Lightweight Optimization Method for Cab Structure Based on Force Path Rearrangement

Abstract

This invention discloses a lightweight optimization method for cab structure based on stress path rearrangement, belonging to the field of intelligent manufacturing technology. This method obtains the stress vectors of structural units under multiple working conditions and determines the main force flow transmission path for each working condition through streamline tracing. The main path is spatially meshed and binary-represented, and the degree of conflict shared by multiple working conditions is statistically analyzed. When the proportion of conflicting meshes exceeds a threshold, a path rearrangement signal is issued. An absorbing algorithm based on iterative control of the cooling coefficient is used to absorbing adjacent units that meet the stress threshold condition layer by layer, with high-stress units as the core. The structural units within the set are then subjected to graded section thinning according to stress quantile values. When the conflict proportion does not exceed the threshold, a lightweighting signal is issued, and the corresponding structural units are subjected to graded thinning according to stress warning intervals. This invention proactively intervenes in the structural design at the load transfer path level, solving the structural redundancy problem caused by multi-working-condition path conflicts, and effectively reducing the weight of the cab structure while ensuring performance.

Description

Technical Field

[0001] This invention relates to the field of intelligent manufacturing technology, specifically to a method for lightweight optimization of cab structure based on force path rearrangement. Background Technology

[0002] With increasing demands for fuel efficiency, environmental protection, and safety, effectively reducing vehicle weight while maintaining strength and safety has become a major challenge in design and manufacturing. More specifically, the cab structure, as a crucial component of the vehicle's safety system, directly impacts vehicle safety, comfort, and fuel economy; therefore, structural optimization methods based on force paths, particularly in cab structure lightweighting, are receiving increasing attention. This method optimizes structural weight by rearranging the force paths of the cab, while ensuring sufficient safety and stability, making it an effective means of improving vehicle performance and reducing carbon emissions.

[0003] Despite some progress in cab structure optimization in recent years, existing design methods still face many challenges. Traditional lightweight design methods often rely on experimentation and experience and fail to adequately consider the optimization of stress paths. Many design schemes tend to focus too much on material weight reduction while neglecting the global optimization of structural mechanical properties, which may lead to imbalances in key performance aspects such as safety and stiffness. In addition, most current methods are still in a relatively simple optimization stage and have failed to achieve precise rearrangement for specific stress paths, resulting in unnecessary material waste and insufficient structural strength. Therefore, existing lightweight design methods not only have certain limitations but also struggle to adapt to the increasingly complex needs of the automotive industry. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a lightweight optimization method for cab structures based on force path rearrangement, which solves the problems mentioned in the background technology.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a lightweight optimization method for cab structure based on force path rearrangement, comprising the following steps:

[0006] S1. Obtain the type and working condition characteristic data of the cab, and determine the main path of force transmission under each type of working condition through streamline tracing analysis;

[0007] S2. Based on the main force transmission path under various working conditions, and combined with the binarization representation method of the main force transmission path under multiple working conditions, analyze the degree of spatial conflict between the main force transmission paths under different working conditions, and screen the three-dimensional mesh conflict units and the three-dimensional mesh independent units respectively. By judging whether there is a risk of conflict in the force path of the cab structure, send out path rearrangement signals or lightweight optimization signals.

[0008] S3. After receiving the lightweight optimization signal, record each structural unit in the main path of force flow transmission under the corresponding working condition of the independent unit of the three-dimensional mesh, and determine the amount of cross-sectional thickness reduction of the corresponding structural unit in combination with the set stress warning interval.

[0009] S4. After receiving the lightweight optimization signal, record each structural unit in the main path of force flow transmission under the corresponding working condition of passing through the three-dimensional mesh conflict unit, and use the swallowing algorithm to perform iterative swallowing optimization analysis of material distribution on the main path of force flow under each working condition to generate the hierarchical lightweight optimization content of the cab structure.

[0010] Preferably, the characteristic data of the type of working condition includes characteristic data of bending working condition, characteristic data of torsion working condition, characteristic data of frontal collision working condition, characteristic data of side collision working condition, and characteristic data of top pressure working condition. Among them, each type of working condition characteristic data includes the stress vector of each structural unit under the corresponding type of working condition, and each stress vector includes the stress value and stress direction.

[0011] Preferably, the logic of streamline tracing analysis is as follows: Based on the stress vector of each structural unit under each type of working condition, extract the stress value and stress direction of each structural unit under the corresponding type of working condition. Take the structural unit to which the working condition load is initially applied as the starting structural unit. For any structural unit connected to the starting structural unit, select the corresponding structural unit with the same stress direction and maximum stress value as the first streamline structural unit. Similarly, analyze the stress value and stress direction of the next structural unit connected to the streamline structural unit and determine the second propulsion streamline structural unit. And so on, determine each propulsion streamline structural unit under the corresponding type of working condition. Use the connection path of each propulsion streamline structural unit under the corresponding type of working condition as the main path of force flow transmission under the corresponding type of working condition.

[0012] Preferably, the logic for analyzing the spatial conflict level of the main force transmission path under different working conditions is as follows: A Cartesian coordinate system for the cab is established with the center of the cab cross-section as the origin. The main force transmission paths under various working conditions are spatially aligned within this Cartesian coordinate system. A spatial grid is then divided at a set fixed interval to obtain several three-dimensional grid units. The spatial conflict level of the main force transmission path under the corresponding working conditions within each three-dimensional grid unit is analyzed. Combined with a multi-working-condition force transmission path binarization representation method, the number of conflicting units and independent units in the three-dimensional grid are counted. If the number of conflicting units exceeds 5% of the total number of three-dimensional grid units, it indicates a risk of conflict in the force path of the cab structure, and a path rearrangement signal is issued. If the number of conflicting units does not exceed 5% of the total number of three-dimensional grid units, it indicates no risk of conflict in the force path of the cab structure, and a lightweight optimization signal is issued.

[0013] Preferably, the logic of the binary representation method for the main force transmission path under multiple working conditions is as follows: if the main force transmission path under the corresponding working condition passes through the corresponding three-dimensional mesh cell, the binary value of the corresponding three-dimensional mesh cell is set to one; if the main force transmission path under the corresponding working condition does not pass through the corresponding three-dimensional mesh cell, the binary value of the corresponding three-dimensional mesh cell is set to zero. The binary values ​​of each three-dimensional mesh cell under the corresponding working condition are counted separately to obtain the total binary value of each three-dimensional mesh cell. If the total binary value of the corresponding three-dimensional mesh cell is less than two, the corresponding three-dimensional mesh cell is recorded as an independent three-dimensional mesh cell; if the total binary value of the corresponding three-dimensional mesh cell is greater than or equal to two, the corresponding three-dimensional mesh cell is recorded as a conflicting three-dimensional mesh cell.

[0014] Preferably, the logic for determining the cross-sectional thickness reduction of the corresponding structural unit is as follows: Select the corresponding three-dimensional mesh independent unit with a total binary value of one, record each structural unit in the main path of force flow transmission under the corresponding type of working condition passing through the three-dimensional mesh independent unit, perform feature recognition on the type of working condition feature data, extract the stress value of each structural unit in the main path of force flow transmission under the corresponding type of working condition passing through the three-dimensional mesh independent unit, and set the stress warning interval of the structural unit in the main path of force flow transmission under each type of working condition, wherein the minimum value and the maximum value in the stress warning interval are the first stress warning threshold and the second stress warning threshold, respectively.

[0015] For any type of working condition, the structural unit in the main path of force flow transmission is defined as follows: structural unit whose stress value is less than the first stress warning threshold in the corresponding stress warning interval is designated as a first-level weight-reducing structural unit, and the reduction amount of the component cross-sectional thickness of the first-level weight-reducing structural unit is set to 3H; structural unit in the corresponding stress warning interval is designated as a second-level weight-reducing structural unit, and the reduction amount of the component cross-sectional thickness of the second-level weight-reducing structural unit is set to 2H; structural unit whose stress value is greater than the second stress warning threshold in the corresponding stress warning interval is designated as a third-level weight-reducing structural unit, and the reduction amount of the component cross-sectional thickness of the third-level weight-reducing structural unit is set to H, where 3H > 2H > H.

[0016] Preferably, the logic for setting the stress warning interval is as follows: For structural units in the main force transmission path under any type of working condition, obtain the stress values ​​of each structural unit in the main force transmission path under the same type of working condition during historical normal testing of the cab, and use them as reference stress values ​​for each structural unit in the main force transmission path under this type of working condition. Preprocess the reference stress values ​​of each structural unit, calculate the mean and standard deviation of the stress values ​​of each structural unit in the main force transmission path under this type of working condition, and determine the product of the standard deviation and the preset margin coefficient. Use the difference between the mean and the product as the first stress warning threshold, and the sum of the mean and the product as the second stress warning threshold. Based on the first stress warning threshold and the second stress warning threshold, determine the stress warning interval of the structural unit in the main force transmission path under each type of working condition. The preset margin coefficient is a positive number not less than one. The preprocessing includes removing outliers based on the quartile method and filling missing values ​​based on the mean imputation method.

[0017] Preferably, the logic of using the swallowing algorithm to perform iterative swallowing optimization analysis of material distribution on the independent force flow main path of each working condition is as follows: after receiving the path rearrangement signal, select the corresponding three-dimensional mesh conflict unit with a total binary value greater than one, and record each structural unit in the force flow transmission main path under the corresponding working condition that passes through the three-dimensional mesh conflict unit. Construct the force flow main path unit set with each structural unit under a single working condition, and merge the force flow main path unit sets of each working condition to construct the swallowing algorithm search space;

[0018] Using all structural units within the main force flow path unit set as the initial seed unit set for the swallowing algorithm, an iterative swallowing process is executed: In each iteration step, all candidate units in the search space of the swallowing algorithm are traversed, and the stress values ​​of each candidate unit are numerically compared. The candidate unit with the largest stress value is selected as the swallowing core unit for the current iteration step. Centered on the swallowing core unit, swallowing condition judgments are performed on each adjacent structural unit. When the stress value of the adjacent structural unit is greater than or equal to the preset swallowing stress threshold of the current iteration step, the adjacent structural unit is recorded as a swallowing unit and marked as swallowing. When the stress value of the adjacent structural unit is less than the preset swallowing stress threshold of the current iteration step, the adjacent structural unit is recorded as an unswallowed unit. After completing one round of swallowing operations corresponding to the current iteration step, the swallowing units that meet the swallowing conditions are included in the initial main force flow path unit set.

[0019] The absorption stress threshold of the current iteration step is updated to the absorption stress threshold of the next iteration step based on the preset cooling coefficient, specifically as follows: In the formula, and These are the swallowing stress thresholds for the k-th iteration step and the (k+1)-th iteration step, respectively. The preset cooling coefficient is c∈(0,1); during multiple iteration steps of the swallowing operation, when the swallowing stress threshold is less than the preset swallowing stress lower limit threshold, the iteration is terminated, the swallowing units that satisfy the swallowing conditions of multiple iteration steps are recorded, and the standard force flow main path unit set is constructed.

[0020] Preferably, the logic for generating the graded lightweight optimization content of the cab structure is as follows: extract the core unit and stress values ​​of each core unit in the standard force flow main path unit set; maintain the original component cross-sectional thickness of the core unit in the standard force flow main path unit set; and perform graded weight reduction operations on each core unit in the standard force flow main path unit set, specifically including:

[0021] Based on the numerical value of the stress value of each phagocytic unit, they are arranged in ascending order to obtain the stress sequence of the phagocytic units. The lower quantile value and the upper quantile value in the stress sequence of the phagocytic units are extracted and used as the lower limit stress threshold and the upper limit stress threshold, respectively. The lower quantile value and the upper limit stress threshold represent the stress values ​​of the phagocytic units at the one-quarter position and three-quarters position in the stress sequence of the phagocytic units, respectively.

[0022] The stress value of each swallowing unit is compared and analyzed with the lower stress threshold and the upper stress threshold. If the stress value of the corresponding swallowing unit is greater than the upper stress threshold, the original component cross-sectional thickness of the corresponding swallowing unit is maintained. If the stress value of the corresponding swallowing unit is between the lower stress threshold and the upper stress threshold, the component cross-sectional thickness of the corresponding swallowing unit is reduced by 1H. If the stress value of the corresponding swallowing unit is less than the lower stress threshold, the component cross-sectional thickness of the corresponding swallowing unit is reduced by 2H.

[0023] This invention provides a lightweight optimization method for cab structure based on force path rearrangement, which has the following beneficial effects:

[0024] (1) By constructing a full-chain optimization framework of path conflict diagnosis, rearrangement, lightweight dual-branch response and graded directional weight reduction, the spatial coupling relationship of multi-condition load transfer paths is used as the direct decision basis for the lightweight design of the cab structure, overcoming the structural redundancy problem caused by treating each load transfer path as an independent object in the existing methods; In the path conflict diagnosis stage, this method introduces a spatial conflict quantification method based on gridded binary representation, which can transform the coincidence and differentiation states of different load flow paths in the cab spatial coordinate system into calculable and comparable numerical indicators, and trigger the selective execution of the path rearrangement mechanism or the lightweight mechanism with clear threshold conditions, so that the lightweight design process has the ability to actively intervene at the path level, rather than passively accepting the material allocation results under the condition of path spatial discreteness; In the path rearrangement stage, iterative swallowing optimization analysis based on swallowing algorithm and cooling coefficient control is adopted, and the stress level decreasing screening mechanism is used to sort the multi-condition load transfer paths. The originally independent main force flow paths were gradually integrated into a standard force flow transmission path system shared by multiple working conditions. This enabled the shared reuse of load-bearing functions at the structural channel level without changing the cab's exterior dimensions or encroaching on the occupant's living space. In the lightweighting implementation phase, differentiated section thickness reduction strategies were implemented based on the functional level of structural units in the force flow path system. Different degrees of thickness reduction were applied to core load-bearing units, auxiliary load-bearing units, and non-path units. This ensured that material reduction was precisely applied to areas with low mechanical contribution, while areas with high mechanical contribution were fully preserved. Ultimately, a significant reduction in the total mass of the cab body-in-white was achieved while meeting the strength and stiffness constraints of each working condition. Overall, the optimization starting point for cab lightweighting design was shifted from adjusting component section dimensions to reconstructing the load transmission path space system, achieving a fundamental leap in the level of optimization variables and providing a complete solution for high load-bearing efficiency lightweight design of cab structures.

[0025] (2) By constructing a binary representation method for the main path of force flow transmission under multiple working conditions and a path conflict degree judgment logic based on grid statistics, a quantitative diagnosis of the spatial coupling relationship of force transmission paths between different working conditions was realized, and a dual-branch response mechanism of path rearrangement signal and lightweight signal was established accordingly. Using a uniform spatial grid in the Cartesian coordinate system of the cab as the analysis carrier, by judging whether the main path of force flow under each working condition passes through the same grid cell and assigning a binary flag value to the grid cell accordingly, the force flow path information that originally existed in the form of a continuous spatial curve was transformed into a binary state matrix on a discrete grid cell. Furthermore, by statistically analyzing the total binary value of each grid cell under multiple working conditions, the grid cell was divided into conflict cells representing the shared paths under multiple working conditions and independent cells representing the exclusive paths under a single working condition, and the proportion of the number of conflict cells to the total number of grid cells was used as the overall criterion for path conflict risk. This representation and judgment process does not rely on the experience judgment or qualitative judgment of the designers. Instead of analysis, this method automatically completes the process through a mathematically defined computational flow, ensuring repeatability and objective consistency of the results. When the proportion of conflicting units exceeds a preset threshold, the path rearrangement signal enables subsequent processes to actively fuse discrete force flow paths using an absorption algorithm, thereby addressing the structural redundancy caused by path space conflicts at the root level. When the proportion of conflicting units does not exceed the threshold, the lightweighting signal allows the optimization process to directly enter the stress-level-based graded weight reduction stage, avoiding unnecessary rearrangement operations on structures with good path overlap, thus saving computational resources and improving optimization efficiency. This dual-branch response mechanism allows this method to adopt appropriate optimization strategies for design objects with different levels of path conflict, balancing the targeted nature of optimization with computational economy, effectively overcoming the computational waste caused by existing methods that still perform global re-analysis when path conflicts are not severe.

[0026] (3) A path fusion mechanism based on the swallowing algorithm and the iterative control of the cooling coefficient is introduced in the path rearrangement branch. A graded section thinning strategy based on the stress level of the structural unit is established in both the path rearrangement branch and the lightweight branch, realizing the effective connection between path-level optimization and component-level optimization. In terms of path fusion, the method uses the merging result of the main path unit set of multi-condition force flow as the search space of the swallowing algorithm. The candidate unit with the highest stress value is determined as the swallowing core, and swallowing condition judgment is performed layer by layer from it to the adjacent units. Only units with stress values ​​not lower than the swallowing stress threshold of the current iteration step can be included in the swallowing set. The swallowing stress threshold is controlled by the cooling coefficient to decrease in round by round, so that the swallowing boundary gradually expands outward from the core bearing area with the highest stress level, and the stress level reaches a reasonable lower limit when the iteration ends. All elements are included in the multi-condition shared path set, while elements in the weak load-bearing area with excessively low stress levels are excluded. This decreasing absorption mechanism ensures that the path fusion process always follows the physically reasonable order of prioritizing the fusion of high-stress areas and the gradual expansion of stress levels. Stress warning intervals or multi-level stress thresholds are further set within the main force flow path. Structural elements on the path are divided into multiple weight reduction levels according to the distribution of their stress values ​​relative to the warning threshold, and progressive reduction in cross-sectional thickness is applied to each level. This allows elements with larger stress margins to receive greater reductions, while elements with stress levels close to or exceeding the upper limit of the warning are kept at their original cross-sectional thickness or only subject to the minimum reduction. A refined tiered allocation is implemented based on the mechanical contribution of each element in the force flow transmission system, thereby achieving an optimal balance between weight reduction and structural safety. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the lightweight optimization method for cab structure based on force path rearrangement according to the present invention.

[0028] Figure 2 This is a graph showing the phagocytic stress threshold of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example

[0031] Please see Figure 1 and Figure 2 This invention provides a lightweight optimization method for cab structure based on force path rearrangement, comprising the following steps:

[0032] S1. Obtain the type and working condition characteristic data of the cab, and determine the main path of force transmission under each type of working condition through streamline tracing analysis;

[0033] The type of working condition characteristic data includes bending working condition characteristic data, torsion working condition characteristic data, frontal collision working condition characteristic data, side collision working condition characteristic data and top pressure working condition characteristic data. Each type of working condition characteristic data includes the stress vector of each structural unit under the corresponding type of working condition, and each stress vector includes the stress value and stress direction.

[0034] In one specific embodiment, the process of acquiring the characteristic data of the type of working condition is as follows: a finite element mesh model containing shell elements is established through the geometric model of the cab body. A hybrid discretization scheme with quadrilateral shell elements as the main element and triangular shell elements as the auxiliary element is selected. The basic size of the element is 10mm. The weld connection is simulated using CWELD elements. The suspension connection point is elastically constrained according to the six-way stiffness characteristics of the rubber bushing in the actual vehicle suspension system. In terms of material properties, the main load-bearing components are selected from B280VK cold-rolled high-strength steel plates with a yield strength of 280MPa, an elastic modulus of 210GPa, a Poisson's ratio of 0.3, and a density of 7850kg / m³. The local reinforcement is selected from B340 / 590DP duplex steel with a yield strength of 340MPa. After the finite element model is completed, the model is checked through modal test data. The calculated first six modal frequencies are compared with the measured values ​​of the physical prototype vehicle. If the frequency deviation exceeds 5%, the weld stiffness parameters are adjusted and recalculated until the model accuracy meets the requirements.

[0035] Secondly, for five types of working conditions—bending, torsion, frontal collision, side impact, and top-impact—working loads were applied at the corresponding load application locations for each condition, and displacement constraints were applied at the suspension mounting points or constraint boundary locations to construct the static equilibrium equations for each condition. For the bending condition, an equivalent uniformly distributed load was applied to the driver's seat mounting point and the floor occupant load-bearing area. A single occupant's standard mass of 75kg was multiplied by gravitational acceleration and converted into a nodal concentrated force applied to the corresponding seat mounting node. The constraint condition was set to constrain all six degrees of freedom at the four suspension mounting points. For the torsion condition, a 20mm vertical forced displacement was applied upwards to the left front suspension mounting point, and a 20mm vertical forced displacement was applied downwards to the right rear suspension mounting point. The remaining suspension points remain in a free state; in the frontal collision test, in accordance with the requirements of the commercial vehicle cab frontal pendulum impact test, the dynamic collision force is converted into a static load using the equivalent static load method. A concentrated force in the longitudinal rearward direction is applied to the connection area between the cab front bulkhead and the lower A-pillar, and the stress value is taken as the equivalent static load peak value corresponding to the collision energy specified by regulations. At the same time, longitudinal and vertical displacements are constrained at the rear suspension mounting points; in the side collision test, an equivalent static concentrated force in the lateral inward direction is applied at the middle height of the cab B-pillar, and the force value is calculated from the pendulum impact energy. Lateral displacements are constrained at the opposite side sill beam position; in the top-pressure test, a uniformly distributed pressure load is applied vertically downward in the center area of ​​the cab roof, and the load amplitude is taken as the top-pressure load value specified by regulations. The constraint conditions are set at the suspension mounting points.

[0036] The static equilibrium equations are solved to obtain the displacement vectors of all nodes under each working condition. Specifically, the overall stiffness matrix, load column vector, and displacement boundary condition constraint equations are constructed for the finite element model of the cab body-in-white under the load and constraint boundary conditions corresponding to each working condition. The overall stiffness matrix is ​​assembled from the stiffness matrices of each element according to the correspondence of the degrees of freedom of the nodes. The stiffness matrix of each element is calculated by Gaussian numerical integration based on the shape function, strain-displacement matrix, and material constitutive matrix of the selected shell element type. After introducing displacement boundary conditions to modify the overall stiffness equations to eliminate rigid body displacements, the linear algebraic equations are solved using a direct sparse solver or a preconditional conjugate gradient iteration method to obtain the displacement vectors of all nodes of the cab structure under each working condition.

[0037] Based on the displacement vector, the stress tensor field of each structural element under each working condition is calculated. For any element, the strain tensor at each Gaussian integration point within the element is first calculated by multiplying the element node displacement vector with the strain-displacement matrix. Then, the stress tensor at each integration point is obtained using the material constitutive relation. This stress tensor contains six independent stress components. When it is necessary to extrapolate the stress at the integration point to the element node or element center, the least squares extrapolation method based on shape functions or the arithmetic mean of the stress at the integration point is used as the representative stress tensor value of the element. The stress tensor field is decomposed into principal stresses. By performing eigenvalue decomposition on the second-order tensor, three principal stress values ​​and three corresponding mutually orthogonal principal direction vectors are obtained. The principal stress values ​​and corresponding principal stress directions of each structural element under each working condition are extracted. The principal stress values ​​and principal stress directions are used as the stress values ​​and stress directions of the stress vector of the structural element under the corresponding working condition, thereby forming characteristic data for each type of working condition.

[0038] The logic of streamline tracing analysis is as follows: Based on the stress vector of each structural unit under each type of working condition, extract the stress value and stress direction of each structural unit under the corresponding type of working condition. Take the structural unit initially subjected to the working condition load as the starting structural unit. For any structural unit connected to the starting structural unit, select the corresponding structural unit with the same stress direction and maximum stress value as the first streamline structural unit. Similarly, analyze the stress value and stress direction of the next structural unit connected to the streamline structural unit and determine the second propulsion streamline structural unit. And so on, determine each propulsion streamline structural unit under the corresponding type of working condition. The connection path of each propulsion streamline structural unit under the corresponding type of working condition is taken as the main path of force flow transmission under the corresponding type of working condition.

[0039] S2. Based on the main force transmission path under various working conditions, and combined with the binarization representation method of the main force transmission path under multiple working conditions, analyze the degree of spatial conflict between the main force transmission paths under different working conditions, and screen the three-dimensional mesh conflict units and the three-dimensional mesh independent units respectively. By judging whether there is a risk of conflict in the force path of the cab structure, send out path rearrangement signals or lightweight optimization signals.

[0040] The logic for analyzing the spatial conflict level of the main force transmission path under different working conditions is as follows: A Cartesian coordinate system for the cab is established with the center of the cab cross-section as the origin. The main force transmission paths under various working conditions are spatially aligned within this system. A spatial grid is then created using a fixed spacing, resulting in several three-dimensional grid cells. The spatial conflict level of the main force transmission path under each working condition within these cells is analyzed. Combined with a binarization representation method for the main force transmission path under multiple working conditions, the number of conflicting cells and independent cells in the three-dimensional grid are counted. If the number of conflicting cells exceeds 5% of the total number of three-dimensional grid cells, it indicates a risk of conflict in the force path of the cab structure, triggering a path rearrangement signal. If the number of conflicting cells does not exceed 5% of the total number of three-dimensional grid cells, it indicates no risk of conflict in the force path of the cab structure, triggering a lightweight optimization signal.

[0041] It should be noted that the midpoint of the line connecting the midpoint of the lower edge of the front bulkhead and the midpoint of the lower edge of the rear bulkhead in the finite element model of the cab body is taken as the center position of the cab cross-section. Using this center position as the origin, a Cartesian coordinate system for the cab is established with the longitudinal direction of the cab as the X-axis, the transverse direction as the Y-axis, and the vertical direction as the Z-axis. The spatial node coordinate data of the main force flow transmission paths corresponding to the five types of working conditions (bending, torsion, frontal collision, side collision, and top impact) determined in S1 are uniformly transformed into this Cartesian coordinate system for spatial alignment to ensure... The various working path conditions are compared and analyzed under a unified spatial reference system. A three-dimensional mesh is created for the cab design space using an equally spaced spatial grid. The fixed spacing refers to the side length of the grid cells in the X, Y, and Z axes, and its value is determined based on the overall dimensions of the cab and the finite element mesh density. In this embodiment, a fixed spacing of 50mm is used, meaning a grid interval is divided every 50mm in the X-axis, Y-axis, and Z-axis directions. This discretizes the entire design space in the cab's Cartesian coordinate system into several cubic three-dimensional mesh cells with a side length of 50mm. These three-dimensional mesh cells constitute the discrete spatial carrier for path conflict analysis.

[0042] The logic of the binary representation method for the main force transmission path under multiple working conditions is as follows: if the main force transmission path under the corresponding working condition passes through the corresponding three-dimensional mesh cell, the binary value of the corresponding three-dimensional mesh cell is set to one; if the main force transmission path under the corresponding working condition does not pass through the corresponding three-dimensional mesh cell, the binary value of the corresponding three-dimensional mesh cell is set to zero. The binary values ​​of each three-dimensional mesh cell under the corresponding working condition are counted to obtain the total binary value of each three-dimensional mesh cell. If the total binary value of the corresponding three-dimensional mesh cell is less than two, the corresponding three-dimensional mesh cell is recorded as an independent three-dimensional mesh cell; if the total binary value of the corresponding three-dimensional mesh cell is greater than or equal to two, the corresponding three-dimensional mesh cell is recorded as a conflicting three-dimensional mesh cell.

[0043] It should be noted that for each three-dimensional mesh cell, the main force transmission path corresponding to the five types of working conditions—bending, torsion, frontal collision, side collision, and top pressure—is traversed one by one. It is determined whether the node coordinate sequence of each propulsion streamline structure unit in the main force transmission path of that working condition falls within the spatial range of the three-dimensional mesh cell. If at least one propulsion streamline structure unit in the main force transmission path of a certain working condition has node coordinates located inside the cubic space enclosed by the six boundary planes of the three-dimensional mesh cell, then the main force transmission path for that type of working condition is determined to pass through the three-dimensional mesh cell, and the binary value of the three-dimensional mesh cell under that working condition is set to one. If none of the node coordinates of all propulsion streamline structure units in the main force transmission path of a certain working condition are located within the spatial range of the three-dimensional mesh cell, then the main force transmission path for that type of working condition is determined to not pass through the three-dimensional mesh cell, and the binary value of the three-dimensional mesh cell under that working condition is set to zero. According to the above judgment and assignment rules, the judgment of each working condition and the assignment of binary values ​​are performed one by one for each three-dimensional mesh cell. Each three-dimensional mesh cell obtains five binary values ​​corresponding to the five working conditions. For each three-dimensional mesh cell, the binary values ​​of the five working conditions are summed to obtain the total binary value of the three-dimensional mesh cell. The total binary value is an integer between one and five. If the total binary value is zero, it means that the three-dimensional mesh cell has not been traversed by the main force transmission path of any working condition. If the total binary value is one, it means that the three-dimensional mesh cell has been traversed by the main force transmission path of only one working condition. The three-dimensional mesh cell is a path channel exclusively occupied by a single working condition. If the total binary value is greater than or equal to two, it means that the three-dimensional mesh cell has been traversed by the main force transmission paths of two or more working conditions. The three-dimensional mesh cell is a path channel shared by multiple working conditions. There is spatial overlap and conflict of force transmission paths at this point.

[0044] S3. After receiving the lightweight optimization signal, record each structural unit in the main path of force flow transmission under the corresponding working condition of the independent unit of the three-dimensional mesh, and determine the amount of cross-sectional thickness reduction of the corresponding structural unit in combination with the set stress warning interval.

[0045] The logic for determining the cross-sectional thickness reduction of the corresponding structural unit is as follows: Select the corresponding three-dimensional mesh independent unit with a total binary value of one, record each structural unit in the main path of force flow transmission under the corresponding type of working condition passing through the three-dimensional mesh independent unit, perform feature recognition on the characteristic data of the type of working condition, extract the stress value of each structural unit in the main path of force flow transmission under the corresponding type of working condition passing through the three-dimensional mesh independent unit, and set the stress warning interval of the structural unit in the main path of force flow transmission under each type of working condition. The minimum and maximum values ​​in the stress warning interval are the first stress warning threshold and the second stress warning threshold, respectively.

[0046] For any type of working condition, the structural unit in the main path of force flow transmission is defined as follows: structural unit whose stress value is less than the first stress warning threshold in the corresponding stress warning interval is designated as a first-level weight-reducing structural unit, and the reduction amount of the component cross-sectional thickness of the first-level weight-reducing structural unit is set to 3H; structural unit in the corresponding stress warning interval is designated as a second-level weight-reducing structural unit, and the reduction amount of the component cross-sectional thickness of the second-level weight-reducing structural unit is set to 2H; structural unit whose stress value is greater than the second stress warning threshold in the corresponding stress warning interval is designated as a third-level weight-reducing structural unit, and the reduction amount of the component cross-sectional thickness of the third-level weight-reducing structural unit is set to H, where 3H > 2H > H.

[0047] It should be noted that the lower the stress value of a path structural unit, the greater its mechanical load-bearing safety margin, and the greater the reduction in cross-sectional thickness it can withstand; conversely, the higher the stress value of a path structural unit, the smaller its mechanical load-bearing safety margin, and the greater the reduction in cross-sectional thickness it can withstand, or no reduction at all. This achieves the lightweighting goal of minimizing material usage while ensuring structural safety. In this embodiment, the base plate thickness reference value H is taken as 0.2 mm, meaning that the cross-sectional thickness reduction of the first-level weight-reduction structural unit is 0.6 mm, the cross-sectional thickness reduction of the second-level weight-reduction structural unit is 0.4 mm, and the cross-sectional thickness reduction of the third-level weight-reduction structural unit is 0.2 mm.

[0048] The logic for setting the stress warning interval is as follows: For structural units in the main force transmission path under any type of working condition, obtain the stress values ​​of each structural unit in the main force transmission path under multiple segments of that type of working condition during the historical normal test of the cab. These stress values ​​are used as reference stress values ​​for each structural unit in the main force transmission path under that type of working condition. The reference stress values ​​of each structural unit are preprocessed, and the mean and standard deviation of the stress values ​​of each structural unit in the main force transmission path under that type of working condition are calculated. The product of the standard deviation and the preset margin coefficient is determined, and the difference between the mean and the product is calculated. The first stress warning threshold is set as the first value, and the sum of the mean and the product is set as the second stress warning threshold. Based on the first and second stress warning thresholds, the stress warning intervals of structural units in the main force transmission path under various working conditions are determined. The preset margin coefficient is a positive number not less than one, which expands the range of the stress warning interval based on the standard deviation to ensure that the warning interval has sufficient inclusiveness. Therefore, the preset margin coefficient is set to 1.5. The preprocessing includes removing outliers based on the quartile method and filling missing values ​​based on the mean imputation method.

[0049] It should be noted that, for any type of working condition, the stress values ​​of each structural unit in the main force transmission path under the same working condition are obtained from the historical normal test of the cab, and are used as the reference stress values ​​of each structural unit in the main force transmission path under this type of working condition. The historical normal test of the cab refers to the simulation analysis data or physical prototype test data accumulated in the development process of cab products of the same series or platform. These data reflect the mechanical response level of the same type of cab structure under the same working condition.

[0050] Preprocessing includes outlier removal based on the quartile method and missing value filling based on the mean. The specific operation for outlier removal based on the quartile method is as follows: Arrange the reference stress values ​​in ascending order, calculate the first and third quartiles, and determine the interquartile range. If a data point is less than the difference between the first quartile and 1.5 times the interquartile range, or greater than the sum of the third quartile and 1.5 times the interquartile range, it is considered an outlier and removed. The specific operation for filling missing values ​​based on the mean method is as follows: For positions where outlier removal results in a vacancy, take the arithmetic mean of the reference stress values ​​of the adjacent elements at that position as the filling value to fill the vacancy.

[0051] In one specific embodiment, taking the bending condition as an example, the reference stress values ​​of each structural unit in the six main force transmission paths of the same series of models of the cab under the bending condition were obtained. After removing outliers using the quartile method, a total of 328 valid reference stress value samples were obtained. The mean of these valid samples was calculated to be 156.3 MPa, and the standard deviation was 28.7 MPa. The product of the standard deviation and the preset margin coefficient of 1.5 was calculated to be 28.7 × 1.5 = 43.05 MPa. Therefore, the stress warning interval of the structural unit in the main force transmission path under the bending condition was determined to be [113.25 MPa, 199.35 MPa]. Correspondingly, the first stress warning threshold was 113.25 MPa, and the second stress warning threshold was 199.35 MPa. For the three-dimensional force transmission path corresponding to the bending condition, the stress warning interval was determined to be [113.25 MPa, 199.35 MPa]. The stress value of a specific structural unit in the independent mesh element is 87.2 MPa, which is less than the first stress warning threshold of 113.25 MPa. Therefore, this structural unit is designated as a first-level weight-reduction structural unit, and its component cross-sectional thickness reduction is set to 3H = 0.6 mm. The stress value of another structural unit is 162.8 MPa, which is within the stress warning range [113.25 MPa, 199.35 MPa]. Therefore, this structural unit is designated as a second-level weight-reduction structural unit, and its component cross-sectional thickness reduction is set to 2H = 0.4 mm. The stress value of yet another structural unit is 221.4 MPa, which is greater than the second stress warning threshold of 199.35 MPa. Therefore, this structural unit is designated as a third-level weight-reduction structural unit, and its component cross-sectional thickness reduction is set to H = 0.2 mm.

[0052] S4. After receiving the lightweight optimization signal, record each structural unit in the main path of force flow transmission under the corresponding working condition of passing through the three-dimensional mesh conflict unit, and use the swallowing algorithm to perform iterative swallowing optimization analysis of material distribution on the main path of force flow under each working condition to generate the hierarchical lightweight optimization content of the cab structure.

[0053] The logic of using the swallowing algorithm to perform iterative swallowing optimization analysis of material distribution on the independent force flow main path of each working condition is as follows: After receiving the path rearrangement signal, select the corresponding three-dimensional mesh conflict unit with a total binary value greater than one, and record each structural unit in the force flow transmission main path under the corresponding working condition that passes through the three-dimensional mesh conflict unit. Construct the force flow main path unit set with each structural unit under a single working condition, and merge the force flow main path unit sets of each working condition to construct the swallowing algorithm search space.

[0054] It should be noted that after receiving the path rearrangement signal, the corresponding 3D mesh conflicting element with a binary total value greater than one is selected. Here, the meaning of a 3D mesh conflicting element with a binary total value greater than one is that the 3D mesh element is simultaneously traversed by the main force flow transmission paths of two or more of the five types of working conditions in the binarization representation of S2. S4 only performs path rearrangement and swallowing optimization for conflicting mesh elements with a binary total value greater than one, while independent mesh elements with a binary total value equal to one undergo weight reduction processing in S3.

[0055] Specifically, for bending conditions, all structural elements in the main path of force flow transmission through the three-dimensional mesh conflict elements are grouped into a set, denoted as the bending condition force flow main path element set; for torsion conditions, the corresponding structural elements are similarly grouped into the torsion condition force flow main path element set; similarly, the frontal collision condition force flow main path element set, the side collision condition force flow main path element set, and the top pressure condition force flow main path element set are constructed respectively; the force flow main path element sets of the above five types of conditions are combined and operated to obtain the swallowing algorithm search space.

[0056] Using all structural units within the main force flow path unit set as the initial seed unit set for the swallowing algorithm, an iterative swallowing process is executed: In each iteration step, all candidate units in the search space of the swallowing algorithm are traversed, and the stress values ​​of each candidate unit are numerically compared. The candidate unit with the largest stress value is selected as the swallowing core unit for the current iteration step. Centered on the swallowing core unit, swallowing condition judgments are performed on each adjacent structural unit. When the stress value of the adjacent structural unit is greater than or equal to the preset swallowing stress threshold of the current iteration step, the adjacent structural unit is recorded as a swallowing unit and marked as swallowing. When the stress value of the adjacent structural unit is less than the preset swallowing stress threshold of the current iteration step, the adjacent structural unit is recorded as an unswallowed unit. After completing one round of swallowing operations corresponding to the current iteration step, the swallowing units that meet the swallowing conditions are included in the initial main force flow path unit set.

[0057] The absorption stress threshold of the current iteration step is updated to the absorption stress threshold of the next iteration step based on the preset cooling coefficient, specifically as follows: In the formula, and These are the swallowing stress thresholds for the k-th iteration step and the (k+1)-th iteration step, respectively. The cooling coefficient is a preset value, and c∈(0,1). In this embodiment, the cooling coefficient c is 0.9, that is, after each iteration step, the swallowing stress threshold drops to 90% of the previous threshold. During the swallowing operation of multiple iteration steps, when the swallowing stress threshold is less than the preset lower limit threshold of swallowing stress, the iteration is terminated, the swallowing units that meet the swallowing conditions of multiple iteration steps are recorded, and the standard force flow main path unit set is constructed.

[0058] It should be noted that the preset swallowing stress threshold for the initial iteration step (i.e., the swallowing stress threshold when k=0, corresponding to the swallowing condition judgment benchmark for the first iteration) is determined as follows: the equivalent stress values ​​of all structural units in the initial seed unit set under their respective working conditions are statistically analyzed, these equivalent stress values ​​are arranged in descending order, a cumulative distribution function of equivalent stress is constructed, and the equivalent stress value corresponding to the upper 0.9 quantile of the cumulative distribution function is taken as the initial swallowing stress threshold; for example: the equivalent stress values ​​of all structural units in the initial seed unit set are distributed between 50.3MPa and 312.7MPa, and the equivalent stress value corresponding to the upper 0.9 quantile is 267.5MPa, so the initial swallowing stress threshold is set to 267.5MPa; the cooling coefficient is taken as 0.9, then the swallowing stress threshold of the first iteration step (k=1) is equal to 240.75MPa.

[0059] The iteration terminates when the absorption stress threshold decreases to a preset lower absorption stress threshold. The lower absorption stress threshold is determined by taking the arithmetic mean of the equivalent stress values ​​of all structural units in the initial seed unit set as the convergence lower limit. This average value reflects the overall central trend of the stress level of the path units. In this embodiment, the arithmetic mean of the equivalent stress values ​​of all structural units in the initial seed unit set is calculated to be 184.2 MPa; therefore, the lower absorption stress threshold is set to 184.2 MPa. As the iteration progresses, the iteration stops when the absorption stress threshold first decreases to less than 184.2 MPa. See details in [link to documentation]. Figure 2 Alternatively, another judgment condition can be selected: when the increase in the number of devoured units between two consecutive iterations is lower than the preset minimum increment value, the iteration is also terminated. The preset minimum increment value can be taken as 1% of the total number of units in the initial seed unit set. That is, when the number of units newly included in the devoured set after a certain round of iteration is less than 1% of the total number of units in the initial seed unit set, the marginal benefit of continuing the iteration is already extremely low, and terminating the iteration can avoid the ineffective consumption of computing resources.

[0060] The logic for generating the graded lightweight optimization content of the cab structure is as follows: extract the core unit and stress values ​​of each core unit in the standard force flow main path unit set; maintain the original component cross-sectional thickness of the core unit in the standard force flow main path unit set; and perform graded weight reduction operations on each core unit in the standard force flow main path unit set, specifically including:

[0061] Based on the numerical value of the stress value of each phagocytic unit, they are arranged in ascending order to obtain the stress sequence of the phagocytic units. The lower quantile value and the upper quantile value in the stress sequence of the phagocytic units are extracted and used as the lower limit stress threshold and the upper limit stress threshold, respectively. The lower quantile value and the upper limit stress threshold represent the stress values ​​of the phagocytic units at the one-quarter position and three-quarters position in the stress sequence of the phagocytic units, respectively.

[0062] The stress value of each swallowing unit is compared and analyzed with the lower stress threshold and the upper stress threshold. If the stress value of the corresponding swallowing unit is greater than the upper stress threshold, the original component cross-sectional thickness of the corresponding swallowing unit is maintained. If the stress value of the corresponding swallowing unit is between the lower stress threshold and the upper stress threshold, the component cross-sectional thickness of the corresponding swallowing unit is reduced by 1H. If the stress value of the corresponding swallowing unit is less than the lower stress threshold, the component cross-sectional thickness of the corresponding swallowing unit is reduced by 2H.

[0063] It should be noted that 1H is the defined baseline value for the thickness of the cab body-in-white base plate, which is 0.2mm, and 2H is 0.4mm.

[0064] In one specific embodiment, the stress value of one absorbing unit is 256.3 MPa, which is greater than the upper stress threshold of 213.8 MPa. Therefore, the original component cross-sectional thickness of the absorbing unit is maintained without thinning. The stress value of another absorbing unit is 178.5 MPa, which is between the lower stress threshold of 142.6 MPa and the upper stress threshold of 213.8 MPa. Therefore, the component cross-sectional thickness of this absorbing unit is reduced by 1H = 0.2 mm. The stress value of yet another absorbing unit is 118.9 MPa, which is less than the lower stress threshold of 142.6 MPa. Therefore, the component cross-sectional thickness of this absorbing unit is reduced by 2H = 0.4 mm.

[0065] It should be noted that the lightweighting schemes for the independent unit regions of the 3D mesh output by S3 and the lightweighting schemes for the conflicting unit regions of the 3D mesh output by S4 together constitute the hierarchical lightweighting optimization of the overall cab structure. By summing the weight reduction results of the two parts, the complete lightweighting optimization scheme for the cab structure is obtained. In practical applications, the final weight of the cab body after optimization is reduced from the initial 285.6 kg to 243.8 kg, with a weight reduction rate of 14.6%, and the strength and stiffness performance indicators under all five types of working conditions meet the design requirements.

[0066] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0067] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0068] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0069] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0070] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0071] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lightweight optimization method for cab structure based on force path rearrangement, characterized in that: Includes the following steps: S1. Obtain the type and working condition characteristic data of the cab, and determine the main path of force transmission under each type of working condition through streamline tracing analysis; S2. Based on the main force transmission path under various working conditions, and combined with the binarization representation method of the main force transmission path under multiple working conditions, analyze the degree of spatial conflict between the main force transmission paths under different working conditions, and screen the three-dimensional mesh conflict units and the three-dimensional mesh independent units respectively. By judging whether there is a risk of conflict in the force path of the cab structure, send out path rearrangement signals or lightweight optimization signals. S3. After receiving the lightweight optimization signal, record each structural unit in the main path of force flow transmission under the corresponding working condition of the independent unit of the three-dimensional mesh, and determine the amount of cross-sectional thickness reduction of the corresponding structural unit in combination with the set stress warning interval. S4. After receiving the lightweight optimization signal, record each structural unit in the main path of force flow transmission under the corresponding working condition of passing through the three-dimensional mesh conflict unit, and use the swallowing algorithm to perform iterative swallowing optimization analysis of material distribution on the main path of force flow under each working condition to generate the hierarchical lightweight optimization content of the cab structure.

2. The lightweight optimization method for cab structure based on force path rearrangement according to claim 1, characterized in that: The characteristic data of the working conditions include bending working condition characteristic data, torsion working condition characteristic data, frontal collision working condition characteristic data, side collision working condition characteristic data and top pressure working condition characteristic data. Among them, each type of working condition characteristic data includes the stress vector of each structural unit under the corresponding working condition, and each stress vector includes the stress value and stress direction.

3. The lightweight optimization method for cab structure based on force path rearrangement according to claim 2, characterized in that: The logic of streamline tracing analysis is as follows: Based on the stress vector of each structural unit under each type of working condition, extract the stress value and stress direction of each structural unit under the corresponding type of working condition. Take the structural unit initially subjected to the working condition load as the starting structural unit, and for any structural unit connected to the starting structural unit, select the corresponding structural unit with the same stress direction and maximum stress value as the first streamline structural unit. Similarly, analyze the stress value and stress direction of the next structural unit connected to the streamline structural unit, and determine the second propulsion streamline structural unit. And so on, determine each propulsion streamline structural unit under the corresponding type of working condition, and take the connection path of each propulsion streamline structural unit under the corresponding type of working condition as the main path of force flow transmission under the corresponding type of working condition.

4. The lightweight optimization method for cab structure based on force path rearrangement according to claim 3, characterized in that: The logic for analyzing the spatial conflict level of the main force transmission path under different working conditions is as follows: A Cartesian coordinate system for the cab is established with the center of the cab cross-section as the origin. The main force transmission paths under various working conditions are spatially aligned within this system. A spatial mesh is then created with a fixed spacing, resulting in several three-dimensional mesh units. The spatial conflict level of the main force transmission path under each working condition within these three-dimensional mesh units is analyzed. Combined with a multi-working-condition force transmission path binarization representation method, the number of conflicting units and independent units in the three-dimensional mesh are counted. If the number of conflicting units exceeds 5% of the total number of three-dimensional mesh units, it indicates a risk of conflict in the force path of the cab structure, triggering a path rearrangement signal. If the number of conflicting units does not exceed 5% of the total number of three-dimensional mesh units, it indicates no risk of conflict in the force path of the cab structure, triggering a lightweight optimization signal.

5. The lightweight optimization method for cab structure based on force path rearrangement according to claim 4, characterized in that: The logic of the binary representation method for the main path of force flow transmission under multiple working conditions is as follows: if the main path of force flow transmission under the corresponding working condition passes through the corresponding three-dimensional mesh cell, the binary value of the corresponding three-dimensional mesh cell is set to one; if the main path of force flow transmission under the corresponding working condition does not pass through the corresponding three-dimensional mesh cell, the binary value of the corresponding three-dimensional mesh cell is set to zero. The binary values ​​of each three-dimensional mesh cell under the corresponding working condition are counted to obtain the total binary value of each three-dimensional mesh cell. If the total binary value of the corresponding three-dimensional mesh cell is less than two, the corresponding three-dimensional mesh cell is recorded as an independent three-dimensional mesh cell; if the total binary value of the corresponding three-dimensional mesh cell is greater than or equal to two, the corresponding three-dimensional mesh cell is recorded as a conflicting three-dimensional mesh cell.

6. The lightweight optimization method for cab structure based on force path rearrangement according to claim 5, characterized in that: The logic for determining the cross-sectional thickness reduction of the corresponding structural unit is as follows: Select the corresponding three-dimensional mesh independent unit with a total binary value of one, record each structural unit in the main path of force flow transmission under the corresponding type of working condition passing through the three-dimensional mesh independent unit, perform feature recognition on the characteristic data of the type of working condition, extract the stress value of each structural unit in the main path of force flow transmission under the corresponding type of working condition passing through the three-dimensional mesh independent unit, and set the stress warning interval of the structural unit in the main path of force flow transmission under each type of working condition. The minimum and maximum values ​​in the stress warning interval are the first stress warning threshold and the second stress warning threshold, respectively. For any type of working condition, the structural unit in the main path of force flow transmission is defined as follows: structural unit whose stress value is less than the first stress warning threshold in the corresponding stress warning interval is designated as a first-level weight-reducing structural unit, and the reduction amount of the component cross-sectional thickness of the first-level weight-reducing structural unit is set to 3H; structural unit in the corresponding stress warning interval is designated as a second-level weight-reducing structural unit, and the reduction amount of the component cross-sectional thickness of the second-level weight-reducing structural unit is set to 2H; structural unit whose stress value is greater than the second stress warning threshold in the corresponding stress warning interval is designated as a third-level weight-reducing structural unit, and the reduction amount of the component cross-sectional thickness of the third-level weight-reducing structural unit is set to H, where 3H > 2H > H.

7. The lightweight optimization method for cab structure based on force path rearrangement according to claim 6, characterized in that: The logic for setting the stress warning interval is as follows: For structural units in the main force transmission path under any type of working condition, obtain the stress values ​​of each structural unit in the main force transmission path under the same type of working condition during the historical normal test of the cab. These stress values ​​are used as reference stress values ​​for each structural unit in the main force transmission path under this type of working condition. The reference stress values ​​of each structural unit are preprocessed, and the mean and standard deviation of the stress values ​​of each structural unit in the main force transmission path under this type of working condition are calculated. The product of the standard deviation and the preset margin coefficient is determined. The difference between the mean and the product is used as the first stress warning threshold, and the sum of the mean and the product is used as the second stress warning threshold. Based on the first and second stress warning thresholds, the stress warning interval of the structural units in the main force transmission path under each type of working condition is determined. The preset margin coefficient is a positive number not less than one. The preprocessing includes removing outliers based on the quartile method and filling missing values ​​based on the mean imputation method.

8. The lightweight optimization method for cab structure based on force path rearrangement according to claim 4, characterized in that: The logic of using the swallowing algorithm to perform iterative swallowing optimization analysis of material distribution on the independent force flow main path for each working condition is as follows: After receiving the path rearrangement signal, select the corresponding three-dimensional mesh conflict unit with a total binary value greater than one, and record each structural unit in the force flow transmission main path under the corresponding working condition that passes through the three-dimensional mesh conflict unit. Construct the force flow main path unit set with each structural unit under a single working condition, and merge the force flow main path unit sets of each working condition to construct the swallowing algorithm search space. Using all structural units within the main force flow path unit set as the initial seed unit set for the swallowing algorithm, the iterative swallowing process is executed: in each iteration step, all candidate units in the search space of the swallowing algorithm are traversed, and the stress values ​​of each candidate unit are numerically compared. The candidate unit with the largest stress value is selected as the swallowing core unit of the current iteration step. Centered on the core unit, the system performs a swallowing condition judgment on each adjacent structural unit. When the stress value of the adjacent structural unit is greater than or equal to the preset swallowing stress threshold of the current iteration step, the adjacent structural unit is recorded as a swallowing unit and marked as swallowing state. When the stress value of the adjacent structural unit is less than the preset swallowing stress threshold of the current iteration step, the adjacent structural unit is recorded as an unswallowed unit. After completing one round of swallowing operations corresponding to the current iteration step, the swallowing units that meet the swallowing conditions are included in the initial force flow main path unit set; The absorption stress threshold of the current iteration step is updated to the absorption stress threshold of the next iteration step based on the preset cooling coefficient, specifically as follows: In the formula, and These are the swallowing stress thresholds for the k-th iteration step and the (k+1)-th iteration step, respectively. The preset cooling coefficient is c∈(0,1); during multiple iteration steps of the swallowing operation, when the swallowing stress threshold is less than the preset swallowing stress lower limit threshold, the iteration is terminated, the swallowing units that satisfy the swallowing conditions of multiple iteration steps are recorded, and the standard force flow main path unit set is constructed.

9. The lightweight optimization method for cab structure based on force path rearrangement according to claim 8, characterized in that: The logic for generating the graded lightweight optimization content of the cab structure is as follows: extract the core unit and stress values ​​of each core unit in the standard force flow main path unit set; maintain the original component cross-sectional thickness of the core unit in the standard force flow main path unit set; and perform graded weight reduction operations on each core unit in the standard force flow main path unit set, specifically including: Based on the numerical value of the stress value of each phagocytic unit, they are arranged in ascending order to obtain the stress sequence of the phagocytic units. The lower quantile value and the upper quantile value in the stress sequence of the phagocytic units are extracted and used as the lower limit stress threshold and the upper limit stress threshold, respectively. The lower quantile value and the upper limit stress threshold represent the stress values ​​of the phagocytic units at the one-quarter position and three-quarters position in the stress sequence of the phagocytic units, respectively. The stress value of each swallowing unit is compared and analyzed with the lower stress threshold and the upper stress threshold. If the stress value of the corresponding swallowing unit is greater than the upper stress threshold, the original component cross-sectional thickness of the corresponding swallowing unit is maintained. If the stress value of the corresponding swallowing unit is between the lower stress threshold and the upper stress threshold, the component cross-sectional thickness of the corresponding swallowing unit is reduced by 1H. If the stress value of the corresponding swallowing unit is less than the lower stress threshold, the component cross-sectional thickness of the corresponding swallowing unit is reduced by 2H.

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