CAE (Computer Aided Engineering)-based strength analysis method for through-type dual-die booster shell

Abstract

The invention relates to a CAE (Computer Aided Engineering)-based strength analysis method for a through type dual-die booster shell, and belongs to the field of CAE. Comprising the following steps: establishing a strength analysis model of the through-type dual-module booster shell, creating a part material, contacting and loading, dividing grids, calculating, obtaining a stress distribution cloud picture of the shell part, locally refining the grids, and verifying an analysis result. The method has the advantages that simulation verification is carried out in the design stage, the number of times of repeated sample verification is reduced, the design efficiency is improved, compared with an existing method, product analysis and simulation are carried out in the design stage, cracking and failure of the shell caused by insufficient design in the experiment process are avoided, a result similar to a test can be obtained on the premise that the test is not carried out, and the design efficiency is improved. And guidance is provided for product design, and the design cost is saved.

Description

Technical Field

[0001] The invention relates to the field of computer-aided engineering (CAE), and in particular to a CAE-based strength analysis method for a through-type dual-mode booster housing. Background Art

[0002] When the conventional double-diaphragm vacuum booster assembly is working, the middle housing, diaphragm and second diaphragm divide the double-diaphragm booster into four chambers. The vacuum chamber and the atmospheric chamber are arranged alternately. The input force of the brake pedal drives the control valve component and the valve body to move. The atmospheric chamber is connected to the atmosphere, and the booster disc and the second booster disc are subjected to the atmospheric pressure to produce a boosting effect. It can be seen that during the working process, the front, middle and rear housings of the booster, the booster disc and the second booster disc will all be subjected to the atmospheric pressure and the feedback force of the master cylinder, which is easy to cause damage during the braking process.

[0003] At present, the strength assessment method of the through-type dual-mode booster shell is mainly a special durability test. The booster with the main cylinder and tank assembly is installed on a durability test bench and subjected to 310,000 durability tests. The durability cycle lasts for 20 days, which is a long time. If the test fails, the part structure needs to be changed and the test needs to be repeated, which lasts for a long period of time. Summary of the invention

[0004] The present invention provides a CAE-based through-type dual-mode booster housing strength analysis method, which aims to save design costs and shorten the verification cycle.

[0005] The technical solution adopted by the present invention comprises the following steps: (1) Establish a strength analysis model for the through-type dual-mode booster housing; Simplify the 3D model of the through-type dual-mode booster assembly, retain the key components that affect the strength of the through-type dual-mode booster shell, save the 3D model in .stp format, and import it into the simulation analysis software; (2) Create part materials; Obtain the material density, elastic modulus, Poisson's ratio, and yield strength of the through-type dual-mode booster analysis model parts under normal temperature conditions, create materials in the simulation software, and assign the materials to the corresponding parts; (3) Create contacts and loads; (4) Divide the grid; (5) Calculate and obtain the stress distribution cloud diagram of the shell parts; Obtain stress distribution cloud diagrams of the front shell, middle shell, and rear shell of the through-type dual-mode booster, and query the maximum stress value and stress position; (6) Locally refine the grid and verify the analysis results; According to the results of preliminary calculations, the stress concentration and excessive deformation points are refined again to ensure the accuracy of the analysis results. The mesh sizes of the key positions of the front shell, middle shell, and rear shell are locally refined until the deviation between the last mesh refinement calculation result and the previous mesh refinement stress calculation result is less than 5% and there are no obvious sharp points in the stress distribution, and the stress and displacement results of the key positions of the parts are obtained.

[0006] The simplified three-dimensional model of the through-type dual-mode booster assembly in step (1) of the present invention includes: 2 sets of locking nuts, a main cylinder body, a front housing, a middle housing, a diaphragm, a rear housing, 2 mounting nuts, a front panel, a second diaphragm, a through rod and 2 support pads.

[0007] The main cylinder body of the present invention has its cylindrical part completely removed, and only the part connected with the through rod is retained, thereby retaining its local features while being able to fully exert its functions.

[0008] The diaphragm of the present invention removes its middle part and only retains the part between the middle shell and the rear shell, which only plays the role of connection and force transmission, and retains its local characteristics under the premise of being able to fully exert its functions.

[0009] The middle part of the second diaphragm of the present invention is removed, and only the part between the front shell and the middle shell is retained, which only plays the role of connection and force transmission, and retains its local characteristics under the premise of being able to fully exert its functions.

[0010] The contact created in step (3) of the present invention includes: The master cylinder body is in frictional contact with the front housing and the locking nut; The front housing is in binding contact with the support pad; The through rod is in binding contact with the locking nut, the support pad and the rear housing; The second diaphragm is in contact with the front shell, the middle shell and the rear shell. The diaphragm is in binding contact with the middle shell and the rear shell; The mounting bolts are in binding contact with the rear housing; The front panel is in frictional contact with the rear housing and is bound and constrained by bolts of the rear housing; The front panel end face is fixed.

[0011] The load in step (3) of the present invention is as follows: according to the actual experimental conditions, the front shell surface is subjected to a pressure of 90 kPa, and the middle shell surface is subjected to a pressure of 90 kPa.

[0012] The overall grid size of the through-type dual-mode booster in step (4) of the present invention is 5 mm to form a grid.

[0013] The advantages of the present invention are that simulation verification is carried out in the design stage, the number of repeated sample verifications is reduced, and the design efficiency is improved. Compared with the previous methods, product analysis and simulation are carried out in the design stage to avoid cracking and failure of the shell during the experiment due to insufficient design. Approximate test results can be obtained without conducting experiments, which provides guidance for product design and saves design costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a simplified analysis model of a through-type dual-mode booster assembly; Figure 2 1. It is a schematic diagram of fixing the end face of the front wall panel; Figure 3 It is the mesh model of the front shell after local refinement; Figure 4 It is a shell mesh model with local refinement; Figure 5 It is the shell mesh model after local refinement; Figure 6 is the stress result diagram of the front shell; Figure 7 is the displacement result diagram of the front shell; Figure 8 is the stress result diagram of the middle shell; Fig. 9 is the displacement result diagram of the middle shell; Fig.10 is the stress result diagram of the rear shell; Fig.11 is the displacement result diagram of the rear shell; Fig.12 It is a flow chart of the invention. DETAILED DESCRIPTION

[0015] The following steps are involved: (1) Establish a strength analysis model for the through-type dual-mode booster housing Simplify the 3D model of the through-type dual-mode booster assembly and retain the key components that affect the strength of the through-type dual-mode booster shell, such as Figure 1 As shown, the model includes: 2 sets of locking nuts 1, main cylinder body (partial) 2, front housing 3, middle housing 4, diaphragm (partial) 5, rear housing 6, 2 mounting nuts 7, front panel (partial) 8, second diaphragm (partial) 9, through rod 10, 2 support pads 11. The 3D model is saved in .stp format and imported into the simulation analysis software Abaqus.

[0016] It is worth noting that the main cylinder, diaphragm and second diaphragm have relatively complex parts structures. The main cylinder's influence on the strength of the through-type dual-mode booster housing is mainly reflected in its contact and interaction with the through-rod on the front housing end face. The diaphragm and second diaphragm's influence on the strength of the through-type dual-mode booster housing are mainly reflected in the connection between the rear housing and the middle housing, and between the front housing and the middle housing. In order to reduce the amount of mesh and save calculation costs, its local features are retained while being able to fully exert its functions. Among them, the main cylinder has its cylindrical part removed and only the part connected to the through-rod (10) is retained; the diaphragm has its middle part removed and only the part between the middle housing (4) and the rear housing (6) is retained, which only plays a role in connecting and transmitting force; the second diaphragm also has its middle part removed and only the part between the front housing (3) and the middle housing (4) is retained, which only plays a role in connecting and transmitting force.

[0017] (2) Create part materials The material density, elastic modulus, Poisson's ratio, and yield strength of the through-type dual-mode booster analysis model parts under room temperature conditions are obtained, and materials are created in the simulation software Abaqus and assigned to the corresponding parts.

[0018] (3) Create contact and load The main cylinder body is in frictional contact with the front housing and the locking nut (Frictional, 0.1); the front housing is in bonded contact with the support pad (Bonded); the through rod is in bonded contact with the locking nut, the support pad, and the rear housing; the second diaphragm is in bonded contact with the front housing, the middle housing, and the rear housing, and the diaphragm is in bonded contact with the middle housing and the rear housing; the mounting bolts are in bonded contact with the rear housing; the front panel is in frictional contact with the rear housing (Frictional, 0.1) and is bound and constrained with the rear housing bolts; the end face of the front panel is fixed, such as Figure 2 ; Load: According to the actual experimental conditions, the front shell surface is subjected to a pressure of 90 kPa, and the middle shell surface is subjected to a pressure of 90 kPa.

[0019] (4) Divide the grid; The overall mesh size of the through-type dual-mode booster is 5mm, forming a grid; (5) Calculate and obtain the stress distribution cloud diagram of the shell parts; Obtain stress distribution cloud diagrams of the front shell, middle shell, and rear shell of the through-type dual-mode booster, and query the maximum stress value and stress position; (6) Locally refine the grid and verify the analysis results; According to the results of the preliminary calculation, the stress concentration and excessive deformation points are further refined to ensure the accuracy of the analysis results. The front shell, middle shell, and rear shell are locally refined, focusing on the position mesh size, such as Figure 3-5Until the deviation between the last mesh refinement calculation result and the previous mesh refinement stress calculation result is less than 5% and there is no obvious sharp point in the stress distribution, the stress and displacement results of the key focus position of the part are obtained, such as Figure 6-11 .

[0020] The result cloud chart shows that the maximum stress of the front shell is concentrated at the edge where it contacts the support pad, and the maximum stress captured at the root of the reinforcement rib is 152.56MPa; the maximum stress of the middle shell is concentrated below the boss, and the maximum stress captured by the refinement part is 186.41MPa; the maximum stress of the rear shell is concentrated at the right-angle bend, and its value is 149.83MPa. According to the principle of material mechanics, if the maximum stress value of the part is less than the yield strength of the material, it means that the part has no plastic deformation and the strength is qualified. If the maximum stress value of the part is greater than the yield strength of the material, it means that the part has plastic deformation under load conditions and cannot be completely restored to its initial state after deformation. Therefore, it is necessary to take improvement measures such as changing the part structure and replacing materials on the premise of meeting the basic requirements of component function and size, until the maximum stress of the part after calculation is less than the yield strength of the material. In addition, in this calculation, the maximum displacement of the front shell is 0.35mm, the maximum displacement of the middle shell is 0.99mm, and the maximum displacement of the rear shell is 0.19mm. The impact of the displacement result on the function of the part should also be considered.

[0021] The above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A CAE-based through-type dual-mode booster housing strength analysis method, characterized in that: The following steps are involved: (1) Establish a strength analysis model for the through-type dual-mode booster housing; Simplify the 3D model of the through-type dual-mode booster assembly, retain the key components that affect the strength of the through-type dual-mode booster shell, save the 3D model in .stp format, and import it into the simulation analysis software; (2) Create part materials; Obtain the material density, elastic modulus, Poisson's ratio, and yield strength of the through-type dual-mode booster analysis model parts under normal temperature conditions, create materials in the simulation software, and assign the materials to the corresponding parts; (3) Create contacts and loads; (4) Divide the grid; (5) Calculate and obtain the stress distribution cloud diagram of the shell parts; Obtain stress distribution cloud diagrams of the front shell, middle shell, and rear shell of the through-type dual-mode booster, and query the maximum stress value and stress position; (6) Locally refine the grid and verify the analysis results; According to the results of preliminary calculations, the stress concentration and excessive deformation points are refined again to ensure the accuracy of the analysis results. The mesh sizes of the key positions of the front shell, middle shell, and rear shell are locally refined until the deviation between the last mesh refinement calculation result and the previous mesh refinement stress calculation result is less than 5% and there are no obvious sharp points in the stress distribution, and the stress and displacement results of the key positions of the parts are obtained.

2. According to the CAE-based through-type dual-mode booster housing strength analysis method of claim 1, it is characterized in that: The simplified three-dimensional model of the through-type dual-mode booster assembly in step (1) includes: 2 sets of locking nuts, a main cylinder body, a front housing, a middle housing, a diaphragm, a rear housing, 2 mounting nuts, a front panel, a second diaphragm, a through rod and 2 support pads.

3. The CAE-based through-type dual-mode booster housing strength analysis method according to claim 2, characterized in that: The main cylinder body has its cylindrical part completely removed, and only the part connected with the through rod is retained, thereby retaining its local features while being able to fully exert its functions.

4. The CAE-based through-type dual-mode booster housing strength analysis method according to claim 2, characterized in that: The middle part of the diaphragm is removed, and only the part between the middle shell and the rear shell is retained, which only plays the role of connection and force transmission, and retains its local characteristics under the premise of being able to fully exert its functions.

5. The CAE-based through-type dual-mode booster housing strength analysis method according to claim 2, characterized in that: The middle part of the second diaphragm is removed, and only the part between the front shell and the middle shell is retained, which only plays the role of connection and force transmission, and retains its local characteristics under the premise of being able to fully exert its function.

6. The CAE-based through-type dual-mode booster housing strength analysis method according to claim 1 is characterized in that: The contact created in step (3) includes: The master cylinder body is in frictional contact with the front housing and the locking nut; The front housing is in binding contact with the support pad; The through rod is in binding contact with the locking nut, the support pad and the rear housing; The second diaphragm is in contact with the front shell, the middle shell and the rear shell. The diaphragm is in binding contact with the middle shell and the rear shell; The mounting bolts are in binding contact with the rear housing; The front panel is in frictional contact with the rear housing and is bound and constrained by bolts of the rear housing; The front panel end face is fixed.

7. The CAE-based through-type dual-mode booster housing strength analysis method according to claim 1 is characterized in that: Load in step (3): According to actual experimental conditions, the front shell surface is subjected to a pressure of 90 kPa, and the middle shell surface is subjected to a pressure of 90 kPa.

8. The CAE-based through-type dual-mode booster housing strength analysis method according to claim 1 is characterized in that: The overall grid size of the through-type dual-mode booster in step (4) is 5 mm to form a grid.

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