Research On Optimization Design Of CFRP Engine Hood

Nowadays, environmental problems such as global warming and oil shortage are serious, and it is expected that these problems are more important in the future. Automobile, as representatives of modern industrial civilization, impose more and more burdens on environment. So it is required to build a new design concept, include energy-saving design, green design, and lightweight design, with promoting the sustainable development of society.Carbon Fiber Reinforced Polymer/Plastic (CFRP) is called the automotive material of the twenty-first century, because of its low density and excellent mechanical performance. Engine hood, as one of the important components of auto-body, is the first choice of the research object. The structure of hood is simple; however the analysis conditions, function characteristics, processing technology, etc are wide representativeness. This dissertation studies the lightweight design of hood using CFRP. In this dissertation, the main research work carried out following.(1) We use life cycle assessment (LCA) method for the automobile to evaluate environmental attribute. Through studying the whole life cycle of automobile products within the energy consumption and pollution emission situation of each stage, determine of environmental impact of automobile products. Analysis results show that composite automobile is more environmentally friendly.(2) This paper introduced the basic mechanical theory of composite; include the theory of laminae and laminates. All of these provide a theoretical basis for the follow-up study.(3) Based on the equivalent stiffness principle, and according to the mechanical properties of composite materials and the structural features of hood, we designed the CFRP hood and analyzed it. Before this, we should determine the analysis conditions of hood, and then we analyzed the original steel hood to receive the performance parameters of the hood. Analysis results show that the composite hood is lighter than original hood, with equivalent stiffness.(4) We used the traditional optimization technology to design the composite hood. The traditional optimization technologies include size optimization and topology optimization. Then according to the characteristics of composite, we developed the new optimization technology of composite structure. The new optimization technology integrated free size optimization, size optimization and shuffle optimization. We used the new method to design the composite hood and analyzed it. Analysis results show that the composite hood can reduce weight further, with equivalent stiffness.(5) Based on the rules in GB/T 24550, we took simulation tests of headform impactors with the original steel hood and the CFRP hood, and then evaluated the performance of hood after the test about the head injure criterion (HIC). Analysis results show that both the original steel hood and the composite hood can meet the requirements.The results of this study show that, Carbon Fiber Reinforced Polymer/Plastic (CFRP) as the alternative materials of steel can be used in automotive industry, which can meet the automobile design requirements about energy-saving design, green design and lightweight design. The methods of CFRP hood design and optimization is also applicable for other composites structures.