The Study Of Integral Coach Body Structure Design And Optimization

In recent years, with the development of the social economy, coach plays an increasinglyimportant role in the transportation industry. In the background of the rapid rise in passenger,many problems come out quickly, such as: largely fuel consumption, polluting emissions andweak in occupant protection. The reasons for these problems are varied, for example: enginesare not good at energy conservation, vehicles without timely maintenance, production qualitydefects, and so on. However, lightweight and passive safety are root causes of these problems.Today mature coach products are mostly used separate type coach body in our country, theadvantages of this kind of structure are simple, easy to install and conducive to mass product,on the other hand, disadvantages of it are heavy and lack of passive safety. Thus, the foreignhigh-class products are mostly used new generation integral coach body structure. Thecharacteristics of this kind of structure are lightweight, high stiffness and excellent passivesafety. In this case, integral coach body is taken as a research object and a new coach bodydesign optimization technique is proposed. The technique which named MMEP(Multiple-body dynamics analysis, Multi-dimensional topology optimization, Engineeringbody structure, Performance verification) constructs a semi-automatic platform of coach bodydesign and optimization, considered static load, dynamic load, rod cross-sectional andthickness of thin-walled beams, the integral coach body design and optimization problems aresolved by this technique at the multi-objective requirements of lightweight and passive safety.Additional, as an example, a coach body section is designed to verify the feasibility of thismethod.Some typical load cases that simulate conditions of coach running is analysis bymultiple-body dynamics, the analysis results which reflect the forces situation of body hardpoints are static loads of the multi-dimensional topology optimization. The topologyoptimization objective is constructed by compromise programming approach, which canweigh static loads and dynamic loads at the same time. Others, this thesis chooses a mostreasonable early design model by the comparison of different static and dynamic weight ratios’topology optimization results. Then, a wireframe model was established base on the early design model.At the stage of engineering coach body structure, the performance of thin-walled beamssuch as SME (Stiffness Mass Efficient), bending strength, compressive strength areconsidered sufficiently, some rules between the performance of thin-walled beams andsectional dimensions feature are concluded during this phase. Analysis the mechanicalcharacteristics of roof, side panel, chassis of coach body structure, adapt the sectionaldimensions depends on the rules. Implement sensitivity analysis for beams of coach body, andselect ten of them to execute thickness optimization. The engineering result appears that theintegral coach body structure is more lightweight than the separate type coach body structure.Test the performance of coach body section, performance indicators include modalcharacteristics and rollover safety. A separate type coach body section is imported as comparemodels and the capability of it is researched in both experiment and simulation analysisapproach. The performance of integral coach body section which designed in this paper ismeasured by simulation analysis. Comparison results that the performance of integral coachbody section is far better than the separated one. In summary, the MMEP is workable forintegral coach body structure design and optimization.