Lightweight materials and design have always been an important topic in automotive industry. The reason why such a factor must be considered first of all is that it would lead to the improvement of such basic functions of cars as the acceleration force and the breaking power, the need to improve fuel efficiency based on the emergence of the various environmental regulations and the era of high oil prices, and the constant necessity for the weight reduction of EVs (electrical vehicles), the next-generation type of vehicle.
For the lightweight of structural components, a lot of composite materials are used instead of metallic materials. The composite materials are used for various structural components throughout the world. Instead of the metallic materials which were used before, the newly-introduced composite materials with light weight can be used in such high-performance fields as the aviation field and the automobile field with the same effect.
Generally, there are a lot of synthetic chemical substances and poisonous substances created following the lifespan of the products used in the field of composite materials, making it almost impossible to recycle them. As a result, they are discarded. Recently, the level of interest for natural fibers in the process of designing and manufacturing composite materials has increased. Compared to the ones made following the chemical composition process, the natural fibers can be recycled with relatively low costs and the capacity of providing fibers continuously. [1-2] Among the previous researches, the one which was carried out by P.J Herrera-Franco focused on the investigation and research of the mechanical characteristics of the Henequen natural fibers. In the research, the mechanical operation of HDPE (high density polyethylene) reinforced with the Henequen fibers was continuously studied. [3] M. Zampaloni studied the kenaf natural-fiber reinforced polypropylene composite materials. The study about the kenaf natural-fiber reinforced polypropylene which can be thermoformed in various fields focuses on the manufacturing process. With the characteristics equal to those of the previous synthetic composite materials, it can be used in various ways. [4] Vincent Placet studied the mechanical characteristics of Hemp. The study focused on the thermal-mechanical analysis and the dynamic-mechanical analysis of Hemp. [5] A number of researches have been recently carried out to investigate the characteristics of the natural fibers.
In this study, structural design and analysis of the automobile bonnet is performed. The flax/vinly ester composite material is applied for structural design. The Vacuum Assisted Resin Transfer Molding-Light(VARTML) manufacturing method is adopted for manufacturing the flax fiber composite bonnet. The VARTML is a manufacturing process that the resin is injected into the fly layered-up fibers enclosed by a rigid mold tool under vacuum. A series of flax/vinyl ester composite panels are manufactured, and several kinds of specimens cut out from the panels are tested to obtain mechanical performance data. In modeling the adult head model to assess the safety by the collision analysis on the panel. To produce a test specimen after the collision by comparing the C-Scan analysis up to a site of injury an damage in the experiment verified the validity of the analysis. Results of the structural design, examined the structural safety through structural analysis and structural testing.