The Study Of Dynamic Simulation Optimization & Test Of Commercial Vehicle Cab Suspension System

In recent years, as China's economic develops so rapidly, the pace of nation-building accelerate, commercial vehicle as an essential tool receives more and more attention. Along with the development of automotive technology, as well as China's road traffic conditions improve, so there has been new requirements on commercial vehicle.In addition to ensuring normal transportation of goods and security, also commercial vehicle should have a certain comfort. So the cab suspension system has been widely applied to improve the commercial vehicle's comfort. The cab suspension system is a second level vibration isolation system.The attenuation of vibration which is from road, engine, frame, as well as the transmission can be very good, so good cab suspension system could increase commercial vehicle comfort greatly.On the basis of reading a lot of literature, the paper introduces the development status quo of the domestic and international commercial vehicle cab suspension technology. Then the paper introduces the main function of the cab suspension, according to Layout form classifies cab suspension system, also it analyses common accessories' performance of the cab suspension system, and elaborates staple research methods of both here and abroad on cab suspension system design study, and then summs up the results of representative research. Later the paper introduces the development of the commonly used research methods such as virtual prototype technology and multi-body dynamic.Next the paper deduces the transfer function of cab single degree freedom model, through which the paper analyses basic methods of vibration isolation. After that the paper introduces multi-body dynamic technology and the ADAMS software modules and functions. This provides sufficient theoretical support for the establishment of model.The interactive method is used to establish cab suspension system model. Through CATIA three-dimensional software, according to the main body(Cab, mount components, seats, etc.) geometry of cab suspension system, the paper builts each of the major components suspension system 3D geometric models. Through the interface software, 3D geometric models are installed into ADAMS in accordance with the actual position, and the corresponding parameters of the mass are modified. Theoretical analysis of the model are done, horizontal steadied stick, shaking table and rubber bushing and the main joint of the cab suspension system are simplified appropriately. Then the paper adds restraint on the model to ensure that the cab moves correctly. After the establishment of model, the paper uses freedom, vibration mode, response function method to verify the accuracy of the model. By comparing, the paper finds out that there is a little difference between established ADAMS cab suspension system rigid model and the results of the test. This is because the actual cab is formed by thin-walled parts and complex interior. Therefore, the model shows coupling state of rigid-body vibration modal and flexibility modal. Nevertheless, the model has been validated to prove that the model can achieve simulation requirements.After the full validation of the model, the paper adopted ADAMS/Vibration module for the simulation analysis of the model. Then the paper analyses the relationship between the location, stiffness and damping parameters of cab suspension components and the frequency domain response of driver's seat vertical acceleration. The result shows that the cab suspension system damping has a greater influence on the vertical acceleration of the seat, and the stiffness and damping which belong to the front cab suspension have greater influence on the vertical acceleration of the seat than the rear cab suspension. This is because of the differences between the structure of front and rear cab suspension, and the different locations of the seat output point.Finally, the paper use the Generalized Reduced Gradient method of ADAMS own optimization analysis to optimize the model. Stiffness and damping of components are defined as variable to optimize the seat acceleration power spectral density of the vertical direction. After optimizing, the stiffness and damping of front suspension have a certain degree of reduction, and those of rear suspension have a certain degree of increase. The power spectral density curve of the seat vertical acceleration shows that the paper gets fairly good optimization results.The paper mainly involves the cab moment of inertia measurement test, cab vibration modal test and the seat output transfer function test. The paper uses the mass line method to measure the cab moment of inertia. The method is more simple, more efficient, more accurate results, and easy to implement and has a certain commonality. And method of cab vibration modal test also has the same characteristics. The three main tests provide great help for getting the main parameters of the cab suspension system and model verification.Through modeling cab suspension system, simulation analysis and optimization of the model, and associated tests are done; the paper concludes the common method in interactively modeling the cab suspension system, and the influence of basic parameters of suspension components on the seat vertical acceleration, and provides some help for the optimization of the model of similar papers.