| With the wide application of new lightweight materials in the car, especially the high-strength steel and aluminum alloys have been applied to the key energy-absorbing body structure widely because of the excellent energy absorption and weight reduction effect,therefore, the matching problem between different yield strength of lightweight materials has become a research hot spot. The key body absorbing structures is the most important parts of automotive to ensure passive safety performance, so the lightweight design at different stages of body development are required to ensure its structural crashworthiness. In the conceptual design phase, the design cycle is short, we need to take into account the costs and weight reduction effect, and then quickly determine the material plan. Multi-stage energy absorbing thin-walled beam is composed of thin-walled beams through welding or bolt connection and is the main energy absorption components of front and rear impact crushing area. It is not ideal through a lot of expensive physical test or time-consuming simulation optimization to determine the material solution, and the empirical formula method can help designers to determine the material solution quickly and scientifically. In the detailed design phase, the body structure and material solution has basically been determined, while still can through optimization algorithm to optimize thickness between the various parts of the body under the premise of guarantee body performance, achieve further lightweight design. So in order to shorten the stages of the design cycle, select a high search efficiency and precision engineering optimization algorithms become an urgent problem.Conceptual design stage, in view of the problem how to choose the most reasonable thickness for a multi-stage energy-absorbing thin-walled beam when the material replaced by lightweight materials, not only assurances of its structure crashworthiness performance, but also achieve the best effect of weight reduction, proposes a multi-material matching method based on empirical formula. After applying this method to a instance that composed by a square crash box and a top-hat front beam, the result showed that the mean dynamic crushing load error of changing the material before and after basically control in less than 10%, and the combination of aluminum and DP steel has the best lightweight effect, weight loss of 34.4%.In addition to the effect of weight reduction need to focus also need to consider the cost factor.Therefore, introducing of the value function to evaluate the overall performance of different materials matching plans and help auto companies according to their own development needs to select the best material matching scheme. Last, using the previous case study on the impact of constant exchange on material selection scheme. Research results show that the value ofconstant exchange associated with car manufacturers more pay attention to lightweight effect or costs, and determines the final best material matching scheme.Detailed design stage, aiming at the complex and expensive black-box problems in engineering, a higher search efficiency and precision of multiple hybrid meta-model method(MHM) is proposed on the basis of hybrid and adaptive meta-modeling method(HAM). Last,the method is applied to the key energy-absorbing components of front cabin subsystem to optimize the thickness. Results show that compared with the initial design reduce weight 5.4kg, reduction ratio 7.2%, while the energy absorption characteristics of the main energy absorbing parts don’t decline and the peak acceleration of the subsystem does not increase.In this paper, based on body development process as the main line, using different multi-material matching methods for the key energy absorbing body structure to realize lightweight design according to the different development phase. Through the study of this paper provides a new train of thought for lightweight car body design, has good engineering application value. |
PDF Full Text Request