A design method for bicycle transmission assembly

Abstract

The present invention belongs to the technical field of computer-aided design, and provides a design method for a bicycle transmission component, wherein a finite element model is obtained by meshing a three-dimensional model of the bicycle transmission component; a load is loaded onto the finite element model to construct a constrained finite element model and obtain a stress cloud map; stress concentration areas and stress relaxation areas are marked on the three-dimensional model according to the stress cloud map; it is determined whether each stress concentration area and stress relaxation area has a negative correlation; the stress concentration area and stress relaxation area that have a negative correlation are adjusted to obtain an optimized three-dimensional model of the bicycle transmission component; the screening accuracy of the concentration-relaxation pair is improved, and the stress concentration and stress relaxation areas are balanced. Not only the yield strength, hardness, fatigue strength, and fatigue crack propagation resistance of the semi-finished transmission component are improved, but also the corresponding quality of the transmission component whose thickness cannot be adjusted in the finished product that has been produced can be guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of computer-aided design, and in particular relates to a design method for a bicycle transmission component. Background Art

[0002] The transmission system of a bicycle, also known as the power transmission system, is mainly composed of key components such as sprockets, chains and transmissions. The sprocket is fixed to the pedals and works closely with the chain that wraps around the rear wheel gear. When the rider pedals, the sprocket rotates, driving the rear wheel to rotate and achieving efficient power transmission. The transmission between the chain and the sprocket depends on the mutual meshing of their tooth structures. In the transmission system of a bicycle, a large number of chain links are used, so the contact relationship between the chain links and the sprockets needs to be accurately calculated. When the shape of the chain links changes, it takes a lot of time to recreate a new model for simulation, especially when complex contact definitions are performed. Through custom development, chain links of different shapes, sprocket installation angles, and tolerances between sprockets and pins can be effectively modeled, simulated, and analyzed.

[0003] In the design of bicycle transmission components, in the early stage of simulation, the requirements of load and speed for bicycle transmission components are not prominent. However, with the long-term use of bicycle transmission components, the problems of stress concentration and stress relaxation make the discontinuity in the chain transmission of bicycle transmission components gradually obvious, resulting in high stress in the pin hole recess and chain link body of bicycle transmission components. What's more, if the chain link line falls below the sprocket link line, the chain will move up and down when meshing, which will cause it to produce strong vibrations when running at high speed. In the long run, the yield strength, hardness, fatigue strength and fatigue crack growth resistance of the transmission component material will all decrease to varying degrees. These reasons lead to the need to increase the load and speed capacity at the locations of stress concentration and stress relaxation in the design of bicycle transmission components. Summary of the invention

[0004] The purpose of the present invention is to provide a design method for a bicycle transmission assembly to solve one or more technical problems existing in the prior art and at least provide a beneficial choice or create conditions.

[0005] In order to achieve the above object, according to one aspect of the present invention, a method for designing a bicycle transmission assembly is provided, the method comprising the following steps:

[0006] S100, inputting a three-dimensional model of a bicycle transmission assembly;

[0007] S200, meshing the three-dimensional model to obtain a finite element model;

[0008] S300, loading the load onto the finite element model to construct a constrained finite element model and obtain a stress contour map;

[0009] S400, marking the stress concentration area and stress relaxation area on the three-dimensional model according to the stress cloud map;

[0010] S500, determining whether each stress concentration region and each stress relaxation region have a negative correlation;

[0011] S600, adjusting the stress concentration area and the stress relaxation area that generate negative correlation to obtain optimized three-dimensional models of the bicycle transmission component.

[0012] Further, in S100, the three-dimensional model of the bicycle transmission assembly is a three-dimensional model of the bicycle transmission assembly made by 3D mapping software or a three-dimensional model of the bicycle transmission assembly acquired by a three-dimensional scanner, and the bicycle transmission assembly includes a chain, a chain ring, and a flywheel.

[0013] Furthermore, the bicycle transmission assembly also includes a transmission, a crank, and a flywheel.

[0014] Among them, the three-dimensional scanner is a handheld three-dimensional scanner.

[0015] Furthermore, in S300, the method of loading a load onto a finite element model to construct a constrained finite element model and obtain a stress cloud map is as follows: importing the finite element model into finite element software, inputting material properties, loading a load onto the finite element model to construct a constrained finite element model, and performing static stress finite element analysis to obtain a stress cloud map.

[0016] Among them, material properties include data such as material, safety factor of variable loads, and structural importance factor of steel structure.

[0017] Preferably, the material is steel structural material.

[0018] Preferably, the steel structure material is Q355B low alloy high strength steel. According to GB / T 1591 standard, the yield limit of the material is: σs≥355 MPa (steel plate thickness t≤16mm); σs≥345 MPa (steel plate thickness t﹥16~40mm); σs≥335 MPa (steel plate thickness t﹥40~63mm), σs represents the yield strength (yield limit) of the steel.

[0019] According to GB / T 50017 "Code for Design of Steel Structures", for steel structures calculated according to the ultimate limit state of bearing capacity, the safety factor of variable load is: γ=0.9*1.4=1.26;

[0020] The structural importance coefficient of the steel structure is: γ0 = 0.95;

[0021] Preferably, for steel plates of different thicknesses, the strength design values ​​are:

[0022] [σs]≥298MPa (steel plate thickness t≤16mm); [σs]≥292MPa (steel plate thickness t﹥16~40mm);

[0023] [σs]≥279MPa (steel plate thickness t﹥40~63mm), σs represents the yield strength (yield limit) of steel.

[0024] Among them, the finite element software is Abaqus software or Ansys software.

[0025] Preferably, the total vertical load of the three-dimensional model of the bicycle transmission assembly under the transmission condition is calculated by finite element software, and the load is loaded onto the finite element model to construct a constrained finite element model under the transmission condition and output a stress cloud diagram.

[0026] Preferably, when applying load constraints, the finite element software takes the contact surface of the chain, flywheel and chain ring under the transmission condition as the load constraint application area.

[0027] Further, in S400, the method of marking the stress concentration area and the stress relaxation area on the three-dimensional model according to the stress cloud map is as follows: graying the stress cloud map to obtain a grayscale image, using a watershed algorithm to obtain multiple dividing lines from the grayscale image, dividing the grayscale image into multiple load areas according to each dividing line, recording the average grayscale value of all points on the grayscale image as the average grayscale; recording the load area in each load area where the average grayscale value of all points is greater than the average grayscale as the stress concentration area; recording the load area in each load area where the average grayscale value of all points is less than the average grayscale as the stress relaxation area.

[0028] Among them, in the grayscale image obtained by graying the stress cloud map, the stress concentration area tends to be brighter, while the stress relaxation area tends to be darker. Therefore, the stress concentration and stress relaxation areas after bearing the load are automatically and roughly screened out.

[0029] As the vertical total load simulation is applied to the bicycle transmission component for a period of time, the various stress concentration areas and stress relaxation areas on the three-dimensional model generally appear in pairs. When stress concentration occurs at a certain position of the bicycle transmission component due to metal fatigue, deformation or fatigue crack extension inside the metal, stress relaxation is likely to occur at another place. For example, a depression (stress relaxation) occurs in one place and a corresponding bulge (stress concentration) occurs in another place with a high probability. Since the two phenomena of stress concentration and stress relaxation are difficult to be monitored or discovered by simulation with a small load when the stress change is small or the change amplitude is not obvious, the present application solves this problem by judging whether the stress concentration area and the stress relaxation area have a negative correlation (a positive correlation means no stress concentration and stress relaxation), thereby determining whether these two positions need to be optimized, thereby improving the life and stability of the bicycle transmission component. The specific method includes:

[0030] Further, in S500, the method for determining whether each stress concentration region and each stress relaxation region have a negative correlation includes: obtaining stress values ​​borne by each stress concentration region and each stress relaxation region according to the stress cloud map; (the stress values ​​borne by the stress concentration region and each stress relaxation region are the average values ​​of the stress values ​​borne by all points in the stress concentration region or the stress relaxation region);

[0031] Each stress concentration region and stress relaxation region is respectively formed into a concentration relaxation pair, and the specific method is: the average stress value of each point in the current stress concentration region is taken as the current stress concentration mean; the stress relaxation region with the smallest absolute value of the difference between the average stress value of each point in each stress relaxation region and the current stress concentration mean is formed into a concentration relaxation pair with the current stress concentration region;

[0032] For each concentrated relaxation pair, if the stress concentration area and the stress relaxation area therein meet the concentrated relaxation condition, it is determined that the concentrated relaxation pair has a positive association, otherwise it is determined that the concentrated relaxation pair has a negative association.

[0033] The concentrated relaxation condition is:

[0034] The AP is the point position of the maximum stress value in the stress concentration region of the concentrated relaxation pair, the BP is the point position of the maximum stress value in the stress relaxation region of the concentrated relaxation pair, and the direction from AP to BP is the stress relaxation direction of the concentrated relaxation pair;

[0035] A straight line passing through a point with the maximum stress value on the boundary of the stress concentration region and a point with the maximum stress value on the boundary of the stress relaxation region is taken as the first straight line; a straight line passing through a point with the minimum stress value on the boundary of the stress concentration region and a point with the minimum stress value on the boundary of the stress relaxation region is taken as the second straight line; the projection area of ​​the area between the first straight line and the second straight line on the stress cloud diagram is recorded as a stress relaxation strip; (a stress relaxation strip is an area between the stress concentration region and the stress relaxation region that gradually develops from stress concentration to stress relaxation along the stress relaxation direction, and the probability of its stress change being a linear change in the stress relaxation direction is relatively high, and the probability of stress in other areas showing a linear change is relatively low relative to the stress relaxation strip. According to this characteristic, the strip area can reflect the change area where the stress across the concentration relaxation pair is connected, thereby ensuring the subsequent finite element continuity judgment);

[0036] For each finite element in the stress relaxation strip, if there is a finite element whose stress value is less than the stress value of a finite element before the finite element in the stress relaxation direction, and the stress value of the finite element is less than the stress value of a finite element after the finite element in the stress relaxation direction, then it is recorded that the stress concentration area and the stress relaxation area do not meet the concentrated relaxation condition; otherwise, it is recorded that the stress concentration area and the stress relaxation area meet the concentrated relaxation condition.

[0037] Among them, the concentrated relaxation condition can accurately reflect whether the stress concentration area and the stress relaxation area in each concentrated relaxation pair produce two areas of stress balance. If the concentrated relaxation condition is met, the concentrated relaxation pair produces mechanical stress balance. Due to the mechanical balance, it is not easy to produce stress concentration or stress relaxation on the actual transmission component. If it is a mechanical imbalance, it is easy to produce stress concentration or stress relaxation on the actual transmission component. However, if the stress conduction direction on the stress relaxation strip is close in size to the stress concentration area and the stress relaxation area, it is still easy to have local nonlinear discontinuous stress conduction problems in stress conduction. Therefore, by simply judging the size of the finite element stress value, it is easy to identify the position of these discontinuous points, resulting in misidentification of the concentrated relaxation condition, thereby reducing the screening accuracy of the negatively associated concentrated relaxation pair. In order to solve this problem, the present application proposes the following method, which improves the recognition accuracy of the concentrated relaxation condition by performing relaxation correction compensation on the stress in the stress conduction direction. The specific method is:

[0038] Preferably, the concentrated relaxation condition is:

[0039] The AP is the point position of the maximum stress value in the stress concentration region of the concentrated relaxation pair, the BP is the point position of the maximum stress value in the stress relaxation region of the concentrated relaxation pair, and the direction from AP to BP is the stress relaxation direction of the concentrated relaxation pair;

[0040] A straight line passing through a point with the maximum stress value on the boundary of the stress concentration region and a point with the maximum stress value on the boundary of the stress relaxation region is taken as the first straight line; a straight line passing through a point with the minimum stress value on the boundary of the stress concentration region and a point with the minimum stress value on the boundary of the stress relaxation region is taken as the second straight line; the projection area of ​​the area between the first straight line and the second straight line on the stress cloud diagram is taken as the stress relaxation bar;

[0041] For each finite element in the stress relaxation strip, calculate the relaxation correction stress value, select the finite element with the largest stress value from the first finite element in the stress relaxation strip to the current finite element and record it as the maximum finite element; select the finite element with the smallest stress value from the first finite element in the stress relaxation strip to the current finite element and record it as the minimum finite element; record the position number of the maximum finite element in each finite element in the stress relaxation strip as AMax; record the position number of the minimum finite element in each finite element in the stress relaxation strip as AMin; take the average value of the stress values ​​of all finite elements from the position number of the current finite element to Amax in the stress relaxation strip as AMaxStr; take the average value of the stress values ​​of all finite elements from the position number of the current finite element to AMin in the stress relaxation strip as AMinStr; take the stress value of the current finite element as CStr; take the difference between AMaxStr and AMinStr as the relaxation correction difference; record the relaxation correction stress value of the current finite element as the sum of CStr and the relaxation correction difference;

[0042] For each finite element in the stress relaxation strip, if there is a finite element whose relaxation-corrected stress value is smaller than the relaxation-corrected stress value of a finite element before the finite element in the stress relaxation direction, and the relaxation-corrected stress value of the finite element is smaller than the relaxation-corrected stress value of a finite element after the finite element in the stress relaxation direction, then it is recorded that the stress concentration area and the stress relaxation area do not satisfy the concentrated relaxation condition; otherwise, it is recorded that the stress concentration area and the stress relaxation area satisfy the concentrated relaxation condition.

[0043] Since the concentrated relaxation that produces negative correlation on the transmission component structure has an unbalanced effect on the transmission of stress, it is necessary to fine-tune the thickness of the area with greater stress concentration in the concentrated relaxation that produces negative correlation according to the area with less stress concentration, so as to balance the stress concentration and stress relaxation, thereby improving the yield strength, hardness, fatigue strength, and fatigue crack growth resistance. The specific method is:

[0044] Furthermore, in S600, the method of adjusting the negatively correlated stress concentration area and the stress relaxation area to obtain the optimized three-dimensional model of the bicycle transmission assembly includes:

[0045] The center point of the stress concentration area that produces negative correlation is denoted as CP1 and the center point of the stress relaxation area is denoted as CP1;

[0046] If the stress value of the stress concentration area that produces a negative correlation is greater than the stress value of the stress relaxation area, the stress concentration area is taken as the adjustment area and the stress relaxation area is taken as the output area; if the stress value of the stress concentration area that produces a negative correlation is less than the stress value of the stress relaxation area, the stress concentration area is taken as the output area and the stress relaxation area is taken as the adjustment area;

[0047] The highest point in the output area on the three-dimensional model is recorded as the highest output point, and the lowest point in the output area is recorded as the lowest output point; the point with the largest stress value in the corresponding position of the adjustment area on the three-dimensional model is recorded as the defect midpoint; the average thickness of the triangular area formed by the defect midpoint, the highest output point, and the lowest output point is taken as the output thickness. If the average thickness of the adjustment area is less than the output thickness, the thickness of the adjustment area is adjusted to the output thickness;

[0048] After making the above adjustments to all stress concentration areas and stress relaxation areas that produce negative correlations, the optimized three-dimensional model of the bicycle transmission component is obtained.

[0049] In order to ensure the yield strength, hardness, fatigue strength and fatigue crack growth resistance of the transmission components whose thickness cannot be adjusted in the finished products, the above method is not applicable to the finished products, but only to the semi-finished products of the transmission components. The specific method for the finished products is as follows:

[0050] Preferably, in S600, the method of adjusting the negatively correlated stress concentration area and the stress relaxation area to obtain the optimized three-dimensional model of the bicycle transmission assembly includes:

[0051] The center point of the stress concentration area that produces negative correlation is denoted as CP1 and the center point of the stress relaxation area is denoted as CP1;

[0052] If the stress value of the stress concentration area that produces a negative correlation is greater than the stress value of the stress relaxation area, the stress concentration area is taken as the adjustment area and the stress relaxation area is taken as the output area; if the stress value of the stress concentration area that produces a negative correlation is less than the stress value of the stress relaxation area, the stress concentration area is taken as the output area and the stress relaxation area is taken as the adjustment area;

[0053] The highest point in the output area on the three-dimensional model is recorded as the highest output point, and the lowest point in the output area is recorded as the lowest output point; the point with the largest stress value in the corresponding position of the adjustment area on the three-dimensional model is recorded as the defect midpoint; the average thickness of the triangular area formed by the defect midpoint, the highest output point, and the lowest output point is taken as the output thickness. If the average thickness of the adjustment area is less than the output thickness, the adjustment area is marked as the area to be strengthened;

[0054] After marking all stress concentration areas and stress relaxation areas that produce negative correlation as above, the optimized three-dimensional model of the bicycle transmission component is obtained.

[0055] Preferably, when the bicycle transmission assembly is produced according to the three-dimensional model of the bicycle transmission assembly, laser shock processing is performed on the marked area to be strengthened at a position corresponding to the bicycle transmission assembly.

[0056] The center point means the geometric center of gravity or the geometric center.

[0057] The present invention also provides a bicycle transmission component design system, the bicycle transmission component design system comprises: a processor, a memory, and a computer program stored in the memory and executable on the processor, the processor implements the steps in the bicycle transmission component design method when executing the computer program, the bicycle transmission component design system can be run in computing devices such as desktop computers, notebook computers, PDAs, and cloud data centers, and the executable system may include, but is not limited to, a processor, a memory, and a server cluster, and the processor executes the computer program to run in the following system units:

[0058] An underground space acquisition unit is used to acquire underground space exploration data of the area to be constructed acquired by ground penetrating radar to perform three-dimensional modeling to obtain a three-dimensional model of the underground space;

[0059] A three-dimensional modeling unit, used for inputting a three-dimensional model of a bicycle transmission assembly;

[0060] A meshing unit is used to mesh the three-dimensional model to obtain a finite element model;

[0061] Stress simulation unit, used to load the finite element model to construct a constrained finite element model and obtain a stress cloud diagram;

[0062] A stress marking unit is used to mark stress concentration areas and stress relaxation areas on the three-dimensional model according to the stress cloud map;

[0063] A correlation judgment unit is used to judge whether each stress concentration area and stress relaxation area has a negative correlation;

[0064] The model optimization unit is used to adjust the stress concentration area and the stress relaxation area that produce negative correlation to obtain the optimized three-dimensional model of the bicycle transmission component.

[0065] The beneficial effects of the present invention are as follows: the present invention provides a design method for a bicycle transmission assembly, which can improve the screening accuracy of concentrated relaxation pairs and balance the stress concentration and stress relaxation areas. It not only improves the yield strength, hardness, fatigue strength, and fatigue crack growth resistance of the semi-finished transmission assembly, but also ensures the corresponding quality of the transmission assembly whose thickness cannot be adjusted in the finished product. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The above and other features of the present invention will become more obvious by describing in detail the embodiments shown in the accompanying drawings. The same reference numerals in the accompanying drawings of the present invention represent the same or similar elements. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other accompanying drawings can be obtained based on these accompanying drawings without creative work. In the accompanying drawings:

[0067] Figure 1 Shown is a flow chart of a method for designing a bicycle transmission assembly;

[0068] Figure 2 The grayscale image obtained by graying the stress cloud map of the bicycle transmission component is shown;

[0069] Figure 3 Shown is a finite element diagram of a finite element model of a bicycle transmission assembly;

[0070] Figure 4 Shown is a design system structure diagram of a bicycle transmission component. DETAILED DESCRIPTION

[0071] The following will be combined with the embodiments and drawings to clearly and completely describe the concept, specific structure and technical effects of the present invention, so as to fully understand the purpose, scheme and effect of the present invention. It should be noted that the embodiments and features in the embodiments of this application can be combined with each other without conflict.

[0072] Example 1

[0073] like Figure 1 The figure shows a flow chart of a design method for a bicycle transmission assembly. Figure 1 A method for designing a bicycle transmission assembly according to an embodiment of the present invention is described below. The method comprises the following steps:

[0074] S100, inputting a three-dimensional model of a bicycle transmission assembly;

[0075] S200, meshing the three-dimensional model to obtain a finite element model;

[0076] S300, loading the load onto the finite element model to construct a constrained finite element model and obtain a stress contour map;

[0077] S400, marking the stress concentration area and stress relaxation area on the three-dimensional model according to the stress cloud map;

[0078] S500, determining whether each stress concentration region and each stress relaxation region have a negative correlation;

[0079] S600, adjusting the stress concentration area and the stress relaxation area that generate negative correlation to obtain optimized three-dimensional models of the bicycle transmission component.

[0080] Further, in S100, the three-dimensional model of the bicycle transmission assembly is a three-dimensional model of the bicycle transmission assembly made by 3D mapping software or a three-dimensional model of the bicycle transmission assembly acquired by a three-dimensional scanner, and the bicycle transmission assembly includes a chain, a chain ring, and a flywheel.

[0081] Among them, the three-dimensional scanner is a handheld three-dimensional scanner.

[0082] Furthermore, in S300, the method of loading a load onto a finite element model to construct a constrained finite element model and obtain a stress cloud map is as follows: importing the finite element model into finite element software, inputting material properties, loading a load onto the finite element model to construct a constrained finite element model, and performing static stress finite element analysis to obtain a stress cloud map.

[0083] Among them, material properties include data such as material, safety factor of variable loads, and structural importance factor of steel structure.

[0084] Preferably, the material is steel structural material.

[0085] Preferably, the steel structure material is Q355B low alloy high strength steel. According to GB / T 50017 "Code for Design of Steel Structures", for steel structures calculated according to the ultimate limit state of bearing capacity, the safety factor of variable load is: γ=0.9*1.4=1.26;

[0086] The structural importance coefficient of the steel structure is: γ0 = 0.95;

[0087] Preferably, for steel plates of different thicknesses, the strength design values ​​are:

[0088] [σs]≥298MPa (steel plate thickness t≤16mm); [σs]≥292MPa (steel plate thickness t﹥16~40mm);

[0089] [σs]≥279MPa (steel plate thickness t﹥40~63mm), σs represents the yield strength (yield limit) of steel.

[0090] Among them, the finite element software is Abaqus software.

[0091] Preferably, the total vertical load of the three-dimensional model of the bicycle transmission assembly under the transmission condition is calculated by finite element software, and the load is loaded onto the finite element model to construct a constrained finite element model under the transmission condition and output a stress cloud diagram.

[0092] Preferably, when applying load constraints, the finite element software takes the contact surface of the chain, flywheel and chain ring under the transmission condition as the load constraint application area.

[0093] Further, in S400, the method of marking the stress concentration area and the stress relaxation area on the three-dimensional model according to the stress cloud map is as follows: graying the stress cloud map to obtain a grayscale image, using a watershed algorithm to obtain multiple dividing lines from the grayscale image, dividing the grayscale image into multiple load areas according to each dividing line, recording the average grayscale value of all points on the grayscale image as the average grayscale; recording the load area in each load area where the average grayscale value of all points is greater than the average grayscale as the stress concentration area; recording the load area in each load area where the average grayscale value of all points is less than the average grayscale as the stress relaxation area.

[0094] Among them, the key source code described in C# language for the specific implementation of the method of marking stress concentration areas and stress relaxation areas on the three-dimensional model according to the stress cloud map is:

[0095] Class StressAnalysis

[0096] {public static void ProcessStressImage(stringinputImagePath)

[0097] { / / Read stress cloud map

[0098] Image<Bgr,Byte> originalImage=newImage<Bgr,Byte> (inputImagePath);

[0099] / / Convert to grayscale image

[0100] Image<Gray,Byte> grayImage=originalImage.Convert<Gray,Byte> ();

[0101] / / Apply the watershed algorithm to obtain the dividing line

[0102] Matmarkers = newMat();

[0103] CvInvoke.Threshold(grayImage,markers,0,255,ThresholdType.BinaryInv|ThresholdType.Otsu);

[0104] CvInvoke.MorphologyEx(markers,markers,MorphOp.Dilate,Mat.Ones(newSize(3,3),DepthType.Cv8U),newPoint(-1,-1),1);

[0105] / / Find the contour

[0106] VectorOfVectorOfPointcontours=newVectorOfVectorOfPoint();

[0107] Mathierarchy = newMat();

[0108] CvInvoke.FindContours(markers,contours,hierarchy,RetrType.List,ChainApproxMethod.ChainApproxSimple);

[0109] / / Divide the load area and calculate the mean

[0110] List <float>meanGrayValues=newList <float>();

[0111] Float totalGrayValue=0;

[0112] int totalPoints=0;

[0113] for(int i = 0; i <contours.Size;i++)

[0114] {var contour=contours[i];

[0115] if(contour.Size>0)

[0116] { / / Create a mask

[0117] Matmask=newMat(grayImage.Size,DepthType.Cv8U,0);

[0118] CvInvoke.DrawContours(mask,contours,i,newMCvScalar(255),-1);

[0119] / / Calculate the average gray value of the current area

[0120] MCvScalarmeanValue=CvInvoke.Mean(grayImage,mask);

[0121] Float meanGray=(float)meanValue.V0;

[0122] meanGrayValues.Add(meanGray);

[0123] totalGrayValue+=meanGray*CvInvoke.CountNonZero(mask);

[0124] totalPoints+=CvInvoke.CountNonZero(mask);}}

[0125] / / Calculate the total average grayscale

[0126] Float averageGray=totalGrayValue / totalPoints;

[0127] / / Classify the area according to the average grayscale

[0128] List <int>stressCRs=newList <int>();

[0129] List <int>stressRelaxationRegions=newList <int>();

[0130] for(int i = 0; i <meanGrayValues.Count;i++)

[0131] {if(meanGrayValues[i]>averageGray)

[0132] {stressCRs.Add(i); / / Get the stress concentration area

[0133] }else{stressRelaxationRegions.Add(i);}} / / Stress relaxation region acquisition

[0134] }.

[0135] like Figure 2 The figure shows a grayscale image obtained by graying the stress cloud map of a bicycle transmission component. In the grayscale image obtained by graying the stress cloud map, the stress concentration area tends to be brighter, while the stress relaxation area tends to be darker. Therefore, the stress concentration and stress relaxation areas after the load are automatically screened out.

[0136] As the vertical total load simulation is applied to the bicycle transmission component for a period of time, the various stress concentration areas and stress relaxation areas on the three-dimensional model generally appear in pairs. When stress concentration occurs at a certain position of the bicycle transmission component due to metal fatigue, deformation or fatigue crack extension inside the metal, stress relaxation is likely to occur at another place. For example, a depression (stress relaxation) occurs in one place and a corresponding bulge (stress concentration) occurs in another place with a high probability. Since the two phenomena of stress concentration and stress relaxation are difficult to be monitored or discovered by simulation with a small load when the stress change is small or the change amplitude is not obvious, the present application solves this problem by judging whether the stress concentration area and the stress relaxation area have a negative correlation (a positive correlation means no stress concentration and stress relaxation), thereby determining whether these two positions need to be optimized, thereby improving the life and stability of the bicycle transmission component. The specific method includes:

[0137] Further, in S500, the method for determining whether each stress concentration region and each stress relaxation region have a negative correlation includes: obtaining stress values ​​borne by each stress concentration region and each stress relaxation region according to the stress cloud map; (the stress values ​​borne by the stress concentration region and each stress relaxation region are the average values ​​of the stress values ​​borne by all points in the stress concentration region or the stress relaxation region);

[0138] Each stress concentration region and stress relaxation region is respectively formed into a concentration relaxation pair, and the specific method is: the average stress value of each point in the current stress concentration region is taken as the current stress concentration mean; the stress relaxation region with the smallest absolute value of the difference between the average stress value of each point in each stress relaxation region and the current stress concentration mean is formed into a concentration relaxation pair with the current stress concentration region;

[0139] For each concentrated relaxation pair, if the stress concentration area and the stress relaxation area therein meet the concentrated relaxation condition, it is determined that the concentrated relaxation pair has a positive association, otherwise it is determined that the concentrated relaxation pair has a negative association.

[0140] The concentrated relaxation condition is:

[0141] The AP is the point position of the maximum stress value in the stress concentration region of the concentrated relaxation pair, the BP is the point position of the maximum stress value in the stress relaxation region of the concentrated relaxation pair, and the direction from AP to BP is the stress relaxation direction of the concentrated relaxation pair;

[0142] The straight line passing through the point with the maximum stress value on the boundary of the stress concentration area and the point with the maximum stress value on the boundary of the stress relaxation area is called the first straight line; the straight line passing through the point with the minimum stress value on the boundary of the stress concentration area and the point with the minimum stress value on the boundary of the stress relaxation area is called the second straight line; the projection area of ​​the area between the first straight line and the second straight line on the stress cloud diagram is called the stress relaxation bar.

[0143] Among them, the key source code of the C# language description of the specific implementation of the method for judging whether each stress concentration area and stress relaxation area has a negative correlation is:

[0144] Class StressCRAnalysis

[0145] { / / Class represents stress concentration area

[0146] Public classStressRegion

[0147] {public List <point>Points{get;set;}

[0148] Public float AverageStress{get;set;}

[0149] Public PointMaxStressPoint{get;set;}

[0150] Public PointMinStressPoint{get;set;}

[0151] Public StressRegion()

[0152] {Points=newList <point>();

[0153] }}

[0154] Public staticvoidAnalyzeStressImage(stringinputImagePath)

[0155] {Image<Gray,Byte> grayImage=newImage<Gray,Byte> (inputImagePath);

[0156] / / 1. Get the classification of stress concentration areas and stress relaxation areas

[0157] var(CRs,relaxationRegions)=GetStressRegions(grayImage);

[0158] / / 2. Form a concentrated relaxation pair

[0159] List <Tuple<StressRegion,StressRegion> >stressPairs=newList <Tuple<StressRegion,StressRegion> >();

[0160] foreach(var CRinCRs)

[0161] {StressRegionbestRelaxationRegion=null;

[0162] Float minDifference=float.MaxValue;

[0163] foreach(var relaxationRelaxationRegions)

[0164] {float difference=Math.Abs(relaxationRegion.AverageStress-CR.AverageStress);

[0165] if(difference <minDifference)

[0166] {minDifference=difference;

[0167] bestRelaxationRegion=relaxationRegion;}}

[0168] if(bestRelaxationRegion!=null)

[0169] {stressPairs.Add(Tuple.Create(CR,bestRelaxationRegion));

[0170] }}

[0171] / / 3. Define the concentrated relaxation conditions and determine positive or negative associations

[0172] foreach(var pairinstressPairs)

[0173] {StressRegionCR=pair.Item1;

[0174] StressRegionrelaxationRegion=pair.Item2;

[0175] / / Check the concentration relaxation condition

[0176] bool isPositiveCorrelation=CheckCRCondition(CR,relaxationRegion);

[0177] string correlationType=isPositiveCorrelation?"Positive correlation":"Negative correlation";

[0178] private static(List <stressregion>,List <stressregion>)GetStressRegions(Image<Gray,Byte> grayImage)

[0179] { / / Classify the area into concentrated and relaxed areas

[0180] List <stressregion>CRs=newList <stressregion>();

[0181] List <stressregion>relaxationRegions=newList <stressregion>();

[0182] / / TODO: Get the area and calculate the average stress value, maximum and minimum stress points, etc.

[0183] return(CRs,relaxationRegions);

[0184] }.

[0185] The stress relaxation strip is an area between the stress concentration area and the stress relaxation area, where stress concentration gradually develops to stress relaxation along the stress relaxation direction. The probability of its stress change showing a linear change trend is relatively high, and the probability of stress showing a linear change in other areas of the stress relaxation strip is relatively low. According to this characteristic, the strip area can reflect the change area of ​​stress connection across the concentrated relaxation pair, thereby ensuring the subsequent finite element continuity judgment;

[0186] like Figure 3 The finite element diagram of the finite element model of the bicycle transmission component is shown. For each finite element in the stress relaxation strip, if there is a finite element whose stress value is smaller than the stress value of a finite element before the finite element in the stress relaxation direction, and the stress value of the finite element is smaller than the stress value of a finite element after the finite element in the stress relaxation direction, then it is recorded that the stress concentration area and the stress relaxation area do not meet the concentrated relaxation condition, otherwise, it is recorded that the stress concentration area and the stress relaxation area meet the concentrated relaxation condition.

[0187] Since the concentrated relaxation that produces negative correlation on the transmission component structure has an unbalanced effect on the transmission of stress, it is necessary to fine-tune the thickness of the area with greater stress concentration in the concentrated relaxation that produces negative correlation according to the area with less stress concentration, so as to balance the stress concentration and stress relaxation, thereby improving the yield strength, hardness, fatigue strength, and fatigue crack growth resistance. The specific method is:

[0188] Furthermore, in S600, the method of adjusting the negatively correlated stress concentration area and the stress relaxation area to obtain the optimized three-dimensional model of the bicycle transmission assembly includes:

[0189] The center point of the stress concentration area that produces negative correlation is denoted as CP1 and the center point of the stress relaxation area is denoted as CP1;

[0190] If the stress value of the stress concentration area that produces a negative correlation is greater than the stress value of the stress relaxation area, the stress concentration area is taken as the adjustment area and the stress relaxation area is taken as the output area; if the stress value of the stress concentration area that produces a negative correlation is less than the stress value of the stress relaxation area, the stress concentration area is taken as the output area and the stress relaxation area is taken as the adjustment area;

[0191] The highest point in the output area on the three-dimensional model is recorded as the highest output point, and the lowest point in the output area is recorded as the lowest output point; the point with the largest stress value in the corresponding position of the adjustment area on the three-dimensional model is recorded as the defect midpoint; the average thickness of the triangular area formed by the defect midpoint, the highest output point, and the lowest output point is taken as the output thickness. If the average thickness of the adjustment area is less than the output thickness, the thickness of the adjustment area is adjusted to the output thickness;

[0192] After making the above adjustments to all stress concentration areas and stress relaxation areas that produce negative correlations, the optimized three-dimensional model of the bicycle transmission component is obtained.

[0193] The key source code of the C# language description of the specific implementation of the method of adjusting the negatively correlated stress concentration area and stress relaxation area to obtain the optimized three-dimensional model of the bicycle transmission component is:

[0194] Class StressAnalysisOptimization

[0195] {public class StressRegion

[0196] {Public List <point3d>Points{get;set;}

[0197] Public floatAverageStress{get;set;}

[0198] Public Point3DCenterPoint{get;set;}

[0199] Public StressRegion()

[0200] {Points=newList <point3d>();}}

[0201] Public static void OptimizeModels(List <Tuple<StressRegion,StressRegion> >stressPairs)

[0202] {foreach(varpairinstressPairs)

[0203] {StressRegionCR=pair.Item1;

[0204] StressRegionrelaxationRegion=pair.Item2;

[0205] / / Find the center points CP1 and CP2

[0206] Point3DCP1=CR.CenterPoint;

[0207] Point3DCP2=relaxationRegion.CenterPoint;

[0208] / / Determine output and adjust area

[0209] StressRegionoutputRegion;

[0210] StressRegionadjustmentRegion;

[0211] if(CR.AverageStress>relaxationRegion.AverageStress)

[0212] {outputRegion=CR;

[0213] adjustmentRegion=relaxationRegion;

[0214] }Else {outputRegion=relaxationRegion;

[0215] adjustmentRegion=CR;}

[0216] / / Calculate the highest and lowest points of the output area

[0217] Point3DhighestOutputPoint=FindHighestPoint(outputRegion);

[0218] Point3DlowestOutputPoint=FindLowestPoint(outputRegion);

[0219] / / Find the maximum stress point in the adjustment area

[0220] Point3DDMPoint=FindMaxStressPoint(adjustmentRegion);

[0221] / / Calculate the average thickness of the output area

[0222] float outputThi=CAThickness(DMPoint,highestOutputPoint,lowestOutputPoint);

[0223] / / Check and adjust the thickness of the adjustment area

[0224] Float DAThickness=CAThicknessOfRegion(adjustmentRegion);

[0225] if(DAThickness <outputThi)

[0226] {AdjustThickness(adjustmentRegion,outputThi);}}

[0227] Console.WriteLine("The optimized 3D model of the bicycle transmission assembly has been generated.");

[0228] }privatestaticPoint3DFindHighestPoint(StressRegionregion)

[0229] { / / Return the point with the highest Z coordinate

[0230] Point3DhighestPoint=region.Points[0];

[0231] foreach(varpointinregion.Points)

[0232] {if(point.Z>highestPoint.Z)

[0233] {highestPoint=point;

[0234] }}returnhighestPoint;}

[0235] Private static Point3DFindLowestPoint(StressRegionregion)

[0236] { / / Return the point with the lowest Z coordinate

[0237] Point3DlowestPoint=region.Points[0];

[0238] foreach(varpointinregion.Points)

[0239] {if(point.Z <lowestPoint.Z)

[0240] {lowestPoint=point;

[0241] }}returnlowestPoint;}

[0242] Private static Point3DFindMaxStressPoint(StressRegionregion)

[0243] { / / Return the point with the largest stress value

[0244] Randomrandom = newRandom();

[0245] Return region.Points[random.Next(region.Points.Count)];}

[0246] Private static float CAThickness(Point3DDMPoint,Point3DhighestPoint,Point3DlowestPoint)

[0247] {Return Math.Abs(highestPoint.Z-lowestPoint.Z) / 2;}

[0248] Private static float CAThicknessOfRegion(StressRegionregion)

[0249] { / / Calculate the average thickness of the area

[0250] Float totalZ=0;

[0251] foreach(var pointinregion.Points)

[0252] {totalZ+=point.Z;

[0253] }returntotalZ / region.Points.Count;}.

[0254] Example 2

[0255] This embodiment 2 replaces the concentrated relaxation condition on the basis of embodiment 1, specifically:

[0256] Preferably, the concentrated relaxation condition is:

[0257] The AP is the point position of the maximum stress value in the stress concentration region of the concentrated relaxation pair, the BP is the point position of the maximum stress value in the stress relaxation region of the concentrated relaxation pair, and the direction from AP to BP is the stress relaxation direction of the concentrated relaxation pair;

[0258] A straight line passing through a point with the maximum stress value on the boundary of the stress concentration region and a point with the maximum stress value on the boundary of the stress relaxation region is taken as the first straight line; a straight line passing through a point with the minimum stress value on the boundary of the stress concentration region and a point with the minimum stress value on the boundary of the stress relaxation region is taken as the second straight line; the projection area of ​​the area between the first straight line and the second straight line on the stress cloud diagram is taken as the stress relaxation bar;

[0259] For each finite element in the stress relaxation strip, calculate the relaxation correction stress value, select the finite element with the largest stress value from the first finite element in the stress relaxation strip to the current finite element and record it as the maximum finite element; select the finite element with the smallest stress value from the first finite element in the stress relaxation strip to the current finite element and record it as the minimum finite element; record the position number of the maximum finite element in each finite element in the stress relaxation strip as AMax; record the position number of the minimum finite element in each finite element in the stress relaxation strip as AMin; take the average value of the stress values ​​of all finite elements from the position number of the current finite element to Amax in the stress relaxation strip as AMaxStr; take the average value of the stress values ​​of all finite elements from the position number of the current finite element to AMin in the stress relaxation strip as AMinStr; take the stress value of the current finite element as CStr; take the difference between AMaxStr and AMinStr as the relaxation correction difference; record the relaxation correction stress value of the current finite element as the sum of CStr and the relaxation correction difference;

[0260] For each finite element in the stress relaxation strip, if there is a finite element whose relaxation-corrected stress value is smaller than the relaxation-corrected stress value of a finite element before the finite element in the stress relaxation direction, and the relaxation-corrected stress value of the finite element is smaller than the relaxation-corrected stress value of a finite element after the finite element in the stress relaxation direction, then it is recorded that the stress concentration area and the stress relaxation area do not satisfy the concentrated relaxation condition; otherwise, it is recorded that the stress concentration area and the stress relaxation area satisfy the concentrated relaxation condition.

[0261] Example 3

[0262] This embodiment 3 replaces the method of adjusting the stress concentration area and the stress relaxation area that generate negative correlation to obtain the optimized three-dimensional model of the bicycle transmission component based on the embodiment 1, which is specifically:

[0263] Preferably, in S600, the method of adjusting the negatively correlated stress concentration area and the stress relaxation area to obtain the optimized three-dimensional model of the bicycle transmission assembly includes:

[0264] The center point of the stress concentration area that produces negative correlation is denoted as CP1 and the center point of the stress relaxation area is denoted as CP1;

[0265] If the stress value of the stress concentration area that produces a negative correlation is greater than the stress value of the stress relaxation area, the stress concentration area is taken as the adjustment area and the stress relaxation area is taken as the output area; if the stress value of the stress concentration area that produces a negative correlation is less than the stress value of the stress relaxation area, the stress concentration area is taken as the output area and the stress relaxation area is taken as the adjustment area;

[0266] The highest point in the output area on the three-dimensional model is recorded as the highest output point, and the lowest point in the output area is recorded as the lowest output point; the point with the largest stress value in the corresponding position of the adjustment area on the three-dimensional model is recorded as the defect midpoint; the average thickness of the triangular area formed by the defect midpoint, the highest output point, and the lowest output point is taken as the output thickness. If the average thickness of the adjustment area is less than the output thickness, the adjustment area is marked as the area to be strengthened;

[0267] After marking all stress concentration areas and stress relaxation areas that produce negative correlation as above, the optimized three-dimensional model of the bicycle transmission component is obtained.

[0268] Among them, the key source code of the C# language description of the specific implementation of the method of adjusting the negatively correlated stress concentration area and stress relaxation area to obtain the optimized three-dimensional model of the bicycle transmission component in this embodiment 3 is:

[0269] Class StressAnalysisOptimization

[0270] { / / Define stress area

[0271] Public class StressRegion

[0272] {public List <point3d>Points { get; set;}

[0273] Public float AverageStress { get; set;}

[0274] Public Point3D CenterPoint { get; set;} / / 中心点

[0275] Public StressRegion()

[0276] { Points = new List <point3d>();}}

[0277] Public static void OptimizeModels(List <Tuple<StressRegion,StressRegion> >stressPairs)

[0278] {foreach(var pairinstressPairs)

[0279] {StressRegionCR=pair.Item1;

[0280] StressRegionrelaxationRegion=pair.Item2;

[0281] / / Center points CP1 and CP2

[0282] Point3DCP1=CR.CenterPoint;

[0283] Point3DCP2=relaxationRegion.CenterPoint;

[0284] / / Determine output and adjust area

[0285] StressRegionoutputRegion;

[0286] StressRegionadjustmentRegion;

[0287] if(CR.AverageStress>relaxationRegion.AverageStress)

[0288] {

[0289] outputRegion=relaxationRegion; / / Take the stress relaxation area as the output area

[0290] adjustmentRegion=CR; / / Take the stress concentration area as the adjustment area

[0291] }else{

[0292] outputRegion=CR; / / Take the stress concentration area as the output area

[0293] adjustmentRegion=relaxationRegion; / / Take the stress relaxation area as the adjustment area

[0294] } / / Find the highest and lowest points in the output area

[0295] Point3DhighestOutputPoint=FindHighestPoint(outputRegion);

[0296] Point3DlowestOutputPoint=FindLowestPoint(outputRegion);

[0297] / / Find the point with the largest stress in the adjustment area (the midpoint of the defect)

[0298] Point3DDMPoint=FindMaxStressPoint(adjustmentRegion);

[0299] / / Calculate output thickness

[0300] floatoutputThi=CAThickness(DMPoint,highestOutputPoint,lowestOutputPoint);

[0301] / / Calculate the average thickness of the adjustment area

[0302] Float DAThickness=CAThicknessOfRegion(adjustmentRegion);

[0303] / / Mark the area to be strengthened

[0304] if(DAThickness <outputThi)

[0305] {MarkPendingEnhancement(adjustmentRegion);

[0306] }}

[0307] Console.WriteLine("The optimized 3D model of the bicycle transmission assembly has been generated.");}

[0308] Private static Point3DFindHighestPoint(StressRegionregion)

[0309] {Point3DhighestPoint=region.Points[0];

[0310] foreach(varpointinregion.Points)

[0311] {if(point.Z>highestPoint.Z)

[0312] {highestPoint=point;

[0313] }}Return highestPoint;}.

[0314] Preferably, when the bicycle transmission assembly is produced according to the three-dimensional model of the bicycle transmission assembly, laser shock processing is performed on the marked area to be strengthened at a position corresponding to the bicycle transmission assembly.

[0315] An embodiment of the present invention provides a design system for a bicycle transmission assembly, such as Figure 4 The figure shows a structural diagram of a bicycle transmission component design system of the present invention. The bicycle transmission component design system of this embodiment comprises: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the above-mentioned bicycle transmission component design system embodiment are implemented.

[0316] The system comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to run in the following units of the system:

[0317] A three-dimensional modeling unit, used for inputting a three-dimensional model of a bicycle transmission assembly;

[0318] A meshing unit is used to mesh the three-dimensional model to obtain a finite element model;

[0319] Stress simulation unit, used to load the finite element model to construct a constrained finite element model and obtain a stress cloud diagram;

[0320] A stress marking unit is used to mark stress concentration areas and stress relaxation areas on the three-dimensional model according to the stress cloud map;

[0321] A correlation judgment unit is used to judge whether each stress concentration area and stress relaxation area has a negative correlation;

[0322] The model optimization unit is used to adjust the stress concentration area and the stress relaxation area that produce negative correlation to obtain the optimized three-dimensional model of the bicycle transmission component.

[0323] The bicycle transmission component design system can be run in computing devices such as desktop computers, laptop computers, PDAs, and cloud servers. The bicycle transmission component design system can run systems including, but not limited to, processors and memories. Those skilled in the art can understand that the example is only an example of a bicycle transmission component design system and does not constitute a limitation on a bicycle transmission component design system. It can include more or fewer components than the example, or combine certain components, or different components. For example, the bicycle transmission component design system can also include input and output devices, network access devices, buses, etc.

[0324] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the design system and operating system of the bicycle transmission component, and uses various interfaces and lines to connect the various parts of the entire bicycle transmission component design system and operating system.

[0325] The memory can be used to store the computer program and / or module, and the processor realizes various functions of the bicycle transmission component design system by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area can store data created according to the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (SecureDigital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0326] Although the description of the present invention has been quite detailed and has been described in particular with respect to several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, so as to effectively cover the intended scope of the present invention. In addition, the present invention is described above with the embodiments foreseeable by the inventors, and its purpose is to provide a useful description, and those non-substantial changes to the present invention that are not currently foreseen may still represent equivalent changes of the present invention. < / stressregion> < / stressregion> < / stressregion> < / stressregion> < / stressregion> < / stressregion> < / point> < / point> < / int> < / int> < / int> < / int> < / float> < / float>

Claims

1. A method for designing a bicycle transmission assembly, characterized in that: The method comprises the following steps: S100, inputting a three-dimensional model of a bicycle transmission assembly; S200, meshing the three-dimensional model to obtain a finite element model; S300, loading the load onto the finite element model to construct a constrained finite element model and obtain a stress contour map; S400, marking the stress concentration area and stress relaxation area on the three-dimensional model according to the stress cloud map; S500, determining whether each stress concentration region and each stress relaxation region have a negative correlation; S600, adjusting the stress concentration area and the stress relaxation area that generate negative correlation to obtain optimized three-dimensional models of the bicycle transmission component; In S400, the method of marking the stress concentration area and the stress relaxation area on the three-dimensional model according to the stress cloud map is as follows: graying the stress cloud map to obtain a gray image, using a watershed algorithm to obtain multiple dividing lines of the gray image, dividing the gray image into multiple load areas according to each dividing line, recording the average gray value of all points on the gray image as the average gray; recording the load area where the average gray value of each point is greater than the average gray as the stress concentration area; recording the load area where the average gray value of each point is less than the average gray as the stress relaxation area; In S500, the method for determining whether each stress concentration region and each stress relaxation region have a negative correlation includes: obtaining stress values ​​borne by each stress concentration region and each stress relaxation region according to the stress cloud map; respectively forming each stress concentration region and each stress relaxation region into a concentration relaxation pair; for each concentration relaxation pair, if the stress concentration region and the stress relaxation region therein meet the concentration relaxation condition, determining that the concentration relaxation pair has a positive correlation, otherwise determining that the concentration relaxation pair has a negative correlation; Among them, the specific method of forming each stress concentration area and stress relaxation area into a concentrated relaxation pair is: taking the average stress value of each point in the current stress concentration area as the current stress concentration mean; forming a concentrated relaxation pair with the current stress concentration area and the stress relaxation area with the smallest absolute value of the difference between the average stress value of each point in the stress relaxation area and the current stress concentration mean.

2. A method for designing a bicycle transmission assembly according to claim 1, characterized in that: In S100, the three-dimensional model of the bicycle transmission assembly is a three-dimensional model of the bicycle transmission assembly made by 3D drawing software or a three-dimensional model of the bicycle transmission assembly acquired by a three-dimensional scanner, and the bicycle transmission assembly includes a chain, a chain ring, and a flywheel.

3. The design method of a bicycle transmission assembly according to claim 1, characterized in that: The concentrated relaxation conditions are: the point position with the maximum stress value in the stress concentration region with AP as the concentrated relaxation pair, the point position with the maximum stress value in the stress relaxation region with BP as the concentrated relaxation pair, and the direction from AP to BP as the stress relaxation direction of the concentrated relaxation pair; A straight line passing through a point with the maximum stress value on the boundary of the stress concentration region and a point with the maximum stress value on the boundary of the stress relaxation region is taken as the first straight line; a straight line passing through a point with the minimum stress value on the boundary of the stress concentration region and a point with the minimum stress value on the boundary of the stress relaxation region is taken as the second straight line; the projection area of ​​the area between the first straight line and the second straight line on the stress cloud diagram is taken as the stress relaxation bar; For each finite element in the stress relaxation strip, if there is a finite element whose stress value is less than the stress value of a finite element before the finite element in the stress relaxation direction, and the stress value of the finite element is less than the stress value of a finite element after the finite element in the stress relaxation direction, then it is recorded that the stress concentration area and the stress relaxation area do not meet the concentrated relaxation condition; otherwise, it is recorded that the stress concentration area and the stress relaxation area meet the concentrated relaxation condition.

4. The design method of a bicycle transmission assembly according to claim 1, characterized in that: The concentrated relaxation condition is replaced by: AP is the point position of the maximum stress value in the stress concentration region of the concentrated relaxation pair, BP is the point position of the maximum stress value in the stress relaxation region of the concentrated relaxation pair, and the direction from AP to BP is the stress relaxation direction of the concentrated relaxation pair; A straight line passing through a point with the maximum stress value on the boundary of the stress concentration region and a point with the maximum stress value on the boundary of the stress relaxation region is taken as the first straight line; a straight line passing through a point with the minimum stress value on the boundary of the stress concentration region and a point with the minimum stress value on the boundary of the stress relaxation region is taken as the second straight line; the projection area of ​​the area between the first straight line and the second straight line on the stress cloud diagram is taken as the stress relaxation bar; For each finite element in the stress relaxation strip, the relaxation correction stress value is calculated, and the finite element with the largest stress value from the first finite element to the current finite element in the stress relaxation strip is selected and recorded as the maximum finite element; The finite element with the smallest stress value from the first finite element in the stress relaxation strip to the current finite element is recorded as the minimum finite element; The position number of each finite element of the maximum finite element in the stress relaxation strip is AMax; The position number of each finite element of the minimum finite element in the stress relaxation strip is AMin; the average stress value of all finite elements from the position number of the current finite element to Amax in the stress relaxation strip is AMaxStr; the average stress value of all finite elements from the position number of the current finite element to AMin in the stress relaxation strip is AMinStr; the stress value of the current finite element is CStr; the difference between AMaxStr and AMinStr is the relaxation correction difference; The relaxation correction stress value of the current finite element is recorded as the sum of CStr and the relaxation correction difference; For each finite element in the stress relaxation strip, if there is a finite element whose relaxation-corrected stress value is smaller than the relaxation-corrected stress value of a finite element before the finite element in the stress relaxation direction, and the relaxation-corrected stress value of the finite element is smaller than the relaxation-corrected stress value of a finite element after the finite element in the stress relaxation direction, then it is recorded that the stress concentration area and the stress relaxation area do not satisfy the concentrated relaxation condition; otherwise, it is recorded that the stress concentration area and the stress relaxation area satisfy the concentrated relaxation condition.

5. The method for designing a bicycle transmission assembly according to claim 1, characterized in that: In S600, the method of adjusting the negatively correlated stress concentration area and the stress relaxation area to obtain the optimized three-dimensional model of the bicycle transmission assembly includes: The center point of the stress concentration area that produces negative correlation is denoted as CP1 and the center point of the stress relaxation area is denoted as CP1; If the stress value of the stress concentration area that produces a negative correlation is greater than the stress value of the stress relaxation area, the stress concentration area is taken as the adjustment area and the stress relaxation area is taken as the output area; if the stress value of the stress concentration area that produces a negative correlation is less than the stress value of the stress relaxation area, the stress concentration area is taken as the output area and the stress relaxation area is taken as the adjustment area; The highest point in the output area on the three-dimensional model is recorded as the highest output point, and the lowest point in the output area is recorded as the lowest output point; the point with the largest stress value in the corresponding position of the adjustment area on the three-dimensional model is recorded as the defect midpoint; the average thickness of the triangular area formed by the defect midpoint, the highest output point, and the lowest output point is taken as the output thickness. If the average thickness of the adjustment area is less than the output thickness, the thickness of the adjustment area is adjusted to the output thickness; After making the above adjustments to all stress concentration areas and stress relaxation areas that produce negative correlations, the optimized three-dimensional model of the bicycle transmission component is obtained.

6. The method for designing a bicycle transmission assembly according to claim 1, characterized in that: In S600, the method of adjusting the negatively correlated stress concentration area and the stress relaxation area to obtain the optimized three-dimensional model of the bicycle transmission assembly includes: The center point of the stress concentration area that produces negative correlation is denoted as CP1 and the center point of the stress relaxation area is denoted as CP1; If the stress value of the stress concentration area that produces a negative correlation is greater than the stress value of the stress relaxation area, the stress concentration area is taken as the adjustment area and the stress relaxation area is taken as the output area; if the stress value of the stress concentration area that produces a negative correlation is less than the stress value of the stress relaxation area, the stress concentration area is taken as the output area and the stress relaxation area is taken as the adjustment area; The highest point in the output area on the three-dimensional model is recorded as the highest output point, and the lowest point in the output area is recorded as the lowest output point; the point with the largest stress value in the corresponding position of the adjustment area on the three-dimensional model is recorded as the defect midpoint; the average thickness of the triangular area formed by the defect midpoint, the highest output point, and the lowest output point is taken as the output thickness. If the average thickness of the adjustment area is less than the output thickness, the adjustment area is marked as the area to be strengthened; After marking all stress concentration areas and stress relaxation areas that produce negative correlation as above, the optimized three-dimensional model of the bicycle transmission component is obtained.

7. A method for designing a bicycle transmission assembly according to claim 6, characterized in that: When the bicycle transmission assembly is produced according to the three-dimensional model of the bicycle transmission assembly, the marked area to be strengthened is subjected to laser shock strengthening treatment at a position corresponding to the bicycle transmission assembly.

Images