| Vehicle ISD is short for a new suspension composed of "Inerter-Spring-Damper", which uses inerter instead of mass element and changes the traditional suspension structure based on classical vibration isolation theory "Mass-Spring-Damper". The ISD suspension has solved the problem that mass element equivalent to circuit elements must be done "ground connection" treatment when the research of traditional suspension applies electromechanical simulation theory, resulting in an asymmetric relationship between electromechanical components. The appearance of ISD suspension provides new ideas and space for the study of vehicle suspension vibration control and vibration isolation technology, but also proposes a series of new issues. Therefore, the study of ISD suspension dynamics characteristic, the topology design method and its key technologies used in vehicles, have important academic value and engineering guiding significance.This thesis mainly studies several theoretical problems and key technologies of new mechanical element inerter and ISD suspension based on dynamic vibration absorber theory. This thesis has investigated deeply in the following aspects:the dynamics characteristic of inerter, ISD suspension electromechanical simulation theory and mechanical impedance analysis method, ISD suspension modeling and parameter optimization based on dynamic vibration absorber theory, dynamic characteristic and vibration isolation mechanism of ISD suspension, ISD suspension topology design and the design methods and implementation scheme, inerter development and performance testing in ISD suspension, the vehicle suspension system ISD bench test, etc., the main work is as follows:Dynamic model of inerter is established; nonlinear factors in the inerter are analyzed; new technologies such as the inerter with variable used qualitative coefficient and damper-inerter integration are analyzed. Aiming at the new features of the ISD suspension, the related basic theories included in research, including mechanical simulation theory, the mechanical impedance analysis method and mechanical network synthesis theory and so on are systematically specified.Structural design theory and method of ISD suspension based on dynamic vibration absorber theory are proposed, and ISD suspension is innovatively designed. This thesis analyzes the structure form, design method, dynamic characteristics and working mechanism of traditional dynamic vibration absorber. This thesis dissects the effects and problems of traditional dynamic vibration absorber in vehicle applications. By comparing dynamic vibration absorber containing inerter with traditional dynamic vibration absorber on their mechanical impedance characteristics, this thesis proves their characteristics of mechanical impedance have equivalence, and reveals the mechanism that inerter can make up for the defects of traditional dynamic vibration absorber. On this basis, ISD suspension based on dynamic vibration absorption theory is designed, this thesis studies single quality ISD suspension model and double quality ISD suspension model separately. This thesis deduces the state equation and the transfer function of double quality ISD suspension model based on a quarter car model. Aiming at the multiparameter and multiple target characteristics of ISD suspension, this thesis puts forward ISD suspension parameters optimization design method based on multiple target genetic algorithm and optimizes design combined with the instance.The ideal elements matching relations of generalized mechanical network based on "Inerter-Spring-Damper" are established. The inherent attributes of element connection vibration control in new mechanical network is revealed. By studying the ISD suspension vibration transfer characteristics, this thesis reveals the multiple vibration transfer feature of the new suspension due to the introduction of the inerter quality impedance, and its attenuation and performance characteristics of restraining low frequency vibration. This thesis analyzes four element factors as the main spring stiffness, deputy spring stiffness, used qualitative factor and damper factor, which act on the vibration transfer characteristics. The suspension undamped free vibration frequency characteristic is deduced. The effect law and working mechanism of element parameters on ISD suspension are obtained. The generalized mechanical network isolation mechanism and force transfer characteristics based on "Inerter-Spring-Damper" is studied. The ideal matching relations between the mechanical network elements which has better vibration isolation effects is established, which is "inerter and spring fit in series, inerter and damper fit in series, spring and damper fit both in series or in parallel".This thesis proposes the mechanical network topology structure analysis and design method of ISD suspension, and designs key technology for improved three-element topological structure. This thesis defines the most representative simple three-element topology. This thesis analyzes the topology properties and structural characteristics of the vehicle mechanical network, and designs a class of improved three-component topology structure which is most suitable to the ISD suspension application. This thesis proposes the performance convergence and divergence classification methods about ISD suspension compared to used qualitative factor, which can be used for screening effective ISD structure rapidly. On the basis of comprehensive comparison of5kinds of improved three-element ISD suspensions, this thesis proves that ISD suspension with L4structure is the most ideal one among the above kinds. ISD suspension based on dynamic vibration absorber theory is ISD suspension with L4structure, which conforms to the ideal element matching relations of generalized mechanical network. Design method and research method are proved to be scientific and effective.Finally, inerter and ISD suspension based on dynamic vibration absorber theory are developed and tested. This thesis discusses the selection methods of inerter in ISD suspension, analyzes the design process of nut-rotary ball screw inerter and develops the inerter sample to test its performance. The designed inerter basically conforms to theoretical model and can meet test requirements. Based on this, this thesis designs the ISD suspension system sample and assembles the ISD suspension as an integrated suspension structure, using sinusoidal input and random input modes for bench performance test. The results shows that:compared with traditional passive suspension which have the same stiffness, in the sinusoidal input conditions, the performance index root-mean-square value in low frequency performance of ISD suspension based on dynamic vibration absorber theory decreases obviously; in the random input conditions, the performance index root-mean-square value of ISD suspension are all lower than traditional passive suspension. When the speed is40km/h, the travel root-mean-square value of suspension decreases16.24%; the body accelerated speed root-mean-square value and tyre dynamic load root-mean-square value have also improved obviously. Test results conform to theoretical research, and prove that ISD suspension based on dynamic vibration absorber theory can effectively improve the working performance of suspension in low frequency. This kind of ISD suspension can obviously decrease travel root-mean-square value and improve both the body accelerated speed root-mean-square value and tyre dynamic load root-mean-square value.The research work in this thesis reveals the working mechanism, natural characteristics and the advantages than traditional passive suspension. The design of ISD suspension combining with inerter theory and dynamic absorber theory conforms to the ideal matching relation of mechanical network element, and can solve many problems of traditional dynamic vibration absorber appearing in vehicle application. The design of ISD suspension enriches and expands the suspension design theory, provides a new direction for improving suspension performance and technological innovation. |
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