Commercial vehicle power assembly suspension system multidisciplinary performance optimization method and system

Abstract

The invention relates to a multidisciplinary performance optimization method and system for a commercial vehicle power assembly suspension system. The method comprises the steps that a 19-degree-of-freedom dynamic model is established for a commercial vehicle; establishing a frame finite element model and a suspension bracket finite element model; solving a vehicle frame modal neutral file, a suspension bracket modal neutral file and suspension bracket modal stress; a rigid-flexible coupling model is established, and the inherent frequency, the vibration mode and the decoupling rate of the power assembly and the suspension vibration isolation rate under the specific working condition are solved; carrying out fatigue working condition dynamic simulation, and solving and outputting modal displacement of the suspension bracket; superposing the modal stress of the suspension bracket and the modal displacement of the suspension bracket, and calculating the fatigue life of the suspension bracket; establishing an optimization target, a constraint condition and an optimization variable; and establishing a multi-objective optimization function, performing multi-disciplinary performance optimization design of the power assembly suspension system by applying a multi-objective optimization algorithm, and outputting an optimization scheme.

Description

Technical Field

[0001] The present invention relates to the technical field of commercial vehicles, and particularly to a multi-disciplinary performance optimization method and system for a power-train mounting system of a commercial vehicle. Background Art

[0002] For commercial vehicles, the power-train mounting system mainly plays roles such as supporting the power train, attenuating the transmission of engine vibrations to the frame and cab, and reducing the self-vibrations of the engine, directly affecting the overall vehicle NVH level, the driving experience of the driver, and the service life of components. Therefore, optimizing the design of the power-train mounting system and the mounting brackets, and achieving a reasonable matching of the parameters of the power-train mounting system and the mounting brackets are of great significance for improving the quality performance and market competitiveness of commercial vehicle products.

[0003] The traditional optimization design of the power-train mounting system of commercial vehicles generally optimizes based on the performance of a certain discipline. For example, the vibration isolation performance of the mounts is optimized by the mount stiffness, or the strength and fatigue performance of the brackets are optimized by the structural parameters of the brackets, while ignoring the coupling effects between performances, resulting in low efficiency and reliability of the optimization design. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-disciplinary performance optimization method and system for a power-train mounting system of a commercial vehicle in view of the deficiencies of the prior art. By establishing a rigid-flexible coupling dynamic model that can take into account both calculation accuracy and efficiency, and considering the flexibility of the bracket and the frame, integrated optimization design of the vibration isolation performance of the mounting system and the fatigue performance of the bracket is carried out, improving the reliability of the design scheme, effectively shortening the development cycle, and reducing the development cost.

[0005] The present invention is implemented by adopting the following technical solutions:

[0006] A multi-disciplinary performance optimization method for a power-train mounting system of a commercial vehicle includes the following steps:

[0007] S1. In view of the structural characteristics of the commercial vehicle, use the Adams / View module of Adams software to establish a 19-degree-of-freedom dynamic model of the power-train mounting system;

[0008] S2. Use HyperMesh software to establish a finite element model of the frame and a finite element model of the mounting bracket; solve the modal neutral file of the frame, the modal neutral file of the mounting bracket, and the modal stress of the mounting bracket based on the modal synthesis method;

[0009] S3. Based on the 19-degree-of-freedom dynamic model, the modal neutral file of the frame, and the modal neutral file of the mounting bracket, establish a rigid-flexible coupling model, and solve the natural frequency, vibration mode, and decoupling rate of the power train, as well as the vibration isolation rate of the mounts under specific working conditions;

[0010] S4. Based on the rigid-flexible coupling model, conduct dynamic simulation of the fatigue condition in the Adams / View module, solve and output the modal displacement of the mount bracket.

[0011] S5. Based on the modal stress recovery theory, superimpose the modal stress of the mount bracket and the modal displacement of the mount bracket in the fatigue analysis software, and then calculate the fatigue life of the mount bracket by the S-N method.

[0012] S6. Take the minimum overall weight of the mount bracket and the maximum mount vibration isolation rate as the optimization objectives; take the natural frequency, decoupling rate of the powertrain and the fatigue life of the mount bracket as the constraint conditions; take the mount stiffness of the powertrain, the installation angle and the thickness parameter of the mount bracket as the optimization variables; establish a multi-objective optimization function for the powertrain mount system and the mount bracket, apply the multi-objective optimization algorithm to conduct the multi-disciplinary performance optimization design of the powertrain mount system, and output the optimization plan.

[0013] As a further description of the invention, step S1 includes:

[0014] The 19-degree-of-freedom dynamics model mainly consists of five parts: the cab, the frame, the powertrain, and the front and rear suspension sub-assemblies. Among them, both the cab and the powertrain consider six degrees of freedom in space, the frame considers three degrees of freedom of Z, Rx, and Ry, and both the front and rear suspension sub-assemblies consider two degrees of freedom of Z and Rx; the mass and moment of inertia of the front and rear suspension sub-assemblies are mainly composed of 3 / 4 of the axle, wheels and leaf springs, and the Bushing force unit is used to connect the components in parallel.

[0015] As a further description of the invention, step S2 includes:

[0016] Use HyperMesh software to establish a finite element model of the frame and a finite element model of the mount bracket, define ASET as the super-element degree-of-freedom reduction boundary at the connection with other components, and solve the frame modal neutral file (*.mnf), the mount bracket modal neutral file (*.mnf) and the mount bracket modal stress (*.op2) based on the modal synthesis method.

[0017] As a further description of the invention, step S3 includes:

[0018] In the Adams / View module, import the frame modal neutral file (*.mnf) and the mount bracket modal neutral file (*.mnf) obtained in step S2 into the 19-degree-of-freedom dynamics model to replace the original rigid body components, establish a rigid-flexible coupling dynamics model, and the flexibility of the flexible body is represented by the modal set.

[0019] Apply the Vibration plug-in of the Adams / View module to solve the natural frequency, vibration mode and decoupling rate of the powertrain in the flexible-rigid coupling model; conduct dynamic simulation under specific working conditions to solve the acceleration time-domain responses a a (t) and a p (t) at the upper and lower points of the mounts, and calculate the vibration isolation rate of the mounts according to the acceleration response curve:

[0020]

[0021] where g i , (i = 1, 2,..., n p ) is the vibration isolation rate at the position of a single mount of the powertrain, and n p is the number of mounts.

[0022] As a further description of the invention, step S4 includes:

[0023] Based on the flexible-rigid coupling model, conduct dynamic simulation under specific working conditions in the Adams / View module to simulate the fatigue driving condition, and solve and output the modal displacement file (*.dac) of the mount bracket.

[0024] As a further description of the invention, step S5 includes:

[0025] Based on the modal stress recovery theory, superimpose the modal stress (*.op2) of the mount bracket obtained in step S2 and the modal displacement (*.dac) of the mount bracket obtained in step S4 in the fatigue analysis software, and then calculate the fatigue life of the mount bracket by the S-N method.

[0026] As a further description of the invention, step S6 includes:

[0027] Taking the minimum overall weight of the mount bracket and the maximum vibration isolation rate of the mounts as the optimization objectives; taking the natural frequency, decoupling rate of the powertrain and the fatigue life of the mount bracket as the constraint conditions; taking parameters such as the mount stiffness of the powertrain, installation angle and the thickness of the mount bracket as the optimization variables; taking into account the requirements of the fatigue performance of the mount bracket, the vibration isolation performance of the mounts and the lightweight of the mount bracket, establish a multi-objective optimization function for the powertrain mount system and the mount bracket, apply a multi-objective optimization algorithm to conduct multi-disciplinary performance optimization design of the powertrain mount system, and output the optimization scheme;

[0028] The multi-objective optimization algorithm adopts an optimization algorithm including but not limited to NSGA-II.

[0029] A multi-disciplinary performance optimization system for a commercial vehicle powertrain mount system includes the multi-disciplinary performance optimization method for a commercial vehicle powertrain mount system described above;

[0030] The system includes:

[0031] A 19-degree-of-freedom dynamic model modeling module, which is used to establish a 19-degree-of-freedom dynamic model of the powertrain mounting system;

[0032] A frame and mounting bracket modal solution module, which is used to solve the frame modal neutral file, the mounting bracket modal neutral file and the mounting bracket modal stress;

[0033] A rigid-flexible coupling model modeling module, which is used to establish a rigid-flexible coupling model based on the 19-degree-of-freedom dynamic model;

[0034] An inherent frequency, decoupling rate and mounting vibration isolation rate solution module, which is used to solve the inherent frequency, vibration mode and decoupling rate of the powertrain and the mounting vibration isolation rate under specific working conditions;

[0035] A rigid-flexible coupling model fatigue condition simulation and modal displacement solution output module, which is used for the fatigue condition simulation of the mounting bracket of the rigid-flexible coupling model and outputs the mounting bracket modal displacement file;

[0036] A mounting bracket fatigue life solution module, which is used to superimpose the mounting bracket modal stress and the mounting bracket modal displacement in a fatigue analysis software, and calculate the mounting bracket fatigue life in combination with the S-N method;

[0037] A multi-objective optimization function establishment and optimization calculation module, which is used to determine the optimization objectives, optimization variables and constraint conditions, establish a multi-objective optimization function for the powertrain mounting system and the mounting bracket, apply a multi-objective optimization algorithm to carry out the multi-disciplinary performance optimization design of the powertrain mounting system, and output the optimization scheme.

[0038] Compared with the prior art, the present invention has the following beneficial technical effects:

[0039] (1) The established rigid-flexible coupling model takes into account the influence of the flexibility of the powertrain mounting bracket and the frame on the vibration isolation performance of the mounting system, and can reflect the vibration coupling relationship between various vehicle systems, greatly improving the solution accuracy of response values such as frequency and vibration isolation rate;

[0040] (2) The established optimization process takes into account the coupling influence of the vibration isolation performance and the bracket structure performance, and the obtained optimization scheme can take into account the requirements of both performance indicators at the same time, improving the reliability of the optimization scheme;

[0041] (3) Through the use of bat commands and software command scripts such as Adams, the established optimization process can realize the automated operation from parameter modification to result output, and perform optimization iteration, improving the calculation efficiency;

[0042] (4) The present invention is applicable to the optimization design of the powertrain mounting system of various layout forms of commercial vehicles. Description of the Drawings

[0043] Figure 1 Schematic diagram of the multidisciplinary performance optimization method for the powertrain mounting system in the embodiment of the present invention;

[0044] Figure 2 Schematic diagram of the simplification of the 19-degree-of-freedom dynamic model in the embodiment of the present invention;

[0045] Figure 3 Finite element model of the mounting bracket for the optimization scheme in the embodiment of the present invention;

[0046] Figure 4 Comparison chart of the thickness of the mounting bracket for the original scheme and the optimization scheme in the embodiment of the present invention;

[0047] Figure 5 Comparison chart of the powertrain mounting stiffness for the original scheme and the optimization scheme in the embodiment of the present invention;

[0048] Figure 6 Comparison chart of the fatigue life of the powertrain mounting bracket for the original scheme and the optimization scheme in the embodiment of the present invention;

[0049] Figure 7 Comparison chart of the rigid body modal frequencies of the powertrain for the original scheme and the optimization scheme in the embodiment of the present invention;

[0050] Figure 8 Comparison chart of the rigid body modal decoupling rates of the powertrain for the original scheme and the optimization scheme in the embodiment of the present invention;

[0051] Figure 9 Comparison chart of the optimization objectives for the original scheme and the optimization scheme in the embodiment of the present invention. Detailed implementation manners

[0052] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0053] Premise explanation: The Adams software refers to the mechanical system dynamics automatic analysis software, and the Adams / View module is a functional module of the Adams software, which is used for modeling, simulation, and optimization analysis;

[0054] The HyperMesh software refers to a finite element simulation software;

[0055] The S-N method refers to the S-N curve, which can describe the basic data of the fatigue performance of materials;

[0056] The bushing force refers to the bushing force, which is a method of applying the mutual force between two components;

[0057] Matlab refers to commercial mathematical software, which is an advanced technical computing language and interactive environment for algorithm development, data visualization, data analysis, and numerical calculation.

[0058] As Figure 1-2 shown, a multidisciplinary performance optimization method for a commercial vehicle powertrain mounting system includes the following steps:

[0059] S1. According to the structural characteristics of the commercial vehicle, use the Adams / View module of Adams software to establish a 19-degree-of-freedom dynamic model of the powertrain mounting system;

[0060] S2. Use HyperMesh software to establish a finite element model of the frame and a finite element model of the mounting bracket; solve the modal neutral file of the frame, the modal neutral file of the mounting bracket, and the modal stress of the mounting bracket based on the modal synthesis method;

[0061] S3. Based on the 19-degree-of-freedom dynamic model, the modal neutral file of the frame, and the modal neutral file of the mounting bracket, establish a rigid-flexible coupling model, and solve the natural frequency, vibration mode, decoupling rate of the powertrain, and the vibration isolation rate of the mount under specific working conditions;

[0062] S4. Based on the rigid-flexible coupling model, conduct a fatigue condition dynamic simulation in the Adams / View module, and solve and output the modal displacement of the mounting bracket;

[0063] S5. Based on the modal stress recovery theory, superimpose the modal stress of the mounting bracket and the modal displacement of the mounting bracket in the fatigue analysis software, and then calculate the fatigue life of the mounting bracket by the S-N method;

[0064] S6. Take the minimum overall weight of the mounting bracket and the maximum vibration isolation rate of the mount as the optimization objectives; take the natural frequency, decoupling rate of the powertrain, and the fatigue life of the mounting bracket as the constraint conditions; take the powertrain mount stiffness, installation angle, and the thickness parameter of the mounting bracket as the optimization variables; establish a multi-objective optimization function for the powertrain mounting system and the mounting bracket, and use the multi-objective optimization algorithm to conduct a multidisciplinary performance optimization design of the powertrain mounting system, and output the optimization plan.

[0065] Further, step S1 includes:

[0066] As Figure 2As shown in the figure, the 19-degree-of-freedom dynamics model mainly consists of five parts: the cab 100, the frame 300, the powertrain 200, the front suspension subassembly 400, and the rear suspension subassembly 500. Among them, both the cab 100 and the powertrain 200 consider six degrees of freedom in space, the frame 300 considers three degrees of freedom of Z, Rx, and Ry, and both the front suspension subassembly 400 and the rear suspension subassembly 500 consider two degrees of freedom of Z and Rx; the mass and moment of inertia of the front and rear suspension subassemblies are mainly composed of 3 / 4 of the axle, wheels, and leaf springs. The components are connected in parallel by Bushing force units, which can reflect the vibration coupling effect between the subsystems of commercial vehicles.

[0067] Further, step S2 includes:

[0068] Use HyperMesh software to establish a finite element model of the frame and a finite element model of the mount bracket. Define ASET as the super-element degree-of-freedom reduction boundary at the connection with other components, and solve the frame modal neutral file (*.mnf), the mount bracket modal neutral file (*.mnf), and the mount bracket modal stress (*.op2) based on the modal synthesis method.

[0069] Among them, the frame modal neutral file (*.mnf) is not optimized iteratively, and the mount bracket modal neutral file (*.mnf) and the mount bracket modal stress (*.op2) are optimized iteratively; therefore, after establishing the finite element model of the mount bracket, write a bat script and a TCL command script for HyperMesh to complete the parameter setting of each mount bracket finite element model, the solution and output of the modal neutral file (*.mnf) and the modal stress file (*.op2). The modal stress file (*.op2) is used for subsequent calculation of the fatigue life of the mount bracket.

[0070] Further, step S3 includes:

[0071] In the Adams / View module, import the frame modal neutral file (*.mnf) and the mount bracket modal neutral file (*.mnf) obtained in step S2 into the 19-degree-of-freedom dynamics model to replace the original rigid body components, and establish a rigid-flexible coupling dynamics model considering the flexibility of the bracket and the frame. The flexibility of the flexible body is represented by a modal set;

[0072] Use the Vibration plug-in of the Adams / View module to solve the natural frequency, vibration mode, and decoupling ratio of the powertrain in the rigid-flexible coupling model; perform a dynamic simulation under specific working conditions to solve the acceleration time-domain responses a a (t) and a p (t) at the upper and lower points of the mount, and calculate the mount isolation ratio according to the acceleration response curve:

[0073]

[0074] wherein, g i , (i = 1, 2, …, n p ) is the vibration isolation rate at the position of a single mount of the powertrain, and n p is the number of mounts.

[0075] Among them, the mount parameters of the rigid-flexible coupling model and the modal neutral file of the mount bracket are iterated with optimization. The bat script and the CMD command script of Adams are written to complete: call Adams / View to import the frame modal neutral file (*.mnf) and the mount bracket modal neutral file (*.mnf) in the 19-degree-of-freedom dynamic model to replace the original rigid body components, and establish a rigid-flexible coupling dynamic model; set parameters such as the stiffness and angle of the powertrain mounts; apply the Vibration plug-in to solve the undamped natural frequency, vibration mode and decoupling rate of the powertrain, and output the results to a text file; conduct a vibration isolation rate condition simulation, and output the vibration acceleration of the upper / lower points of the mount to a text file; write a Matlab script to read the frequency and decoupling rate analysis results output by Adams / View, and select the frequency, vibration mode and decoupling rate of the powertrain; write a Matlab script to read the mount acceleration results output by the vibration isolation rate condition simulation, and solve the vibration isolation rate of the mount.

[0076] Further, step S4 includes:

[0077] Based on the rigid-flexible coupling model, conduct a dynamic simulation of the fatigue driving condition under specific conditions in the Adams / View module, and solve and output the modal displacement file (*.dac) of the mount bracket.

[0078] Among them, write the bat command and the CMD command script of Adams, call Adams / View to complete the simulation of the vehicle driving condition by applying vertical displacement time-domain excitation to the left and right sides of the front and rear suspension spring lower components in the rigid-flexible coupling dynamic model, complete the fatigue condition simulation, and output the modal displacement file (*.dac) of each mount bracket in the Durability plug-in as the load spectrum for the fatigue calculation of the mount bracket.

[0079] Further, step S5 includes:

[0080] Based on the modal stress recovery theory, superimpose the modal stress (*.op2) of the mount bracket obtained in step S2 and the modal displacement (*.dac) of the mount bracket obtained in step S4 in the fatigue analysis software, and then calculate the fatigue life of the mount bracket by the S-N method.

[0081] Among them, write a bat script to call the fatigue analysis software to superimpose the modal stress (*.op2) and modal displacement (*.dac) of the suspension bracket, calculate the fatigue life in combination with the material parameters of the bracket, and output the fatigue result file in HyperMesh format (*.hyp); then write a bat command and a TCL command script for HyperMesh to read the fatigue result file (*.hyp) and output the minimum fatigue life of the suspension bracket.

[0082] Further, step S6 includes:

[0083] Among them, taking the minimum overall weight of the suspension bracket and the maximum suspension vibration isolation rate as the optimization objectives; taking the natural frequency, decoupling rate of the powertrain and the fatigue life of the suspension bracket as the constraint conditions; taking parameters such as the suspension stiffness of the powertrain, installation angle and the thickness of the suspension bracket as the optimization variables; taking into account the fatigue performance of the suspension bracket, the suspension vibration isolation performance and the lightweight requirements of the suspension bracket, establish a multi-objective optimization function for the powertrain suspension system and the suspension bracket, apply a multi-objective optimization algorithm to carry out the multi-disciplinary performance optimization design of the powertrain suspension system, and output the optimization scheme;

[0084] The multi-objective optimization algorithm adopts an optimization algorithm including but not limited to NSGA-II; among them, using the multi-objective optimization algorithm, combined with the written software command script, the Adams, HyperMesh and fatigue analysis software are called in the background to complete the automated calculation from the modification of suspension parameters to the output of results, and the optimization scheme is output.

[0085] A multi-disciplinary performance optimization system for a commercial vehicle powertrain suspension system includes the multi-disciplinary performance optimization method for the commercial vehicle powertrain suspension system described above;

[0086] The system includes:

[0087] A 19-degree-of-freedom dynamics model modeling module for establishing a 19-degree-of-freedom dynamics model of the powertrain suspension system;

[0088] A frame and suspension bracket modal solution module for solving the frame modal neutral file, the suspension bracket modal neutral file and the suspension bracket modal stress; the frame modal neutral file (*.mnf) is not optimized iteratively, and the suspension bracket modal neutral file (*.mnf) and the suspension bracket modal stress (*.op2) are optimized iteratively; therefore, after establishing the finite element model of the suspension bracket, write a bat script and a TCL command script for HyperMesh to complete the parameter setting of each suspension bracket finite element model, the solution and output of the modal neutral file (*.mnf) and the modal stress file (*.op2), and the modal stress file (*.op2) is used for subsequent calculation of the fatigue life of the suspension bracket;

[0089] The rigid-flexible coupling model modeling module is used to establish a rigid-flexible coupling model based on the 19-degree-of-freedom dynamic model. Since the suspension parameters and the modal neutral file of the suspension bracket of the rigid-flexible coupling model change with the optimization iteration, a bat script and an Adams CMD command script are written to complete the following: Call Adams / View to import the frame modal neutral file (*.mnf) and the suspension bracket modal neutral file (*.mnf) into the 19-degree-of-freedom dynamic model to replace the original rigid body components, and establish a rigid-flexible coupling dynamic model.

[0090] The natural frequency, decoupling rate, and suspension vibration isolation rate solving module is used to solve the natural frequency, vibration mode, and decoupling rate of the powertrain, as well as the suspension vibration isolation rate under specific working conditions.

[0091] The rigid-flexible coupling model fatigue condition simulation and modal displacement solving and output module is used for the fatigue condition simulation of the suspension bracket of the rigid-flexible coupling model and output the modal displacement file of the suspension bracket.

[0092] The suspension bracket fatigue life solving module is used to superimpose the modal stress and modal displacement of the suspension bracket in the fatigue analysis software, and calculate the fatigue life of the suspension bracket in combination with the S-N method. Call the fatigue analysis software through the bat command, superimpose the stress of each order of each suspension bracket and the modal displacement of the corresponding order of the modal, obtain the stress time domain spectrum, and then calculate the fatigue life of the structure through the S-N method and output the fatigue result file in HyperMesh format (*.hyp). And write the bat command and the TCL command script of HyperMesh, read the fatigue result file (*.hyp) and output the minimum fatigue life of the bracket as one of the responses of the multi-objective optimization function.

[0093] The multi-objective optimization function establishment and optimization calculation module is used to determine the optimization objectives, optimization variables, and constraint conditions, establish the multi-objective optimization function of the powertrain suspension system and the suspension bracket, apply the multi-objective optimization algorithm to carry out the multi-disciplinary performance optimization design of the powertrain suspension system, and output the optimization scheme.

[0094] As Figures 3-5 shown below, a specific example is used to illustrate the application of the above multi-disciplinary performance optimization method and system for the vehicle powertrain suspension system.

[0095] For a certain light truck model, the 6-degree-of-freedom dynamic model in space only considers the powertrain, including six degrees of freedom in the longitudinal x, lateral y, vertical z, roll Rx, pitch Ry, and yaw Rz directions. Establish a 6-degree-of-freedom dynamic model in space as the original scheme. And write the bat command and the Adams CMD script to complete the modification of the suspension parameters, the solution of the rigid body mode, and the result output. And carry out subsequent calculations.

[0096] Based on this, a 19-degree-of-freedom dynamic model is established as the optimization scheme; based on the light truck model parameters, a finite element model of its powertrain mount bracket is established, as Figure 3 shown, and bat commands and TCL scripts of HyperMesh are written to modify parameters such as the bracket thickness, and the modal neutral file (*.mnf) of the mount bracket is solved for subsequent establishment of the rigid-flexible coupling model;

[0097] A rigid-flexible coupling model of the powertrain mount system is established, where the flexible body of the powertrain mount bracket is obtained by solving the bracket finite element model, as Figure 2 shown, bat commands and CMD scripts of Adams are written to call Adams to modify parameters such as the powertrain mount stiffness and angle, import the modal neutral file of the bracket into the 19-degree-of-freedom dynamic model to replace the original component, establish the rigid-flexible coupling model, and complete the solution of the vibration isolation rate, static displacement, etc. of the powertrain mount, as well as the dynamic solution of the fatigue condition of the mount bracket, and output the modal displacement of the bracket for subsequent bracket fatigue calculation;

[0098] Bat commands are written to call the fatigue analysis software, the stress of each order of each mount bracket is superimposed with the modal displacement of the corresponding order of the mode to obtain the stress time domain spectrum, and then the fatigue life of the structure is calculated by the S-N method, and the fatigue result file in HyperMesh format (*.hyp) is output; and bat commands and TCL command scripts of HyperMesh are written to read the fatigue result file (*.hyp) and output the minimum fatigue life of the bracket;

[0099] The multi-objective optimization algorithm is adopted to integrate the bat commands and script files written above, call software such as Adams and HyperMesh to solve the rigid body mode, vibration isolation rate, and fatigue life of the powertrain mount system, etc., and perform optimization variable iteration according to the optimization objectives and constraints.

[0100] For this light truck model, multidisciplinary optimization of the vibration isolation performance of the powertrain mount and the structural performance of the bracket is carried out, and the three optimization elements are as follows:

[0101]

[0102] As Figures 4-5 shown, the original scheme and the optimization scheme take the bracket thickness and the mount stiffness as the optimization variables, as Figure 9 shown, the original scheme and the optimization scheme take the total weight of the mount bracket and the minimum value of the Z-direction vibration isolation rate at all mount positions as the optimization objectives, as Figures 6-8, the original solution and the optimized solution are subject to the fatigue life, frequency, and decoupling rate of the suspension bracket; it can be clearly seen that after changing the optimization variables in the optimized solution compared with the original solution, other constraint conditions are also met. While reducing the weight of the suspension bracket for the optimization objective, the vibration isolation rate of the suspension system is improved, taking into account the requirements of both performance indicators and enhancing the reliability of the optimized solution.

[0103] Although the present invention has been described in detail by referring to the accompanying drawings and in conjunction with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and all such modifications or substitutions should be within the scope of the present invention. / Any person skilled in the art within the technical scope disclosed by the present invention can easily conceive of changes or substitutions, which should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A multi-disciplinary performance optimization method for a commercial vehicle powertrain mounting system, characterized in that, It includes the following steps: S1. According to the structural characteristics of commercial vehicles, use the Adams / View module of Adams software to establish a 19-degree-of-freedom dynamic model of the powertrain mounting system; S2. Use HyperMesh software to establish a finite element model of the frame and a finite element model of the mounting bracket; solve the modal neutral file of the frame, the modal neutral file of the mounting bracket, and the modal stress of the mounting bracket based on the modal synthesis method; S3. Based on the 19-degree-of-freedom dynamic model, the modal neutral file of the frame, and the modal neutral file of the mounting bracket, establish a rigid-flexible coupling model, and solve the natural frequency, vibration mode, decoupling rate of the powertrain, and the vibration isolation rate of the mounts under specific working conditions; S4. Based on the rigid-flexible coupling model, conduct a dynamic simulation of the fatigue working condition in the Adams / View module, and solve and output the modal displacement of the mounting bracket; S5. Based on the modal stress recovery theory, superimpose the modal stress of the mounting bracket and the modal displacement of the mounting bracket in the fatigue analysis software, and then calculate the fatigue life of the mounting bracket by the S-N method; S6. Take the minimum overall weight of the mounting bracket and the maximum vibration isolation rate of the mounts as the optimization objectives; take the natural frequency, decoupling rate of the powertrain, and the fatigue life of the mounting bracket as the constraint conditions; take the powertrain mounting stiffness, installation angle, and the thickness parameter of the mounting bracket as the optimization variables; Establish a multi-objective optimization function for the powertrain mounting system and the mounting bracket, apply the multi-objective optimization algorithm to conduct a multi-disciplinary performance optimization design of the powertrain mounting system, and output the optimization plan.

2. The multi-disciplinary performance optimization method for a commercial vehicle powertrain mounting system according to claim 1, characterized in that, Step S1 includes: The 19-degree-of-freedom dynamic model mainly consists of five parts: the cab, the frame, the powertrain, and the front and rear suspension sub-assemblies. Among them, both the cab and the powertrain consider six degrees of freedom in space, the frame considers three degrees of freedom of Z, Rx, and Ry, and both the front and rear suspension sub-assemblies consider two degrees of freedom of Z and Rx; the mass and moment of inertia of the front and rear suspension sub-assemblies are mainly composed of 3 / 4 of the axle, wheels, and leaf springs. The Bushing force unit is used to connect each component in parallel.

3. The multi-disciplinary performance optimization method for a commercial vehicle powertrain mounting system according to claim 2, characterized in that, Step S2 includes: Use HyperMesh software to establish a finite element model of the frame and a finite element model of the mounting bracket. Define ASET as the super-element degree-of-freedom reduction boundary at the connection with other components, and solve the modal neutral file (*.mnf) of the frame, the modal neutral file (*.mnf) of the mounting bracket, and the modal stress (*.op2) of the mounting bracket based on the modal synthesis method.

4. The multi-disciplinary performance optimization method for a commercial vehicle powertrain mounting system according to claim 3, characterized in that, Step S3 includes: In the Adams / View module, import the modal neutral file (*.mnf) of the frame and the modal neutral file (*.mnf) of the mounting bracket obtained in step S2 into the 19-degree-of-freedom dynamic model to replace the original rigid body components, and establish a rigid-flexible coupling dynamic model. The flexibility of the flexible body is represented by a modal set; Apply the Vibration plug-in of the Adams / View module to solve the natural frequency, vibration mode and decoupling rate of the powertrain in the rigid-flexible coupling model; conduct dynamic simulations under specific working conditions to solve the time-domain acceleration responses a a (t) and a p (t), and calculate the vibration isolation rate of the mounts according to the acceleration response curve: where g i , (i = 1, 2, …, n p ) is the vibration isolation rate at the position of a single mount of the powertrain, and n p is the number of mounts.

5. The multi-disciplinary performance optimization method for a commercial vehicle powertrain mounting system according to claim 4, characterized in that, Step S4 includes: Based on the rigid-flexible coupling model, conduct a dynamic simulation of the specific working condition in the Adams / View module to simulate the fatigue driving condition, and solve and output the modal displacement file (*.dac) of the mounting bracket.

6. The multi-disciplinary performance optimization method for a commercial vehicle powertrain mounting system according to claim 5, characterized in that, Step S5 includes: Based on the modal stress recovery theory, in the fatigue analysis software, the modal stress (*.op2) of the mounting bracket obtained in step S2 is superimposed with the modal displacement (*.dac) of the mounting bracket obtained in step S4, and then the fatigue life of the mounting bracket is calculated by the S-N method.

7. The multi-disciplinary performance optimization method for a commercial vehicle powertrain mounting system according to claim 6, characterized in that, Step S6 includes: Taking the minimum overall weight of the mounting bracket and the maximum mounting vibration isolation rate as the optimization objectives; taking the natural frequency, decoupling rate of the powertrain and the fatigue life of the mounting bracket as the constraint conditions; taking parameters such as the mounting stiffness of the powertrain, the installation angle and the thickness of the mounting bracket as the optimization variables; taking into account the requirements of the fatigue performance of the mounting bracket, the mounting vibration isolation performance and the lightweight of the mounting bracket, establishing a multi-objective optimization function for the powertrain mounting system and the mounting bracket, applying a multi-objective optimization algorithm to optimize the multi-disciplinary performance design of the powertrain mounting system, and outputting an optimization plan; The multi-objective optimization algorithm adopts an optimization algorithm including but not limited to NSGA-II.

8. A multi-disciplinary performance optimization system for a commercial vehicle powertrain mounting system, characterized in that, Including the multi-disciplinary performance optimization method of the commercial vehicle powertrain mounting system according to any one of claims 1-7; The system includes: A 19-degree-of-freedom dynamics model modeling module for establishing a 19-degree-of-freedom dynamics model of the powertrain mounting system; A frame and mounting bracket modal solution module for solving the frame modal neutral file, the mounting bracket modal neutral file and the mounting bracket modal stress; A rigid-flexible coupling model modeling module for establishing a rigid-flexible coupling model based on the 19-degree-of-freedom dynamics model; A natural frequency, decoupling rate and mounting vibration isolation rate solution module for solving the natural frequency, vibration mode and decoupling rate of the powertrain and the mounting vibration isolation rate under specific working conditions; A rigid-flexible coupling model fatigue condition simulation and modal displacement solution output module for simulating the fatigue condition of the mounting bracket of the rigid-flexible coupling model and outputting the mounting bracket modal displacement file; A mounting bracket fatigue life solution module for superimposing the mounting bracket modal stress and the mounting bracket modal displacement in the fatigue analysis software and calculating the mounting bracket fatigue life in combination with the S-N method; A multi-objective optimization function determination and optimization calculation module for determining the optimization objectives, optimization variables and constraint conditions, establishing a multi-objective optimization function for the powertrain mounting system and the mounting bracket, applying a multi-objective optimization algorithm to optimize the multi-disciplinary performance design of the powertrain mounting system, and outputting an optimization plan.

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