Dynamic Load Analysis For Transmission Housing Based On Rigid-Flexible Vehicle Model

In this dissertation, Research work is carried out with the Science and Technology Support Program from Science and Technology Bureau of Changchun City- Integrated technology research and product development of topology optimization of automotive transmission based on load spectrum. In view of the characteristics of convoluted road conditions, changing loads and so on for light trucks, and the insufficient consideration of the effects of flexible characteristics of the key assembly to its dynamic performances during the current design process of automotive assemblies and parts, research focusing on the dynamic load characteristics of vehicle and key assemblies under roughness road excitation is implemented.First, based on reviewing the researching status and developing trend of rigid-flexible coupling system dynamics in the field of automobile mechanics, a research frame about using the fixed-interface component mode synthesis to analyze dynamic characteristics of rigid-flexible coupling system of vehicle is proposed; and the basic theory on rigid-flexible coupling system dynamics and the simulation software ADAMS are discussed, particularly the establishment of the rigid-flexible coupling model and the Craig-Bampton fixed interface component mode synthesis for solving this model in ADAMS, lay basis for the building and simulation of the rigid-flexible vehicle model.Subsequently, combined the application of ADAMS/Car with Hypermesh, a rigid-flexible coupling system dynamic model of a light truck is established. According to the specific structural features of the assembly, we establish front suspension, rear suspension, powertrain, steering system, body, tieres and other subsystem models for a vehicle. With the fixed interface component mode synthesis method, by the application of Hypermesh, a finite element analyzing model of transmission box and leaf spring is built, using experimental modal, the calculated modal is verified, based on this work, a rigid-flexible coupling system dynamic model of the vehicle is established, and according to the measured data of pulse input and random input road tests of the vehicle, the simulation results are qualitatively verified. Finally, in accordance with the theory of road roughness, a three-dimensional model of road in which the road roughness is random varying in the longitudinal and lateral dimensions is established; simulations of the vehicle under different speeds and roads are conducted to analyze the dynamic loading characteristics of transmission housing. The simulation results show that when the vehicle drives on a B-class road with a 60 Km/h speed, the dynamic load of transmission box increases by about 65% than the maximum static load. Vehicle speed is an important factor that infects the dynamic load of the transmission housing. the root mean square value of dynamic load increases about 25% when the vehicle speed changes from 70km/h to 50km/h. we compare the structure stiffness under dynamic and static load which generated from the simulation of the transmission housing dynamic load, and find that the max deformation and max stress are significantly improved comparing to the static load. Under the static load, the deformation of the transmission housing is mainly shaft end. But under the dynamic load, the deformation of the transmission housing is the housing torsion deformation along the longitudinal axle. By application of the dynamic load of transmission housing extracted in this paper, structure optimization analysis for the housing are studied, a good practical effect in engineering projects coming into being.According to the applications of the principals of vehicle dynamics and simulation analyzing methods, researches on the establishment of rigid-flexible coupling system dynamic model of vehicle, simulation and experimental verification of vehicle dynamics, analyzing and application of the dynamic loading characteristics of transmission housing are respectively carried out, and the results of this job are applied to the production and inspection of transmission housing product, consequently, a lightweight design purpose is achieved under the premise of the product using life, and meanwhile, the basis for the establishment of virtual product digital development process integrated CAE analysis technology is provided.