CN104866634A - Shell plate sinking-resistance simulation analysis method of car body outer covering part - Google Patents

Abstract

The invention provides a simulation analysis method for the dent resistance of the outer panel of the outer panel of the vehicle body, comprising: creating a three-dimensional model of the indenter; dividing the three-dimensional model of the indenter into a finite element grid; assigning the divided finite element network of the indenter grid material properties to obtain the finite element model of the indenter; import the finite element model of the indenter into the finite element model of the vehicle body outer cover to be analyzed; The specified forced displacement of the outer panel of the outer panel of the vehicle body, and then the specified forced displacement is unloaded to return the pressure head to the initial position; and the dent resistance analysis data of the anti-dent analysis point is obtained through calculation. In the simulation analysis method for the dent resistance of the outer panel of the outer panel of the vehicle body of the present invention, the specified forced displacement is loaded on the reference point of the indenter, which ensures that the contact analysis between the indenter and the outer panel of the outer panel of the vehicle body is easier to converge, and reduces the simulation The debugging time of the analyzed model greatly improves the efficiency and accuracy of the simulation analysis.

Description

Simulation and analysis method of dent resistance of outer panel of body outer panel

technical field

The invention relates to the technical field of sag resistance simulation analysis of an outer panel of an outer cover of an automobile body, in particular to a simulation analysis method for the dent resistance of an outer panel of an outer cover of a vehicle body.

Background technique

The outer panels of the car's body panels (such as door panels, side panels, fender panels, engine hood panels, trunk panels, and roof panels, etc.) will deform under certain loads. The so-called "sag", usually refers to the ability of the outer panel of the outer panel of the body to withstand the external load, resist the deflection of the dent and the deformation of the local dent, and maintain the original shape as the dent resistance of the outer panel of the outer panel of the body. Since the outer panel of the automobile outer cover can be seen by consumers, if the outer panel undergoes a large deformation under a small load, it will seriously affect consumers' impression of the quality of the car, and even cause a "quality crisis" for the entire brand. ", causing significant economic losses to the enterprise. Therefore, it is necessary to ensure sufficient dent resistance of the vehicle body outer cover. Using the simulation analysis method to pre-study the dent resistance of the outer panel of the body outer panel can greatly reduce the development cost, and at the same time can improve the development efficiency, and can ensure that the design goal can be achieved before the prototype is manufactured. It can be seen that the simulation analysis of the dent resistance of the outer panel of the body outer panel has important practical value.

At present, the loading methods of the simulation analysis methods in the industry are concentrated force or uniform load. The curvature of the indenter and the outer panel of the outer body panel are prone to contact errors, that is, the contact analysis between the indenter and the outer surface of the outer panel of the outer body panel is not easy to converge, which increases the model debugging time and makes the simulation analysis more efficient. and the accuracy is not high.

Contents of the invention

The technical problem to be solved by the present invention is that in the existing simulation analysis method for the anti-denting of the outer panel of the outer panel of the vehicle body, the contact analysis between the indenter and the outer surface of the outer panel of the outer panel of the vehicle body is difficult to converge during the loading process, which increases the time for model debugging A simulation analysis method for the dent resistance of the outer panel of the outer body panel is provided.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is to provide a method for simulation and analysis of the dent resistance of the outer panel of the outer panel of the vehicle body, said method comprising:

Create a 3D model of the indenter;

dividing the three-dimensional model of the indenter into a finite element grid;

endowing the divided finite element grid material properties of the indenter to obtain the finite element model of the indenter;

Import the finite element model of the indenter into the finite element model of the outer body cover to be analyzed, and make the indenter perpendicular to the outer surface of the outer panel of the outer body cover and face the indenter Adjust the distance between the indenter and the anti-dent analysis point to a preset distance at the preset anti-dent analysis point on the outer panel of the outer panel of the vehicle body;

According to the predefined contact properties of the indenter with the outer surface of the outer panel of the vehicle body outer panel, a specified forced displacement perpendicular to the outer panel of the outer panel of the vehicle body is loaded on the preset reference point of the indenter , and then unload the specified forced displacement to return the pressure head to the initial position;

Calculate and obtain the anti-sag analysis data of the anti-sag analysis point.

Further, the created three-dimensional model of the indenter includes a main body of the indenter and an indenter head connected to one end of the main body of the indenter.

Further, the main body of the indenter is cylindrical, the head of the indenter is arc-shaped, and the bottom of the head of the indenter is in contact with one end of the main body of the indenter.

Further, the outer diameter of the indenter body is 80 mm, the arc radius of the outer surface of the indenter head is 132.2 mm; the length of the indenter body is 36 mm, and the wall thickness of the indenter body is 2mm, the wall thickness of the head of the indenter is 2mm.

Further, the "dividing the finite element grid for the three-dimensional model of the indenter" is specifically:

The indenter body of the three-dimensional model of the indenter is divided into finite element grids in the form of shell elements, and the indenter body of the three-dimensional model of the indenter is divided into finite element grids in the form of solid elements.

Further, the contact property between the pressure head and the outer surface of the outer panel of the vehicle body outer cover is predefined as:

Define the outer surface of the head of the indenter and the outer surface of the outer panel of the outer cover of the vehicle body as a contact surface, the outer surface of the outer panel of the outer cover of the vehicle body is the main surface, and the outer surface of the head of the indenter As a slave surface, the contact mode of the outer surface of the head of the indenter and the outer surface of the outer panel of the vehicle body outer cover is small slip.

Further, the specified forced displacement is obtained by the following method:

Loading a limit forced displacement greater than the specified forced displacement on the reference point, setting the output contact reaction force at the reference point;

Obtaining the displacement data of the anti-dent analysis point and the contact reaction force data at the reference point during the moving process of the indenter through calculation;

The displacement when the anti-concave analysis point outputs a specified contact reaction force at the reference point is set as the specified forced displacement.

Further, the value of the limit forced displacement is 20mm.

Further, the value of the specified contact reaction force is 400N.

Further, the "obtaining the anti-concavity analysis data of the anti-concavity analysis point by operation" includes:

Obtaining the displacement data of the anti-dent analysis point during the moving process of the indenter through calculation, so as to obtain the maximum deformation and residual deformation of the anti-dent analysis point;

The contact reaction force data output at the reference point during the movement of the indenter is obtained through calculation.

Further, after the "operation to obtain the anti-sag analysis data of the anti-sag analysis point" also includes:

Combining the displacement data of the anti-dent analysis point and the contact reaction force data output at the reference point, drawing the anti-dent analysis load-unload curve of the outer panel of the outer panel of the vehicle body, the anti-dent analysis load-unload curve Consists of a loading curve and an unloading curve, where,

The loading curve represents the corresponding relationship between the displacement of the anti-dent analysis point and the contact reaction force output at the reference point during the movement of the indenter towards the outer panel of the outer body panel;

The unloading curve represents the corresponding relationship between the displacement of the anti-sag analysis point and the contact reaction force output at the reference point during the retraction process of the indenter.

According to the method for simulating and analyzing the dent resistance of the outer panel of the outer panel of the vehicle body of the present invention, the reference point of the indenter is loaded with a specified forced displacement (a forced boundary condition), and a better specified forced displacement can be obtained in advance, so , there is no need to consider the curvature change of the outer panel of the outer body panel in the analysis process, no matter what the status of the outer panel of the outer body panel is during the loading process, the anti-sag analysis point of the outer panel of the outer body panel will eventually reach this forced displacement, and The movement direction of the indenter is also forced, and the indenter will not slip. In this way, the contact process between the indenter and the outer panel of the outer body panel is more smooth, and it is almost unnecessary to consider the difference between the indenter and the outer panel of the outer panel of the vehicle body. Problems such as contact errors have greatly improved the efficiency of model debugging, reduced model debugging time, improved the convergence speed of contact analysis, and greatly improved the efficiency and accuracy of simulation analysis.

Description of drawings

Fig. 1 is a block flow diagram of a simulation analysis method for the dent resistance of an outer panel of a vehicle body outer panel provided by an embodiment of the present invention;

Fig. 2 is a half-sectional view of the three-dimensional model of the indenter;

Fig. 3 is a top view of the three-dimensional model of the indenter;

Fig. 4 is the schematic diagram of the finite element model of pressure head;

Fig. 5 is a block flow diagram of a method for simulating and analyzing the dent resistance of the outer panel of the vehicle body outer panel provided by another embodiment of the present invention;

Figure 6 is a schematic representation of an anti-dent analysis load-unload curve.

The reference signs are as follows:

10. Indenter body; 20. Indenter head.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

As shown in Figure 1, the simulation analysis method for the dent resistance of the outer panel of the outer panel of the vehicle body provided by an embodiment of the present invention includes the following steps:

101. Create a three-dimensional model of the indenter; in this embodiment, the created three-dimensional model of the indenter is shown in Figure 2 and Figure 3, which includes the main body 10 of the indenter and the indenter connected to one end of the main body 10 of the indenter Head 20. The software for creating the 3D model of the indenter can be Auto CAD, Catia, UG, etc. Preferably, the indenter body 10 is cylindrical, the indenter head 20 is arc-shaped, and the bottom of the indenter head 20 is in contact with one end of the indenter body 10 . The outer diameter of the indenter body 10 should not be too large or too small. If it is too large, the dent resistance of the local area cannot be detected; if it is too small, there will be too many points to be detected, which will greatly increase the workload. For the anti-dent of the board, the indenter head 20 is set in an arc shape; preferably, the outer diameter D1 of the indenter body 10 is 80mm, and the arc radius R1 of the outer surface of the indenter head is 132.2mm ; In addition, the length L1 of the indenter body is 36mm, the wall thickness of the indenter body is 2mm, and the wall thickness of the indenter head 20 is 2mm; preferably, the inner part of the indenter head 20 The surface is parallel to its outer surface, that is, the arc radius of the inner surface of the indenter head 20 is 132.2 mm.

Of course, in other embodiments, the created three-dimensional model of the indenter can also be an existing hemispherical or cylindrical indenter.

102. Perform geometric cleaning on the created three-dimensional model of the indenter. The geometric cleaning is carried out in the pre-processing software, and the geometric cleaning includes removing unnecessary points, lines, small chamfers and small round holes in the three-dimensional model of the indenter, and supplementing missing surfaces and lines in the three-dimensional model of the indenter. The pre-processing software is finite element analysis software, such as Hypermesh or ANSYS.

103. Dividing the 3D model of the indenter into a finite element grid; in this embodiment, as shown in FIG. 4 , dividing the indenter body 10 of the 3D model of the indenter into a finite element grid W1 in the form of shell elements, The indenter body 20 of the three-dimensional model of the indenter is divided into a finite element mesh W2 in the form of solid elements. Preferably, the side length of the finite element grid W1 and the finite element grid W2 is 6 mm. The indenter body 10 is not in contact with the surface of the outer cover during the simulation analysis process, and it is suitable to use shell elements to divide the finite element mesh, and it is not necessary to draw all solid elements. This treatment can reduce the number of indenter meshes and reduce the model calculation time. The process of dividing the finite element mesh of the three-dimensional model of the indenter is also carried out in the above-mentioned pre-processing software. If the divided finite element style does not meet the requirements (the size or the Jacobian matrix does not meet the requirements), then re-divide the finite element mesh of the three-dimensional model 0 of the indenter until it is qualified.

104. Giving the entire finite element grid divided by the three-dimensional model of the indenter a rigid body property to obtain a finite element model of the indenter. That is, in this embodiment, the material property of the indenter is a rigid body.

105. Import the finite element model of the indenter into the finite element model of the vehicle body outer cover to be analyzed, and make the indenter perpendicular to the outer surface of the outer panel of the vehicle body outer cover and the indenter is positive For the preset anti-dent analysis point on the outer panel of the outer panel of the vehicle body, adjust the distance between the indenter and the anti-dent analysis point to a preset distance; reserve a certain gap between the contact surfaces (preset distance), which can make the contact process smoother and facilitate the convergence of contact analysis. A preferred value of the preset distance is 1 mm. In this embodiment, the finite element model of the outer cover of the vehicle body exists in ABAQUS or Radioss software, that is, the finite element model of the indenter is imported into ABAQUS or Radioss software for simulation analysis.

106. According to the predefined contact properties between the indenter and the outer surface of the outer panel of the vehicle body outer panel, load the specified reference point perpendicular to the outer panel of the outer panel of the vehicle body on the preset reference point of the indenter. Forced displacement, and then unloading the specified forced displacement to return the pressure head to the initial position.

In this embodiment, the contact property between the indenter and the outer surface of the outer panel of the outer panel of the vehicle body is predefined as:

Define the outer surface of the head of the indenter and the outer surface of the outer panel of the outer cover of the vehicle body as a contact surface, the outer surface of the outer panel of the outer cover of the vehicle body is the main surface, and the outer surface of the head of the indenter As a slave surface, the contact mode of the outer surface of the head of the indenter and the outer surface of the outer panel of the vehicle body outer cover is small slip. Set the harder surface (the outer surface of the outer panel of the body outer panel) as the main surface, and the softer surface (the outer surface of the head of the indenter) as the secondary surface, so that the indenter and the outer panel of the outer body panel Contact analysis is easier to converge. During the actual contact process, the axis of the indenter should be kept at the same position, and no large slippage between the contact surfaces is allowed. Therefore, the outer surface of the head of the indenter and the outer panel of the outer cover of the vehicle body The contact mode of the outer surface is set to small slip. Contact properties can be pre-set in ABAQUS or Radioss software.

In this embodiment, the reference point is the geometric center of the indenter body. The prescribed forced displacement is loaded at the geometric center of the indenter body.

In this embodiment, the specified mandatory displacement X _r is obtained in advance by the following method:

Loading a limit forced displacement X ₀ greater than the specified forced displacement X _r on the reference point, setting the output contact reaction force at the reference point;

The operation obtains the displacement data of the anti-sag analysis point and the contact reaction force data at the reference point in the moving process of the indenter; this operation is carried out in ABAQUS or Radioss software, and its operation method is the software's own Function.

Set the displacement of the anti-concave analysis point when the specified contact reaction force is output at the reference point as the specified forced displacement X _r . Preferably, the value of the limit forced displacement X ₀ here is set to 20mm. Because, after a lot of practice and data accumulation, it is found that when the forced displacement X ₀ loaded on the indenter is set to 20mm, the contact reaction force output at the reference point is greater than 400N. Preferably, the value of the specified contact reaction force is 400N, and the value of the specified forced displacement is 10mm. Because, after a lot of practice and data accumulation, when the contact reaction force output at the reference point is 400N, the anti-dent process of the outer panel of the outer body panel can be studied in detail, and the buckling of the outer panel of the outer panel can be identified time load. As shown in FIG. 6 , in this embodiment, when the contact reaction force output at the reference point is 400N, the corresponding specified mandatory displacement X _r is 10mm.

107. Obtain the dent resistance analysis data of the dent resistance analysis point through calculation.

In this embodiment, the anti-dent analysis data includes the displacement data of the anti-dent analysis point during the movement of the indenter and the contact reaction force data output at the reference point during the movement of the indenter . The "obtaining the anti-concavity analysis data of the anti-concavity analysis point by operation" includes:

(1) Obtain the displacement data of the anti-concave analysis point during the moving process of the indenter through calculation, so as to obtain the maximum deformation and residual deformation of the anti-concave analysis point; during the loading process, the specified forced displacement X _r is completely When loading, the displacement of the anti-sag analysis point corresponds to the maximum deformation of the anti-sag analysis point; while in the unloading process, when the specified forced displacement X _r is fully loaded, the displacement of the anti-sag analysis point corresponds to the Residual deformation (permanent deformation) at the analysis point against concavity. The displacement data of the anti-concave analysis point during the moving process of the indenter obtained by the above calculation is performed in ABAQUS or Radioss software, and the calculation method is a function of the software itself. By evaluating the two parameters of maximum deformation and residual deformation, the dent resistance performance of the outer panel of the body outer cover is controlled to meet the design requirements.

(2) Calculate and obtain the contact reaction force data output at the reference point during the movement of the indenter.

108. Combining the displacement data of the anti-dent analysis point and the contact reaction force data output at the reference point, draw the anti-dent analysis load-unload curve of the outer panel of the outer panel of the vehicle body, and the anti-dent analysis load-unload curve The unloading curve consists of a loading curve and an unloading curve; a typical anti-sag analysis loading-unloading curve is shown in Figure 6, where the solid line in Figure 6 represents the loading curve, while the dotted line represents the unloading curve. The loading curve represents the corresponding relationship between the displacement of the anti-dent analysis point and the contact reaction force output at the reference point during the movement of the indenter towards the outer panel of the vehicle body outer cover; the unloading The curve represents the corresponding relationship between the displacement of the anti-concave analysis point and the contact reaction force output at the reference point during the retraction process of the indenter. By drawing the anti-concave analysis loading-unloading curve shown in Figure 6, it is possible to intuitively observe whether buckling occurs during loading and unloading, the displacement at the maximum load (maximum deformation) and the residual displacement after unloading (residual deformation).

According to the method for simulating and analyzing the dent resistance of the outer panel of the outer body panel of the present invention, the reference point of the indenter is loaded with a specified forced displacement (a forced boundary condition), and a better specified forced displacement can be pre-determined Therefore, it is not necessary to consider the curvature change of the outer panel of the body outer panel in the analysis process. Regardless of the state of the outer panel of the outer panel of the vehicle body during the loading process, the anti-dent analysis point of the outer panel of the outer panel of the vehicle body must eventually reach this mandatory Displacement, and the movement direction of the indenter is also forced, the indenter will not slip, so that the contact process between the indenter and the outer panel of the outer body panel is more smooth, and there is almost no need to consider the contact between the indenter and the outer panel of the outer body panel Problems such as contact errors in the process greatly improve the efficiency of model debugging, reduce model debugging time, improve the convergence speed of contact analysis, and greatly improve the efficiency and accuracy of simulation analysis.

In addition, as shown in FIG. 5, another embodiment of the present invention also provides a simulation analysis method for the dent resistance of the outer panel of the outer panel of the vehicle body. The method includes the following steps:

201. Create a three-dimensional model of the indenter, wherein the created three-dimensional model of the indenter is shown in FIG. 2 and FIG. 3 , which includes the indenter main body 10 and the indenter head 20 connected to one end of the indenter main body 10 . The software for creating the 3D model of the indenter can be Auto CAD, Catia, UG, etc.

In this embodiment, the indenter body 10 is cylindrical, the indenter head 20 is arc-shaped, and the bottom of the indenter head 20 is in contact with one end of the indenter body 10 . The outer diameter of the indenter body 10 should not be too large or too small. If it is too large, the dent resistance of the local area cannot be detected; if it is too small, there will be too many points to be detected, which will greatly increase the workload. For the anti-dent of the board, the indenter head 20 must be set in an arc shape; preferably, the outer diameter D1 of the indenter body 10 is 80 mm, and the arc radius R1 of the outer surface of the indenter head is 132.2 mm; in addition, the length L1 of the indenter body is 36mm, the wall thickness of the indenter body is 2mm, and the wall thickness of the indenter head 20 is 2mm; preferably, the indenter head 20 The inner surface is parallel to the outer surface, that is, the arc radius of the inner surface of the indenter head 20 is 132.2 mm.

202. Perform geometric cleaning on the created three-dimensional model of the indenter. The geometric cleaning is carried out in the pre-processing software, and the geometric cleaning includes removing unnecessary points, lines, small chamfers and small round holes in the three-dimensional model of the indenter, and supplementing missing surfaces and lines in the three-dimensional model of the indenter. The pre-processing software is finite element analysis software, such as Hypermesh or ANSYS.

203. Divide the finite element meshes of the indenter body 10 and the indenter head 20 of the three-dimensional model of the indenter respectively; specifically, as shown in FIG. 4 , divide the indenter body 10 of the three-dimensional model of the indenter into The finite element mesh W1 in the form of shell elements is divided into the finite element mesh W2 in the form of solid elements for the indenter body 20 of the three-dimensional model of the indenter. Preferably, the side length of the finite element grid W1 and the finite element grid W2 is 6 mm. The indenter body 10 is not in contact with the surface of the outer cover during the simulation analysis process, and it is suitable to use shell elements to divide the finite element mesh, and it is not necessary to draw all solid elements. This treatment can reduce the number of indenter meshes and reduce the model calculation time. The process of dividing the finite element meshes of the indenter body 10 and the indenter head 20 of the three-dimensional model of the indenter is also carried out in the above-mentioned pre-processing software. If the divided finite element style does not meet the requirements (the size or the Jacobian matrix does not meet the requirements), then re-divide the finite element meshes for the indenter body 10 and the indenter head 20 of the indenter three-dimensional model until it is qualified.

204 . Assign rigid body properties to the finite element mesh W1 of the indenter body 10 , and assign flexible body properties to the finite element mesh W2 of the indenter head 20 to obtain a finite element model of the indenter. That is, in this embodiment, the material properties of the finite element grid divided by the indenter are divided into two parts, the material property of the finite element grid W1 of the indenter body 10 is a rigid body, and the finite element grid W2 of the indenter head 20 The material property of is Flexible Body. The indenter body 10 is not in direct contact with the outer panel of the body cover, and mainly plays a role in transferring loads. Using a rigid body can not only express the load transfer relationship, but also reduce the calculation scale of the finite element model and improve efficiency. The indenter head 20 is directly in contact with the outer panel of the vehicle body outer cover. Since the outer panel of the vehicle body outer cover has a constantly changing curvature, the indenter head 20 is set as a flexible body (such as a rubber material). , can ensure that the contact between the indenter head 10 and the outer panel of the outer panel of the vehicle body is more sufficient, so that the analysis of the contact between the indenter and the outer surface of the outer panel of the outer panel of the vehicle body is easier to converge.

205. Import the finite element model of the indenter into the finite element model of the outer body cover to be analyzed, and make the indenter perpendicular to the outer surface of the outer panel of the outer body cover and the head of the indenter The head is facing the preset anti-dent analysis point on the outer panel of the outer panel of the vehicle body, and the distance between the head of the indenter and the anti-dent analysis point is adjusted to a preset distance; a certain distance is reserved between the contact surfaces. The gap (preset distance) can make the contact process smoother, which is conducive to the convergence of contact analysis. A preferred value of the preset distance is 1 mm. In this embodiment, the finite element model of the outer cover of the vehicle body exists in ABAQUS or Radioss software, that is, the finite element model of the indenter is imported into ABAQUS or Radioss software for simulation analysis.

206. According to the predefined contact properties between the indenter and the outer surface of the outer panel of the vehicle body outer cover, load a specified reference point perpendicular to the outer panel of the outer body cover on the preset reference point of the indenter. Forced displacement, and then unloading the specified forced displacement to return the pressure head to the initial position.

In this embodiment, the contact property between the indenter and the outer surface of the outer panel of the outer panel of the vehicle body is predefined as:

Define the outer surface of the head of the indenter and the outer surface of the outer panel of the outer cover of the vehicle body as a contact surface, the outer surface of the outer panel of the outer cover of the vehicle body is the main surface, and the outer surface of the head of the indenter As a slave surface, the contact mode of the outer surface of the head of the indenter and the outer surface of the outer panel of the vehicle body outer cover is small slip. Set the harder surface (the outer surface of the outer panel of the body outer panel) as the main surface, and the softer surface (the outer surface of the head of the indenter) as the secondary surface, so that the indenter and the outer panel of the outer body panel Contact analysis is easier to converge. During the actual contact process, the axis of the indenter should be kept at the same position, and no large slippage between the contact surfaces is allowed. Therefore, the outer surface of the head of the indenter and the outer panel of the outer cover of the vehicle body The contact mode of the outer surface is set to small slip. Contact properties can be pre-set in ABAQUS or Radioss software.

In this embodiment, the reference point is the geometric center of the indenter body. The prescribed mandatory load is loaded at the geometric center of the ram body.

In this embodiment, the specified mandatory displacement _Xr is obtained by the following method:

Loading a limit forced displacement X ₀ greater than the specified forced displacement X _r on the reference point, setting the output contact reaction force at the reference point;

The operation obtains the displacement data of the anti-sag analysis point and the contact reaction force data at the reference point in the moving process of the indenter; this operation is carried out in ABAQUS or Radioss software, and its operation method is the software's own Function.

Set the displacement of the anti-concave analysis point when the specified contact reaction force is output at the reference point as the specified forced displacement X _r . Preferably, the value of the limit forced displacement X ₀ here is set to 20mm. Because, after a lot of practice and data accumulation, it is found that when the forced displacement X ₀ loaded on the indenter is set to 20mm, the contact reaction force output at the reference point is greater than 400N. Preferably, the value of the specified contact reaction force is 400N, and the value of the specified forced displacement is 10mm. Because, after a lot of practice and data accumulation, when the contact reaction force output at the reference point is 400N, the anti-dent process of the outer panel of the outer body panel can be studied in detail, and the buckling of the outer panel of the outer panel can be identified time load. As shown in FIG. 6 , in this embodiment, when the contact reaction force output at the reference point is 400N, the corresponding specified mandatory displacement X _r is 10mm.

207. Obtain the dent resistance analysis data of the dent resistance analysis point through calculation.

In this embodiment, the anti-dent analysis data includes the displacement data of the anti-dent analysis point during the movement of the indenter and the contact reaction force data output at the reference point during the movement of the indenter . The "obtaining the anti-concavity analysis data of the anti-concavity analysis point by operation" includes:

(1) Obtain the displacement data of the anti-concave analysis point during the moving process of the indenter through calculation, so as to obtain the maximum deformation and residual deformation of the anti-concave analysis point; during the loading process, the specified forced displacement X _r is completely When loading, the displacement of the anti-sag analysis point corresponds to the maximum deformation of the anti-sag analysis point; while in the unloading process, when the specified forced displacement X _r is fully loaded, the displacement of the anti-sag analysis point corresponds to the Resisting residual deformation (permanent deformation) of concave analysis points. The displacement data of the anti-concave analysis point during the moving process of the indenter obtained by the above calculation is performed in ABAQUS or Radioss software, and the calculation method is a function of the software itself. By evaluating the two parameters of maximum deformation and residual deformation, the dent resistance performance of the outer panel of the body outer cover is controlled to meet the design requirements.

(2) Calculate and obtain the contact reaction force data output at the reference point during the movement of the indenter.

208. Combining the displacement data of the anti-dent analysis point and the contact reaction force data output at the reference point, draw the anti-dent analysis load-unload curve of the outer panel of the outer panel of the vehicle body, and the anti-dent analysis load-unload curve The unloading curve consists of a loading curve and an unloading curve; a typical anti-sag analysis loading-unloading curve is shown in Figure 6, where the solid line in Figure 6 represents the loading curve, while the dotted line represents the unloading curve. The loading curve represents the corresponding relationship between the displacement of the anti-dent analysis point and the contact reaction force output at the reference point during the movement of the indenter towards the outer panel of the vehicle body outer cover; the unloading The curve represents the corresponding relationship between the displacement of the anti-concave analysis point and the contact reaction force output at the reference point during the retraction process of the indenter. By drawing the anti-concave analysis loading-unloading curve shown in Figure 6, it is possible to intuitively observe whether buckling occurs during loading and unloading, the displacement at the maximum load (maximum deformation) and the residual displacement after unloading (residual deformation).

According to the method for simulating and analyzing the dent resistance of the outer panel of the outer panel of the vehicle body of the present invention, the reference point of the indenter is loaded with a specified forced displacement (a forced boundary condition), and a better specified forced displacement can be obtained in advance, so , there is no need to consider the curvature change of the outer panel of the outer body panel in the analysis process, no matter what the status of the outer panel of the outer body panel is during the loading process, the anti-sag analysis point of the outer panel of the outer body panel will eventually reach this forced displacement, and The movement direction of the indenter is also forced, and the indenter will not slip. In this way, the contact process between the indenter and the outer panel of the outer body panel is more smooth, and it is almost unnecessary to consider the difference between the indenter and the outer panel of the outer panel of the vehicle body. Problems such as contact errors have greatly improved the efficiency of model debugging, reduced model debugging time, improved the convergence speed of contact analysis, and greatly improved the efficiency and accuracy of simulation analysis.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (11)

1. A method for simulation and analysis of the dent resistance of the outer panel of the vehicle body outer cover, is characterized in that, the method comprises: Create a 3D model of the indenter; dividing the three-dimensional model of the indenter into a finite element grid; endowing the divided finite element grid material properties of the indenter to obtain the finite element model of the indenter; Import the finite element model of the indenter into the finite element model of the outer body cover to be analyzed, and make the indenter perpendicular to the outer surface of the outer panel of the outer body cover and face the indenter Adjust the distance between the indenter and the anti-dent analysis point to a preset distance at the preset anti-dent analysis point on the outer panel of the outer panel of the vehicle body; According to the predefined contact properties of the indenter with the outer surface of the outer panel of the vehicle body outer panel, a specified forced displacement perpendicular to the outer panel of the outer panel of the vehicle body is loaded on the preset reference point of the indenter , and then unload the specified forced displacement to return the pressure head to the initial position; Calculate and obtain the anti-sag analysis data of the anti-sag analysis point. 2. The method for simulating and analyzing the dent resistance of the outer panel of the vehicle body outer panel according to claim 1, wherein the created three-dimensional model of the indenter includes a main body of the indenter and an indenter connected to one end of the main body of the indenter. head head. 3. The method for simulating and analyzing the dent resistance of the outer panel of the outer panel of the vehicle body according to claim 2, wherein the main body of the indenter is cylindrical, the head of the indenter is arc-shaped, and the indenter is The bottom of the head portion is docked with one end of the main body of the indenter. 4. The method for simulating and analyzing the dent resistance of the outer panel of the outer panel of the vehicle body according to claim 3, wherein the outer diameter of the indenter body is 80mm, and the arc radius of the outer surface of the indenter head is is 132.2mm; the length of the indenter body is 36mm, the wall thickness of the indenter body is 2mm, and the wall thickness of the indenter head is 2mm. 5. The method for simulating and analyzing the dent resistance of the outer panel of the vehicle body outer panel according to claim 2, wherein the "dividing the three-dimensional model of the indenter into a finite element grid" is specifically: The indenter body of the three-dimensional model of the indenter is divided into finite element grids in the form of shell elements, and the indenter body of the three-dimensional model of the indenter is divided into finite element grids in the form of solid elements. 6. The method for simulating and analyzing the dent resistance of the outer panel of the outer panel of the vehicle body according to claim 2, wherein the contact property between the indenter and the outer surface of the outer panel of the outer panel of the vehicle body is predefined as: Define the outer surface of the head of the indenter and the outer surface of the outer panel of the outer cover of the vehicle body as a contact surface, the outer surface of the outer panel of the outer cover of the vehicle body is the main surface, and the outer surface of the head of the indenter As a slave surface, the contact mode of the outer surface of the head of the indenter and the outer surface of the outer panel of the vehicle body outer cover is small slip. 7. The method for simulating and analyzing the dent resistance of the outer panel of the vehicle body outer panel according to claim 1, wherein the specified forced displacement is obtained by the following method: Loading a limit forced displacement greater than the specified forced displacement on the reference point, setting the output contact reaction force at the reference point; Obtaining the displacement data of the anti-dent analysis point and the contact reaction force data at the reference point during the moving process of the indenter through calculation; The displacement when the anti-concave analysis point outputs a specified contact reaction force at the reference point is set as the specified forced displacement. 8 . The method for simulating and analyzing the dent resistance of the outer panel of the outer panel of the vehicle body according to claim 7 , wherein the value of the limit forced displacement is 20 mm. 9 . The simulation analysis method for the dent resistance of the outer panel of the outer panel of the vehicle body according to claim 7 , wherein the value of the specified contact reaction force is 400N. 10. The method for simulating and analyzing the dent resistance of the outer panel of the outer panel of the vehicle body according to any one of claims 1 to 9, characterized in that the "calculation to obtain the dent resistance analysis data of the anti-dent analysis point" includes : Obtaining the displacement data of the anti-dent analysis point during the moving process of the indenter through calculation, so as to obtain the maximum deformation and residual deformation of the anti-dent analysis point; The contact reaction force data output at the reference point during the movement of the indenter is obtained through calculation. 11. The method for simulating and analyzing the dent resistance of the outer panel of the outer panel of the vehicle body according to claim 10, characterized in that, after the "operation to obtain the dent resistance analysis data of the described dent resistance analysis point" also includes: Combining the displacement data of the anti-dent analysis point and the contact reaction force data output at the reference point, drawing the anti-dent analysis load-unload curve of the outer panel of the outer panel of the vehicle body, the anti-dent analysis load-unload curve Consists of a loading curve and an unloading curve, where, The loading curve represents the corresponding relationship between the displacement of the anti-dent analysis point and the contact reaction force output at the reference point during the movement of the indenter towards the outer panel of the outer body panel; The unloading curve represents the corresponding relationship between the displacement of the anti-sag analysis point and the contact reaction force output at the reference point during the retraction process of the indenter.