Topological optimization method applied to suspension arm, suspension arm, hoisting arm frame device and self-loading and unloading transport vehicle

Abstract

The invention relates to the technical field of operation machinery, and provides a topological optimization method applied to a suspension arm, the suspension arm, a hoisting arm frame device and a self-loading and self-unloading transport vehicle, and the method comprises the following steps: establishing an initial model of the suspension arm, dividing grids based on the initial model, and defining a design domain; applying constraint conditions to the initial model of the suspension arm in a corresponding design domain; determining a topological optimization method of the suspension arm according to the constraint conditions, and setting corresponding initial topological optimization parameters; based on the initial topological optimization parameters, sensitivity analysis and optimization iterative calculation are carried out on the topological optimization finite element model, and target topological optimization parameters are obtained; obtaining a model of the target suspension arm based on the target topological optimization parameters; and extracting the optimized density distribution for checking, and carrying out finite element analysis on the sealing distribution which does not meet the requirement again until a manufacturable geometric model is generated. On the premise that the mechanical property is guaranteed, the balance of light weight and high strength of the suspension arm can be achieved through topological optimization design.

Description

Technical Field

[0001] This invention relates to the field of construction machinery technology, and in particular to a topology optimization method for crane booms, crane booms, lifting boom devices, and self-loading and unloading transport vehicles. Background Technology

[0002] With the continued growth in demand for efficient loading and unloading in the logistics and transportation industry, side-loading self-loading transport vehicles, as a type of special vehicle that enables rapid assembly and disassembly of the cargo compartment and flexible cargo transfer, have been widely used in warehousing logistics, engineering construction, and other fields. The cargo compartment of a side-loading self-loading transport vehicle is assembled to the frame via a detachable structure. The frame is equipped with a lifting boom, which, through lifting and swinging movements, can lift the entire cargo compartment from the ground onto the frame or lift it from the frame to a designated location, thereby improving cargo transfer efficiency and expanding the operational range of traditional forklift loading and unloading.

[0003] As a core component of self-loading and unloading vehicles, the lifting boom accounts for a significant portion of the vehicle's weight and directly impacts its load-bearing capacity and energy consumption. However, existing technologies often suffer from overly conservative designs regarding boom rigidity, stability, and reliability, resulting in redundant mass in the boom structure. This means that the material stress under actual working loads is far below the allowable value, leading to a waste of raw materials such as steel. This increases manufacturing costs and limits the achievement of overall vehicle lightweighting goals. Summary of the Invention

[0004] This invention provides a topology optimization method for crane booms, a crane boom, a crane boom device, and a self-loading and unloading transport vehicle, to solve the above-mentioned technical defects in the prior art, and to achieve a balance between lightweight and high strength through structural optimization design while ensuring the rigidity and stability of the lifting.

[0005] A first aspect of the present invention provides a topology optimization method for a crane boom, comprising the following steps: An initial model of the boom is established, and a mesh is generated and a design domain is defined based on the initial model. The initial model of the boom includes side plates, surrounding plates, and reinforcing plates. Constraints are imposed on the initial model of the boom in the corresponding design domain; The topology optimization method for the boom is determined based on the constraints, and the corresponding initial topology optimization parameters are set. Based on the initial topology optimization parameters, sensitivity analysis and optimization iteration calculations are performed on the topology optimization finite element model to obtain the target topology optimization parameters; based on the target topology optimization parameters, the model of the target boom is obtained. The optimized density distribution is extracted and stress / deformation is checked. For sealing distributions that do not meet the requirements, finite element analysis is performed again until a manufacturable geometric model is generated.

[0006] According to the topology optimization method for crane booms provided by the present invention, the step of establishing an initial model of the crane boom and dividing the mesh and defining the design domain based on the initial model includes: Create a simplified multibody model of the crane and the self-loading transport vehicle in Adams; Run Adams dynamics simulation to obtain the attitude of the boom, stress distribution of the boom, deformation and load transfer path of key parts under extreme working conditions; Create a finite element model in the Hypermesh preprocessing software, and perform geometric modeling, mesh generation, and material property definition for the boom.

[0007] According to the topology optimization method for booms provided by the present invention, the step of applying constraints to the initial model of the boom in the corresponding design domain includes: Define the load case, design variables, response, optimization objective, and constraints.

[0008] According to the topology optimization method for a crane boom provided by the present invention, the step of determining the topology optimization method for the crane boom based on the constraints, and setting the corresponding initial topology optimization parameters, includes: Based on the previously defined constraints, the variable density method is used as the core topology optimization method, and the initial optimization parameters are set using finite element software.

[0009] According to the topology optimization method for crane booms provided by the present invention, the step of performing sensitivity analysis and optimization iteration calculation on the topology optimization finite element model based on initial topology optimization parameters to obtain target topology optimization parameters; and obtaining the target crane boom model based on the target topology optimization parameters, includes: Import the initial finite element model into OptiStruct, set the optimization type to topology optimization, the objective function to mass minimization, and the constraints to: maximum deformation ≤ 10 mm, maximum stress ≤ 431 MPa. OptiStruct iteratively updates the element density and gradually removes material from low-stress regions; Based on the density distribution optimized by OptiStruct, regions with element density > 0.3 are extracted as the final material distribution, and the initial topology is generated using CAD software (such as SolidWorks).

[0010] A second aspect of the present invention provides a boom designed based on the topology optimization method applied to booms according to any one of the claims, comprising: The first side plate has multiple first weight-reducing through holes spaced apart on it; The second side plate is spaced apart from and opposite to the first side plate. The second side plate is provided with a plurality of second weight-reducing holes at intervals. The positions of the plurality of second weight-reducing holes and the positions of the plurality of first weight-reducing through holes are arranged in a one-to-one correspondence. Multiple side panels are sequentially connected end to end between the first side panel and the second side panel, and are connected to each side panel to form a box-shaped structure; The reinforcing plate is located inside the cavity of the box-shaped structure.

[0011] According to the boom provided by the present invention, the first side plate and the second side plate are each divided into a first region, a second region and a third region connected in sequence; The first region is provided with a first hinge hole for connecting the swing arm, the second region is provided with a second hinge hole for connecting the hydraulic cylinder, and the third region is provided with a third hinge hole for connecting the lifting component.

[0012] According to the boom provided by the present invention, the bottoms of the first region, the second region, and the third region are flush. The height of the second region is greater than the height of the first region and the third region, respectively; the height of the first region and the third region gradually increases from the position away from the second region to the position where the second region is located.

[0013] A third aspect of the present invention provides a lifting boom device, comprising: Swing arm, suitable for mounting to chassis vehicles; The boom described in any one of the claims, wherein one end of the boom is hinged to the swing arm, and the other end of the boom is connected to the lifting component; A hydraulic drive system is connected to the swing arm and the boom respectively, and is adapted to drive the swing arm and the boom to swing respectively.

[0014] A fourth aspect of the present invention provides a self-loading and unloading transport vehicle, comprising: Chassis vehicle; And the aforementioned lifting boom device, which is symmetrically arranged at both ends of the chassis vehicle.

[0015] This invention addresses the lightweight and high-strength requirements of the boom for self-loading and unloading vehicles. With the core principle of reducing material redundancy and retaining key load-bearing areas, it optimizes the structural design through topology optimization technology while ensuring mechanical performance. This achieves a balance between lightweight and high strength, improving the economy and operational efficiency of self-loading and unloading vehicles while ensuring the safety and reliability of the boom.

[0016] Specifically, the optimized boom has a reduced total weight, resulting in significant weight reduction and directly lowering the self-loading and unloading vehicle's tare weight. This not only reduces material costs but also, according to the energy consumption formula for transport vehicles, lowers energy consumption per operation.

[0017] The boom provided by this invention achieves the goal of lightweighting the boom while ensuring structural strength and rigidity through the coordinated design of symmetrical weight-reducing holes and cross-hole reinforcing plates. At the same time, it reduces manufacturing costs by optimizing the processing technology and assembly process.

[0018] The lifting boom device and self-loading and unloading transport vehicle provided by the present invention, because they include the above-mentioned boom, possess all the advantages of the above-mentioned boom. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this invention 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 invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a flowchart of a topology optimization method for booms provided in an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the extreme working conditions of the topology optimization method for booms provided in the embodiments of the present invention.

[0022] Figure 3 This is a force diagram of the extreme working condition in Adams simulation of the topology optimization method applied to the boom provided in the embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the structure of the initial model established in the topology optimization method for booms provided in this embodiment of the invention.

[0024] Figure 5 This is a cell density diagram in the topology optimization method for booms provided in this embodiment of the invention.

[0025] Figure 6 It is a CAD model derived from the topology optimization method for crane booms provided in the embodiments of the present invention.

[0026] Figure 7 This is the topology structure designed by the topology optimization method for booms provided in this embodiment of the invention.

[0027] Figure 8 This is a finite element analysis diagram of the topology structure designed using the topology optimization method for booms, provided in an embodiment of the present invention.

[0028] Figure 9 This is a structural diagram of a traditional crane boom.

[0029] Figure 10 It is a simulation comparison of the deformation of traditional boom structures and topological structures.

[0030] Figure 11 This is a simulation comparison of the stress conditions of traditional boom structures and topological structures.

[0031] Figure 12 This is a schematic diagram of the boom structure provided in an embodiment of the present invention.

[0032] Figure 13 This is a front view of the boom provided in an embodiment of the present invention.

[0033] Figure 14 This is a structural schematic diagram of the self-loading and unloading transport vehicle provided in an embodiment of the present invention.

[0034] Figure 15 This is a side view of the self-loading and unloading transport vehicle provided in an embodiment of the present invention.

[0035] Figure label: 10. Crane boom; 11. First side plate; 111. First weight reduction hole; 12. Second side plate; 121. Second weight reduction hole; 13. Enclosure plate; 14. Reinforcing plate; 141. First sub-reinforcing plate; 142. Second sub-reinforcing plate; 15. First hinge hole; 16. Second hinge hole; 17. Third hinge hole; 20. Chassis vehicle; 30. Swing arm; 40. Outrigger. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0038] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0039] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0040] Figure 1 This is a flowchart of a topology optimization method for booms provided in an embodiment of the present invention.

[0041] See Figure 1 This invention provides a topology optimization method for a boom, which can be applied to self-loading and unloading transport vehicles and can also be extended to the optimization design of other working machinery structures (such as crane booms and aerial work platform booms).

[0042] The topology optimization method applied to the boom includes the following steps S100 to S500.

[0043] Step S100: Establish the initial model of the boom, and divide the mesh and define the design domain based on the initial model. The initial model of the boom includes side plates, side plates, and reinforcing plates.

[0044] It is understandable that when building the initial model and meshing, the initial model should be built first, and then the meshing and design domain definition should be carried out.

[0045] The initial model construction process includes the following steps: Based on the actual function of the crane boom of the self-loading and unloading transport vehicle (such as lifting 5-20 tons of goods), a 3D model of the boom is drawn using 3D software (such as SolidWorks). The boom includes side plates, perimeter plates, and reinforcing plates. The thickness of the side plates can be set to 10mm. The boom can be made of Q690 steel or Q345 steel. This embodiment of the invention uses Q690 steel as an example for illustrating the various components of the boom. The side plates are the left and right vertical main plates, which bear the main bending moment of the boom. The thickness of the perimeter plates can be set to 8mm. The perimeter plates are sealing plates arranged around the side plates, and the perimeter plates connect the side plates to form a closed box beam structure. The thickness of the reinforcing plates can be set to 12mm. The reinforcing plates are arranged in the middle of the side plates to prevent local buckling of the boom (such as side plate instability when lifting eccentric loads).

[0046] Pre-reserve installation interfaces on the 3D model of the boom, such as hinge holes for the boom, swing arm, and hydraulic system. These areas are defined as non-optimizable regions, and the material needs to be retained with a fixed density of 1.

[0047] The mesh generation and design domain definition process includes the following steps: Import the 3D model of the boom into finite element preprocessing software (such as Hypermesh), and discretize it using tetrahedral elements (CTETRA4) with an element size of 5mm. For key areas such as the edge of the reinforcing plate and the vicinity of the hinge hole, the element size is refined to 2mm.

[0048] Except for the internal area of ​​the box girder, excluding the mounting interface and reinforcing plate, i.e. the cavity between the side plate and the surrounding plate, which is an optimizable area (the material can be deleted or retained), the remaining area is a non-optimizable region (density constraint is 1).

[0049] Step S200: Apply constraints to the initial model of the boom in the corresponding design domain (simulating real working conditions), where the constraints include typical working conditions and boundary conditions.

[0050] Understandably, considering the actual operating scenarios of self-loading and unloading vehicles, multi-physics constraints are applied to cover all possible stress states. Typical operating conditions include the following scenarios: 1) Static load condition: Lifting the maximum load (20 tons of cargo), the load is applied to the end of the boom (3m from the hinge point), and the direction is vertically downward.

[0051] 2) Dynamic load condition: Considering the acceleration during lifting (e.g., take 0.6g, which is 60% of the gravitational acceleration), the dynamic load = 20 tons × (1 + 0.6) = 32 tons.

[0052] 3) Wind load condition: The wind speed during operation is 15m / s (corresponding to wind pressure of 0.15kN / m²), and the wind load acts on the side of the boom in a horizontal direction (perpendicular to the hoisting direction).

[0053] 4) Off-center loading condition: Simulates the offset of the center of gravity of the cargo (200mm away from the center line), generating a bending moment (M=20 tons × 0.2m=4 tons·m).

[0054] The boundary conditions include the following scenarios: The boom and the hinged lugs mounted on the chassis are constrained with three translational degrees of freedom in the X, Y, and Z directions (UX=UY=UZ=0), allowing only rotation about the Z-axis (RZ=0). The welded area of ​​the reinforcing plate and the side plate is bound together to ensure local stiffness continuity; the chassis connection point is constrained to limit translation in the X direction (UX=0) to simulate longitudinal vibration during vehicle movement.

[0055] Step S300: Determine the topology optimization method for the boom based on the constraints, and set the corresponding initial topology optimization parameters; Understandably, when choosing a topology optimization method, the Variable Density Method (SIMP) can be used based on the constraints. The element density variable ρe (0 ≤ ρe ≤ 1) represents the presence or absence of material (ρe = 1 for solid, ρe = 0 for empty). The objective function is to minimize flexibility (i.e., maximize structural stiffness), mathematically expressed as: minC(ρ) = u T K(ρ)u; Where C(ρ) represents the structural flexibility, and the smaller the value, the greater the stiffness; u: represents the node displacement vector; K(ρ): Represents the global stiffness matrix that depends on the element density ρ.

[0056] The element stiffness matrix can be expressed as: K e (ρ e )= ; ρ e : Represents the density variable of element e (0≤ρ) e ≤1); p: Represents the penalty factor (usually 2-3), used to suppress intermediate densities (such as ρ). e ≈0.5); : Represents the initial stiffness matrix when the element density is 1.

[0057] When setting the corresponding initial topology optimization parameters, for example: the material is Q690 steel, the elastic modulus E=206GPa, Poisson's ratio ν=0.3, and the allowable stress [σ]=431MPa. Convergence criteria: density change rate <0.3% / iteration step, or compliance change <0.8%. Manufacturing constraints: minimum element size 5mm (avoiding excessively thin wall thickness), minimum hole diameter 12mm (facilitating subsequent welding or assembly). Symmetry constraints: utilizing the left-right symmetry of the boom, only half of the model is optimized, reducing computational load.

[0058] Step S400: Based on the initial topology optimization parameters, perform sensitivity analysis and optimization iteration calculation on the topology optimization finite element model to obtain the target topology optimization parameters; based on the target topology optimization parameters, obtain the model of the target boom.

[0059] Understandably, the iterative optimization process includes finite element analysis, sensitivity calculation, and density correction. This is automatically executed through the topology optimization module of the finite element software, with the specific steps as follows (taking Hypermesh as an example): Initial finite element analysis: Calculate the stress and deformation of the initial model under static load conditions.

[0060] Sensitivity calculation: Based on the partial derivative of the objective function (compliance) with respect to the density of each element, the sensitive areas of the material are determined (high stress areas such as the middle of the side plate and near the reinforcing plate need to retain the material, while low stress areas such as the outer cavity of the side plate can be deleted).

[0061] Density correction: Delete elements with density < 0.2 (considered as invalid material), set the density of elements with density > 0.8 to 1 (retain solids), and perform linear interpolation in the intermediate density region (0.2-0.8); Mesh reconstruction: The corrected density field is reconstructed to avoid element distortion (e.g., re-meshing when the element aspect ratio is >5). Repeated iterations: Perform finite element analysis, sensitivity calculation and density correction again until convergence (approximately 12-15 iterations).

[0062] Step S500: Extract the optimized density distribution and perform stress / deformation verification. For sealing distributions that do not meet the requirements, perform finite element analysis again until a manufacturable geometric model is generated.

[0063] Understandably, the box girder's interior forms "X"-shaped intersecting stiffeners, and the hollow material on the outer side plates is removed. A new finite element analysis is then performed: The maximum stress is 339 MPa (still lower than the allowable stress of 431 MPa); the end deflection is 6 mm (40% lower than the initial model); and the weight is reduced by 28% (from an initial weight of 600 kg to an optimized weight of 432 kg).

[0064] The feasibility of manufacturing the crane boom has been adjusted as follows: Sharp corner treatment: After optimization, there is a sharp corner at the intersection of the "X" shaped ribs (stress concentration factor 1.8). The stress concentration is reduced by rounding the corner (radius 8mm) (the factor is reduced to 1.3). Thickening of thin-walled areas: Areas with a wall thickness of less than 6mm after local optimization (such as non-critical areas on the outer side of the side plate) are locally thickened to 8mm by density correction (to avoid deformation during processing). Geometric repair: Use drawing software (such as SolidWorks) to clean up the geometry, delete small holes (<12mm), merge redundant features, and generate a manufacturable 2D engineering drawing (annotating plate thickness, hole positions, and welding process, such as CO2 gas shielded welding for reinforcing plates and side plates).

[0065] The optimized structure, through adjustments such as rounded corners and local thickening, is fully compatible with existing manufacturing processes (such as laser cutting, stamping, and CO2 shielded welding). Actual processing verification shows that the welding deformation of the optimized boom is comparable to that of the traditional structure, requiring no additional tooling; the positional accuracy of the mounting interfaces (hinged lugs, hydraulic hinge holes) meets design requirements and can be directly assembled with the vehicle body.

[0066] It is understood that the embodiments of the present invention address the lightweight and high-strength requirements of the boom of a self-loading and unloading vehicle. With the core objective of reducing material redundancy and retaining key load-bearing areas, the structural design is optimized through topology optimization technology while ensuring mechanical performance, thereby achieving a balance between lightweight and high strength. This improves the economy and operational efficiency of the self-loading and unloading vehicle while ensuring the safety and reliability of the boom.

[0067] Specifically, the optimized boom has a reduced total weight, resulting in significant weight reduction and directly lowering the self-loading and unloading vehicle's tare weight. This not only reduces material costs but also, according to the energy consumption formula for transport vehicles, lowers energy consumption per operation.

[0068] Figure 2 This is a schematic diagram of the extreme working conditions of the topology optimization method for booms provided in the embodiments of the present invention. Figure 3 This is a force diagram of the extreme working condition in Adams simulation of the topology optimization method applied to the boom provided in the embodiment of the present invention. Figure 4 This is a schematic diagram of the structure of the initial model established in the topology optimization method for booms provided in this embodiment of the invention.

[0069] Furthermore, an initial model of the boom is established, and a mesh is generated and a design domain is defined based on the initial model. The initial model of the boom includes side plates, side panels, and reinforcing plates, including: Create a simplified multibody model of the crane and the self-loading transport vehicle in Adams; Run Adams dynamics simulation to obtain the attitude of the boom, stress distribution of the boom, deformation and load transfer path of key parts under extreme working conditions; Create a finite element model in the Hypermesh preprocessing software, and perform geometric modeling, mesh generation, and material property definition for the boom.

[0070] In other words, this embodiment of the invention addresses the design optimization needs of the boom by using a collaborative process of determining extreme working conditions through Adams multibody dynamics simulation and HyperMesh finite element preprocessing to accurately obtain the mechanical properties of the boom under the most severe working conditions, and to provide a high-quality finite element model for subsequent topology optimization or strength analysis.

[0071] Based on Adams simulation to determine the ultimate working condition, Adams (MSC Adams), as a multibody dynamics simulation software, is used to simulate the motion and forces of the boom during actual operation, focusing on determining the load and constraint conditions of the furthest working condition (ultimate working condition). The specific steps are as follows: like Figure 2 As shown, a simplified multibody model (model building) of the crane boom and self-loading transport vehicle is created in Adams, including: The boom body (simplified as a rigid body or a flexible body, depending on the simulation accuracy requirements); Body hinge point (define a rotary joint to simulate the rotation of the boom around the body). Cargo model (simplified as a concentrated mass block, connected to the end of the boom via force elements); Environmental loads (wind loads, inertial forces, etc., are applied through force elements or functions).

[0072] Definition of extreme working conditions: Based on the actual operating scenarios of self-loading and unloading vehicles, the "farthest working condition" is defined as the state where the boom extends horizontally to the maximum operating radius (e.g., 10m) and the maximum load is lifted (e.g., 20 tons). Under this condition, the boom bears the maximum bending moment and tensile force, which is the critical state of structural strength and stiffness.

[0073] Specific parameter settings: Load: End concentrated force = 20 tons × 9.8 m / s² = 196 kN (gravity) + 20 tons × 0.5g × 9.8 m / s² = 98 kN (dynamic load acceleration), total 294 kN; Constraints: The vehicle body hinge point restricts the X / Y / Z translational degrees of freedom (only rotation around the Z axis is allowed); Wind load: Based on the working environment wind speed of 15 m / s (wind pressure 0.15 kN / m²), it is horizontally loaded along the side of the boom (perpendicular to the lifting direction).

[0074] like Figure 3 As shown, Adams dynamics simulation was run to obtain the stress distribution, deformation, and load transfer path of key components (such as side plates and surround plates) of the boom under extreme conditions. For example, the simulation results show that the bending moment is the largest in the middle of the side plate, and stress concentration occurs at the connection between the surround plate and the side plate, providing key basis for the design domain definition of the subsequent finite element model.

[0075] HyperMesh is a professional finite element preprocessing software used to convert the initial model of a boom (side plates, side plates, stiffening plates) into a high-quality finite element model. The specific steps are as follows: like Figure 4 As shown, import the initial model of the boom (CAD format, such as STEP or IGES), which includes side plates (10mm thick), surrounding plates (8mm thick), reinforcing plates (12mm thick), and mounting interfaces (hinged lugs, hydraulic connection holes); remove small chamfers (<2mm), redundant holes (diameter <10mm), and small bosses (height <3mm) to avoid mesh distortion; merge the weld gaps (gap <0.5mm) between the side plates and surrounding plates to ensure geometric continuity.

[0076] Grid generation: The tetrahedral element (CETRA4) is used as the main element, while hexahedral elements (CETRA8) are used for key parts (such as the edge of the reinforcing plate and the hinge ear plate) to improve accuracy.

[0077] The global unit size is 5mm (balancing computational efficiency and accuracy), and the density in key areas (such as the area with the largest bending moment in the middle of the side plate and the connection between the enclosure and the side plate) is reduced to 2mm.

[0078] HyperMesh's "Mesh Quality Check" function ensures that the element aspect ratio is <5, warpage is <5°, and Jacobian matrix distortion is <0.7, thus avoiding calculation errors caused by poor mesh quality.

[0079] The boom is made of Q690 steel, and its material properties are defined in HyperMesh as follows: elastic modulus 206 GPa, Poisson's ratio 0.3, and density 7850 kg / m³. 3 Allowable stress 431 MPa (based on a safety factor of 1.6 for the material yield strength of 345 MPa).

[0080] Design domain definition (optimizable and non-optimizable regions): Based on Adams simulation results and engineering experience, the boom is divided into optimizable and non-optimizable regions.

[0081] Non-optimizable domain (materials must be retained): Mounting interface (hinged ear plate, hydraulic connection hole): thickness 12mm, area defined as density fixed at 1 (solid); reinforcing plate thickness 12mm, area welded to side plate (binding constraint) defined as non-optimizable; connection between enclosure and side plate (stress concentration area): 50mm wide area defined as non-optimizable (to avoid cracking).

[0082] Optimizable areas (material adjustable): the cavity area between the side plate and the enclosure plate (non-critical load-bearing area); the gap area between the reinforcing plates (no installation interface or low stress).

[0083] The embodiments of this invention, determined through Adams simulation, represent the farthest operating condition (maximum working radius + maximum load), realistically reflecting the most severe stress state of the boom in actual operation. Traditional empirical designs often underestimate the load under extreme conditions (e.g., considering only static loads), while this invention obtains key parameters such as end bending moment and side plate stress through dynamic simulation, avoiding insufficient structural strength or redundant design due to misjudgment of operating conditions. Subsequent finite element verification showed that the maximum stress of the optimized boom under extreme conditions is 339 MPa (lower than the allowable stress of 431 MPa), meeting safety requirements.

[0084] HyperMesh's fine mesh generation and material definition ensure the accuracy of the finite element model and avoid stress calculation errors caused by mesh distortion. The load transfer path of the boom (load → end → side plate → enclosure plate → reinforcing plate → vehicle body) was clearly defined through Adams simulation. This path was accurately simulated in the finite element model through constraint and contact settings (such as the binding constraint between the side plate and the enclosure plate), ensuring that the stress distribution is consistent with reality.

[0085] By defining optimizable and non-optimizable regions, precise weight reduction was achieved. Material in optimizable regions (such as side panel cavities) was removed or thinned (thickness reduced from 10mm to 8mm), resulting in weight reduction. Material in critical non-optimizable regions (such as reinforcing plates and mounting interfaces) was retained and locally thickened (reinforcing plate thickness increased from 12mm to 15mm), avoiding localized strength deficiencies caused by weight reduction.

[0086] Traditional crane design requires multiple trials and tests for verification. However, this invention achieves rapid iteration of "virtual verification → model optimization → physical manufacturing" through the collaboration of Adams simulation and HyperMesh preprocessing. This can shorten the design cycle, reduce the number of trials, and lower R&D costs.

[0087] Furthermore, constraints are imposed on the boom within the corresponding design domain, including: 1) Define the load case (maximum force 1.52E5N). The load case definition must cover all possible stress states of the boom during actual operation, with a focus on the maximum stress case (corresponding to the key load-bearing scenario in the design domain). Specific implementation steps are as follows: Analyzing the sources of load: The main loads on the boom include lifting load (static load), lifting acceleration (dynamic load), wind load, and eccentric load. According to the operating specifications of self-loading and unloading transport vehicles, the maximum stress condition is defined as: Static load: The maximum load to be lifted (e.g., 20 tons of cargo), with the load acting at the end of the boom (L=3m from the hinge point), in a vertically downward direction; Dynamic load: Considering the acceleration during lifting (take 0.5g), dynamic load = 20 tons × (1 + 0.5) = 30 tons (30 × 9.8kN = 294kN); Wind load: The wind speed in the working environment is 15m / s (wind pressure 0.15kN / m²). The wind load acts on the side of the boom in a horizontal direction (perpendicular to the lifting direction). The equivalent concentrated force is 0.15kN / m² × boom side area (assuming side area = 2m²) = 0.3kN. Off-center loading: Simulates the offset of the center of gravity of the cargo (d=0.2m from the center line), generating a bending moment M=20 tons × 0.2m=4 tons·m (40kN·m).

[0088] Load Combination and Application: In finite element software (such as Hypermesh), apply the above loads to the boom end in the most stringent combination (static load + dynamic load + wind load + eccentric load). Specific Operation: A concentrated force (294kN + 0.3kN = 294.3kN) is applied at the end node of the boom. An inertial force (-20 tons × 0.5g = -98kN, simulating acceleration in the opposite direction) is applied to the center of mass of the boom. Apply wind load (0.3kN, horizontal direction) to the side of the boom. Apply a bending moment (40 kN·m) at the center of gravity of the cargo.

[0089] 2) Define design variables (selecting the element regions for topology optimization of the boom). The selection of design variables must be based on the structural stress distribution and functional requirements, clearly defining the optimizable regions (where materials can be removed) and the non-optimizable regions (where materials must be retained). The specific implementation steps are as follows: Initial model analysis: First, the stress distribution contour map of the boom is obtained through finite element analysis (such as static analysis). Results show: The stress is highest in the middle of the side plate, which is the main load-bearing area; stress concentration at the connection between the side plate and the enclosure plate should be retained; the stress in the area covered by the reinforcing plate is lower and can be optimized; stress dispersion in the installation interface (hinged lug, hydraulic hole) area should be retained.

[0090] Design domain division: Based on stress distribution, the boom is divided into optimizable and non-optimizable domains: Non-optimizable domain (fixed density of 1): connection points, reinforcement plate coverage area, and installation interfaces. Optimizable domain (adjustable density): the cavity area between the side plate and the surrounding plate, where stress is lower and material redundancy is higher.

[0091] 3) Define the responses (two responses: total boom mass and boom deformation displacement). The responses are the input and output metrics for optimization, and the quantification objectives must be clearly defined. The specific implementation is as follows: Total mass response: The mass of each element of the boom is calculated and summed using the material properties defined by the finite element software (e.g., the density of Q690 steel is 7850 kg / m³), resulting in the total mass M. This response serves as the "minimization objective" for optimization.

[0092] Deformation and displacement response: Define a displacement monitoring point at the end of the boom (load application point) and calculate its total deformation delta in the vertical direction (Y-axis). This response serves as the "constraint" for optimization.

[0093] 4) Define the optimization objective (minimizing the total mass of the boom is the objective). The optimization objective is explicitly quantified using a mathematical expression, usually a minimization function: minf(ρ)=∑e e ρ0V e ; Where: f(ρ) is the objective function (total mass minimization); e is the density variable of the e-th unit; ρ0 is the actual density of the material; V e Let e ​​be the volume of the e-th unit; N is the sum of the units in the model.

[0094] 5) Define constraints (overall boom deformation less than 10mm). Constraint conditions are implemented using the "Constraint Setting" function of the finite element software. Specific steps: Displacement constraints are applied to the monitoring point (load application point) at the end of the boom; deformation in other directions (X / Z axis) is unconstrained; implicit constraint: density of all elements (to avoid excessive material removal leading to local failure).

[0095] This invention, through topology optimization design, removes a large amount of material from the optimizable domain, reducing the total mass of a single boom by 70 kg. The material in the cavity area between the side plate and the enclosure plate is essentially removed, leaving only a small amount of material in the stress concentration area, achieving the goal of lightweighting and reducing structural weight.

[0096] The optimized boom's vertical deformation at the end under maximum stress conditions meets the design constraints. The deformation mainly originates from material removal within the optimizable domain, but due to the rigid support of the reinforcing plate and mounting interface, the overall stiffness is not significantly reduced. This not only satisfies the deformation constraints but also ensures operational accuracy.

[0097] The optimized boom has a maximum stress of 339 MPa (lower than the allowable stress of 431 MPa for Q690 steel), and the stress concentration area is controlled by retaining the material (density=1). Fatigue life analysis (based on SN curves) shows that the optimized structure has a 1.5-fold longer fatigue life (stress amplitude reduced by 20%), a reasonable stress distribution, meets the requirements for long-term operation, and is strong, safe, and reliable.

[0098] After optimization, the sharp corners at the intersection of the "X" shaped ribs are transitioned with rounded corners to reduce the stress concentration factor; after local optimization, areas with a wall thickness of <6mm (such as non-critical areas on the outer side of the side plate) are locally thickened to 8mm through density correction (to avoid processing deformation).

[0099] Furthermore, the topology optimization method for the boom is determined based on the constraints, and the corresponding initial topology optimization parameters are set, including: This application addresses the lightweight design requirements of crane booms. Based on pre-defined constraints (maximum stress, deformation limits, and mass minimization objectives), it employs the Variable Density Method (SIMP) as the core topology optimization method, combined with finite element software (such as Hypermesh) to set initial optimization parameters, achieving a balance between precise weight reduction and performance assurance. The specific implementation steps and effect analysis are as follows: Topology optimization methods need to balance computational efficiency, structural complexity adaptability, and engineering practicality. Considering the actual requirements of the boom (box girder structure, multiple load conditions, and manufacturing feasibility), the variable density method (SIMP, Solid Isotropic Material Penalization) was ultimately chosen for the following reasons: SIMP directly represents the presence or absence of material through element density, and its objective function is to minimize flexibility (i.e. maximize structural stiffness). Its mathematical form is easy to implement in finite element software.

[0100] SIMP can handle complex geometries such as cavities and reinforcing plates inside box girders without requiring prior assumptions about material distribution, making it suitable for multi-area optimization needs of booms.

[0101] SIMP's penalty factor (p) can suppress intermediate density (avoiding "gray area" materials), and the resulting optimized structure is close to the actual manufacturable hollow structure, reducing the amount of post-processing work.

[0102] 2. Set initial topology optimization parameters Parameter settings must be based on the boom's material properties, operating constraints, and design objectives. Specific parameters are as follows (using the hypermesh OptiStruct module as an example):

[0103] In practice, import the initial finite element model of the boom (which has been meshed and material properties defined) and ensure that the optimizable domain (side plate cavity) and the non-optimizable domain (installation interface, reinforcing plate) have been marked by the Design Variable function (the density of the optimizable domain can vary freely, while the density of the non-optimizable domain is fixed at 1).

[0104] Optimize target and constraint settings: Objective function: Minimize the total mass; Constraints: Maximum deformation displacement ≤ 10mm (displacement constraint is applied at the monitoring point at the end of the boom); maximum stress ≤ 431MPa (Von Mises stress is limited by the “Stress Constraint” function); lower limit of element density = 0.3 (to avoid local failure caused by excessive material removal).

[0105] In the “Topology Optimization” module, enter the above parameters (material properties, penalty factor, convergence criterion, etc.) and define the design variables (the element set of the optimizable domain).

[0106] Initial solution and parameter calibration: Run the initial optimization iteration (about 5-8 times) and observe the results: If the deformation exceeds 10mm, check whether the constraints are missing (such as wind load not being fully applied); if the stress exceeds 431MPa, adjust the range of the non-optimizable domain (expand the coverage area of ​​the reinforcing plate); if the mass reduction after optimization is insufficient (<20%), increase the penalty factor p (e.g., from 3 to 3.5) to suppress ineffective materials.

[0107] Final convergence and result extraction: When the density change rate is <0.3% and the compliance change is <0.5%, the optimization convergence is achieved, and the optimized density distribution cloud map is extracted (showing the areas where the material is retained and removed).

[0108] Traditional prototyping methods require multiple trials, resulting in high costs. However, this invention, through topology optimization and virtual verification via parameter calibration, allows for design completion in a single trial, shortening the development cycle and reducing costs. While ensuring the safety performance of the boom, it significantly reduces structural weight, improving the economy and operational efficiency of the self-loading and unloading transport vehicle.

[0109] Figure 5 This is a cell density diagram in the topology optimization method for booms provided in this embodiment of the invention. Figure 6 It is a CAD model derived from the topology optimization method for crane booms provided in the embodiments of the present invention. Figure 7 This is the topology structure designed by the topology optimization method for booms provided in this embodiment of the invention.

[0110] Furthermore, based on the initial topology optimization parameters, sensitivity analysis and iterative optimization calculations are performed on the topology optimization finite element model to obtain the target topology optimization parameters; based on the target topology optimization parameters, the model of the target boom is obtained, including: Calculate using OptiStruct and post-process the results in Hyperview to view the element density map, such as... Figure 5 As shown, the results are analyzed to determine whether the requirements are met. If not, design variables, response parameters, etc., need to be adjusted. If the requirements are met, CAD data is output, such as... Figure 6 As shown.

[0111] Understandably, this stage uses initial topological parameters (such as penalty factor p=3, convergence criterion = density change rate < 0.3%) as a basis, and obtains the target topological parameters through OptiStruct calculation. The specific steps are as follows: Import the initial finite element model (including optimizable and non-optimizable domains, load cases, and constraints) into OptiStruct. Set the optimization type to "Topology Optimization," the objective function to minimize mass, and the constraints to maximum deformation ≤ 10 mm and maximum stress ≤ 431 MPa. After starting the calculation, OptiStruct iteratively updates the element density (\rho_e) and gradually removes material from low-stress regions.

[0112] After the calculation is completed, use HyperView to view the result file (.fem). Focus on analyzing the boom element density map. Boom: The color gradient represents the element density (red→yellow→blue corresponds to ρ_e=1→0.5→0). The blue area is the material that is recommended to be removed, and the red area is the key load-bearing area that needs to be retained.

[0113] Confirm whether the vertical deformation at the end of the boom is ≤10mm by using the boom deformation cloud diagram; check whether the maximum stress of the boom is ≤431MPa (Von Mises stress) by using the boom stress cloud diagram.

[0114] If the density map shows that the cavity outside the side plate (non-critical area) still has a high density (\rho_e>0.7), it indicates that the material in this area is redundant and the range of optimizable domain can be expanded; if the stress cloud map shows that the stress at the connection between the enclosure and the side plate exceeds the limit (σ>431MPa), then this area needs to be defined as a non-optimizable domain (density fixed at 1).

[0115] The boom design is based on the CAD topology optimization structure. Considering the boom's manufacturability, the main body adopts a sheet metal structure, and weight-reducing holes are set in the optimization area, resulting in a boom topology structure that is easy to process and weld, suitable for engineering applications. Figure 7 As shown.

[0116] Understandably, based on the density distribution optimized by OptiStruct, regions with element densities > 0.3 are extracted as the final material distribution, and the initial topology is generated using CAD software (such as SolidWorks). To adapt to engineering processing (sheet metal forming, welding), the following adjustments are required: The main body of the boom is made of sheet metal (8-12mm thick), using bending and stamping processes to replace complex casting, reducing costs and improving production efficiency. Key design principles: The optimized area (originally optimizable region) is designed as a regular weight-reducing groove (such as rectangular or trapezoidal), avoiding sharp angles (minimum fillet radius = 8mm), facilitating stamping; the reinforcing plate and side plate use lap or butt welds (avoiding stress concentration in fillet welds), with weld spacing ≥50mm to ensure welding quality.

[0117] Weight-reducing holes (12-15mm in diameter) should be installed in the optimized area (low-stress zone) with a spacing of ≥20mm (to avoid local instability). The location of the weight-reducing holes should avoid the principal stress flow lines (determined by stress cloud diagram) and should be preferentially arranged in non-critical areas at the connection between the side plate and the surrounding plate.

[0118] Figure 8 This is a finite element analysis diagram of the topology structure designed using the topology optimization method for booms, provided in an embodiment of the present invention.

[0119] See Figure 8 To ensure that the optimized structure meets the usage requirements, its stiffness and strength performance needs to be verified through finite element analysis. The specific steps are as follows: Import the optimized CAD model into finite element software (such as Hypermesh), re-mesh (5mm element size, 2mm in critical areas), define material properties (Q690 steel, E=206 GPa, nu=0.3), and apply loads consistent with the initial working conditions (maximum force 1.52E5N, dynamic load, wind load, etc.).

[0120] Analysis of the boom stress cloud diagram shows that the maximum Von Mises stress of the boom is 339 MPa (≤ allowable stress 431 MPa), which is basically the same as the original structure, with no local stress concentration; the vertical deformation at the end of the boom meets the constraints.

[0121] By calculating the first natural frequency (12Hz in the original structure → 14.6Hz after optimization), the stiffness was increased by 21.3% (stiffness is proportional to the square of the natural frequency); the critical buckling load (Euler load) was 1.15 times that of the original structure (the optimized structure is less prone to local buckling). The stress and displacement contour maps of the new structure were obtained. After topology optimization, the boom strength was basically the same, but the stiffness was increased by 21.3%, resulting in better overall stiffness.

[0122] The optimized boom has a total mass reduction of 70 kg, primarily due to material removal from the optimizable domain (side plate cavity). The first natural frequency has increased from 12 Hz to 14.6 Hz (stiffness increase of 21.3%), effectively avoiding the dominant vibration frequency during vehicle operation and preventing fatigue damage caused by resonance. The maximum stress is 339 MPa (≤431 MPa), meeting the safety requirements for long-term operation.

[0123] Figure 9 This is a structural diagram of a traditional crane boom. Figure 10 It is a simulation comparison of the deformation of traditional boom structures and topological structures. Figure 11 This is a simulation comparison of the stress conditions of traditional boom structures and topological structures.

[0124] See Figures 9 to 11 The optimized area design features regular weight-reducing grooves (rectangular / trapezoidal) with an 8mm rounded corner radius, allowing for direct stamping (single-process cost < 50 RMB), replacing traditional casting (single-process cost > 200 RMB). Weight-reducing holes can be mass-produced using a drilling machine without complex tools; the reinforcing plate and side plate use lap welds, reducing welding time by 25% and lowering labor and energy costs.

[0125] In addition to the initial maximum stress condition, additional verification was conducted under conditions such as off-center loading (cargo center of gravity shifted by 200mm) and wind load (wind speed 20m / s). Results showed that the maximum stress was <431MPa and the deformation <10mm. Based on the SN curve (Q690 steel fatigue limit ≈180MPa), the optimized structure's fatigue life is 1.8 times that of the original structure (stress amplitude reduced by 25%), meeting the requirements of a self-loading and unloading transport vehicle operating 10 times per day with a 5-year lifespan. A prototype was manufactured, and the measured end deformation was 8.1mm (<2% error compared to simulation), and the first-order frequency was 14.5Hz (<0.7% error compared to simulation), verifying the accuracy of the simulation model.

[0126] Therefore, the optimized boom reduces weight by 35%, increases stiffness by 21.3%, maintains stable strength, and reduces manufacturing costs by 40% (saving on materials and processing costs).

[0127] Figure 12 This is a schematic diagram of the boom structure provided in an embodiment of the present invention.

[0128] See Figure 12 The present invention also provides a boom 10 designed based on a topology optimization method applied to the boom 10, including a first side plate 11, a second side plate 12, a plurality of surrounding plates 13 and a reinforcing plate 14.

[0129] The first side plate 11 is provided with a plurality of first weight-reducing through holes at intervals; the second side plate 12 is provided at intervals and opposite to the first side plate 11, and the second side plate 12 is provided with a plurality of second weight-reducing holes 121 at intervals, the positions of the plurality of second weight-reducing holes 121 and the positions of the plurality of first weight-reducing through holes are provided one-to-one; a plurality of surrounding plates 13 are sequentially connected end to end between the first side plate 11 and the second side plate 12, and are connected with each side plate to form a box-shaped structure; the reinforcing plate 14 is provided in the cavity of the box-shaped structure.

[0130] In other words, the boom 10 provided in this embodiment of the invention adopts a box-beam symmetrical structure, consisting of four parts: a first side plate 11, a second side plate 12, a surrounding plate 13, and a reinforcing plate 14. The core design parameters are as follows (taking a self-loading and unloading transport vehicle that can lift 20 tons of goods as an example): The materials of the first side plate 11 and the second side plate 12 can be Q690 steel or Q345 steel. The first weight-reducing through holes are spaced apart on the first side plate 11. The hole shape is rectangular (length × width = 80mm × 40mm), the hole spacing S = 150mm (center distance), and the distance between the hole edge and the upper and lower edges of the side plate is ≥ 50mm (to avoid stress concentration). The second weight-reducing hole 121 is on the second side plate 12 and corresponds one-to-one with the first weight-reducing through holes (the hole shape, size, and position are completely symmetrical) to ensure balanced weight reduction on both sides.

[0131] The side panels are cut using laser cutting (accuracy ±0.5mm). The first weight-reducing through hole is punched out (die cutting, no burrs on the hole edge). Then the edge of the side panel is processed by a bending machine (bending radius R=10mm to avoid stress concentration at sharp angles).

[0132] The material of the enclosure plate 13 can be Q690 steel, and there can be 6 enclosure plates 13 connected end to end to form a ring frame; each enclosure plate 13 is welded to the first side plate 11 and the second side plate 12 on both sides respectively, and the weld can be a fillet weld to form a closed box section. After the enclosure plate 13 is cut from steel plate, the edges are ground flat (to remove burrs) and a welding bevel is reserved (bevel angle 30°, depth 2mm).

[0133] The reinforcing plate 14 is also made of Q690 steel (12mm thick) and is arranged in an "X" shape. The reinforcing plate 14 is cut by laser cutting and the edges are rounded (R=5mm) to avoid stress concentration when welding with the side plate.

[0134] During assembly, the boom 10 is assembled with the six side panels 13 in sequence with the first side panel 11 and the second side panel 12 (using positioning fixtures to ensure symmetry), and the fillet welds are welded using CO2 gas shielded welding (current 180A, voltage 25V, welding speed 150mm / min).

[0135] After the side plate and the surrounding plate 13 are welded, the reinforcing plate 14 is placed between the first weight reduction hole 111 and the second weight reduction hole 121, and positioned by spot welding (weld spacing 20mm), and then fully welded (weld leg height h=8mm).

[0136] Compared to the traditional boom 10, the boom 10 provided in this embodiment of the invention has a reduced weight of the side plate. The overall rigidity of the side plate is enhanced by the reinforcing plate 14, reducing end deformation and distributing stress evenly to the hole wall and the area of ​​the reinforcing plate 14, reducing the maximum stress to 339 MPa (below the allowable stress).

[0137] This invention, through the coordinated design of symmetrical weight-reducing holes and cross-hole reinforcing plates 14, achieves the goal of lightweighting the boom 10 while ensuring structural strength and rigidity. Simultaneously, by optimizing the processing technology and assembly flow, manufacturing costs are reduced. This structure has broad application prospects in self-loading and unloading transport vehicles, cranes, and other operating machinery.

[0138] Figure 13 This is a front view of the boom 10 provided in an embodiment of the present invention.

[0139] See Figure 13 In some embodiments of the present invention, the first side plate 11 and the second side plate 12 are each divided into a first region, a second region and a third region connected in sequence. The first region is provided with a first hinge hole 15 for connecting the swing arm 30, the second region is provided with a second hinge hole 16 for connecting the hydraulic cylinder, and the third region is provided with a third hinge hole 17 for connecting the hoisting component.

[0140] Essentially, the first side plate 11 and the second side plate 12 are symmetrical structures (like the left and right side plates of the boom 10), together forming the main frame of the boom 10. Each side plate is divided into three continuous regions along its length (or the direction of force): First region: near one end of the side plate (e.g., the root), it has a first hinge hole 15 (circular or oblong), used for hinged connection with the swing arm 30 (or the previous boom segment). Second region: located in the middle of the side plate, it has a second hinge hole 16 (usually an oblong hole, allowing for slight displacement of the hydraulic cylinder piston rod during extension and retraction), used for connecting a hydraulic cylinder (e.g., a lifting cylinder or a swing cylinder). Third region: near the other end of the side plate (e.g., the free end), it has a third hinge hole 17 (a dedicated hole for connecting to lifting components, possibly with a locating pin groove), used for installing lifting components (e.g., hooks, grippers).

[0141] The first hinge hole 15 is connected to the lug of the swing arm 30 via a pin, allowing the swing arm 30 to swing around the pin (such as the luffing action of the boom 10). A copper sleeve or a spherical bearing can be installed between the pin and the hinge hole to reduce friction and wear. The second hinge hole 16 is hinged to the piston rod end of the hydraulic cylinder (the piston rod end is a ball joint or a lug with a spherical bearing). The elongated hole design allows the hydraulic cylinder to compensate for minor deformations or installation errors of the side plate during extension and retraction, avoiding jamming. The other end of the hydraulic cylinder is usually hinged to the chassis 20 or the other side plate, driving the side plate to swing or lift. The third hinge hole 17 is fixed to the lifting component (such as a hook beam) via bolts or a pin. The center of gravity of the lifting component must match the line of action of the force of the second hinge hole 16 to avoid eccentric loading on the side plate.

[0142] Furthermore, the bottoms of the first, second, and third regions are aligned, with the height of the second region being greater than that of the first and third regions, respectively. The heights of both the first and third regions gradually increase from a position further away from the second region towards its location.

[0143] This means that, from both ends of the side plate (away from the second region) towards the center of the second region, the height of the first and third regions gradually increases. That is, the height of the first region near the root is relatively low, and the height gradually increases as it transitions to the second region; the height of the third region also gradually increases as it transitions from the free end to the second region. The bottom of all regions (the reference surface connected to the base plate) remains flush.

[0144] In some embodiments of the present invention, the weight reduction hole is located away from the first hinge hole 15, the second hinge hole 16 and the third hinge hole 17, and the shape of the weight reduction hole includes, but is not limited to, a triangle, a quadrilateral or a pentagon.

[0145] It is understood that, through the partitioned design and height gradient features of the side plates, the embodiments of the present invention optimize stress distribution, connection reliability and manufacturing process while ensuring the strength of key stress areas.

[0146] Specifically, the second region, as the core load-bearing area of ​​the hydraulic cylinder connection (bearing bending moment and shear force), increases local stiffness by increasing its height, avoiding plastic deformation or cracking caused by stress concentration. The height of the first and third regions gradually increases from the edge to the second region, making the stress distribution of the side plates more uniform. They mainly bear smaller bending moments (such as the self-weight of the swing arm 30 or the eccentric load of the lifting components), while the high-height central region bears the main load, which conforms to the principle of equal strength design and reduces material redundancy.

[0147] Continue reading Figure 12 In some embodiments of the present invention, the reinforcing plate 14 includes a first sub-reinforcing plate 14114 and a second sub-reinforcing plate 14214, which are connected to each other and are arranged at an angle to each other to form an "X" shaped structure.

[0148] Figure 14 This is a structural schematic diagram of the self-loading and unloading transport vehicle provided in an embodiment of the present invention. Figure 15 This is a side view of the self-loading and unloading transport vehicle provided in an embodiment of the present invention.

[0149] See Figure 14 and Figure 15 This invention provides a lifting boom device, which includes a swing arm 30, a boom 10, and a hydraulic system. The swing arm 30 is adapted to be installed on a chassis vehicle 20. One end of the boom 10 is hinged to the swing arm 30, and the other end of the boom 10 is connected to a lifting component. The hydraulic drive system is connected to the swing arm 30 and the boom 10 respectively, and is adapted to drive the swing arm 30 and the boom 10 to swing.

[0150] The lifting boom device provided in this embodiment of the invention, because it includes the aforementioned boom 10, possesses all the advantages described above.

[0151] Continue reading Figure 14 and Figure 15 The present invention also provides a self-loading and unloading transport vehicle, which includes a chassis 20, a swing arm 30, outriggers 40 and a boom 10 of any one of the above.

[0152] The chassis 20 serves as the basic platform for the entire vehicle, supporting the weight of the swing arm 30, outriggers 40, and boom 10. It achieves its transportation function through a traveling mechanism. The chassis 20 typically employs a wheeled or tracked traveling mechanism (such as a heavy-duty truck chassis) with sufficient load-bearing capacity to meet the combined weight requirements of the boom 10, the cargo, and the chassis itself. The chassis 20 has pre-installed hinge seats for the swing arm 30 (usually a lug structure) and outriggers 40. The outrigger 40 hinge seats are located near the hinge point of the swing arm 30 and are used to connect the outriggers 40.

[0153] The swing arm 30 is a box girder or truss structure. One end of the swing arm 30 is connected to the swing arm 30 hinge seat of the chassis vehicle 20 through the first hinge shaft (allowing it to swing around a horizontal axis). The other end of the swing arm 30 is provided with a boom 10 hinge seat (for connecting the boom 10). A hydraulic cylinder mounting position (such as an ear plate or mounting plate) is reserved in the middle or root of the swing arm 30 for fixing the hydraulic cylinder of the swing arm 30.

[0154] One end of the hydraulic cylinder of the swing arm 30 is hinged to the chassis 20 frame (fixed point), and the other end is hinged to the middle section of the swing arm 30 (such as near the root). When the cylinder extends or retracts, it drives the swing arm 30 to swing up and down around the hinge axis of the chassis 20 through pushing and pulling action. The swing function of the swing arm 30 can lift the boom 10 from the transport state (horizontally stored above the chassis 20) to the working state (vertically or tilted towards the loading and unloading target), or adjust the horizontal coverage range of the boom 10.

[0155] The boom 10 is a fixed box-girder structure. The second hinge hole 16 in the middle of the boom 10 is connected to the piston rod end of the boom 10 hydraulic cylinder, and the first hinge hole 15 at the root of the boom 10 is connected to the boom 10 hinge seat at the top of the swing arm 30, allowing it to rotate around a horizontal axis. One end of the boom 10 hydraulic cylinder is hinged to the root of the swing arm 30, and the other end is connected to the second hinge hole 16 of the boom 10 via a pin. When the hydraulic cylinder extends or retracts, it drives the boom 10 to rotate around its hinge axis with the swing arm 30, thereby lifting or lowering the boom 10.

[0156] The outrigger 40 is a retractable hydraulic cylinder structure (or a linkage-type mechanical structure). A foot plate is installed at the lower end of the outrigger 40 to increase the contact area and prevent sinking. The middle part of the outrigger 40 is connected to the outrigger 40 hinge seat of the chassis vehicle 20, allowing the outrigger 40 to swing around a vertical or horizontal axis. When the piston rod of the outrigger 40 cylinder extends, it pushes the outrigger 40 downwards, and the foot plate contacts the ground, preventing the chassis vehicle 20 from tipping over. When the piston rod of the outrigger 40 cylinder retracts, the outrigger 40 returns to the chassis vehicle 20, reducing the overall width of the vehicle.

[0157] The operating procedure for self-loading and unloading transport vehicles is as follows: Transportation status: The swing arm 30 retracts with its hydraulic cylinder, and is horizontally stored above the chassis 20. The boom 10 retracts with its hydraulic cylinder, and is retracted and fixed to the top of the swing arm 30. The outriggers 40 retract with their hydraulic cylinders, and are pulled back to the chassis 20. The entire vehicle can then be transported to the work site via the chassis 20's walking mechanism. Upon arrival at the work site, the outriggers 40 are activated, pushing them downwards to extend, with the foot plates contacting the ground to ensure operational stability.

[0158] Operating status: Activate the hydraulic cylinder of boom 30 to swing boom 30 upward from the transport position to the operating angle, aligning the top of boom 10 with the goods to be loaded / unloaded (such as cargo boxes, pallets, or containers). Activate the hydraulic cylinder of boom 10 to rotate boom 10 around its hinge axis with boom 30, lowering the lifting device (such as a hook or grabber) to the goods position and completing the hooking; then reverse the operation of the hydraulic cylinder of boom 10 to lift the goods to the target height. Through the coordinated action of the hydraulic cylinders of boom 10 and boom 30, the goods are placed in the target position; then reverse the operation of each cylinder to retract boom 10 and boom 30, retract the outriggers 40, and return to the transport state, completing one self-loading / unloading cycle.

[0159] It is understood that, in this embodiment of the invention, the hinged connection between the swing arm 30 and the boom 10, along with the automated drive of the hydraulic cylinder, eliminates the need for manual assistance in hooking and moving goods, thus reducing labor intensity. The outriggers 40, the ground, and the chassis 20 form a stable triangular support structure, preventing the entire vehicle from tipping over due to uneven loading of the boom 10. The hydraulic system (cylinders and pipelines) is centrally located under the chassis 20 frame, providing ample maintenance space and facilitating troubleshooting and repair. If the operating range needs to be upgraded (e.g., increasing the length of the boom 10), only the boom 10 needs to be replaced, without modifying the entire vehicle structure, demonstrating strong scalability. It is suitable for scenarios such as logistics warehousing and construction site loading and unloading, improving loading and unloading efficiency and operational safety.

[0160] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A topology optimization method applied to crane booms, characterized in that, Includes the following steps: An initial model of the boom is established, and a mesh is generated and a design domain is defined based on the initial model. The initial model of the boom includes side plates, surrounding plates, and reinforcing plates. Constraints are imposed on the initial model of the boom in the corresponding design domain; The topology optimization method for the boom is determined based on the constraints, and the corresponding initial topology optimization parameters are set. Based on the initial topology optimization parameters, sensitivity analysis and optimization iteration calculations are performed on the topology optimization finite element model to obtain the target topology optimization parameters; based on the target topology optimization parameters, the model of the target boom is obtained. The optimized density distribution is extracted and stress / deformation is checked. For sealing distributions that do not meet the requirements, finite element analysis is performed again until a manufacturable geometric model is generated.

2. The topology optimization method for crane booms according to claim 1, characterized in that, The process of establishing an initial model of the boom, and meshing and defining the design domain based on the initial model, includes: Create a simplified multibody model of the crane and the self-loading transport vehicle in Adams; Run Adams dynamics simulation to obtain the attitude of the boom, stress distribution of the boom, deformation and load transfer path of key parts under extreme working conditions; Create a finite element model in the Hypermesh preprocessing software, and perform geometric modeling, mesh generation, and material property definition for the boom.

3. The topology optimization method applied to a crane boom according to claim 1, characterized in that, The imposition of constraints on the initial model of the boom in the corresponding design domain includes: Define the load case, design variables, response, optimization objective, and constraints.

4. The topology optimization method applied to a crane boom according to claim 1, characterized in that, The step of determining the topology optimization method for the boom based on the constraints, and setting the corresponding initial topology optimization parameters, includes: Based on the previously defined constraints, the variable density method is used as the core topology optimization method, and the initial optimization parameters are set using finite element software.

5. The topology optimization method applied to a crane boom according to claim 1, characterized in that, Based on the initial topology optimization parameters, sensitivity analysis and optimization iteration calculations are performed on the topology optimization finite element model to obtain the target topology optimization parameters. Based on the target topology optimization parameters, the model of the target boom is obtained, including: Import the initial finite element model into OptiStruct, set the optimization type to topology optimization, the objective function to mass minimization, and the constraints to: maximum deformation ≤ 10 mm, maximum stress ≤ 431 MPa. OptiStruct iteratively updates the element density and gradually removes material from low-stress regions; Based on the density distribution optimized by OptiStruct, regions with element density > 0.3 are extracted as the final material distribution, and the initial topology is generated using CAD software.

6. A crane boom, designed based on the topology optimization method applied to crane booms according to any one of claims 1 to 5, characterized in that, include: The first side plate has multiple first weight-reducing through holes spaced apart on it; The second side plate is spaced apart from and opposite to the first side plate. The second side plate is provided with a plurality of second weight-reducing holes at intervals. The positions of the plurality of second weight-reducing holes and the positions of the plurality of first weight-reducing through holes are arranged in a one-to-one correspondence. Multiple side panels are sequentially connected end to end between the first side panel and the second side panel, and are connected to each side panel to form a box-shaped structure; The reinforcing plate is located inside the cavity of the box-shaped structure.

7. The boom according to claim 6, characterized in that, The first side plate and the second side plate are each divided into a first region, a second region and a third region connected in sequence; The first region is provided with a first hinge hole for connecting the swing arm, the second region is provided with a second hinge hole for connecting the hydraulic cylinder, and the third region is provided with a third hinge hole for connecting the lifting component.

8. The boom according to claim 7, characterized in that, The bottoms of the first region, the second region, and the third region are flush. The height of the second region is greater than the height of the first region and the third region, respectively; The height of both the first region and the third region gradually increases from a position away from the second region towards the position where the second region is located.

9. A lifting boom device, characterized in that, include: Swing arm, suitable for mounting to chassis vehicles; The boom according to any one of claims 6 to 8, wherein one end of the boom is hinged to the swing arm, and the other end of the boom is connected to a lifting component; A hydraulic drive system is connected to the swing arm and the boom respectively, and is adapted to drive the swing arm and the boom to swing respectively.

10. A self-loading and unloading transport vehicle, characterized in that, include: Chassis vehicle; And the lifting boom device as described in claim 9, wherein the lifting boom device is symmetrically arranged at positions near both ends of the chassis vehicle.

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