Mobility and Vehicle Mechanics

19-38

Authors: Giovanni Belingardi, Brunetto Martorana

Vehicle weight reduction (and in turn reduction of fuel consumption, noxious gas and greenhouse gas emissions), manufacturing costs and riding comfort are pushing toward relevant growth the amount of polymeric materials employed in modern cars. At the same time the main performance of the car (and in particular safety and NVH comfort) should be maintained. In order to pursue this trend, it is important to carry out research and innovation on new polymer-based materials, with a high structural performance to weight ratio to replace standard materials, such as mild steel, for structural components. The base costs of composite materials are still relatively too high, therefore research activities are needed to reduce manufacturing costs of composite components. On the other hand the use of composites offer advantages not only in terms of lightweight but also in terms of parts integration, TTM reduction, etc. Innovative components can take advantage from new materials but need for proper design rules and proper manufacturing technologies. Cycle times and production volumes are key factors. The production value chain and the research have to work in order to overtake some technological limits (joining technologies, recyclability, repairing, safety, costs, …) for a wider employment of lightweight materials. This paper is presenting some recent results in the design of vehicle components with composite materials and is also presenting some recent achievements in the use of thermoplastic adhesives, nanomodified by ferromagnetic particles, sensitive to the electromagnetic field finalized to speed up both the manufacturing and the dismounting processes.

55-62

Authors: THE MECHANICAL BEHAVIOUR OF MATERIAL IN AUTOMOTIVE ENGINEERING REINFORCED BY STRONG FIBRES

Laminate is made from layers mutually bonded to form multilayered composite. Composite materials consist two or more constituents such as fibres and matrix. Matrix bond fibres together, gives shape of composite, have role in transfer loads to fibre. Usually fibres are 60-70% of composite volume and they are made of carbon, glass, aramid (such as kevlar) or metal. In the present paper we study wave propagation bulk waves. The properties of these waves are determined by the dependence between the propagation direction and constitutive properties of media. Here we study slowness surfaces, as indicators of dynamical behavior, in order to obtain information about wave propagation in arbitrary directions. The surfaces associated with wave front surfaces are slowness surfaces, with slowness defined by the inverse of the wave front speeds. Constitutive equations are developed for material which is made of unidirectionally reinforced thin sheets, which form model of material. Degrees of wave surfaces deviations depend on the degrees of anisotropy, and may give valuable information about dynamic deformations. The materials used in the present analysis are fibre reinforced materials with two families of continuous elastic and mechanically equivalent fibres, having axes of symmetry along bisectors of the fibre directions and along the normal to the plane tangent to fibres.