Dynamic transfer characteristics simulation system and method of automobile bracket based on boundary equivalent modeling

Abstract

The invention discloses a dynamic transfer characteristic simulation system of an automobile bracket with boundary equivalent modeling, which comprises a rigid equivalent modeling module and a rigidity parameter definition module, wherein the rigid equivalent modeling module is used to perform rigid equivalent modeling on a body boundary and a suspension boundary by using the rigid equivalent principle of automobile parts, and generate a rigid equivalent model of the body boundary and the suspension boundary; the rigidity parameter definition module is used to perform corresponding rigidity parameter definitions on the rigid equivalent models of the body boundary and the suspension boundary by using the rigidity value definition principle of automobile parts. The invention can perform boundary equivalent modeling analysis of an automobile bracket without a body model or when rapid verification is required.

Description

Technical Field

[0001] The invention relates to the technical field of automobile simulation analysis, and in particular to a boundary equivalent modeling automobile bracket dynamic transfer characteristic simulation system and method. Background Art

[0002] As a key link in the vehicle transmission path, the automobile bracket is connected to the vehicle body at the top and to the vehicle suspension triangle arm, connecting rod, vehicle suspension, etc. at the bottom. There are also lateral stabilizer bars, steering gears, etc. installed on the bracket. At present, in the industry, the NVH simulation for the bracket mainly includes free state simulation, installation state simulation installed on the vehicle body, and constraint state simulation of the rigidification of the installation point. For the installation state simulation installed on the vehicle body, it must be carried out with the model of the vehicle body. In the process of automobile product development, chassis parts including brackets are often developed before the vehicle body. At this time, performance analysis and verification with the state of the vehicle body model cannot be carried out. In addition, after the vehicle body model is brought in, the model scale becomes larger, the model becomes more complex, and the simulation verification cycle is greatly lengthened. At this time, a scientific and verified model boundary condition equivalence method can be more efficiently and flexibly applied to simulation analysis in the early or late stages of development. Summary of the invention

[0003] The purpose of the present invention is to provide a vehicle bracket dynamic transfer characteristics simulation system and method based on boundary equivalent modeling. The present invention can perform boundary equivalent modeling analysis of the vehicle bracket without a vehicle body model or when rapid verification is required.

[0004] To achieve this purpose, the present invention designs a vehicle bracket dynamic transfer characteristic simulation system with boundary equivalent modeling, which includes a rigid equivalent modeling module and a rigidity parameter definition module. The rigid equivalent modeling module is used to perform rigid equivalent modeling on the vehicle body boundary and the suspension boundary by using the rigid equivalent principle of automobile parts, and generate a rigid equivalent model of the vehicle body boundary and the suspension boundary;

[0005] The stiffness parameter definition module is used to define the corresponding stiffness parameters of the rigid equivalent models of the body boundary and the suspension boundary respectively according to the stiffness value definition principle of automobile parts.

[0006] The body boundary is divided into the case where the bracket and the body are elastically connected through rubber bushings and the case where the bracket and the body are directly rigidly connected;

[0007] For the case where the bracket of the body boundary is elastically connected to the body through a rubber bushing, when the body side installation point dynamic stiffness value is greater than 5 times the bushing stiffness value, the rigid equivalent model of the body boundary is the rigid constraint boundary model, otherwise the rigid equivalent model of the body boundary is the body boundary CELAS unit model A;

[0008] When the bracket is rigidly connected to the vehicle body by bolts, the rigid equivalent model of the vehicle body boundary is the vehicle body boundary CELAS unit model B.

[0009] The suspension boundary rigidity equivalent model includes the steering gear rigidity equivalent model when the steering gear is installed on the bracket and the swing arm rigidity equivalent model when the swing arm is installed on the bracket;

[0010] Among them, the steering gear rigidity equivalent model is divided into the following two cases:

[0011] The design mass of the steering gear is known, but the structure of the steering gear is unknown. In this case, the steering gear rigid equivalent model includes the rigid unit and concentrated mass of the entire steering gear.

[0012] The design mass of the steering gear is known, and the structure of the steering gear is known. In this case, the steering gear rigid equivalent model includes the rigid unit and concentrated mass of the internal mechanism of the steering gear housing;

[0013] The swing arm rigidity equivalent model when the swing arm is installed on the bracket is divided into the following two cases:

[0014] When the swing arm bushing stiffness is 0.8 to 1 times of the swing arm installation point stiffness on the bracket under the rigid constraint state, the swing arm rigid equivalent model includes the fourth CELAS unit, the swing arm kinematic subunit, the swing arm rigid unit and the swing arm concentrated mass. The fourth CELAS unit is used to simulate the bushing on the body side of the swing arm, the swing arm kinematic subunit is used to simulate the ball joint on the outside of the equivalent swing arm, the swing arm rigid unit is used for the swing arm body, and the swing arm concentrated mass is used for the equivalent swing arm weight.

[0015] When the swing arm bushing stiffness is less than 0.1 times of the inching stiffness of the swing arm installed on the bracket in the rigid constraint state, the swing arm rigid equivalent model includes the fifth CELAS unit and the rigid boundary, the fifth CELAS unit is used to simulate the bushing on the swing arm bracket side, and the rigid boundary is used to equivalent the swing arm body.

[0016] Beneficial effects of the present invention:

[0017] 1. The patent of the present invention can effectively solve the problem that the dynamic transfer characteristics of the bracket cannot be accurately simulated when there is no body model in the early stage of project development simulation analysis; the dynamic transfer characteristics of the bracket need to be simulated under boundary conditions close to the actual vehicle in order to more accurately guide the design. The development of chassis parts precedes the development of the body, so the early stage of bracket development faces the problem of inaccurate boundary conditions. The patent of the present invention solves the problem that there are no boundary conditions in the early stage of bracket development and the dynamic transfer characteristics of the bracket cannot be accurately simulated by simplifying and simulating the boundary conditions.

[0018] 2. Effectively solve the problem that the performance targets of the bracket modal and the dynamic stiffness of the attachment points on the bracket cannot be judged in the simulation analysis in the early stage of project development without a vehicle body, thereby greatly improving the efficiency of the early development of the bracket, shortening the development cycle, and reducing development costs. In addition to being related to the bracket body, the bracket modal and attachment point dynamic stiffness performance are also closely related to the boundary conditions of the bracket. In the early stage of development, there is no real vehicle body boundary, which makes it impossible to accurately judge the achievement of the bracket modal and dynamic stiffness performance targets through simulation. The patent of this invention can accurately simulate the boundary conditions of the bracket body, thereby solving the problem of the inability to judge the performance of the bracket in the early stage, improving development efficiency and shortening the development cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention;

[0020] Figure 2 Comparison diagram of equivalent modeling and test for the bracket boundary;

[0021] Figure 3 A schematic diagram of the bracket boundary of the present invention;

[0022] Figure 4 The figure is a schematic diagram of the application of the present invention on a bracket. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0024] like Figures 1 to 4 The automobile bracket dynamic transfer characteristic simulation system with boundary equivalent modeling shown is characterized in that it includes a rigid equivalent modeling module and a rigidity parameter definition module, wherein the rigid equivalent modeling module is used to perform rigid equivalent modeling on the vehicle body boundary and the suspension boundary by using the rigid equivalent principle of automobile parts, and generate a rigid equivalent model of the vehicle body boundary and the suspension boundary;

[0025] The stiffness parameter definition module is used to define the corresponding stiffness parameters of the rigid equivalent models of the body boundary and the suspension boundary respectively according to the stiffness value definition principle of automobile parts.

[0026] In the above technical solution, the body boundary is divided into a case where the bracket and the body are elastically connected via a rubber bushing and a case where the bracket and the body are directly rigidly connected;

[0027] For the case where the bracket of the body boundary is elastically connected to the body through a rubber bushing, when the body side installation point dynamic stiffness value is greater than 5 times the bushing stiffness value (at this time, the body side installation point dynamic stiffness value >> bushing stiffness value), the rigid equivalent model of the body boundary is the rigid constraint boundary model, otherwise the rigid equivalent model of the body boundary is the body boundary CELAS unit model A;

[0028] When the bracket is rigidly connected to the vehicle body by bolts, the rigid equivalent model of the vehicle body boundary is the vehicle body boundary CELAS unit model B.

[0029] In the above technical solution, the suspension boundary rigidity equivalent model includes a steering gear rigidity equivalent model when the steering gear is installed on the bracket and a swing arm rigidity equivalent model when the swing arm is installed on the bracket;

[0030] Among them, the steering gear rigidity equivalent model is divided into the following two cases:

[0031] The steering gear design mass is known, but the steering gear structure is unknown. In this case, the steering gear rigid equivalent model includes the entire rigid unit and concentrated mass of the steering gear. The main node of the rigid unit is located at the design center of gravity of the steering gear, and the other two slave nodes are connected to the mounting point of the steering gear. This mounting point refers to the mounting point of the steering gear on the bracket, a total of two;

[0032] The design mass and structure of the steering gear are known. At this time, the rigid equivalent model of the steering gear includes the rigid units and concentrated mass of the internal mechanism of the steering gear housing, and the steering gear housing is meshed separately; the main node of the rigid unit is located at the design center of gravity of the steering gear, and the other slave nodes are connected to the mounting point of the steering gear mechanism on the housing, and the housing is mounted on the bracket.

[0033] The anti-roll bar is installed on the bracket through rubber bushings, and its two ends are connected to other suspension systems through ball joints. Therefore, the anti-roll bar is a component with weak boundary constraints, and its constraint effect on the bracket is very small. Its influence is directly ignored and no equivalence is performed.

[0034] The left and right swing arms have a total of 4 inner mounting points, which are installed on the bracket through bushings. The two outer mounting points are connected to the suspension steering knuckle through ball joints. Because there are many constraint points, they have a certain constraint effect on the bracket. The equivalent of the swing arm is handled as follows:

[0035] The swing arm rigidity equivalent model when the swing arm is installed on the bracket is divided into the following two cases:

[0036] When the swing arm bushing stiffness is 0.8 to 1 times of the swing arm installation point stiffness on the bracket under the rigid constraint state, the swing arm has a strong constraint effect on the bracket. The swing arm rigid equivalent model includes the fourth CELAS unit, the swing arm motion subunit, the swing arm rigid unit and the swing arm concentrated mass. The fourth CELAS unit is used to simulate the bushing on the body side of the swing arm, the swing arm motion subunit is used to simulate the ball joint on the outside of the equivalent swing arm, the swing arm rigid unit is used for the swing arm body, the swing arm concentrated mass is used for the equivalent swing arm weight, and the main node of the swing arm rigid unit is the center of gravity position of the swing arm.

[0037] When the stiffness of the swing arm bushing is less than 0.1 times of the inching stiffness of the swing arm installed on the bracket in the rigid constraint state, the constraint effect of the swing arm on the bracket is weak. The swing arm rigid equivalent model includes the fifth CELAS unit and the rigid boundary. The fifth CELAS unit is used to simulate the bushing on the swing arm bracket side, and the rigid boundary is used to equivalent the swing arm body. The bracket body is connected to the fifth celas unit.

[0038] Regarding the engine torsion mount boundary, both ends of the torsion mount are bushings, one end is connected to the bracket, and the other end is connected to the powertrain system. Generally, the bushing stiffness at the large end of the torsion rod is very small, which is much smaller than the dynamic stiffness of the mounting point on the bracket side of the torsion rod in the rigid constraint state. At this time, the constraint effect of the torsion rod on the bracket is very weak, and the influence of the torsion rod is not considered directly.

[0039] The NVH performance of the bracket mainly includes two aspects: modal and dynamic stiffness performance. According to modal theory, each mode is decoupled, but the result of dynamic stiffness is the response result after the superposition of all modes in the modal space. Therefore, the stiffness in the CELAS unit is set as follows:

[0040] For all CELAS element stiffness parameters, there are two methods to define them:

[0041] (1) Only the modal performance of the bracket is analyzed. When judging and optimizing, the dynamic stiffness values ​​of each simulated component at the bracket modal target value are brought in to improve the simulation efficiency. The simulated components are components equivalent to celas units, such as swing arms and steering systems. The object of simulation analysis is the bracket;

[0042] (2) It is necessary to analyze the dynamic stiffness performance of the bracket, that is, to analyze the dynamic stiffness performance, and bring it into the properties of the celas unit when judging and optimizing, and the dynamic stiffness curves of each simulated component to improve the calculation accuracy;

[0043] Furthermore, as mentioned above, there are two types of objects simulated by the CELAS unit: one is the stiffness of structural parts, such as the local structural stiffness of the mounting point on the side of the vehicle body; the other is the stiffness of rubber parts, such as the stiffness of the mounting bushing of the bracket; the stiffness parameters of these two types of objects are obtained by the following method:

[0044] (1) For the local structural stiffness of the vehicle body side mounting point, the stiffness comes from three aspects: actual value, competitor value or target value. If it is an actual value, the stiffness of the frequency point corresponding to the modal frequency is directly taken or the dynamic stiffness curve is brought into the celas unit; if it is a competitor value, the stiffness of the corresponding frequency point is directly taken or the curve is brought in; if it is a target value, only the target value can be brought in.

[0045] (2) For rubber bushings, stiffness also comes from three aspects: actual value, competitor value or target value. The stiffness value selection method is the same as the local structure of the installation point. The difference is that due to the limitations of test conditions, the frequency band of the bushing's dynamic stiffness curve is limited. At this time, it is necessary to interpolate and approximate to achieve a higher frequency (generally higher than 100Hz) rubber bushing dynamic stiffness value or a wider frequency (20-100Hz) test dynamic stiffness curve and bring it into the celas unit.

[0046] In the above technical solution, for the case where the body boundary is a case where the bracket and the body are elastically connected through a rubber bushing:

[0047] The body boundary CELAS unit model A includes a first CELAS unit A, a second CELAS unit A and a third CELAS unit A, and the first CELAS unit, the second CELAS unit and the third CELAS unit respectively simulate the translational stiffness of the body mounting point in the front-to-back direction, the left-to-right direction and the height direction;

[0048] The stiffness parameter definition of the rigid constraint boundary model is as follows: the stiffness is infinite and simplified as a fixed constraint;

[0049] The stiffness parameters of the first CELAS unit A, the second CELAS unit A and the third CELAS unit A are defined as follows: the stiffness of the first CELAS unit A is equal to the front-to-back translation stiffness value of the competitive rubber bushing, the target rubber bushing or the actual rubber bushing (the target value is derived from the performance concept book in the early stage of project development);

[0050] The stiffness of the second CELAS unit A is equal to the left-right translation stiffness value of the competitor rubber bushing, the target rubber bushing or the actual rubber bushing;

[0051] The stiffness of the third CELAS unit A is equal to the height direction translational stiffness value of the competitor rubber bushing, the target rubber bushing or the actual rubber bushing.

[0052] In the above technical solution, for the case where the bracket and the vehicle body are rigidly connected by bolts:

[0053] The vehicle body boundary CELAS unit model B includes a first CELAS unit B, a second CELAS unit B and a third CELAS unit B;

[0054] The stiffness parameters of the first CELAS unit B are defined as follows: the front-rear translational stiffness value of the competitive vehicle body mounting point, the target vehicle body mounting point or the actual vehicle body mounting point;

[0055] The stiffness parameters of the second CELAS unit B are defined as follows: the left-right translation stiffness value of the competitive vehicle body mounting point, the target vehicle body mounting point or the actual vehicle body mounting point;

[0056] The stiffness parameters of the third CELAS unit B are defined as follows: the height direction translational stiffness value of the competitor body mounting point, the target body mounting point or the actual body mounting point.

[0057] In the above technical solution, for a known steering gear design mass and an unknown steering gear structure, the stiffness parameter of the rigid unit of the steering gear as a whole is defined as infinite stiffness, and the concentrated mass is the design mass of the steering gear assembly.

[0058] For a known steering gear design mass and a known steering gear structure, the stiffness parameter of the rigid unit of the internal mechanism of the steering gear housing is equal to infinity, and the mass of the concentrated mass is the design mass of the internal mechanism of the steering gear assembly.

[0059] In the above technical scheme, when the stiffness of the swing arm bushing is 0.8 to 1 times of the dynamic stiffness of the swing arm when installed on the bracket under the rigid constraint state, the stiffness parameters of the fourth CELAS unit, the swing arm kinematic subunit, the swing arm rigid unit and the concentrated mass of the swing arm are defined in the following manner: the stiffness of the fourth CELAS unit is equal to the stiffness of the swing arm bushing on the vehicle body side, the stiffness of the swing arm kinematic subunit is equal to the dynamic stiffness of the swing arm bushing on the wheel side, the swing arm is regarded as a rigid body, the stiffness of the rigid unit simulating the swing arm is infinite, and the concentrated mass of the swing arm is equal to the design mass of the swing arm.

[0060] When the stiffness of the swing arm bushing is between 0.1 and 0.8 times of the dynamic stiffness of the swing arm at the mounting point in the rigid constraint state, the swing arm rigid equivalent model includes the sixth CELAS unit and the rigid boundary A. The sixth CELAS unit is used to simulate the swing arm, and the rigid boundary A is used to equivalent the wheel-side steering knuckle. The stiffness parameters of the sixth CELAS unit and the rigid boundary A are defined as follows: the stiffness of the sixth CELAS unit is equal to the stiffness of the swing arm bushing, and the stiffness of the rigid boundary is equal to the stiffness of the bushing mounting point on the swing arm.

[0061] When the stiffness of the swing arm bushing is less than 0.1 times of the inching stiffness of the swing arm installed on the bracket in the rigid constraint state, the stiffness parameters of the fifth CELAS unit and the rigid boundary are defined as follows: the stiffness of the fifth CELAS unit is equal to the stiffness of the swing arm bushing on the vehicle body side, and the stiffness of the rigid boundary is infinite.

[0062] A boundary equivalent modeling method for simulating and analyzing the dynamic transfer characteristics of an automobile bracket comprises the following steps:

[0063] Step 1: Use the rigid equivalence principle of automobile parts to perform rigid equivalent modeling on the body boundary and suspension boundary to generate a rigid equivalent model of the body boundary and suspension boundary;

[0064] Step 2: Use the definition principle of automobile component stiffness values ​​to define the corresponding stiffness parameters of the rigid equivalent models of the body boundary and suspension boundary.

[0065] The present invention realizes NVH-oriented automobile bracket equivalent modeling and simulation analysis through a CELAS unit, a kinematic pair simulation unit, a concentrated mass unit, a vehicle body mounting point dynamic stiffness, and a rubber bushing static stiffness and dynamic stiffness.

[0066] The present invention solves the following technical problems:

[0067] First, it solves the problem of being unable to accurately simulate the dynamic transfer characteristics of the bracket when there is no body model in the early stage of project development;

[0068] Second, it solves the problem that the performance targets of the bracket modal and the dynamic stiffness of the bracket attachment point cannot be determined in the absence of a body model in the early stage of project development.

[0069] Third, in the process of bracket performance verification and optimization design, the NVH performance of the bracket with a body model can be accurately predicted without a body model, and the efficiency of solution verification and simulation analysis is greatly improved.

[0070] Combine the following Figure 2 and Figure 4 , taking the application of the present invention on a certain bracket as an example, the present invention is further described in detail. Figure 4 The finite element model state after the present invention is applied to a bracket is shown, which embodies the specific scheme of the method:

[0071] 1. The bracket and the vehicle body in the case are rigidly connected by bolts. The boundary of the vehicle body is equivalent to the CELAS unit. The other side is rigidly constrained. The dynamic stiffness curve is derived from the actual test results.

[0072] 2. The detailed structure of the steering gear is known. The steering gear body is equivalent to a shell mesh model and a rigid unit + concentrated mass. The main node of the rigid unit is located at the design center of gravity of the steering gear, and the other two slave nodes are connected to the installation point of the steering gear. The concentrated mass unit is located at the design center of gravity.

[0073] 3. The lateral stabilizer bar is equivalent to a concentrated mass, and the mass is evenly distributed at two installation points.

[0074] 4. In the case, the bushing stiffness on the bracket side of the swing arm is greater than the installation point dynamic stiffness in the bracket constraint state in most directions. Overall, the swing arm is equivalent to a rigid unit, the weight of the swing arm is equivalent to a concentrated mass, and the main node of the rigid unit is the center of gravity of the swing arm.

[0075] 5. The influence of the torsion rod is not considered.

[0076] Attached Figure 2The dynamic stiffness results of the present invention and the test results after being applied to a certain bracket are compared. From the comparison results, it can be seen that the present invention can replace the conventional modeling method under the premise of ensuring accuracy. This solves the problem that the dynamic transfer characteristics of the bracket under the actual vehicle state cannot be accurately simulated when there is no vehicle body in the early stage of project development simulation analysis, and the problem that the bracket mode and the dynamic stiffness performance target of the attachment point on the bracket cannot be determined when there is no vehicle body model in the early stage of project development.

[0077] The present invention performs boundary condition equivalence by judging the strength of the constraint effect of boundary conditions on the research object, and is mainly used for the efficient development of the NVH performance of front and rear brackets in the early stage of project development.

[0078] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A dynamic transfer characteristics simulation system for automobile brackets based on boundary equivalent modeling, characterized in that: It includes a rigid equivalent modeling module and a rigidity parameter definition module, wherein the rigid equivalent modeling module is used to perform rigid equivalent modeling on the vehicle body boundary and the suspension boundary by using the rigid equivalent principle of automobile parts, and generate a rigid equivalent model of the vehicle body boundary and the suspension boundary; The stiffness parameter definition module is used to define the corresponding stiffness parameters of the stiffness equivalent models of the body boundary and the suspension boundary respectively by using the stiffness value definition principle of automobile parts; The suspension boundary rigidity equivalent model includes the steering gear rigidity equivalent model when the steering gear is installed on the bracket and the swing arm rigidity equivalent model when the swing arm is installed on the bracket; Among them, the steering gear rigidity equivalent model is divided into the following two cases: The design mass of the steering gear is known, but the structure of the steering gear is unknown. In this case, the steering gear rigid equivalent model includes the rigid unit and concentrated mass of the entire steering gear. The design mass of the steering gear is known, and the structure of the steering gear is known. In this case, the steering gear rigid equivalent model includes the rigid unit and concentrated mass of the internal mechanism of the steering gear housing; The swing arm rigidity equivalent model when the swing arm is installed on the bracket is divided into the following two cases: When the swing arm bushing stiffness is 0.8 to 1 times of the swing arm installation point stiffness on the bracket under the rigid constraint state, the swing arm rigid equivalent model includes the fourth CELAS unit, the swing arm kinematic subunit, the swing arm rigid unit and the swing arm concentrated mass. The fourth CELAS unit is used to simulate the bushing on the body side of the swing arm, the swing arm kinematic subunit is used to simulate the ball joint on the outside of the equivalent swing arm, the swing arm rigid unit is used for the swing arm body, and the swing arm concentrated mass is used for the equivalent swing arm weight. When the swing arm bushing stiffness is less than 0.1 times of the inching stiffness of the swing arm installed on the bracket in the rigid constraint state, the swing arm rigid equivalent model includes the fifth CELAS unit and the rigid boundary, the fifth CELAS unit is used to simulate the bushing on the swing arm bracket side, and the rigid boundary is used to equivalent the swing arm body.

2. The method for simulating and analyzing the dynamic transfer characteristics of a vehicle bracket based on boundary equivalent modeling according to claim 1 is characterized in that: The body boundary is divided into the case where the bracket and the body are elastically connected through rubber bushings and the case where the bracket and the body are directly rigidly connected; For the case where the bracket of the body boundary is elastically connected to the body through a rubber bushing, when the body side installation point dynamic stiffness value is greater than 5 times the bushing stiffness value, the rigid equivalent model of the body boundary is the rigid constraint boundary model, otherwise the rigid equivalent model of the body boundary is the body boundary CELAS unit model A; For the case where the bracket and the body are rigidly connected by bolts, the rigid equivalent model of the body boundary is the body boundary CELAS unit model B; For the case where the body boundary is elastically connected between the bracket and the body through a rubber bushing: The vehicle body boundary CELAS unit model A includes a first CELAS unit A, a second CELAS unit A and a third CELAS unit A; The stiffness parameter definition of the rigid constraint boundary model is as follows: the stiffness is infinite and simplified as a fixed constraint; The stiffness parameters of the first CELAS unit A, the second CELAS unit A and the third CELAS unit A are defined as follows: the stiffness of the first CELAS unit A is equal to the front-to-back translation stiffness value of the competitive rubber bushing, the target rubber bushing or the actual rubber bushing; The stiffness of the second CELAS unit A is equal to the left-right translation stiffness value of the competitor rubber bushing, the target rubber bushing or the actual rubber bushing; The stiffness of the third CELAS unit A is equal to the translational dynamic stiffness value in the height direction of the competitor rubber bushing, the target rubber bushing or the actual rubber bushing; For the case where the bracket is rigidly connected to the vehicle body by bolts: The vehicle body boundary CELAS unit model B includes a first CELAS unit B, a second CELAS unit B and a third CELAS unit B; The stiffness parameters of the first CELAS unit B are defined as follows: the front-rear translational stiffness value of the competitive vehicle body mounting point, the target vehicle body mounting point or the actual vehicle body mounting point; The stiffness parameters of the second CELAS unit B are defined as follows: the left-right translation stiffness value of the competitive vehicle body mounting point, the target vehicle body mounting point or the actual vehicle body mounting point; The stiffness parameters of the third CELAS unit B are defined as follows: the height direction translational stiffness value of the competitor body mounting point, the target body mounting point or the actual body mounting point.

3. The method for simulating and analyzing the dynamic transfer characteristics of a vehicle bracket based on boundary equivalent modeling according to claim 1, characterized in that: For a steering gear with known design mass and unknown structure, the stiffness parameter of the rigid unit of the steering gear as a whole is defined as infinite stiffness, and the concentrated mass is the design mass of the steering gear assembly.

4. The method for simulating and analyzing the dynamic transfer characteristics of a vehicle bracket based on boundary equivalent modeling according to claim 1, characterized in that: For a known steering gear design mass and a known steering gear structure, the stiffness parameter of the rigid unit of the internal mechanism of the steering gear housing is equal to infinity, and the mass of the concentrated mass is the design mass of the internal mechanism of the steering gear assembly.

5. The method for simulating and analyzing the dynamic transfer characteristics of a vehicle bracket based on boundary equivalent modeling according to claim 1, characterized in that: When the stiffness of the swing arm bushing is 0.8 to 1 times of the dynamic stiffness of the swing arm installed on the bracket under the rigid constraint state, the stiffness parameters of the fourth CELAS unit, the swing arm kinematic subunit, the swing arm rigid unit and the concentrated mass of the swing arm are defined as follows: the stiffness of the fourth CELAS unit is equal to the stiffness of the swing arm bushing on the body side, the stiffness of the swing arm kinematic subunit is equal to the dynamic stiffness of the swing arm bushing on the wheel side, the stiffness of the swing arm rigid unit is infinite, and the concentrated mass of the swing arm is equal to the design mass of the swing arm.

6. The method for simulating and analyzing the dynamic transfer characteristics of a vehicle bracket based on boundary equivalent modeling according to claim 1, characterized in that: When the stiffness of the swing arm bushing is less than 0.1 times of the inching stiffness of the swing arm installed on the bracket in the rigid constraint state, the stiffness parameters of the fifth CELAS unit and the rigid boundary are defined as follows: the stiffness of the fifth CELAS unit is equal to the stiffness of the swing arm bushing on the vehicle body side, and the stiffness of the rigid boundary is infinite.

7. A simulation and analysis method for dynamic transfer characteristics of automobile brackets based on boundary equivalent modeling of the system described in claim 1, characterized in that: It includes the following steps: Step 1: Use the rigid equivalence principle of automobile parts to perform rigid equivalent modeling on the body boundary and suspension boundary to generate a rigid equivalent model of the body boundary and suspension boundary; Step 2: Use the definition principle of automobile component stiffness values ​​to define the corresponding stiffness parameters of the rigid equivalent models of the body boundary and suspension boundary.

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