A discrete element-based simulation method for wire harness cable layout and outer diameter

Abstract

The application belongs to the field of wire harness cable layout and simulation, and specifically relates to a wire harness cable layout and outer diameter simulation calculation method based on discrete elements, which comprises the following steps: 1) all cable numbers and diameter information are obtained through a data interface or an input mode of a text editor, data validity is tested, the data are imported into a calculation system, and an import state is displayed to facilitate checking and checking; 2) according to all cable numbers and diameter information, a random position algorithm is used to simulate a random position state of the cables before wire harness binding; 3) based on the cable position state before wire harness binding and setting of a calculation assumption condition, movement of the cables in a tightening process after wire harness binding is simulated, and final coordinate values of all cables, a cable layout diagram and a wire harness outer diameter value are obtained. The application provides different engineering solutions close to actual engineering conditions, and is suitable for all cable combination conditions that can be applied in actual engineering, including combinations of any number and any size.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of wire harness cable layout and simulation, in particular to a wire harness cable layout and outer diameter simulation calculation method based on discrete elements. BACKGROUND

[0002] In the fields of aviation, automobiles, etc., there are hundreds or thousands of wire harness sections in a model, which need to be repeatedly calculated for cable layout and outer diameter in different development stages and different maturity, to support wire harness space model design and analysis (wire harness bending radius, structure perforation, space isolation distance, etc.), wire harness accessory and installation material selection (wire harness sleeve, connector tail clip, support clamp, etc.), and wire harness performance analysis and optimization (current-carrying temperature rise, electromagnetic interference, arc damage, etc.).

[0003] There are three main methods for wire harness outer diameter calculation in the current industry, among which method 2 is widely used.

[0004] 1. Diameter coefficient method: (When all cable diameters are the same and are d, it can be simplified as D = K x d), where K is the outer diameter calculation coefficient, which is obtained from the wire harness outer diameter calculation coefficient table.

[0005] 2. Area superposition method: Generally, K is taken as (square area superposition), and there are projects that take K as 1 (circle area superposition, minimum K value), 1.154, 1.2, 1.286 (which can be understood as gradually increasing the gap factor, and 1.286 is the default value of CHS electrical design software), and other different empirical values. For example, the patent entitled "Wire Harness Outer Diameter Estimation Method" with the publication number CN110879911 takes K as 1 in essence; the patent entitled "Automobile Wire Harness Outer Diameter Calculation Method, System, Medium and Equipment" with the publication number CN113836641 takes K as 1.225 to 1.265 in essence; and the paper "Research on Wire Harness Diameter Estimation Method Based on Gap Compensation" (Coaching Machine 2020. No. 1) is essentially an optimization calculation research on a certain typical K value for a certain cable combination.

[0006] 3. Arrangement and filling method: all cables in the wire harness are initially arranged in a certain order (such as diameter size), and are gradually arranged in layers or different circle layers from the inside to the outside, and the minimum envelope circle is solved. Related research includes the patent entitled "Design Method for Minimum Diameter of Multi-strand Wire Harness Sheath" with the publication number CN102184275, and the patent entitled "Outer Diameter Simulation of Aircraft Wire Harness and Outer Diameter Estimation Method of Main Wire Harness" with the publication number CN113962024.

[0007] However, there are many defects in the above three existing methods. For example, in the paper "Comparative Analysis of Calculation Methods for Wiring Harness Diameter of Civil Aircraft" (Military and Civilian Dual-Use Technology and Products 20179(2)), some values ​​of the diameter coefficient method (hereinafter referred to as method 1) and the area superposition method (hereinafter referred to as method 2) in the above background technology were analyzed and compared. The error of method 1 is relatively large, and method 2 is recommended. Although method 2 is the most widely used, its ideal K value should be different under different cable combinations. This is why there are different K values ​​in different project backgrounds. It is difficult to select a universal K value that is applicable to a wide variety of wiring harnesses. In some combinations (such as a small number of cables, large differences in cable diameters, etc.), the error in the calculation of the wiring harness diameter is large, and method 2 can only roughly calculate the wiring harness diameter and cannot obtain the corresponding cable layout at the same time.

[0008] Although the arrangement and filling method (hereinafter referred to as method 3) can simultaneously obtain the cable layout and the corresponding harness outer diameter, it has certain manual operations and restrictions on the cable layout sorting (such as arranging from large to small, etc.), and it is not easy to calculate under certain cable combinations (such as cable diameters with large differences, etc.). Therefore, it is basically not used in the industry.

[0009] In actual engineering, it can be considered that the combination of cables in the wire harness is infinite, the binding layout is completely random, and the outer diameter of the wire harness will be different under different layout conditions. When measuring the outer diameter of the wire harness, there will also be differences in different directions and positions. Because the cable insulation and sheath materials have a certain elasticity and compressibility, the outer diameter of the wire harness will also change with the tightness of the binding. Therefore, there is no single optimal solution for the outer diameter of the wire harness and the cable layout in actual engineering. What should be explored is an engineering solution that can adapt to the above multiple situations.

[0010] Therefore, based on the above-mentioned defects of the prior art, establishing a fast and accurate wiring harness cable layout and wiring harness outer diameter simulation calculation method has important engineering application value. Summary of the Invention

[0011] The present invention aims to provide a computer simulation method based on the simplified discrete element method (DEM). This method can import all the cable diameter information of the wiring harness, simulate the initial random placement of the cables during the actual wiring harness cable binding process, the bundle contraction process, and the cable movement process, and obtain different cable layouts and corresponding bundle outer diameters through multiple iterative calculations. The entire process and results can be displayed graphically in real time. In addition, auxiliary functions such as allowing the display scale to be set, allowing the manual adjustment of any cable position by dragging the graphics at the initial position and during the calculation process, and allowing the elastic overlap value between cables to be set are provided to improve the convenience, flexibility, and accuracy of the operation process.

[0012] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a wiring harness cable layout and outer diameter simulation calculation method based on discrete elements, comprising the following steps:

[0013] 1) Obtain all cable number and diameter information through data interface or input mode of text editor, perform data validity test, import into calculation system, and display import state for checking and comparing;

[0014] 2) According to all cable number and diameter information, simulate cable random position state before harness binding through random position algorithm;

[0015] 3) Based on cable position state before harness binding, set calculation assumption condition, simulate cable movement in harness binding tightening process, obtain all cable final coordinate value, cable layout diagram and harness outer diameter value.

[0016] The step 2) comprises the following steps:

[0017] 2-1) Set initial maximum outer diameter value of the harness, and display by using auxiliary operation A1;

[0018] 2-2) Traverse all cables to be placed randomly, determine the value interval [X] of the x coordinate of the cable i to be placed according to the harness outer diameter and the cable diameter, and the interval ensures that the cable position is within the harness outer diameter envelope;

[0019] 2-3) Randomly generate the x coordinate of the cable according to the value interval [X] of the x coordinate of the cable i to be placed, and initialize the value interval [Y] of the y coordinate of the cable i, which ensures that the cable position is within the harness outer diameter envelope;

[0020] 2-4) Traverse all placed cables, and determine the coordinate interval [y] between the cable i to be placed and the placed cable j that will cause interference;

[0021] 2-5) Traverse the value interval [Y] of the y coordinate of the cable i to be placed, determine the relationship between the nth value [Yn] of the interval [Y] and [y], and adjust [Yn] so as not to contain [y];

[0022] 2-6) If the value interval [Y] of the y coordinate of the cable i to be placed is empty, return to step 2-3); otherwise, randomly generate the y coordinate of the cable i in the value interval [Y] of the y coordinate, combine the x coordinate determined in step 2-3) to obtain the placement coordinate of the cable i to be placed, and place the cable according to the coordinate; if the calculation exceeds the set maximum number of iterations, [Y] is always empty, return to step 2-1) to increase the initial outer diameter of the harness;

[0023] 2-7) After random initialization of the cable position, manual adjustment of the cable position is allowed through auxiliary operation A2 to simulate the possible human adjustment in actual engineering.

[0024] The auxiliary operation A1 is adjusting the coordinate axis display scale method, by adjusting the screen resolution and the coordinate axis scale, the interval size of x and y coordinate axis is determined, and then the initial outer diameter of the wire harness is adjusted;

[0025] The auxiliary operation A2 is manual adjustment of the cable position after the random initial position and the wire harness outer diameter shrinkage calculation, the adjusted position needs to meet the following conditions:

[0026] Within the wire harness outer diameter envelope; and the contact overlap with the wire harness outer diameter envelope is within the maximum allowed value; at the same time, the contact overlap with all other cable circles is within the maximum allowed value.

[0027] In the step 2-2) to step 2-4), the value interval [X] of the x direction coordinate of the cable to be placed i is: [-(R-r i ), (R-r i )];

[0028] According to the wire harness outer diameter and the x coordinate of the cable to be placed i, the initialization of the cable y coordinate value interval [Y] is:

[0029]

[0030] When |r i -r j |> |x i -x j |, the y value interval [y] of the interference between the cable to be placed i and the placed cable j is:

[0031]

[0032] Wherein, R is the outer diameter of the wire harness, r i , x i , y i is the diameter and coordinate of the cable to be placed, r j , x j , y j is the diameter and coordinate of the placed cable.

[0033] The step 2-5) is specifically:

[0034] If the relationship between the interval [y] and the nth value interval [Yn] of the interval [Y] is: there is partial overlap, the overlapping part is cancelled;

[0035] If the relationship between the interval [y] and the nth value interval [Yn] of the interval [Y] is: Then adjust the interval [Yn] to two discontinuous intervals;

[0036] If the relationship between the interval [y] and the nth value interval [Yn] of the interval [Y] is: then the interval [Yn] is cancelled.

[0037] The calculation assumes conditions, including:

[0038] a. The cable force is only considered elastic extrusion force generated by contact overlap, not considering the boundary friction;

[0039] b. After each wire harness contraction, the cable completes each movement to the new position due to external force and is static;

[0040] c. The force between the cables is a passive conduction force, which is proportional to the overlap between the cables, and the contact force between the cables is set to equal the overlap value;

[0041] d. The contact force between the cable and the wire harness is the main driving force during movement, and the specific value needs to be calculated in combination with the cable force to ensure correct movement of the cable;

[0042] e. The position movement vector of each cable in each calculation cycle is equal to its resultant force vector.

[0043] The step 3) includes the following steps:

[0044] 3-1) gradually contract the wire harness outer diameter envelope according to the set step size, each contraction is a main calculation cycle, and the contraction step size is taken as a display pixel unit to realize process visualization and calculation accuracy; and auxiliary operation A3 is used to set the maximum allowed overlap value of the cable;

[0045] 3-2) calculate the force between all cables and the wire harness boundary after the wire harness outer diameter envelope is contracted or the cable is moved for one cycle;

[0046] 3-3) determine the calculation strategy according to the cable force and the boundary limit condition:

[0047] If all cables are not under force, or the movement calculation cycle exceeds the maximum set value, return to step 3-1), and continue to contract the wire harness outer diameter;

[0048] If there is a force on the cable, the contact overlap between the cable and the wire harness is within the maximum allowed value, and the movement calculation cycle is within the maximum set value, go to step 3-4), and move the cable to a new position;

[0049] If the contact overlap between the cable and the wire harness reaches the maximum allowed value, go to step 3-5), and the wire harness outer diameter is contracted;

[0050] 3-4) move the cable to a new position according to the force on all cables, and return to step S3-2) to recalculate the force on all cables;

[0051] 3-5) When the cable and the wire harness contact overlap reaches the maximum allowable value, the wire harness outer diameter is contracted, and the wire harness outer diameter value, all cable coordinate values, and the cable layout diagram are obtained; if the calculation result is not satisfactory, the cable position is adjusted by using the auxiliary operation A2, and then the step 3-1) is returned to perform multiple iteration calculations.

[0052] The auxiliary operation A3 is specifically:

[0053] The maximum allowable value of the cable contact overlap is set, which is defined as the maximum allowable number of pixels of the cable circle overlapping with other cable circles and the wire harness outer diameter circle, and is understood as the cable elastic value to prevent the cable from being blocked by movement.

[0054] The step 3-2) is specifically:

[0055] (1) Obtain the contact force between the cables:

[0056] The force vector of each cable is the superposition value of the force vectors of all cables in contact overlap, that is:

[0057] F a线缆间合力 +F ab +F ac +...F an

[0058] Wherein, F ab =F ba , F ac =F ca , F an =F na , and n is the number of the last cable.

[0059] (2) Obtain the contact force between the cable and the wire harness:

[0060] If the cable overlaps with the wire harness outer diameter envelope, the force direction points to the wire harness center, and the contact force value is the overlap value multiplied by the adjustment coefficient k, so as to ensure that the cable is correctly moved to the envelope track without overlapping with the wire harness; k value is transformed into a quadratic equation by the following equation, that is:

[0061] ||F a线缆间合力 +k×F a线束 +P a ||2=R-r a

[0062] Wherein, R is the wire harness outer diameter, P a , r a are the current coordinate matrix and diameter of the cable a respectively; the small value solution of the above equation is the adjacent position; the large value solution is the other side position symmetrical to the wire harness center;

[0063] (3) Obtain the total force on the cable:

[0064] The resultant force on the cable is the sum of the contact force vectors between the cables and the contact force vector between the cable and the harness, i.e.:

[0065] F a合力 = F a线缆间合力 + F a线束 .

[0066] In step 3-4, the cable is moved to a new position, i.e.:

[0067] P′ a = P a + F a合力

[0068] where P a , P′ a are the coordinates of the cable before and after movement, respectively, and F a合力 is the resultant force vector on the cable.

[0069] The present application has the following advantages and benefits:

[0070] 1. General applicability: The present application is applicable to all cable combination situations that can be applied in actual engineering, including combinations of any number and any size.

[0071] 2. Accuracy and completeness: The present application provides different engineering solutions for the outer diameter of the harness and the layout of the cables by simulating the actual harness binding process, which are close to the actual engineering situation. The solution set includes complete information such as the outer diameter of the harness, the coordinates of all cable positions, and the cable layout diagram.

[0072] 3. Operational flexibility: The present application provides auxiliary functions such as manually adjusting cable positions, setting the maximum allowed overlap value of the cables, and adjusting the display scale of the coordinate axis, which can assist the algorithm in obtaining ideal calculation results.

[0073] 4. Speed and visibility: The present application realizes the algorithm process through a computer program, and the single calculation simulation process is controlled within 1 minute. The entire calculation process and results are visualized. BRIEF DESCRIPTION OF DRAWINGS

[0074] Figure 1 The present application is based on the flowchart of the harness cable layout and outer diameter simulation calculation method;

[0075] Figure 2 The flowchart of the cable random position algorithm of the present application;

[0076] Figure 3 The example diagram of the two random position calculation results of the same cable combination of the present application;

[0077] Figure 4The principle diagram of the force between the cables in the application (typical example of the force between the cables);

[0078] Figure 5 The principle diagram of the force between the cables and the wire harness in the application (typical example of the force between the cables and the wire harness);

[0079] Figure 6 The coordinate axis proportion schematic diagram of the auxiliary method A1 in the application;

[0080] Figure 7 The effect example diagram of the embodiment of the application. DETAILED DESCRIPTION

[0081] The application will be further described in detail below in combination with the drawings and embodiments.

[0082] The scheme adopts a computer simulation method based on a simplified discrete element method (DEM) (note: the discrete element method is a numerical simulation method for predicting the motion characteristics of granular media, and is widely used in the fields of geotechnical engineering and the like), can import all cable diameter information of the wire harness, simulates the initial random placement of the cables in the actual wire harness cable binding process, the wire harness binding shrinkage and the movement process of the cables, and obtains different cable layouts and corresponding wire harness outer diameters through multiple iteration calculations, and the whole process and results can be displayed in real time in a graphical manner. In addition, auxiliary functions such as allowing to set a display proportion, allowing to manually adjust the position of any cable through graphical dragging in the initial position and during the calculation process, and allowing to set an elastic overlap value between the cables are provided, so as to improve the convenience, flexibility and accuracy of the operation process.

[0083] The specific process steps are as shown in Figure 1 The method flowchart of the wire harness cable layout and outer diameter simulation calculation based on the discrete element in the application, and the specific process steps are described as follows:

[0084] Step S1: Check and import the wire harness cable data. All cable numbers and diameter information are obtained through a data interface or a text editor and the like, data validity is checked, the data are imported into the calculation system, and the import state is displayed for checking and checking.

[0085] Step S2: Simulate the random position state of the cables before the wire harness binding. The initial maximum outer diameter value of the wire harness is set, all imported cables are randomly generated and placed in the wire harness outer diameter envelope through a random position algorithm, and the process is displayed. The process steps are described in detail in Figure 2 The coordinate value interval of the cable i to be placed is calculated as follows:

[0086] The x value interval is: [- (R-r i ), (R-r i )];

[0087] The initial y value interval is:

[0088] When |r i -r j | > |x i -x j |, the y value interval of interference between the to-be-placed cable i and the placed cable j is:

[0089] (Note: R is the outer diameter of the wire harness, r i , x i , y i are the diameter and coordinates of the to-be-placed cable, and r j , x j , y j are the diameter and coordinates of the placed cable)

[0090] To avoid insufficient wire harness envelope space leading to no space for subsequent cable placement, the initial maximum outer diameter value of the wire harness can be reasonably set (i.e., adjust the display scale through auxiliary step A1), such as aviation applications, which can typically be set to 10-100mm range according to the size of the wire harness. For details, see Figure 3 .

[0091] Step S3: Simulate the movement of the cable during the tightening process of the wire harness binding. To simplify the calculation, the following important assumptions are made by assuming that the main influencing physical factors are concerned, and the effects of secondary factors such as cable mass, friction, movement speed, movement time, etc. are ignored and simplified. The calculation assumption conditions are set as follows:

[0092] 1) All forces on the cable only consider the elastic extrusion force generated by contact overlap, and do not consider the friction between the boundaries;

[0093] 2) After each wire harness contraction, the cable completes each movement to the new position due to external force and is static;

[0094] 3) The force between the cables is a passive conduction force, which is proportional to the overlap between the cables, and the contact force value between the cables is set to be equal to the overlap value;

[0095] 4) The contact force value between the cable and the wire harness is the main driving force in the movement process, and the specific value needs to be calculated in combination with the force between the cables to ensure correct movement of the cable.

[0096] 5) The position movement vector of each cable in each calculation cycle is equal to its resultant force vector.

[0097] Step S3-1: Simulate the process of gradually tightening and contracting the wire harness. The wire harness outer diameter envelope is gradually contracted by a set step size, and each contraction is a main calculation cycle. To achieve process visualization and calculation accuracy, the contraction step size can be taken as one display pixel unit.

[0098] Step S3-2: Calculate the force situation of all cables and the bundle boundary after the bundle envelope is shrunk or the cable is moved for one cycle.

[0099] (1) Force situation of cable-cable contact: the force vector of each cable is the superposition of the force vectors of all the cables that are in contact with it. A typical example of the force situation is shown in Figure 4 , that is,

[0100] F a线缆间合力 +F ab +F ac +...; and F ab =F ba , F ac =F ca ,...

[0101] (2) Force situation of cable-bundle contact: if the cable is in contact with the bundle envelope, the force direction points to the center of the bundle, and the contact force value is the overlapping amount multiplied by the adjustment coefficient k to ensure that the cable is correctly moved to the envelope track in contact with the bundle (not overlapping). The value of k can be transformed into a quadratic equation by the following equation (the small value solution should be taken as the adjacent position; the large value solution is the other side position symmetric to the center of the bundle):

[0102] ||F a线缆间合力 +k×F a线束 +P a ||2=R-r a , where R is the outer diameter of the bundle, P a , r a are the current coordinate matrix and diameter of cable a, and a typical example of the force situation is shown in Figure 5 .

[0103] (3) Total force on the cable: the sum of the cable-cable contact force vector and the bundle contact force vector, that is,

[0104] F a合力 =F a线缆间合力 +F a线束

[0105] Step S3-3: Determine the subsequent steps according to the force situation of the cable, including:

[0106] 3-3-1) All cables are not under force, or the movement calculation cycle exceeds the maximum set value, return to step S-1, and continue to shrink the outer diameter of the bundle;

[0107] 3-3-1) There is a force situation for the cable, the cable and the bundle contact overlap is within the maximum allowed value, and the movement calculation cycle is within the maximum set value, enter step S-4, and move the cable to a new position;

[0108] 3-3-1) When the contact overlap between the cable and the wire harness reaches the maximum allowable value, go to step S3-5, and the wire harness outer diameter contraction is complete.

[0109] Step S3-4: Move the cable to a new position according to the force condition of all cables, and then go back to step S3-2 to recheck the calculation of the force condition of all cables. The calculation of the new position of the cable is as follows:

[0110] P' a = P a + F a合力

[0111] Wherein, P a , P' a are the coordinates before and after the cable moves, respectively.

[0112] Step S3-5: When the contact overlap between the cable and the wire harness reaches the maximum allowable value, the wire harness outer diameter contraction is complete, at which time the wire harness outer diameter value, all cable coordinate values, and cable layout diagram can be read. If the calculation result is not satisfactory, the cable circle position can be manually adjusted through auxiliary step A2, and then go back to step S3-1 for multiple iteration calculations.

[0113] Auxiliary step A1: Provide the function of adjusting the display scale of the coordinate axis, which is convenient for optimizing the calculation accuracy and result display. The coordinate axis origin is located at the center of the screen, and the coordinate axis scale unit is pixel / mm. For example, Figure 6 As shown in the example, the screen resolution is 1920*1080, the coordinate axis scale is 20 pixels / mm, the display coordinate axis x interval is about (-48mm, 48mm), and the y interval is about (-27mm, 27mm).

[0114] Auxiliary step A2: Provide the function of manually adjusting the cable position, which can manually adjust the cable position after the random initial position and the wire harness outer diameter contraction calculation. The adjusted position needs to meet the following conditions:

[0115] 1) Within the wire harness outer diameter envelope;

[0116] 2) The contact overlap with the wire harness outer diameter envelope is within the maximum allowable value;

[0117] 3) The contact overlap with all other cable circles is within the maximum allowable value.

[0118] Auxiliary step A3: provide a function of setting the maximum allowed value of cable contact overlap (understood as the elasticity of the cable). The cable actually has a certain elasticity and can be deformed and compressed. If it is a purely rigid object, it will cause movement to be blocked. To solve this problem, the "maximum allowed overlap value" parameter is introduced in the calculation, which is defined as the maximum allowed number of pixels of the overlap between the cable circle and other cable circles and the outer diameter circle of the cable bundle. If the coordinate axis scale is 20 pixels / mm and the maximum allowed overlap is 5 pixels, the actual maximum allowed overlap can be converted to 0.25 mm. The larger the allowed overlap value, the more conducive to the movement between the cables and the contraction calculation of the cable bundle, but too large overlap may deviate from the actual situation and cause the result to be distorted. It is recommended to calculate in combination with the manual adjustment of the cable position function.

[0119] The final implementation effect example of the scheme is shown in Figure 7 For the cable bundle of 52 cable combinations, the two random calculation layout results correspond to the outer diameters of the cable bundle of 35.7 mm and 35.5 mm, respectively.

[0120] In summary, the technical key points of the application are:

[0121] 1. The cable position is initialized by the efficient random position algorithm to simulate the random position state of the cable before the cable bundle is tied.

[0122] 2. The discrete element method application assumption condition is set reasonably to ignore and simplify the secondary physical impact factors, calculate and simulate the cable stress and movement, simulate the envelope shrinkage of the cable bundle and the movement process of the cable during the cable bundle tying process.

[0123] 3. The input data checking, calculation simulation process, and movement state real-time display are realized by computer, and finally the effective engineering data such as the outer diameter of the cable bundle, the position coordinates of all cables, and the cable layout diagram under different cable layouts can be obtained.

[0124] 4. The manual adjustment of the cable position is allowed to simulate the possible human adjustment in the actual engineering.

[0125] 5. The maximum allowed overlap value of the cable is allowed to be set to simulate the elastic deformation and shrinkage of the cable.

[0126] 6. The coordinate axis display scale is allowed to be set to realize the effective calculation accuracy and display effect.

[0127] Therefore, combined with the key technical points of the application, the rapid and accurate cable bundle layout and cable bundle outer diameter simulation calculation method realized by the application has important engineering application value.

[0128] Those skilled in the art can understand that the above description is only the preferred embodiment of the present application, and the features described in various embodiments of the present disclosure and / or claims can be combined or combined, even if such combination or combination is not explicitly described in the present disclosure. It is not intended to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacement for part of the technical features, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0129] Although preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to these embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application. Obviously, those skilled in the art can make various modifications and changes to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and changes of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and changes.

Claims

1. A method for simulating and calculating wiring harness cable layout and outer diameter based on discrete elements, characterized in that: The following steps are involved: 1) Obtain all cable numbers and diameters through the data interface or text editor, perform data validity verification, import them into the calculation system, and display the import status for easy inspection and verification; 2) Based on the number and diameter information of all cables, a random position algorithm is used to simulate the random position state of the cables before the harness is tied; 3) Based on the cable position status before the harness is tied and the calculation assumptions are set, the movement of the cables during the harness tightening process is simulated to obtain the final coordinate values ​​of all cables, the cable layout diagram, and the outer diameter of the harness; The step 3) comprises the following steps: 3-1) Gradually shrink the outer diameter envelope of the harness according to the set step size. Each shrinkage is a main calculation cycle. To achieve process visualization and calculation accuracy, the shrinkage step size is one display pixel unit. And use auxiliary operation A3 to set the maximum allowable cable overlap value; 3-2) Calculate the stress between all cables and on the boundaries of the harness after the outer diameter envelope of the harness shrinks or the cables move for one cycle; 3-3) Determine the calculation strategy based on the cable stress conditions and boundary constraints: If all cables are not stressed, or the movement calculation cycle exceeds the maximum set value, return to step 3-1) and the outer diameter of the harness continues to shrink; If the cable is under stress, the cable and harness contact overlap is within the maximum allowable value, and the movement calculation cycle is within the maximum set value, proceed to step 3-4) and move the cable to the new position; If the contact and overlap between the cable and the harness reaches the maximum allowable value, proceed to step 3-5) and the outer diameter of the harness is shrunk; 3-4) moving the cables to new positions based on the stress conditions of all cables, and returning to step S3-2) to recalculate the stress conditions of all cables; 3-5) When the overlap between the cables and the harness reaches the maximum allowable value, the harness outer diameter is completely shrunk, and the harness outer diameter value, all cable coordinate values, and cable layout diagram are obtained. If the calculation results are not satisfactory, adjust the cable position through auxiliary operation A2 and return to step 3-1) for multiple iterative calculations.

2. The method for simulating and calculating wiring harness cable layout and outer diameter based on discrete elements according to claim 1, characterized in that: The step 2) comprises the following steps: 2-1) Set the initial maximum outer diameter of the harness and display it using auxiliary operation A1; 2-2) Traverse all cables to be randomly placed, and determine the x-coordinate value interval [X] of the cable to be placed i based on the outer diameter of the harness and the cable diameter. This interval ensures that the cable position is within the outer diameter envelope of the harness; 2-3) Randomly generate the x-coordinate of the cable i to be placed according to the x-coordinate value interval [X], and initialize the y-coordinate value interval [Y] of the cable i, which ensures that the cable position is within the outer diameter envelope of the harness; 2-4) Traverse all placed cables and determine the coordinate interval [y] where the cable to be placed i will interfere with the already placed cable j; 2-5) Traverse the y-coordinate value interval [Y] of the cable to be placed i, determine the relationship between the n-th segment value [Yn] of the interval [Y] and [y], and adjust [Yn] so that it does not include [y]; 2-6) If the y-coordinate value interval [Y] of the cable to be placed i is an empty set, return to step 2-3); otherwise, randomly generate the y-coordinate of cable i within the y-coordinate value interval [Y], and combine it with the x-coordinate determined in step 2-3) to obtain the placement coordinates of cable i to be placed, and place the cable according to the coordinates; if the calculation exceeds the set maximum number of loops, [Y] is always an empty set, and return to step 2-1) to increase the initial outer diameter of the harness; 2-7) After the cable position is randomly initialized, manual adjustment of the cable position is allowed through auxiliary operation A2 to simulate the human adjustment that may exist in actual engineering.

3. The method for simulating and calculating wiring harness cable layout and outer diameter based on discrete element method according to claim 2, characterized in that: The auxiliary operation A1 is to adjust the coordinate axis display ratio method, by adjusting the screen resolution and the coordinate axis ratio, determine the interval size of the x and y coordinate axes, and then adjust the initial outer diameter of the wire harness; The auxiliary operation A2 is to manually adjust the cable position after the random initial position and the calculation of the harness outer diameter shrinkage. The adjusted position must meet the following conditions: Within the outer diameter envelope of the harness; and the contact overlap with the outer diameter envelope of the harness is within the maximum allowable value; at the same time, the contact overlap with all other cable circles is within the maximum allowable value.

4. The method for simulating and calculating wiring harness cable layout and outer diameter based on discrete elements according to claim 2, characterized in that: In the steps 2-2) to 2-4): The value range [X] of the x-direction coordinate of the cable i to be placed is: [-(Rr i ),(Rr i )]; According to the outer diameter of the harness and the x-coordinate of the cable i to be placed, the cable y-coordinate value range [Y] is initialized as: When | r i -r j |>|x i -x j |, the y value range [y] where the cable to be placed i interferes with the placed cable j is: Among them, R is the outer diameter of the harness, r i 、x i 、y i is the diameter and coordinates of the cable to be placed, r j 、x j 、y j are the diameter and coordinates of the placed cables.

5. The method for simulating and calculating wiring harness cable layout and outer diameter based on discrete elements according to claim 2, characterized in that: The steps 2-5) are specifically: If the relationship between interval [y] and the nth segment value [Yn] of interval [Y] is: there is partial overlap, then the overlapping part is cancelled; If the relationship between the interval [y] and the nth value [Yn] of the interval [Y] is: Then the adjustment interval [Yn] is two discontinuous intervals; If the relationship between the interval [y] and the nth value [Yn] of the interval [Y] is: Then cancel the interval [Yn].

6. The method for simulating and calculating wiring harness cable layout and outer diameter based on discrete elements according to claim 1, characterized in that: The calculation assumptions include: a. All forces acting on the cable only consider the elastic extrusion force caused by contact overlap, and do not consider the friction between boundaries; b. Each time the harness is retracted, the cable moves to a new position due to external force and stops; c. The force between cables is a passive conductive force. Since its value is proportional to the overlap between cables, the contact force between cables is set equal to the overlap value. d. The contact force between the cable and the harness is the main driving force of the movement process. The specific value needs to be calculated based on the force between the cables to ensure the correct movement of the cables. e. The position movement vector of the cable in each calculation cycle is equal to its resultant force vector.

7. The method for simulating and calculating wiring harness cable layout and outer diameter based on discrete element method according to claim 1, characterized in that: The auxiliary operation A3 is specifically as follows: Set the maximum allowed cable contact overlap value. This value is defined as the maximum number of pixels that a cable circle can overlap with other cable circles and the outer diameter of the harness. It is also understood as the cable elasticity value to prevent cable movement from getting stuck.

8. The method for simulating and calculating wiring harness cable layout and outer diameter based on discrete elements according to claim 1, characterized in that: The step 3-2) is specifically as follows: (1) Obtaining the contact force between cables: The resultant force vector on each cable is the superposition of the force vectors of all cables that are in contact with or overlap with other cables, that is: F a线缆间合力 =F ab +F ac +...F an Among them, F ab =F ba , F ac =F ca , F an =F na , n is the number of the last cable; (2) Obtain the contact force between the cable and the harness: If the cable contacts and overlaps the outer diameter of the harness, the force is directed toward the center of the harness. The contact force is the overlap value multiplied by the adjustment factor k to ensure that the cable moves correctly to the envelope track that contacts and does not overlap the harness. The k value is converted into a quadratic equation by the following equation: ||F a线缆间合力 +k×F a线束 +P a ||2=R-r a Among them, R is the outer diameter of the harness, P a 、r a are the current coordinate matrix and diameter of cable a respectively; the smaller value solution of the above formula is the adjacent position; the larger value solution is the position on the other side symmetrical with respect to the center of the harness; (3) Obtain the resultant force on the cable: The resultant force acting on the cable is the sum of the contact force vector between the cables and the contact force vector of the harness, that is: F a合力 =F a线缆间合力 +F a线束 Among them, F a线束 is the harness contact force vector.

9. The method for simulating and calculating wiring harness cable layout and outer diameter based on discrete elements according to claim 1, characterized in that: In step 3-4), the cable is moved to a new location, that is: P' a =P a +F a合力 Among them, P a 、P' a are the coordinates before and after the cable moves, F a合力 is the vector of the resultant force acting on the cable.

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