The Optimization Design For Lightweight To Auto Body Based On Performance Pertinence And Performance Margin

Safety, energy conversation and environmental protection are the three themes of modern automobile technology. Throughout the history of automobile industry, especially entering the 21 st century Post-industrial era, facing the increasingly serious traffic accident, energy shortages and C emissions. Governments around the world in order to solve these problems, they have put forward higher requirements for the development of automotive technology, such as vehicle safety, requirements on emissions and fuel consumption, etal. Lightweight is one of main methods to saving energy and reducing consumption, and it is also the major direction for future automobile technology development to every automobile manufacturers around the world.However, when studying the new vehicle models, automobile manufacturers are tending to take safety performance as program calibration. First, it is bound by regulations and standards of the state, such as GB20071-2006, C-NCAP and E-NCAP, etal. Second, the safety performance index is one of the most direct attentions to car users. Therefore, on the process of automobile design and research, how to ensure the vehicle safety performance, and realize the lightweight design at the meanwhile become critical and problematic issues for DRE. That is because crashworthiness is the foundation of car crash safety, lightweight is one of main methods to saving energy and reducing consumption, but there is the possibility of conflict between crashworthiness and lightweight when doing the body structure design.In order to eliminate the conflict of contradictory problems, this paper has reviewed some design methods for body crashworthiness and lightweight at home and abroad. Summarized that take the strain energy of various components during automobile collision as design analysis carrier, then doing optimal design in view of the critical parts for auto body structure crashworthiness and lightweight.Firstly, taking the vehicle 50km/h side impact as example, according to C-NCAP management specification, and establish the CAE calculation model in that case, which lay a foundation for crashworthiness and lightweight optimization design analysis in view of the body structure in later paragraphs. For car body structure crashworthiness design requirements, The method of sensitivity analysis to the structure of the body parts can be extended to its performance pertinence analysis, which means the influence degree of the critical parts to the crashworthiness performance during the collision; For body structure lightweight design goal, on the basis of meeting its crashworthiness, taking the material yield strength of the critical component above as the optimal threshold, and then taking the actual stress of various parts as design basis in the process of collision, compute the optimal surplus amount, which defined as performance margin of the parts.Secondly, analysis the degree of influence or relevance to various body parts in different impact conditions for the vehicle passive safety performance, then subtract the vehicle body structure. In the practical side crash simulation analysis, based on the principle of body structure above, adapt to a method of applying velocity and displacement boundary conditions, and simplify the CAE simulation computation model further.Lastly, based on the analysis method of the performance pertinence and margin, and apply it to the design in side impact safety of a particular SUV, at the meanwhile, take the minimal body mass as optimized design goal, and take the side crashworthiness as constraint conditions. Then based on the DPS data processing system, using uniform experimental design method, and arrange simulation testing scheme, then using polynomial regression analysis method to fitting the test sample point dates, which will get the approximate model. On this basis, using optimization algorithms, named complex method, to conduct iterative calculation. Mostly, the optimization results should be given to the original simulation model, and compare with the real vehicle collision results. Studies show that optimization of the crashworthiness design has ensured the body crashworthiness, reduced the quality of the auto body at the meanwhile, eventually realized dual goal of crashworthiness and lightweight.