Study On Multi-material Selection For Autobody Based On PSI Method

Autobody is an important part of vehicle, whose mass accounts for 40% to 60% of the total mass of vehicle. Lightweight of autobody is an effective means of saving the materials and energy. The heavier of autobody, the higher fuel consumption and environment pollution. There are three ways to achieve the lightweight of autobody: the first is to apply the optimization design of the autobody structure; the second is to introduce advanced manufacturing technology; the third is to use various lightweight materials.The application range of lightweight materials in autobody is rising year by year as the appearance of high quality lightweight materials and the innovation of new manufacturing process. An excellent multi-material autobody needs the best combination of lightweight, material properties, manufacturability, cost and other properties. With respect to the single material, multi-material autobody can play an effective role in ensuring good performance and lightweight. The concept that “Lightweight autobody structure with Multi-Materials combination and suitable material should be used in right position” has become the new trend of Auobody design. Therefore, research on the material matching technology is of vital important in the development of multi-material autobody design.Most multiple attribute decision making methods used in multi-material selection need the designer to determine the relative weights of the relationship between different material properties, which will bring uncertainty to selection results. Preference selection index(PSI) method is a novel tool to select best alternative from given alternatives without deciding relative importance between attributes. PSI method will be used in the study of multi-material selection for autobody considering a variety of factors such as the cost, weight, comfort and safety, environment friendly, etc. Specific work is as follows:(1) Introduce the implementation steps and calculation process of the PSI method. Using overall preference value, preference selection index(Ii) for each alternative is calculated and alternative with higher value of preference selection index(Ii) is selected as the best.(2) Determine the alternative materials and evaluation criterions. There will be 16 different candidate materials in the study, includes Q235, AISI 1035,40 Cr, BH180, 500 DP, HSLA460, 0Cr18Ni9, AISI410, AL5050, AL6010, AZ61, Ti-6Al-4V, CFRP, GFRP, HDPE and Aramid-aluminum composite materials. Meanwhile, the study will be based on six different evaluation criterions: Nature properties; Manufacturability; Usability; Safety and comfort performance; Environmental friendliness; Recycling property.(3) Taking the door as an example for multi-material selection in the paper. Determine the material selection decision matrix of the door through a series of means like simulation analysis and calculation 、 referring to information literature 、 questionnaire etc. Then accomplish the calculation process of the PSI method using the MATLAB programming. Finally, preference selection index(Ii) for each alternative of the door is calculated and the material selection results will be obtained.(4) After the material selection based on PSI method, a performance contrast with previous material combination plan is implemented. The weight, cost and basic performance of the door before and after the material replacement is implemented, which is used to verify the effectiveness of the proposed method in this paper.By contrast we find that the PSI method is utility in multi-materials selection process for components of autobody, which will reduce the weight and ensure the performance of autobody at the same time. In this paper, the proposed method is widely used in autobody parts,which will furtherly enrich the study of multi-material Selection for autobody.