18 TH INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS 1 Introduction Advanced composite materials are finding an increasing role in car manufacturing because of their favorable specific stiffness. The use of these materials allows to reduce structures’ weight without compromising stiffness, this helps developing cars with improved performances. An even more important reason to reduce car weight comes from environmental considerations [1]. Fuel is consumed for two main reasons: moving the mass of the car and overcoming the resistance of the air. At usual urban speed air resistance is relatively small and almost the entire fuel consumption is due to the displacement of the mass of the car. On the other hand the car mass is steadily growing because of safety regulations and the protective equipment they entail, and of the many other systems that make a modern car comfortable but heavy as well. There is a growing consensus about introducing more and more composites, even in structural roles, to reduce weight and therefore save fuel. The reduction of wheel weight would bring even more beneficial effects since the wheels do not only move rigidly with the car but they, obviously, rotate and therefore are responsible for a quota of kinetic energy bigger than that they share with the car mass. The present paper was generated when the authors were studying the possibility of making lighter composite wheels for automotive applications and were investigating various possibilities to increase their stiffness. Nevertheless, the significance of the main results is not limited to composite wheels only. One of the most important parameters to qualify the behaviour of a wheel is its specific stiffness, i.e. the ratio stiffness/weight. In fact, lighter unsprung weight results in improved vehicle handling, response and control [2], while the wheel stiffness assures a better interaction between the tire and the ground. Nowadays most of the best performing automotive wheels are made of metallic alloys. Concerning composite materials, fiber-reinforced plastics (FRP) are currently used in high performance bike and motorbike wheels. FRP are more expensive than metallic materials and, moreover, their fatigue behaviour is not well known. On one hand these reasons discourage the use of this kind of materials for car rims but, on the other hand, they are characterized by better specific properties and therefore composite materials are a natural candidate to manufacture stiffer and lighter rims. Wheels made of metallic alloys constitute the natural element of comparison for composite wheels which have to result, if possible, stiffer and lighter with a comparable cost. The cost constraint is particularly demanding because composite materials can achieve extraordinary performances, but only if expensive materials are used. However an industrial production of composite wheels cannot rely on materials which can be afforded only by a small fraction of the potential customers. Another possibility to increase the wheel stiffness, keeping its cost under control, could rely on the use of sandwich structures, possibly coupled with FRP. In the present paper we analyze the possibility of increasing the stiffness of a wheel rim by means of a sandwich structure: in section 2 the main concept of sandwich structures is presented, in section 3 the models and their results are discussed and finally in section 4 some concluding remarks are reported. 2 The sandwich concept Sandwich structures find an application in many structural fields such as spacecraft, aircraft, train and car structures, wind turbine blades, boat or ship superstructures… Their geometry can vary widely, but their common feature is a lightweight thick core, included between two thin stiff skins. The core APPLICATION OF SANDWICH STRUCTURES TO AUTOMOTIVE RIMS A. Romeo 1* , D. P. Boso 1 , U. Galvanetto 1 1 Dipartimento di Costruzioni e Trasporti, Università degli Studi di Padova, Padova, Italy * Corresponding author(romeo@dic.unipd.it) Keywords: automotive wheel rim, sandwich structures, fem