Joint surface pressure distribution prediction method for dynamic analysis of aluminum-steel bolt connecting piece

Abstract

The invention discloses a joint surface pressure distribution prediction method for kinetic analysis of an aluminum-steel bolt connecting piece, which comprises the following steps of: performing mathematical representation on pressure distribution of a joint surface by adopting a polygonal function, and changing geometric parameters to perform multi-group finite element static analysis to obtain a mathematical representation parameter set of the pressure distribution of the joint surface; performing quartic polynomial fitting on the mathematical characterization parameters of the pressure distribution of the joint surface and the geometric parameter set to obtain a mathematical relational expression of the mathematical characterization parameters of the pressure distribution of the joint surface and the geometric parameters; and correcting the joint surface pressure distribution prediction model by considering the changed bolt pre-tightening force. The invention provides the joint surface pressure distribution prediction method for dynamic analysis of the aluminum-steel bolt connecting piece, and important practical values are provided for calculation of the joint surface connection rigidity, prediction of the dynamic performance of the bolt connecting piece and evaluation of the cyclic fatigue life.

Description

Technical Field

[0001] The present invention relates to a method for predicting the pressure distribution on the joint surface of a dissimilar material mechanical connector, and particularly to a method for predicting the pressure distribution on the joint surface for the dynamic analysis of an aluminum-steel bolt connector. Background Art

[0002] As a reliable connection method, bolt connection is widely used in the connection of mechanical structures. The bolt connector transmits loads and motions through the contact interface, and the mechanical properties of the joint surface restrict the performance of the overall structure. In the dynamic working conditions of bolt connectors, the bolt pre-tightening force often changes, resulting in the difficulty of quantitatively characterizing the pressure distribution on the joint surface. The pressure distribution on the joint surface has an important impact on the connection stiffness and dynamic performance of the bolt connection. Therefore, it is of great significance to propose a pressure distribution model that is convenient for mathematical characterization and computational analysis, and then to use it to update dynamic parameters such as the pressure distribution on the joint surface in real time during the overall dynamic analysis of bolt connectors, for the prediction of the connection stiffness of bolt connectors and the analysis of dynamic performance.

[0003] Currently, the pressure distribution on the joint surface of bolt connections is mainly obtained through experimental methods. However, in working scenarios such as the forward design of bolt connections, the cost of obtaining a large number of bolt connection test pieces is relatively high. It is difficult to statistically analyze its variation law through simulation methods and then perform polynomial mathematical characterization, and the characterization parameters lack physical meaning. Therefore, the present invention establishes a prediction model for the pressure distribution on the joint surface of aluminum-steel bolt connectors with the bolt nominal diameter, the thickness of the steel connector, the thickness of the aluminum connector, and the bolt pre-tightening force as influencing factors. According to the geometric parameters of the aluminum-steel bolt connector and the bolt pre-tightening force, the pressure distribution on the joint surface can be predicted in real time and dynamically, effectively solving the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for predicting the pressure distribution on the joint surface for the dynamic analysis of aluminum-steel bolt connectors. The present invention determines the geometric parameters that affect the pressure distribution on the joint surface, determines an anchored bolt pre-tightening force, uses a broken-line function to mathematically characterize the pressure distribution on the joint surface, performs finite element static analysis under N groups of different geometric parameters and obtains the mathematical characterization parameter set of the pressure distribution on the joint surface, performs a fourth-degree polynomial fitting on the geometric parameter set and the mathematical characterization parameter set of the pressure distribution on the joint surface to obtain the mathematical relationship between each mathematical characterization parameter of the pressure distribution on the joint surface and the geometric parameters. Finally, multiply the numerically determined pressure distribution on the joint surface by the ratio of the bolt pre-tightening force to be predicted to the anchored bolt pre-tightening force, thereby establishing a prediction model for the pressure distribution on the joint surface of aluminum-steel bolt connectors with geometric dimensions and bolt pre-tightening force as parameter inputs, laying a foundation for the calculation of the joint surface connection stiffness, the prediction of the overall dynamic performance of bolt connectors, and the evaluation of cyclic fatigue life.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for predicting the pressure distribution of the joint surface for the dynamic analysis of aluminum-steel bolt connections, comprising the following steps:

[0007] (1) Establish a three-dimensional geometric model of the bolt connection according to the geometric characteristics of the bolt connection. The bolt connection is a single-bolt connection structure, including bolts, nuts, steel connectors, and aluminum connectors. The steel connector, aluminum connector, and nut are simplified into annular cylindrical structures, the bolt head is simplified into a cylindrical structure, the threaded connection part is ignored, and the bolt pores remain unchanged in multiple groups of finite element static analyses.

[0008] (2) Import the three-dimensional geometric model of the bolt connection into the finite element analysis software, set the material properties of the three-dimensional geometric model of the bolt connection, perform finite element mesh division on the three-dimensional geometric model. The steel connector and the aluminum connector should adopt swept mesh division. The steel connector and the aluminum connector should have at least 4 layers of meshes in the thickness direction to ensure the analysis accuracy, and obtain the finite element model of the aluminum-steel bolt connection;

[0009] (3) Create a path on one side of the steel connector or the aluminum connector on the joint surface of the finite element model of the aluminum-steel bolt connection to output the joint surface pressure distribution data. The starting point and the ending point of the path are the bolt edge and the outer edge of the connector respectively;

[0010] (4) Apply the bolt pre-tightening force to the surface of the bolt empty rod of the finite element model of the bolt connection. The bolt pre-tightening force can be set to any value, but it needs to remain unchanged in subsequent multiple groups of finite element static analyses as the anchored bolt pre-tightening force;

[0011] (5) Define each contact pair of the bolt connection: the contact mode of the bolt-nut contact surface is "bonding", and the contact modes of the bolt-connector contact surface, nut-connector contact surface, and steel connector-aluminum connector contact surface are "friction", and the friction coefficient is 0.15;

[0012] (6) Perform a static analysis on the finite element model of the bolt connection in the pre-tightened state to obtain the joint surface pressure distribution data on the path;

[0013] (7) Mathematically characterize the joint surface pressure distribution based on the piecewise function, and fit the mathematical characterization parameters of the piecewise function by the least squares method;

[0014] (8) Change the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector to obtain N groups of different combinations of the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector, which are used as the input for the prediction model fitting; modify the geometric dimensions of the bolt connector according to N groups of different geometric parameter combinations and perform static analysis to obtain N groups of different data sets of the mathematical characterization parameters of the broken line function, which are used as the output of the prediction model fitting;

[0015] (9) Perform a fourth-degree polynomial fitting on the geometric parameter set of the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector and the data set of the mathematical characterization parameters of the broken line to obtain the mathematical relationship between the mathematical characterization parameters of the broken line function and the geometric parameters;

[0016] (10) Numerically multiply the numerical value of the joint surface pressure distribution that can be predicted by the geometric parameters by the ratio of the bolt pre-tightening force to be predicted to the pre-tightening force of the anchor bolt, and the joint surface pressure distribution of the aluminum-steel bolt connector with different nominal diameters of the bolt, thicknesses of the steel connector, thicknesses of the aluminum connector, and bolt pre-tightening forces can be predicted.

[0017] The mathematical characterization of the pressure distribution of the aluminum-steel bolt connector in step (7) is a broken line function. Generally, the pressure shows two broken lines with different attenuation rates as the radial distance increases. The segmentation point of the two broken lines is a fixed point, as shown in Equation (1):

[0018]

[0019] In Equation (1), k1 is the slope of the first line, k2 is the slope of the second line, r is the radial distance starting from the edge of the screw hole, r max is the maximum radius of the joint surface pressure distribution, and r0 is the segmentation point of the broken line function.

[0020] The broken line function characterization parameters of the joint surface pressure distribution in step (7) are fitted based on the least squares method, specifically as follows:

[0021] Extract the results of the finite element static analysis, and determine r0 and r according to the pressure distribution characteristics in the results of the finite element static analysis max ; the results of the finite element static analysis include the data points on the inner broken line at the radial distance of 0 to r0: (r1, p1), (r2, p2)... (r m , p m ) and the data points on the outer broken line at the radial distance of r0 to r max : (r m+1 , p m+1 ), (r m+2 , p m+2 )... (r n , p n );

[0022] Calculate the average radial distance of each of the two broken lines:

[0023]

[0024] In Equation (2), is the average radial distance of the data points on the inner broken line, is the average radial distance of the data points on the outer broken line;

[0025] Calculate the average pressure of each of the two broken lines:

[0026]

[0027] In Equation (3), is the average pressure of the data points on the inner broken line, is the average pressure of the data points on the outer broken line;

[0028] The fitting target of the inner broken line is: p a = k1x + b1, and the fitting target of the outer broken line is: p b = k2x + b2;

[0029] Calculate the sum of squared residuals of the data points of each of the two broken lines:

[0030]

[0031] In Equation (4), V a is the sum of squared residuals of the data points on the inner broken line, V b is the sum of squared residuals of the data points on the outer broken line;

[0032] The fitting calculation results of k1 and k2 are obtained by taking the partial derivatives of the above sum of squared residuals with respect to k1 and k2 respectively:

[0033]

[0034] In step (8), perform stretching or compression in the ANSYS~Workbench~SpaceClaim module to quickly modify the geometric parameters of the three-dimensional geometric model of the bolt connection and import them into the ANSYS Workbench finite element analysis module.

[0035] In step (9), the quartic polynomial fitting objective function of k1, k2, and r max is:

[0036]

[0037] In Equation (6), f1(m, x, y), f2(m, x, y), and f3(m, x, y) are k1, k2, and r maxThe fitting objective function, where m, x, and y are the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector respectively. They are k1, k2, and r respectively. max The coefficients in the fitting objective function, m i , x j , y k are the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector in each set of finite element simulations.

[0038] In step (10), the pressure distribution on the joint surface of the target bolt pre-tightening force is equal to the pressure distribution on the joint surface under the anchoring pre-tightening force multiplied numerically by the ratio of the target bolt pre-tightening force to the anchoring bolt pre-tightening force. As shown in Equation (7):

[0039]

[0040] In Equation (7), N0 is the anchoring bolt pre-tightening force, N is the target bolt pre-tightening force, P(r) is the pressure distribution on the joint surface under the target pre-tightening force, and N / N0 is the ratio of the target bolt pre-tightening force to the anchoring bolt pre-tightening force.

[0041] Compared with the prior art, the present invention has the following beneficial technical effects:

[0042] The method for predicting the pressure distribution on the joint surface for the dynamic analysis of aluminum-steel bolt connectors proposed by the present invention is applicable to aluminum-steel bolt connectors of various standard bolt models, geometric dimensions, and bolt pre-tightening forces. By changing the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector in the ANSYS~Workbench~SpaceClaim module, N sets of different geometric parameter combinations are obtained; after performing finite element static analysis, the pressure distribution data on the joint surface of the aluminum-steel bolt connector is obtained, and a broken-line function is used to mathematically characterize the pressure distribution on the joint surface to obtain N sets of broken-line function mathematical characterization parameter sets; the parameter sets of the nominal diameter of the bolt, the thickness of the aluminum connector, and the thickness of the steel connector are subjected to a fourth-degree polynomial fitting with the broken-line function mathematical characterization parameter sets to obtain the mathematical relationship between the mathematical characterization parameters of the pressure distribution on the joint surface and each geometric parameter; finally, the pressure value on the joint surface under the anchoring bolt pre-tightening force that can be predicted by the geometric parameters is multiplied by the ratio of the bolt pre-tightening force to be predicted to the anchoring bolt pre-tightening force, and the pressure distribution on the joint surface under different nominal diameters of the bolt, thicknesses of the steel connector, thicknesses of the aluminum connector, and bolt pre-tightening forces can be predicted. Compared with the usual experimental methods, the method for predicting the pressure distribution on the joint surface of aluminum-steel bolt connections of the present invention has the advantages of significantly reducing costs and being able to predict dynamically and in real time, providing important practical value for the dynamic prediction of the connection stiffness of the bolt connection joint surface and dynamic analysis. Description of the Drawings

[0043] Figure 1Flow chart of a prediction method for the pressure distribution of the joint surface for the dynamic analysis of an aluminum-steel bolt connection in the present invention.

[0044] Figure 2 It is a three-dimensional geometric model of the bolt connection.

[0045] Figure 3 It is the finite element model mesh of the bolt connection.

[0046] Figure 4 It is the joint surface path of the bolt connection.

[0047] Figure 5 It is the pressure distribution nephogram of the joint surface.

[0048] Figure 6 It is the radial pressure distribution of the joint surface.

[0049] Figure 7 It is the comparison between the pressure distribution of the joint surface based on the prediction model and the simulation. Among them, (a) is the anchoring pre-tightening force of 35000N, and (b) is the target pre-tightening force of 60000N. Specific implementation manner

[0050] The present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation manners:

[0051] The present invention proposes a prediction method for the pressure distribution of the joint surface of an aluminum-steel bolt connection. A three-dimensional geometric model is established according to the geometric characteristics of the bolt connection. Based on the finite element static analysis, the pressure distribution of the aluminum-steel bolt connection joint surface along the radial direction is obtained. A broken-line function is used to mathematically characterize the pressure distribution of the joint surface. The geometric parameters are changed and multiple groups of finite element static analyses are performed to obtain the mathematical characterization parameter set of the broken-line function. The mathematical characterization parameters of the broken-line function and the geometric parameters are fitted by a quartic polynomial. The pressure value of the joint surface under the anchoring bolt pre-tightening force that can be predicted by the geometric parameters is multiplied by the ratio of the pre-tightening force of the bolt to be predicted to the pre-tightening force of the anchoring bolt, with reference to Figure 1 , this method includes the following steps:

[0052] (1) According to the geometric characteristics of the bolt connection, a geometric model of the bolt connection is established based on the ANSYS~Workbench~SpaceClaim module. The bolt connection is a single-bolt connection structure, including a bolt, a nut, a steel connector, and an aluminum connector. The steel connector, the aluminum connector, and the nut are simplified into an annular cylindrical structure, the bolt head is simplified into a cylindrical structure, the threaded connection part is ignored, and the bolt pore is kept at 0.5mm.

[0053] Such as Figure 2The established geometric model of the bolt connection is shown. 1 is the bolt, 2 is the steel connection part, 3 is the aluminum connection part, and 4 is the nut. The specific geometric parameters are as follows: the nominal diameter of the bolt is 12 mm, the upper and lower parts are annular cylindrical parts with an inner diameter of 6.5 mm and an outer diameter of 22.5 mm, and the thicknesses of the upper and lower parts are 14 mm and 4 mm respectively.

[0054] (2) Import the above three-dimensional geometric model into the ANSYS~Workbench finite element static analysis module, and set the material properties of the bolt, nut, steel connection part, and aluminum connection part in the three-dimensional geometric model respectively. The upper part is the steel connection part, and the lower part is the aluminum connection part. The material properties include elastic modulus, Poisson's ratio, and density. Mesh the three-dimensional geometric model. The meshing method for the upper and lower parts is sweep, and a finite element model of the aluminum-steel bolt connection is created.

[0055] As Figure 3 is a 1-mm finite element mesh with 215,105 nodes and 47,220 elements.

[0056] (3) Create 4 contact pairs according to the generated solid mesh, namely the contact surface between the bolt and the upper part, the contact surface between the upper part and the lower part, the contact surface between the lower part and the nut, and the contact surface between the bolt and the nut. The contact form of the contact surface between the bolt and the nut is "bonded", and the contact methods of the bolt-connection part contact surface, nut-connection part contact surface, and steel connection part-aluminum connection part contact surface are "friction", and the friction coefficient is set to 0.15. Apply a bolt pre-tightening force to the annular surface of the bolt shank. Create a local coordinate system at the center of the bolt hole on the joint surface, add a path to the local coordinate system, the starting point of the path is the edge of the bolt hole, and the ending point of the path is the edge of the upper part.

[0057] As Figure 4 is the path created on one side of the upper part of the joint surface. The starting point of the path is on the inner diameter of the steel connection part, and the ending point is on the outer edge of the steel connection part.

[0058] (4) After applying a 35,000-N pre-tightening force to the bolt shank surface, perform a static analysis on the aluminum-steel bolt connection, as Figure 5 shown in the pressure distribution nephogram of the joint surface. From Figure 5 it can be seen that the pressure distribution characteristics of the joint surface are that the contact pressure is evenly distributed along the circumferential direction of the bolt hole, decreases radially along the joint surface, has a small negative slope before the segmentation point, has a large negative slope after the segmentation point, and the contact pressure becomes 0 after reaching the maximum action radius. The pressure distribution in the radial direction of the joint surface is as Figure 6 shown.

[0059] (5) According to the pressure distribution characteristics of the joint surface, use a piecewise function to mathematically characterize the pressure distribution of the bolt connection joint surface, as shown in Equation (1):

[0060]

[0061] In Equation (1), k1 is the slope of the first segment of the line, k2 is the slope of the second segment of the line, r is the radial distance starting from the edge of the screw hole, r max The maximum radius of the joint surface pressure distribution, and r0 is the segmentation point of the piecewise function.

[0062] Since the joint surface pressure is evenly distributed around the screw hole, the mathematical expression of Equation (1) specifically refers to the mathematical characterization of the pressure distribution along the radial direction of the screw hole on the aluminum-steel bolt connection joint surface.

[0063] Based on the least squares method to fit the piecewise function characterization parameters of the joint surface pressure distribution:

[0064] Extract the results of the finite element static analysis, and determine r0 and r according to the pressure distribution characteristics in the finite element static analysis results max ; The finite element static analysis results include the data points on the inner fold line at a radial distance of 0 to r0: (r1, p1), (r2, p2) … (r m , p m ) and the data points on the outer fold line at a radial distance of r0 to r max : (r m+1 , p m+1 ), (r m+2 , p m+2 ), … (r n , p n );

[0065] Calculate the average value of the radial distance of each of the two fold lines:

[0066]

[0067] In Equation (2), is the average value of the radial distance of the data points on the inner fold line, is the average value of the radial distance of the data points on the outer fold line;

[0068] Calculate the average value of the pressure of each of the two fold lines:

[0069]

[0070] In Equation (3), is the average value of the pressure of the data points on the inner fold line, is the average value of the pressure of the data points on the outer fold line;

[0071] The fitting target of the inner fold line is: p a = k1x + b1, and the fitting target of the outer fold line is: p b = k2x + b2;

[0072] Calculate the sum of squared residuals of the data points of each of the two broken lines:

[0073]

[0074] In Equation (4), V a is the sum of squared residuals of the data points on the inner broken line, and V b is the sum of squared residuals of the data points on the outer broken line;

[0075] The calculation results of k1 and k2 can be obtained by taking the partial derivatives of the above sum of squared residuals with respect to k1 and k2 respectively:

[0076]

[0077] (6) Change the geometric parameters of the simulation samples: nominal diameter of the bolt, thickness of the steel connector, and thickness of the aluminum connector. The nominal diameters of the bolts are 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, and 20 mm respectively, and the thicknesses of the steel connector and the aluminum connector are 2 mm, 4 mm, 6 mm, 8 mm, 10 mm, 12 mm, and 14 mm respectively, combining to obtain 294 sets of geometric parameter sets. By stretching or scaling the three-dimensional geometric model in the ANSYS~Workbench~SpaceClaim module, the geometric model of the bolt connector can be quickly modified. After performing the corresponding finite element static analysis and the mathematical characterization of the broken line function, a set of mathematical characterization parameters of the contact surface pressure distribution under 294 different geometric parameter combinations is obtained.

[0078] (7) Perform a fourth-degree polynomial fitting on the parameter sets of the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector and the parameter set of the mathematical characterization of the broken line function to obtain the mathematical relationship between the mathematical characterization parameters of the broken line function and the geometric parameters;

[0079] In the above fourth-degree polynomial fitting, the fourth-degree polynomial fitting objective functions of k1, k2, and r max are:

[0080]

[0081] In Equation (6), f1(m, x, y), f2(m, x, y), and f3(m, x, y) are the fitting objective functions of k1, k2, and r max respectively, m, x, and y are the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector respectively, are the coefficients in the fitting objective functions of k1, k2, and r max respectively, and m i , x j , y k are the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector in each finite element simulation.

[0082] Within the range of changes in geometric parameters, predict the pressure distribution on the aluminum-steel bolt connection joint surface under a nominal diameter of 14 mm bolt, 9 mm steel connector, 5 mm aluminum connector, and a bolt pre-tightening force of 60,000 N. According to the mathematical relationship between the broken-line function mathematical characterization parameters and geometric parameters in (6), calculate the mathematical characterization coefficients of the joint surface pressure distribution at an anchoring pre-tightening force of 35,000 N at this time: k1 = -27.2276; k2 = -38.6238; r max = 5.4467 mm. Keep the maximum contact radius of the above pressure distribution value unchanged and multiply it numerically by (60,000 / 35,000) to obtain the predicted distribution of the pressure on the aluminum-steel bolt connection joint surface under a bolt pre-tightening force of 60,000 N, and conduct simulation comparison verification.

[0083] The comparison between the model prediction results and the finite element simulation results of the joint surface pressure distribution is as Figure 7 shown. It can be seen from the figure that the coincidence degree of the two curves is relatively high and the error is small. Therefore, the method for predicting the joint surface pressure distribution for the dynamic analysis of aluminum-steel bolt connectors proposed in this patent can effectively predict the pressure distribution on the aluminum-steel bolt connection joint surface, laying a foundation for the calculation of the joint surface connection stiffness, and has important practical value for the prediction of the dynamic performance of bolt connections under external loads and the evaluation of cyclic fatigue life.

Claims

1. A prediction method for the pressure distribution of the joint surface used in the dynamic analysis of aluminum-steel bolt connections, characterized in that Specifically, it includes the following steps: Step 1: Create a three-dimensional geometric model of the aluminum-steel bolt connection according to the geometric characteristics of the aluminum-steel bolt connection. The three-dimensional geometric model of the aluminum-steel bolt connection consists of a bolt, a nut, a steel connection part, and an aluminum connection part; Step 2: Import the three-dimensional geometric model of the aluminum-steel bolt connection into finite element analysis software, construct a finite element model of the aluminum-steel bolt connection and perform a static analysis to obtain the result of the pressure distribution on the joint surface; Step 3: Use a piecewise function to mathematically characterize the joint surface pressure distribution, fit and extract the piecewise function characterization parameters for the mathematical characterization of the joint surface pressure distribution based on the least squares method. The piecewise function characterization parameters consist of the slope k1, the slope k2, the maximum contact radius r max and the piecewise point r0 of the piecewise function; Step 4: Change the combination of the three geometric parameters, namely the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector, and repeat steps (1) to (3) N times to obtain N sets of geometric parameter sets of the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector, as well as the mathematical characterization parameter sets of the k1, k2, and r max piecewise function, where the geometric parameter set is used as the input for fitting the prediction model, and the mathematical characterization parameter set of the piecewise function is used as the output for fitting the prediction model; Step 5: Fit the mathematical representation parameter sets of k1, k2, and r max with the geometric parameter sets of the bolt nominal diameter, the thickness of the steel connector, and the thickness of the aluminum connector by a quartic polynomial fit to obtain the mathematical relationship between k1, k2, and r max and the bolt nominal diameter, the thickness of the steel connector, and the thickness of the aluminum connector, and construct a prediction model for the pressure distribution of the aluminum-steel bolt connection joint surface based on the bolt nominal diameter, the thickness of the steel connector, and the thickness of the aluminum connector as input parameters; Step 6: Keep the maximum contact radius r of the joint surface pressure distribution of the prediction model unchanged, multiply the joint surface pressure by the ratio of the target bolt pre-tightening force to the anchoring bolt pre-tightening force, and obtain a prediction model for the joint surface pressure distribution of the aluminum-steel bolt connection with four parameters including the bolt nominal diameter, the thickness of the steel connector, the thickness of the aluminum connector, and the bolt pre-tightening force. max ​ 2. The prediction method for the pressure distribution of the joint surface for the dynamic analysis of aluminum-steel bolt connectors according to claim 1, characterized in that, In Step 1, the steel connection part, the aluminum connection part, and the nut of the aluminum-steel bolt connection are simplified into an annular cylindrical structure, the bolt head is simplified into a cylindrical structure, the threaded connection part is ignored, and the bolt pores remain unchanged in multiple groups of finite element static analyses.

3. A method for predicting the pressure distribution of the joint surface for the dynamic analysis of an aluminum-steel bolt connection according to claim 1, characterized in that In Step 2, the finite element model mesh of the aluminum-steel bolt connection should ensure at least 4 layers of meshes in the thickness direction of the steel connection part and the aluminum connection part; the path is added to one side of the steel connection part or the aluminum connection part on the joint surface to view the static analysis result of the contact pressure distribution along the radial direction on the joint surface. The starting point of the path is the edge of the screw hole, and the ending point of the path is the outer edge of the joint surface; the bolt pre-tightening force always remains unchanged as the anchoring pre-tightening force and is applied to the surface of the bolt shank.

4. A method for predicting the pressure distribution of the joint surface for the dynamic analysis of an aluminum-steel bolt connection member according to claim 1, wherein In Step 3, the pressure distribution of the aluminum-steel bolt connection shows a broken line with two different slopes as the radial distance increases. The mathematical representation is a broken line function, and the segmentation point of the two broken lines is a fixed point, as shown in Equation (1): In formula (1), k1 is the slope of the first line segment, k2 is the slope of the second line segment, r is the radial distance starting from the edge of the screw hole, r max is the maximum radius of the mating surface pressure distribution, and r0 is the segmentation point of the piecewise function.

5. A prediction method for the pressure distribution of the joint surface for the dynamic analysis of an aluminum-steel bolt connection member according to claim 1, characterized in that In Step 3, the parameter characterization of the broken line function of the pressure distribution on the joint surface is fitted based on the least squares method, specifically as follows: Extract the finite element static analysis results, and determine r0 and r according to the pressure distribution characteristics in the finite element static analysis results max ; The finite element static analysis results include data points on the inner fold line at a radial distance of 0 to r0: (r1, p1), (r2, p2)... (r m , p m ) and data points on the outer fold line at a radial distance of r0 to r max : (r m+1 , p m+1 ), (r m+2 , p m+2 ),... (r n , p n ); Calculate the average value of the radial distance of each of the two broken lines: In formula (2), is the average radial distance of the data points on the inner fold line, is the average radial distance of the data points on the outer fold line; Calculate the average value of the pressure of each of the two broken lines: In formula (3), is the average pressure of the data points on the inner fold line, is the average pressure of the data points on the outer fold line; The fitting target of the inner broken line is: p a = k1x + b1, and the fitting target of the outer broken line is: p b = k2x + b2; Calculate the sum of the squares of the residuals of the data points of each of the two broken lines: In formula (4), V a is the sum of the squared residuals of the data points on the inner fold line, and V b is the sum of the squared residuals of the data points on the outer fold line; The fitting results of k1 and k2 are obtained by taking the partial derivatives of the above sum of the squares of the residuals with respect to k1 and k2 respectively:

6. A method for predicting the pressure distribution of the joint surface for the dynamic analysis of an aluminum-steel bolt connection according to claim 1, characterized in that In step 5, k1, k2, and r max The quartic polynomial fitting objective function is as follows: In Equation (6), f1(m, x, y), f2(m, x, y), and f3(m, x, y) are the fitting objective functions of k1, k2, and r respectively, where m, x, and y are the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector respectively. max The coefficients in the fitting objective functions of k1, k2, and r respectively, where m, x, and y are the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector respectively. The coefficients in the fitting objective functions of k1, k2, and r respectively. max In the fitting objective functions. i , x j , y k Are the nominal diameter of the bolt, the thickness of the steel connector, and the thickness of the aluminum connector in each group of finite element simulations.

7. A method for predicting the pressure distribution of the joint surface for the dynamic analysis of an aluminum-steel bolt connection member according to claim 1, characterized in that In Step 6, the joint surface pressure of the target bolt pre-tightening force is equal to the joint surface pressure under the anchoring bolt pre-tightening force multiplied by the ratio of the target bolt pre-tightening force to the anchoring bolt pre-tightening force, as shown in Equation (7): In Equation (7), N0 is the anchoring bolt pre-tightening force, N is the target bolt pre-tightening force, P(r) is the function characterizing the joint surface pressure distribution under the target bolt pre-tightening force, and N / N0 is the ratio of the target bolt pre-tightening force to the anchoring bolt pre-tightening force.

Images