Study On Lightweight Material Selection For Autobody Based On Fuzzy VIKOR Method

Autobody is an important part of vehicle, its mass accounts for40%to60%of the total massof vehicle. The function of autobody is placing drivers, passengers and goods. The heavier ofautomobile, the higher fuel consumption and environment pollution. So it’s necessary to reducethe mass of vehicle through the technology of lightweight design. Lightweight design ofautobody is be much accounted by various automobile companies and a large number of experts.There are three ways to achieve the lightweight design of autobody: the first is applying theoptimization design of the autobody structure; the second is using a lot of lightweight materials;the third is introducing advanced manufacturing technology. The optimization design of structurecan make the autobody and parts more thin-walled, miniaturized and compound. The mostcommon lightweight materials are high-strength steels, aluminum alloys, magnesium alloys,carbon fiber reinforced plastic (CFRP), ceramics, and so on. Advanced manufacturing technologyhas a wide range of development, such as Rapid Prototyping Manufacturing, Laser WeldingTechnology and Non-destructive Testing Technology. Nowadays, new lightweight materials areemergence in a row, so the researchers have more choices to develop a new vehicle type. How tochoose more reasonable materials for different parts of the autobody is a difficult problem toresearcher. To resolve this problem, this article study on fuzzy VIKOR method to choice lightweight materials for autobody.The fuzzy VIKOR method belongs to multi-attribute decision making (MADM). Thismethod commonly used in economics and management, financial investment, project evaluations,military decision and many other areas. The function of fuzzy VIKOR method is allow thedecision makers to choice the most reasonable program in limited schemes. In this study, theschemes is new lightweight materials which have used in autobody, such as Bake Hardenablesteel (BH), Dual Phase steel (DP), High Strength Low Alloy Steel (HSLA), Martenistic steel,Aluminum5xxx,6xxx sheets, Magnesium sheets, Titanium sheets, Carbon Fiber ReinforcedPlastic (CFRP) and High Density Polyethylene (HDPE). The fuzzy VIKOR method needs tworequirements to make decision: the first is building integrated decision matrix which is composedof various properties of different materials; another is the weight of different properties ofmaterials to parts of autobody. Some properties of materials in decision matrix are only expressedby fuzzy numbers. This paper adopts the questionnaires to obtain relevant information. Theweight of different properties of materials is relevant to the design goal and performancerequirements of parts in autobody.The different parts of autobody have different performances and functions. In order tochoice more reasonable materials and meet the function requirement for parts of autobody, thisarticle select Ease of Manufacturing, Environmental Friendliness, Durability, Cost, TemperaturePerformance, Fuel Economy, NVH, Torsional Stiffness, Dent Resistance, Bending Stiffness andCrashworthiness as the important design performances for autobody. The Experts Grading Method can determine important degree of those design performances to different components ofautobody. Different component performances relevant to material attributes, so this paper obtainthe relationship between component performances and material attributes by the House of Quality(HOQ).The function of HOQ is establishing the link between customer needs and engineeringmetrics. The customer needs are customers demand for a product or service, and the engineeringmetrics are means adopted to realize the customer needs. In this paper, the customer needs aredesign performances for components of autobody, and the engineering metrics are materialattributes, which is Density, Price, Young’s modulus, Tensile strength, Total elongation,Formability, Joinability, Paintability, Corrosion, CO2Emission and Disposal. Through the HOQ,the important degree of customer needs to different components of autobody is transformed to theweight of material attributes.The fuzzy VIKOR method can get the best material selection scheme from all of thealternatives for parts of autobody based on integrated decision matrix and accurate weight ofmaterial attributes. The autobody who is made by those materials has better qualities and lowercost and mass. After choice the ideal materials for components of autobody by fuzzy VIKORmethod, this paper also build CAE model to verify the accuracy of the fuzzy VIKOR methodthrough calculating the Mass, Dynamic and Static stiffness and Crashworthiness of the originalmodel and new models replaced by the best material selection scheme. The presented studyshowed that the fuzzy VIKOR method is utility in multi-materials selection process for components of autobody.