Engine Hood Lightweight Design Based On Overall Satisfaction

With the progress of science and technology and enhancement of nationaleconomy, automotive industry in individual country has achieved rapid development,especially the development trend of China’s auto market more strong. However,come with the energy and environmental issues increasingly prominent. Based onlong-term sustainable development, there has been an increasingly louder call forenergy conservation and environmental protection in the world, bringingunprecedented pressure to automotive industry.Auto lightweight, as an effective wayto save energy and protect environment and to improve vehicle performance, hasbecome the world’s auto industry development trend. Lightweight has become animportant topic for the sustainable development of automobile industry in ourcountry，as the world’s largest automobile production and marketing country.Not simply to reduce weight, automobile lightweight is to ensure that under thepremise of the basic performance not affected and no increase in manufacturing costas far as possible, minimize automobile weight through the integrated use of varioustechnologies, so as to realize the comprehensive goals of energy conservation andemissions reduction and the improvement of vehicle performance. At present,lightweight technology is mainly focused on the structure optimization design,using new lightweight materials (low density of lightweight materials such asaluminum alloy, magnesium alloy, composite materials and high strength steel) toreplace traditional materials and the new technology. In comparison, the effect oflightweight materials substitution is more pronounced.Firstly, this paper takes the engine hood of certain model as the research object,establishes CAE models under five common working conditions (forward bendingcondition, lateral bending condition, torsion condition, sinking-resistance conditionsand free modal), and then submits to RADIOSS solver to get the hood CAEanalysis results for the upcoming lightweight design to establish reference standards.Secondly, determine ST14for inner and aluminum alloy for outer, aluminum alloy,magnesium alloy and laminated steel as four kinds of material substitution plans ofthe hood considering lightweight material application status. To make full use ofmaterial properties and reduce cost, draw up size optimization scheme based onmass target and displacement and frequency constraint. Determine the optimum hood thickness by conducting size optimization on engine hood of four kinds ofmaterial substitution plans with the optimization tool-OPTISTRUCT, so as torealize lightweight design.At last, introduce a selection method for lightweightschemes based on overall satisfaction in order to transfer qualitative schemeevaluation into quantitative so as to evaluate relative merits of various lightweightschemes more reasonably. This method is conducted as follows. On the basis ofstructural performance analysis on the hood and considering the factors of qualityand cost, estimate the weight of various factors on the scheme selection, makecomprehensive evaluation for each scheme based on overall satisfaction, and thensort overall satisfaction values respectively to every scheme to determine thescheme with maximum overall satisfaction value as the best lightweight scheme.