Automobile finite element sealing strip analysis method

Abstract

The application discloses a kind of automobile finite element sealing strip analysis method, by establishing the stiffness coefficient minimum 1D-discrete unit of negligible output as the probe of sealing strip ballast, only need to extract the component of 1Dforce of this unit in X, Y, Z three directions and carry out vector addition in post-processing process, then according to its set stiffness coefficient, the ballast of the sealing strip corresponding to this 1D unit can be obtained, the ballast force thereof can be obtained by bringing in the sealing strip ballast-ballast force curve measured by experiment, according to the need of simulation, the linear density of 1D-discrete unit probe sampling point is adjusted, so that the sealing strip ballast force of different accuracy degrees can be obtained, to achieve the purpose of carefully and accurately extracting the sealing strip ballast force of three-dimensional grid drawing in LS-Dyna.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of automobile finite element analysis, and particularly relates to a method for analyzing a finite element sealing strip of an automobile. BACKGROUND

[0002] In the process of implementing the present application, the inventors found that the prior art at least has the following problems:

[0003] A sealing strip is an elastic material used to fill the gaps in the automobile doors, windows, sunroofs, etc. Its main function is to prevent external air and moisture from entering the vehicle, while reducing the noise inside the vehicle. It has the functions of waterproofing, dustproofing, sound insulation, shock absorption, etc., and plays an important role in improving the overall performance and comfort of the automobile.

[0004] The jacking force of the sealing strip directly affects the user's experience in terms of vehicle sealing and door closing sound quality. Since the deformation posture of the sealing strip is different under different pressure loads, the reaction force curve is in the form of a piecewise function. Therefore, when using LS-Dyna to perform simulation calculation including the sealing strip, a CAE model of the sealing strip is usually established in the form of a three-dimensional grid to make the simulation structure more accurate. However, the use of this form causes certain difficulties in extracting the reaction force of the sealing strip, especially in simulation of sealing strips that are long in length and have uneven pressure loads during the dynamic process, such as back doors, side doors, etc. In the post-processing of such models, the pressure load reaction force of the sealing strip often needs to be extracted in a more detailed and accurate manner.

[0005] Currently, there are mainly two methods for simulating sealing strips in the field of finite elements. One is to simplify the sealing strip into a finite number of elastic 1D units by using Hooke's law, and to define the stiffness of the units using force and displacement curves. This type of sealing strip is easy to establish, and its pressure load reaction force is also easy to extract. However, the posture change of the sealing strip under pressure load is severely lost, which leads to inaccurate pressure load reaction force in the simulation process. At the same time, the segments of the sealing strip established using this method are associated and discrete, making it difficult to accurately represent the mutual influence between the sealing strip units. The other method is to directly divide 3D grids using the solid data of the sealing strip, and then assign unit attributes and materials. The simulation model of the sealing strip generated in this way has a posture change and pressure load reaction force close to reality after calibration, and the simulation results are relatively accurate. However, it can only extract the resultant force of the pressure load reaction force of the entire sealing strip, which causes certain difficulties in the detailed study of the influence of the sealing strip on the vehicle body and door cover. SUMMARY

[0006] The technical problem solved by the present application is to provide an automobile finite element sealing strip analysis method.

[0007] To solve the above technical problem, the technical solution adopted by the present application is as follows:

[0008] 1) confirming the length D0 of the sealing strip in the radial section in the direction of the pressure load;

[0009] 2) importing the CAD model of the sealing strip and positioning the sealing strip;

[0010] 3) performing finite division on the center line of the mounting surface obtained in step 2);

[0011] 4) establishing 1D-discrete unit probes according to the number of segments and the segment point positions divided in step 3) and connecting the primary and secondary sealing members;

[0012] 5) assigning material properties to the 1D-discrete unit probes established in step 4);

[0013] 6) setting the preload of each 1D-discrete unit probe obtained in step 5) according to the gap of the primary and secondary sealing members;

[0014] 7) post-processing stage;

[0015] 8) obtaining the pressure load counterforce of the sealing strip.

[0016] In the above step 1), the length D0 is the size measured in the natural state of the sealing strip without pressure load.

[0017] In the above step 2), the center line of the mounting surface of the sealing strip and the vehicle body or door cover is extracted, and the sealing strip is positioned through the center line.

[0018] In the above step 3), the density of the 1D-discrete unit probe is determined.

[0019] In the above step 5), the material property is the stiffness coefficient.

[0020] In the above step 6), when the length of any 1D-discrete unit probe changes to D0, the 1D force is a unique constant F0, and the value of F0 is equal to the stiffness coefficient*D0 of the 1D-discrete unit probe.

[0021] In the above-mentioned step 7), the components of the 1D force of each 1D-discrete unit probe in the X, Y, Z three directions are extracted and vectorially added to obtain F1. According to the setting in step 6), the value of F1 is equal to the stiffness coefficient of the 1D-discrete unit probe * the length D1 of the radial cross section of the sealing strip in the design ballast direction in the current analysis step.

[0022] In the above-mentioned step 8), the ballast amount of the sealing strip at the corresponding position of the 1D-discrete unit probe is obtained according to the relationship between D0 and D1, and the ballast reaction force is obtained in combination with the experimentally measured sealing strip ballast amount-ballast reaction force curve.

[0023] The body and door cover model includes the sealing strip surface and the related support.

[0024] One of the technical solutions in the above-mentioned technical solution has the following advantages or beneficial effects: by extracting the center line of the installation plane of the sealing strip and performing controllable finite division thereon to establish a 1D-discrete unit as a probe, the ballast amount of the sealing strip in the dynamic process is indirectly obtained by detecting the output of the 1D-discrete without affecting the simulation result, and the ballast reaction force of the sealing strip is obtained after mathematical transformation. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A schematic diagram of the automobile finite element sealing strip analysis method provided in the embodiment of the present application;

[0026] Figure 2 A schematic diagram of the automobile finite element sealing strip analysis method provided in the embodiment of the present application;

[0027] Figure 3 A schematic diagram of the automobile finite element sealing strip analysis method provided in the embodiment of the present application;

[0028] Figure 4 A schematic diagram of the automobile finite element sealing strip analysis method provided in the embodiment of the present application;

[0029] Figure 5 A schematic diagram of the automobile finite element sealing strip analysis method provided in the embodiment of the present application; DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] Embodiment one

[0032] An automobile finite element seal strip analysis method, comprising the following steps:

[0033] 1) confirming the length D0 of the seal strip in the direction of the ballast in the radial cross section;

[0034] 2) importing the CAD model of the seal strip and positioning the seal strip;

[0035] 3) performing finite division on the centerline of the mounting surface obtained in step 2);

[0036] 4) establishing 1D-discrete unit probes according to the number of segments and the segment point positions divided in step 3) and connecting the primary and secondary seal members;

[0037] 5) assigning material properties to the 1D-discrete unit probes established in step 4);

[0038] 6) setting the preload of each 1D-discrete unit probe obtained in step 5) according to the gap of the primary and secondary seal members;

[0039] 7) post-processing stage;

[0040] 8) obtaining the ballast reaction force of the seal strip.

[0041] In the above step 1), the length D0 is the size measured in the natural state of the seal strip without ballast.

[0042] In the above step 2), the centerline of the mounting surface of the seal strip on the vehicle body or door cover is extracted, and the positioning of the seal strip is performed through the centerline.

[0043] In the above step 3), the density of the 1D-discrete unit probe is determined.

[0044] In the above step 5), the material property is the stiffness coefficient.

[0045] In the above step 6), any 1D-discrete unit probe has a unique value F0 of 1Dforce when the length changes to D0, and F0 is equal to the stiffness coefficient of the 1D-discrete unit probe *D0 in value.

[0046] In the above step 7), the components of the 1Dforce of each 1D-discrete unit probe in the X, Y, and Z directions are extracted and vector summed to obtain F1, and according to the setting in step 6), F1 is equal to the stiffness coefficient of the 1D-discrete unit probe * the length D1 of the seal strip radial cross section in the current analysis step in the design ballast direction in value.

[0047] In the above-mentioned step 8), the sealing strip pressure load at the position corresponding to the 1D-discrete unit probe is obtained according to the relationship between D0 and D1, and the pressure load reaction force is obtained by combining the experimentally measured sealing strip pressure load-pressure load reaction force curve.

[0048] The body and door cover model includes a sealing strip surface and its related support.

[0049] One of the above technical solutions has the following advantages or beneficial effects: by extracting the center line of the installation plane of the sealing strip and performing controllable finite division thereon to establish a 1D-discrete unit as a probe, the sealing strip pressure load in the dynamic process is indirectly obtained by detecting the output of the 1D-discrete without affecting the simulation results, and the sealing strip pressure load reaction force is obtained after mathematical transformation.

[0050] Embodiment two

[0051] Referring to Figures 1 to 5 A finite element sealing strip analysis method for a vehicle, comprising the following steps:

[0052] 1) Confirm and measure the length D0 of the radial cross section of the sealing strip in the design pressure load direction under the natural pressure load-free state;

[0053] The initial length of the sealing strip unit is calibrated in this way.

[0054] 2) Import the CAD model of the sealing strip, and extract the center line of the installation surface of the sealing strip and the vehicle body or door cover;

[0055] The sealing strip is positioned by the center line.

[0056] 3) Finite division is performed on the installation surface center line obtained in step 2 to determine the density of the 1D-discrete unit probe;

[0057] The greater the probe density, the more accurate the simulation results, but at the same time, the model configuration workload and calculation time are increased.

[0058] 4) Establish the 1D-discrete unit probe according to the number of segments and segment point positions divided in step 3, and connect the primary and secondary sealing parts;

[0059] The purpose of this step is to establish the connection between the open-close part and the vehicle body at the position corresponding to the probe.

[0060] 5) Assign material properties to the 1D-discrete unit probe established in step 4, mainly to assign a very small stiffness coefficient;

[0061] Assigning a very small stiffness coefficient does not affect the simulation results, and at the same time, the distance between the open-close part and the vehicle body can be solved by the axial force of the unit.

[0062] 6) According to the gap between the primary and secondary seal, set the preload of each 1D-discrete unit probe obtained in step 5, so that the 1D force of any 1D-discrete unit probe is a unique value F0 when the length changes to D0, which is generally equal in value to the stiffness coefficient of the 1D-discrete unit probe *D0;

[0063] The advantage of setting in this way is to facilitate the calculation of the ballast.

[0064] 7) Extract the components of the 1D force of each 1D-discrete unit probe in the X, Y, Z three directions in the post-processing stage and perform vector addition to obtain F1, if set according to step 6, F1 is equal in value to the stiffness coefficient of the 1D-discrete unit probe * the length D1 of the radial cross section of the seal strip in the design ballast direction at the current analysis step;

[0065] 8) According to the relationship between D0 and D1, the seal strip ballast amount of the corresponding position of the 1D-discrete unit probe is obtained, and the seal strip ballast reaction force is obtained by combining the experimentally measured seal strip ballast amount-ballast reaction force curve.

[0066] The prerequisite for using 1D-discrete units to extract the force of the seal strip is to have a complete model of the primary and secondary seal parts. The following will take the sealing relationship between the vehicle body and the door cover as an example to illustrate this method.

[0067] Among them, the vehicle body and door cover model at least includes the seal strip surface and its related supporting parts.

[0068] By extracting the center line of the installation plane of the seal strip and performing controllable finite division thereon, a 1D-discrete unit is established as a probe. Without affecting the simulation results, the seal strip ballast amount in the dynamic process is indirectly obtained by detecting the output of the 1D-discrete, and the seal strip ballast reaction force is obtained after mathematical transformation.

[0069] Example three

[0070] The commonly used simulation method in the field of finite elements is to simplify the seal strip into a 1D unit with elasticity by using Hooke's law. This method completely ignores the influence of the structure of the seal strip on the movement, and at the same time makes the seal strip discretization inaccurate in mechanical properties. The second is to use the seal strip entity, directly perform mesh division, and assign attributes and materials to simulate the seal strip. In the simulation process, the shape change and mechanical performance of the seal strip can be better simulated, but it is difficult to extract the seal strip ballast reaction force in detail, so a more effective method needs to be developed.

[0071] The basic assumption of the method is that the counterforce of the sealing strip is essentially determined by its ballast amount. By segmenting the centerline of the mounting surface of the sealing strip, a finite number of 1D-discrete unit probes with negligible output are established. The relationship between the output and the ballast amount of the sealing strip is established through mathematical transformation, and the ballast amount obtained by solving is brought into the ballast amount-counterforce curve to obtain the counterforce of the sealing strip.

[0072] An automobile finite element sealing strip analysis method, comprising the following steps:

[0073] 1. Open the CAD model of the sealing strip, at this time the sealing strip is in a natural state without ballast, as shown in Figure 1 ;

[0074] 2. Measure the length D0 of the radial cross section of the sealing strip in the design ballast direction in the natural state without ballast, as shown in Figure 2 ;

[0075] 3. Extract the centerline of the mounting surface of the sealing strip, as shown in Figure 3 ;

[0076] 4. Divide the centerline extracted in step 3 into a finite number of segments, as shown in Figure 4 , the distance between each point in the figure is 10mm along the curve length;

[0077] 5. Establish 1D-discrete unit probes according to the positions of the segmented points generated in step 4, and connect the primary and secondary sealing elements with them, as shown in Figure 5 ;

[0078] 6. Set the material and properties of the 1D-discrete unit probes established in step 5, and set the preload of each unit according to the method in the foregoing;

[0079] 7. Output the 1D force of the 1D-discrete unit probes in the post-processing process, and obtain

[0080] The following proves the relationship between the sealing strip counterforce extracted by the 1D-discrete unit probe and the directly output contact force, and the output results are shown in Table 1:

[0081]

[0082] As can be seen from Table 1, the sealing strip counterforce obtained by using the 1D-discrete unit probe has a small difference with the directly output results, and the method is effective.

[0083] By establishing a 1D-discrete unit with negligible stiffness coefficient as a probe of the sealing strip ballast, only the 1D force components in X, Y and Z directions of the unit are extracted and vector added in the post-processing, and the ballast of the sealing strip corresponding to the 1D unit can be obtained according to the set stiffness coefficient, and the ballast reaction force can be obtained by bringing the ballast reaction force curve of the sealing strip measured in the experiment, the line density of the 1D-discrete unit probe sampling point is adjusted according to the simulation needs, so that the sealing strip ballast reaction force with different accuracy can be obtained, so as to achieve the purpose of accurately and precisely extracting the sealing strip ballast reaction force drawn by using three-dimensional grid in LS-Dyna.

[0084] After adopting the above scheme, based on the finite element modeling software, the center line of the mounting surface of the sealing strip is divided, the 1D-discrete unit probe is established according to the segmentation, and the probe output is extracted and then transformed by mathematics to extract the sealing strip ballast force in detail.

[0085] In the description of the present application, it should be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inner", "front", "central", "both ends" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0086] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "setting", "connecting", "fixing", "screw connection" and the like should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited, the above-mentioned terms in the present application can be understood according to the specific meaning of the above-mentioned terms in the present application according to the specific circumstances.

[0087] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method of analyzing an automotive finite element weatherstrip, characterized by, The method comprises the following steps: 1) confirming the length D0 of the sealing strip in the direction of the ballast in the radial section; 2) importing the CAD model of the sealing strip and positioning the sealing strip; extracting the center line of the mounting surface of the sealing strip and the vehicle body or the door cover, and positioning the sealing strip through the center line; 3) performing finite division on the mounting surface center line obtained in step 2); 4) establishing a 1D-discrete unit probe according to the number of segments and the segment point positions divided in step 3) and connecting the primary and secondary sealing members; 5) assigning material properties to the 1D-discrete unit probe established in step 4); 6) setting the preload of each 1D-discrete unit probe obtained in step 5) according to the gap of the primary and secondary sealing members; when the length of any 1D-discrete unit probe changes to D0, the 1D force of the 1D-discrete unit probe is a unique constant F0, and the value of F0 is equal to the stiffness coefficient of the 1D-discrete unit probe * D0; 7) post-processing stage; extracting the components of the 1D force of each 1D-discrete unit probe in the X, Y and Z directions and performing vector addition to obtain F1; according to the setting in step 6), the value of F1 is equal to the stiffness coefficient of the 1D-discrete unit probe * the length D1 of the radial section of the sealing strip in the direction of the designed ballast at the current analysis step; 8) obtaining the ballast reaction force of the sealing strip; obtaining the ballast amount of the sealing strip at the corresponding position of the 1D-discrete unit probe according to the relationship between D0 and D1, and obtaining the ballast reaction force by combining the ballast amount-ballast reaction force curve measured by experiment.

2. The automotive finite element weatherstrip analysis method of claim 1 wherein, In the above step 1), the length D0 is the size of the sealing strip measured in the natural state without ballast.

3. The automotive finite element weatherstrip analysis method of claim 2 wherein, In the above step 3), the density of the 1D-discrete unit probe is determined.

4. The automotive finite element weatherstrip analysis method of claim 3 wherein, In the above step 5), the material property is the stiffness coefficient.

5. The automotive finite element weatherstrip analysis method of claim 4 wherein, The vehicle body and door cover model includes the sealing strip surface and its related support members.

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