... The node along or When there is a unit displacement in the direction, the stiffness of the tetrahedral element will cause stress at the nodes. of or Nodal forces caused by direction; , , These represent the displacements of nodes numbered i, j, and k, respectively.

[0020] Based on the principle of static equivalence, the element load is distributed across each node of the element, which is the planar nodal force. The planar nodal forces are then analyzed separately. , , By combining the element stiffness matrix, the nodal displacements can be obtained. , , .

[0021] The process of fusing all units in the discretized structure is achieved using the mesh module in the ANSYS Workbench software.

[0022] The process of obtaining the stress-deformation results of the overall structure of the pallet includes the following steps:

[0023] Based on the pre-established objective function, optimization is performed with the goal of minimizing the overall structural mass of the pallet. Element elements that do not meet the set mass retention percentage are deleted, and the elements that meet the requirements are used to build a continuum to obtain a discretized structure that meets the constraints.

[0024] The objective function is the relationship function between the independent variable and the dependent variable; the independent variable is each unit in the discretized structure, and the dependent variable is the sum of the masses of all units in the discretized structure, i.e., the overall structural mass of the pallet.

[0025] The constraints are: the stress threshold and strain threshold of each element in the discretized structure.

[0026] The transformer air cushion vehicle pallet includes support beams, an upper panel, side panels, a lifting plate, a lower panel, support legs, and pads. Multiple support beams are fixed to the lower surface of the upper panel, and the upper surface of the lower panel is fixed to each support beam. Support legs are symmetrically fixed to both sides of the lower surface of the lower panel, and two parallel pads are provided between two support legs for contact with the air cushion vehicle. Each pad is fixed to the lower surface of the lower panel. Side panels are fixed to the outer edge of the upper panel, and a lifting plate for lifting and transferring the pallet is fixed to the side panels.

[0027] Wherein: both the upper panel and the lower panel are rectangular, the lower panel has the same length as the upper panel, and the width of the upper panel is greater than the width of the lower panel.

[0028] Multiple support beams are uniformly fixed to the lower surface of the upper panel along its length, and the length of the support beams is equal to the width of the upper panel.

[0029] The legs and shims are both arranged along the length of the lower panel, and the length of the legs and shims is equal to the length of the lower panel.

[0030] The support leg includes a support frame and a support plate. The support frame is fixed to the lower surface of the lower panel, and multiple support plates are uniformly fixed to the support frame along its length.

[0031] The support plates at both ends of the support frame are right-angled trapezoids, the support plates between the two ends are isosceles trapezoids, and the space between two adjacent support plates is an isosceles trapezoidal cutout A.

[0032] On the lower plate inside each of the legs, the corresponding position of each of the hollowed-out portions A is a hollowed-out portion B in the shape of an isosceles trapezoid.

[0033] The support frame is a rectangular frame, the length of which is equal to the length of the lower panel, and the outer side of the support frame is coplanar with the edge of the lower panel; the support plate is fixed to the inner side of the support frame, and each support plate has a leg reinforcing iron fixed to its outer side.

[0034] The support leg reinforcing iron is fixed to the middle position of the outer side of the support plate. The support leg reinforcing iron is rectangular, and the sum of the thicknesses of the support plate and the support leg reinforcing iron is equal to the thickness of the support frame.

[0035] The distance between the outer sides of the support frame of the two legs is equal to the width of the lower panel, and the spacing between the two legs is greater than the width of the air cushion vehicle.

[0036] The support beam is a square steel tube, and each support beam is parallel to the others. The length of the support beam is twice the distance between the two legs.

[0037] The present invention has the following beneficial effects and advantages:

[0038] (1) Optimize the structure, improve the stress mode, and avoid excessive bending moment that could cause fatigue failure between the components of the pallet;

[0039] (2) Replace experimental verification with computer simulation, discover problems in the simulation process, and then optimize the design to improve the efficiency and quality of the design.

[0040] (3) It optimizes the problem of unreasonable material use in actual structural design and reduces material usage costs. Attached Figure Description

[0041] Figure 1 This is a flowchart of the method of the present invention;

[0042] Figure 2 The original three-dimensional model of the tray of this invention;

[0043] Figure 3 The improved design of the tray in this invention is shown in the three-dimensional model diagram.

[0044] Figure 4 A 3D model of the tray after the optimized design of this invention;

[0045] Wherein: 1 is the support beam, 2 is the top panel, 3 is the side panel, 4 is the hanging plate, 5 is the bottom panel, 6 is the support leg, 7 is the pad, 8 is the support leg reinforcement, 9 is the support plate, 10 is the support frame, 11 is the hollow part A, and 12 is the hollow part B. Detailed Implementation

[0046] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0047] like Figure 1 and Figure 2 The existing pallet structure is as follows: A transformer air cushion vehicle pallet includes a support beam 1, an upper panel 2, side panels 3, a lifting plate 4, a lower panel 5, support legs 6, and pads 7. Multiple support beams 1 are fixed to the lower surface of the upper panel 2. The upper surface of the lower panel 5 is fixed to each support beam 1. Support legs 6 are symmetrically fixed to both sides of the lower surface of the lower panel 5. Two parallel pads 7 are provided between two support legs 6 for contact with the air cushion vehicle. Each pad 7 is fixed to the lower surface of the lower panel 5. Side panels 3 are fixed to the outer edge of the upper panel 2, and a lifting plate 4 for lifting and transferring the pallet is fixed to the side panels 3. Each support leg 6 includes a support frame 10 and support plates 9. The support frame 10 is fixed to the lower surface of the lower panel 5, and multiple support plates 9 are uniformly fixed along the length of the support frame 10. The support frame 10 is a rectangular frame, the length of the support frame 10 is equal to the length of the lower panel 5, and the outer side of the support frame 10 is coplanar with the edge of the lower panel 5; the support plate 9 is fixed to the inner side of the support frame 10, and each of the support plates 9 has a leg reinforcing iron 8 fixed to its outer side.

[0048] (1) A 280T pallet was selected for modeling and finite element analysis calculation. The pallet weighs about 9t and has a load capacity of 280t. The structure is inverted "U". The support beam is made of I-beams. There are 14 support beams and 14 reinforcing irons. The contact surface between the legs and the ground is fixed and constrained. The 280t load is vertically applied to the upper plate and the direction of gravity acceleration is set to be perpendicular to the upper plate and downward. All existing pallets are inverted "U" shaped structures. The triangular area where the support leg reinforcing iron and the lower plate are combined is prone to fatigue failure. Excessive deformation of the upper and lower plates makes it impossible for the air cushion vehicle to cooperate with the pallet. Insufficient strength of the support beams leads to excessive deformation of the upper and lower plates and side plates.

[0049] (2) Analyze the calculation results; retrieve the overall deformation and stress images of the pallet and find that the maximum deformation occurs at the center of the pallet panel and the maximum stress occurs at the welded joint surface between the support leg and the lower panel; the deformation trend shows that the panel is prone to excessive indentation, support leg deformation, excessive side plate deformation and stress concentration, etc. At the same time, in order to meet the load-bearing capacity, the material usage of this structure must be increased to improve the safety factor. The above are the shortcomings of the inverted "U" shaped structure.

[0050] (3) To address the design shortcomings of the inverted "U" shaped pallet, structural improvements were made. The heavy I-beams were replaced with square steel pipes, which have better strength and toughness. The number of support beams and reinforcing irons was reduced, the thickness of the leg steel plates was decreased, and the length of the support beams was increased by half of the original size, evenly distributed between the two legs. The improved pallet weighs approximately 6.2t, significantly less than the original inverted "U" shaped pallet. Since the dimensions of the air cushion vehicle are fixed, the spacing between the pallet legs remains unchanged. This structure effectively avoids the problem of excessive bending moment under heavy loads in the inverted "U" shaped structure. (Structural optimization and lightweight design of the pallet)

[0051] (4) The improved pallet structure was converted to Parasolid.x_t format using SolidWorks and imported into the ANSYS Workbench static analysis module for finite element calculation. Model simplification: The hanging plate was removed because the circular holes at the hanging plate were not conducive to mesh generation and the hanging plate did not play a role in load bearing; Static model settings: According to the actual situation, the material of all pallet parts was set to Q345B, Young's modulus 2E+11Pa, Poisson's ratio 0.3, and material density 7850kg / m³. The pallet is a welded part, so the connection method of all joint surfaces was set to Bonded; According to the finite element method, the overall structure is a continuum. The continuum is then discretized into a finite number of elements and nodes. To improve the calculation accuracy and efficiency, the mesh generation method was set according to the structural characteristics of each part. The upper and lower panels and support beams were meshed using a hexahedral mesh method, and the two legs were meshed using a tetrahedral mesh method. A total of 17408 elements were generated. The number of nodes is 80,131. Boundary conditions are set: According to the actual situation, the pallet will bear the transformer for a long time. This working condition is very likely to cause the pallet to fail. Therefore, fixed constraints are set on the contact surfaces between the two legs of the pallet and the ground. The direction of gravitational acceleration is perpendicular to the upper panel and downward. A force of 2.8E+6N (280t) is set perpendicular to the upper panel and downward. Static calculation and post-processing: The stiffness and strength results are obtained. The maximum deformation and maximum stress occur on the upper panel. The stiffness is about 0.9mm different from the original inverted "U" shaped pallet. The maximum stress is 126.91MPa, which is better than the maximum stress of 143.97MPa of the original inverted "U" shaped pallet. At the same time, the leg deformation of the improved scheme is less than 0.59mm, the stress is less than 14.1MPa, and no stress concentration occurs at any position of the whole, which greatly enhances the safety and stability.

[0052] (5) Perform topology optimization calculations on the improved structure to further reduce weight while meeting stiffness and strength requirements. Link the above static analysis module to the topology optimization module for optimization calculations. Set fixed constraints on the contact surface between the outrigger and the ground. Apply a 2.8E+6N (280t) load vertically to the upper plate. Set the direction of gravitational acceleration to be perpendicular to the upper plate and downward. Initially set the mass constraint to retain 70% of the mass (i.e., reduce the mass by 30%) and perform calculations.

[0053] The mathematical optimization model is established as follows: Represents a discretized unit; This represents the sum of the masses of the discretized units; Indicates stress; Indicates strain.

[0054]

[0055] As described in (4), the upper and lower panels and supporting beams of the tray continuum are regular in structure. Therefore, a hexahedral division method is adopted to decompose the hexahedron into a continuous planar structure. Each face of the hexahedron is a four-node structure. The nodal force relationship of this planar structure is: where, This represents the planar nodal forces of a hexahedral element (any plane of the hexahedron is a four-nodal plane); This represents a submatrix of the stiffness matrix of a hexahedral element (i.e., a submatrix of the element stiffness matrix), specifically represented as numbered... The node along or When there is a unit displacement in the direction, the stiffness of the hexahedral element will cause stress at the nodes. of or Nodal forces caused by direction; Indicates the number is The displacement of the nodes.

[0056]

[0057] The continuous support leg structure of the pallet has an irregular structure, so a tetrahedral partitioning method is adopted to decompose the tetrahedron into a continuous planar structure. Each face of the tetrahedron is a three-node structure, and the nodal force relationship of this planar structure is as follows: This represents the planar nodal forces of a tetrahedral element (any plane of the tetrahedron is a three-nodal plane); This represents a submatrix of the tetrahedral element stiffness matrix (i.e., a submatrix of the element stiffness matrix), specifically represented as numbered... The node along or When there is a unit displacement in the direction, the stiffness of the tetrahedral element will cause stress at the nodes. of or Nodal forces caused by direction; Indicates the number is The displacement of the nodes.

[0058]

[0059] ( —Nodal forces; — Element stiffness matrix; —Nodal displacement)

[0060] As described in step (4) above, after discretizing the continuum into elements, each element remains a continuous, uniform, isotropic, and perfectly elastic body. After discretization, each element is analyzed as an independent entity. To simplify the stress state of each element, the external loads on the element are shifted to the nodes to become nodal loads. The nodal equilibrium equations for the entire continuum of the tray are established as follows:

[0061] ( —Overall stiffness matrix; —Global nodal displacement array; —Global nodal load array)

[0062] After meshing the tray continuum, the nodal force discretization model is established as follows: A submatrix representing the global stiffness matrix, specifically represented by nodes. With nodes In a structure, elements are interconnected through several plane elements. The superposition of the submatrices of the stiffness matrices of all these plane-related elements constitutes a submatrix of the overall stiffness matrix. In this embodiment, m and r = 1…80131.

[0063]

[0064] The relationship between the element stiffness matrix and the global stiffness matrix is ​​as follows: .

[0065] In the optimization calculation, after the optimization module divides the grid into elements and fixes the constraints, for each element, since the correspondence between the local and global encodings of the nodes is determined, the position and mechanical meaning of any submatrix in the stiffness matrix of each element within the global stiffness matrix are also clear. Therefore, the global stiffness matrix is ​​determined. Based on the input load magnitude and location, the displacement of each node can be calculated, and then the stress and strain results for each element are obtained from the stress-strain relationship. To avoid singularities in the global stiffness matrix, the convergence accuracy is set to [value missing] during the calculation. The above data is input into the computer for calculation, and multiple iterative calculations are performed automatically. The calculation converges after 16 iterations, and the calculation is complete. Convergence criterion: [The calculation is completed on the 16th iteration...] The round of iterations simultaneously satisfies the deletion rate and the fact that the weights of two adjacent iterations are sufficiently close, i.e. If the condition is met, the optimization iteration terminates. The calculation is complete. Indicates the deletion rate; Indicates the overall structural weight of the pallet; , For convergence accuracy.

[0066]

[0067] (6) Post-process the calculation results. After the optimization calculation is completed, define the element deletion criteria: After setting the target optimization percentage (30% quality deletion, 70% retention), that is, set the element deletion threshold to 0.3, complete the calculation according to the set convergence accuracy, obtain the stress and deformation results of the overall structure according to the stress and strain results of each element of the continuum, eliminate elements that do not meet the requirements according to the element deletion threshold, leave the elements that meet the requirements, build a continuum with the left elements, and obtain the optimized structure. Remodel the optimized model structure. The self-weight of the modeled pallet is 5.4t. Verify the optimized structure by setting the same load and constraint conditions for calculation. Figure 4 As shown, the trapezoidal section between the support leg reinforcing irons and the trapezoidal areas on both sides of the lower panel corresponding to the deleted positions of the support legs have been removed.

[0068] (7) Post-process the calculation results, retrieve the data of pallet stiffness, strength, fatigue life and safety factor, and analyze them according to the distribution results.

[0069] (8) If the optimized structural stiffness, strength, fatigue life and safety factor meet the production and use conditions, then the design scheme is determined; if the above results do not meet the safe production and use conditions, then the quality constraints of topology optimization are reset and re-optimized until the optimization results meet the safe production and use conditions.

[0070] The design method of this embodiment is as follows: Figure 1 As shown, this method is based on the improved and designed structure of a 280t transformer air cushion vehicle pallet, using Q345B high-strength structural steel as the material. The specific method is as follows:

[0071] (1) Select a 280T pallet for modeling, such as Figure 2 Finite element analysis was performed. The pallet weighs approximately 9 tons and has a load capacity of 280 tons. Its structure is an inverted "U" shape, with I-beams as the support beams. There are 14 support beams and 14 reinforcing irons. Fixed constraints were set on the contact surfaces between the outriggers and the ground. A 280-ton load was vertically applied to the top plate, with the direction of gravitational acceleration set perpendicular to the top plate and downwards. Based on actual usage, all existing pallets have an inverted "U" shape. Areas prone to fatigue failure include the triangular area where the support leg reinforcing irons meet the bottom plate; excessive deformation of the top and bottom plates prevents the air cushion vehicle from fitting with the pallet; and insufficient strength of the support beams leads to excessive deformation of the top, bottom, and side plates.

[0072] (2) Analyze the calculation results; retrieve the overall deformation and stress data of the pallet. The maximum deformation is 4.4061 mm, located at the center of the pallet panel. The maximum stress is 143.57 MPa, located at the welded joint surface between the support leg and the lower panel. The deformation trend shows that excessive panel indentation, support leg deformation, excessive side plate deformation, and stress concentration are likely to occur. At the same time, in order to meet the load-bearing capacity, the amount of material used in this structure must be increased to improve the safety factor. The above are the shortcomings of the inverted "U" shaped structure.

[0073] (3) Structural improvements were made to address the design shortcomings of the inverted "U" shaped pallet, such as... Figure 3 The heavy I-beams were replaced with high-strength and high-toughness square steel tubes. The number of support beams and reinforcing irons was reduced, the thickness of the leg plates was decreased, and the length of the support beams was increased by half, evenly distributed between the two legs. The improved pallet weighs approximately 6.2 tons, significantly less than the original inverted "U"-shaped pallet. Since the dimensions of the air cushion vehicle are fixed, the spacing between the pallet legs remains unchanged. This structure effectively avoids the problem of excessive bending moments under heavy loads inherent in the inverted "U"-shaped structure. (Patrolley structural optimization and lightweight design)

[0074] (4) Finite element analysis was performed on the improved pallet structure to obtain stiffness and strength results. The maximum deformation (5.3672 mm) and maximum stress (126.9 MPa) occurred on the upper panel. The stiffness was about 0.9 mm different from the original inverted "U" shaped pallet structure. The maximum stress was 126.91 MPa, which was better than the maximum stress of 143.97 MPa of the original inverted "U" shaped pallet structure. At the same time, the deformation of the legs of the improved scheme was less than 0.59 mm, the stress was less than 14.1 MPa, and no stress concentration occurred at any position of the whole structure, which greatly enhanced the safety and stability.

[0075] (5) Optimize the improved structure to further reduce weight while meeting stiffness and strength requirements. Use the ANSYS Workbench Topology Optimization module to perform optimization calculations. Set fixed constraints on the contact surface between the outrigger and the ground. Apply a 280t load vertically to the upper plate. Set the direction of gravitational acceleration to be perpendicular to the upper plate and downward. Initially set the mass constraint to retain 70% of the mass (i.e., reduce the mass by 30%). Use the finite element method for calculation.

[0076] (6) Post-process the calculation results. The optimization results show the parts that can be optimized away: the trapezoidal area between two adjacent reinforcing irons on the leg and the trapezoidal areas on both sides of the lower panel corresponding to the trapezoidal areas of the leg; remodel the optimized model structure as follows: Figure 4The modeled pallet weighs 5.8t. The optimized structure is verified by setting the same load and constraints for calculation. The calculation results are post-processed to retrieve and analyze the pallet stiffness, strength, fatigue life and safety factor data.

[0077] (7) The optimized pallet has a maximum deformation of 5.6406 mm and a maximum stress of 127.21 MPa, both located between the two support beams of the upper panel. Compared with the structure before optimization, the maximum deformation increased by 5.2% and the maximum stress increased by 0.23%, both meeting the design requirements. The stress and strain changes before and after optimization are very small and meet the design requirements. Moreover, the mass is significantly reduced after optimization, indicating that the deleted element did not appear on the main force transmission path of the pallet continuum. The minimum fatigue life is 1.3435 × 10⁻⁶ mm. 5 This occurred at the point of maximum stress on the upper panel, close to the design maximum fatigue life of 1.0 × 10⁻⁶. 6 The minimum safety factor was 0.6776, which also occurred at the point of maximum stress on the upper panel. All other parts had safety factors above 5, meeting the requirements for safe production and use. The results also showed no stress concentration at the junction of the pallet legs and the lower panel, and no significant bending moments were observed on either the upper or lower panel, indicating significant optimization results.

[0078] (8) The simulation method loads a 280t load onto the upper plate, which is different from the actual result of the transformer tank sitting on the tray. In the actual tank, the contact between the upper plate and the bottom plate does not cause large deformation between the two support beams. Although the maximum deformation, maximum stress, minimum fatigue life and minimum safety factor of the simulation occur on the upper plate, the actual values ​​are better than the simulation results.

[0079] (9) Comprehensive analysis shows that the design indicators have a high safety factor and a significant reduction in material usage, achieving the design goals. The optimization results are modeled as follows: Figure 4 In actual use, laminated wood of a certain thickness should be installed on the top plate and the lower end of the support legs, and fixed with hex bolts to prevent the metal structure from damaging the ground and the outer surface of the transformer tank. All metal structure joints must be welded.

[0080] like Figure 4 As shown, this pallet structure includes a support beam 1, an upper panel 2, side panels 3, a lifting plate 4, a lower panel 5, support legs 6, and pads 7. Multiple support beams 1 are fixed to the lower surface of the upper panel 2, and the upper surface of the lower panel 5 is fixed to each support beam 1. Support legs 6 are symmetrically fixed to both sides of the lower surface of the lower panel 5. Two parallel pads 7 are provided between the two support legs 6 for contact with the air cushion vehicle. Each pad 7 is fixed to the lower surface of the lower panel 5. The outer edge of the upper panel 2 is fixed to the side panel 3, and a lifting plate 4 for lifting and transferring the pallet is fixed to the side panel 3.

[0081] In this embodiment, both the upper panel 2 and the lower panel 5 are rectangular. The lower panel 5 has the same length as the upper panel 2, and the width of the upper panel 2 is greater than the width of the lower panel 5. The upper panel 2 and the lower panel 5 are parallel, and the plane containing the center line of the upper panel 2 in the length direction and the center line of the lower panel 5 in the length direction is perpendicular to the upper panel 2 and the lower panel 5.

[0082] In this embodiment, multiple support beams 1 are uniformly fixed to the lower surface of the upper panel 2 along its length. The length of each support beam 1 is equal to the width of the upper panel 2. In this embodiment, the support beams 1 are square steel tubes, and each support beam 1 is parallel to the others. The length of each support beam 1 is twice the distance between the two support legs 6.

[0083] In this embodiment, both the support leg 6 and the pad 7 are arranged along the length of the lower panel 5, and the lengths of the support leg 6 and the pad 7 are equal to the length of the lower panel 5.

[0084] In this embodiment, the support leg 6 includes a support frame 10, a support plate 9, and a support leg reinforcing iron 8. The support frame 10 is a rectangular frame, fixed to the lower surface of the lower panel 5. The length of the support frame 10 is equal to the length of the lower panel 5, and the outer side of the support frame 10 is coplanar with the edge of the lower panel 5. Multiple support plates 9 are uniformly fixed along the length direction inside the support frame 10. The support plates 9 at both ends of the support frame 10 are right-angled trapezoids, and the support plates 9 between the two ends are isosceles trapezoids. Between two adjacent support plates 9, there is an isosceles trapezoidal cutout A11. In this embodiment, the support plates 9 are fixed to the inner side of the support frame 10, and a support leg reinforcing iron 8 is fixed to the middle position of the outer side of each support plate 9. The support leg reinforcing iron 8 is rectangular, and the sum of the thicknesses of the support plates 9 and the support leg reinforcing iron 8 is equal to the thickness of the support frame 10. On the lower panel 5 inside each leg 6, corresponding to the position of each cutout A11, there is an isosceles trapezoidal cutout B12. The design of cutout A11 and cutout B12 reduces the amount of raw materials used and the cost while ensuring that the pallet strength can support a load of 280t.

[0085] In this embodiment, the distance between the outer sides of the support frame 10 of the two legs 6 is equal to the width of the lower panel 5, and the distance between the two legs 6 is greater than the width of the air cushion vehicle.

[0086] The pallet material of this invention is Q345B high-strength structural steel.

[0087] The optimized pallet structure avoids excessive bending moment that could lead to fatigue failure between pallet components. The pallet has high support strength and a reasonable structural design, which can prevent deformation and cracking failures, ensuring good safety during the transfer and storage of transformers.

Claims

1. A method of designing a transformer air cushion vehicle pallet, characterized by, The method comprises the following steps: The whole structure of the tray is taken as a continuum, and the continuum is decomposed into a discretized structure; The continuum is decomposed into the discretized structure, specifically: the continuum is divided into a finite number of units and a finite number of nodes, and the grid is divided according to the structural characteristics of each part: The upper panel, the lower panel and the support beam are divided by a hexahedral grid division method, and the two legs are divided by a tetrahedral grid division method, so as to realize the discretization of the tray structure; Stress analysis is performed on each unit in the discretized structure, all units in the discretized structure are fused, and then the stress deformation result of the whole structure of the tray is obtained; The stress deformation result of the whole structure of the tray is obtained, comprising the following steps: According to the pre-established objective function, the minimum mass of the whole structure of the tray is taken as the target for optimization, units that do not meet the set quality retention percentage are deleted, units that meet the requirement are retained to establish a continuum, and a discretized structure that meets the constraint condition is obtained; The objective function is a function of independent variables and dependent variables; the independent variables are each unit in the discretized structure, and the dependent variables are the mass of all units in the discretized structure, that is, the mass of the whole structure of the tray; The constraint condition: the stress threshold and the strain threshold of each unit in the discretized structure; According to the stress analysis of each unit and the stress deformation result of the whole structure of the tray, the discretized structure is optimized to obtain an optimized tray structure.

2. The method of designing a transformer air cart tray of claim 1, wherein, The stress analysis of each unit in the discretized structure is specifically: For each hexahedral unit of the upper panel, the lower panel and the support beam, the node force relationship of any plane is: ； wherein, , , , denote the nodal forces of the nodal points a, b, c, d of the hexahedral element plane, respectively; denote the sub-matrices of the stiffness matrix of the hexahedral element, in particular the nodal forces caused in the directions or of the nodal points with unit displacement in the directions or of the nodal points due to the stiffness of the hexahedral element; , , , denote the displacements of the nodal points i, j, k, m, respectively; According to the static equivalent principle, the unit load dispersion unit is dispersed on each node, that is, the plane node force; according to the plane node force 、 、 、 and the unit stiffness matrix, the node displacement 、 、 、 is obtained.

3. The method of designing a transformer air cart tray of claim 1, wherein, The stress analysis of each unit in the discretized structure is specifically: For each tetrahedral unit of the two legs, the node force relationship of any plane is: ； wherein, , , denote the nodal forces of the tetrahedron element nodal points a, b, c respectively; denote the sub-matrix of the stiffness matrix of the tetrahedron element, which specifically denotes the nodal force caused in the direction of or of the nodal point due to the stiffness of the tetrahedron element when the nodal point has a unit displacement in the direction of or ; , , denote the displacements of the nodal points numbered i, j, k respectively;​ According to the static equivalent principle, the unit load dispersion unit is dispersed on each node, that is, the plane node force, and the node displacement is obtained according to the plane node force 、 、 and the unit stiffness matrix 、 、 .

4. The method of designing a transformer air cart tray of claim 1, wherein, The fusion of all units in the discretized structure is realized by the mesh module in the ANSYS Workbench software.

5. The transformer air cushion cart tray designed by the design method of claim 1, characterized by: It comprises a support beam (1), an upper panel (2), a side plate (3), a lifting plate (4), a lower panel (5), a leg (6) and a pad iron (7), wherein the lower surface of the upper panel (2) is fixedly connected with a plurality of support beams (1), the upper surface of the lower panel (5) is fixedly connected with each support beam (1), the lower surface of the lower panel (5) is fixedly connected with the leg (6) on both sides, two pad irons (7) are arranged between the two legs (6), the two pad irons (7) are parallel to each other and are used for contacting the air cushion vehicle, and each pad iron (7) is fixedly connected with the lower surface of the lower panel (5); the outer edge of the upper panel (2) is fixedly connected with the side plate (3), the side plate (3) is fixedly connected with the lifting plate (4) used for lifting and transferring the tray; the upper panel (2) and the lower panel (5) are rectangular, the length of the lower panel (5) is equal to that of the upper panel (2), and the width of the upper panel (2) is greater than that of the lower panel (5); The leg (6) comprises a support frame (10) and a support plate (9), the support frame (10) is fixedly connected to the lower surface of the lower panel (5), and a plurality of support plates (9) are uniformly fixed in the support frame (10) along the length direction. The support plate (9) at both ends of the support frame (10) is a right trapezoid, the support plate (9) between both ends is an isosceles trapezoid, and the space between two adjacent support plates (9) is an isosceles trapezoidal hollow part A (11); the support frame (10) is a rectangular frame, the length of the support frame (10) is equal to the length of the lower plate (5), and the outer side of the support frame (10) is coplanar with the edge of the lower plate (5); the support plate (9) is fixed to the inner side of the support frame (10), and the outer side of each support plate (9) is fixed with a support leg reinforcing iron (8); The lower plate (5) inside each support leg (6) is provided with an isosceles trapezoidal hollow part B (12) corresponding to the position of each hollow part A (11).

6. The transformer air cushion cart tray of claim 5, wherein: The support beam (1) is a square steel pipe, each support beam (1) is parallel to each other, and the length of the support beam (1) is twice the distance between the two support legs (6).

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