Ett kandidatexamensarbete inom lättviktskonstruktioner .

Sammanfattning: Due to recent legal enactments regarding carbon dioxide emissions, the car industry is facing higher demands. An effective way of reducing these emissions is to minimize the weight of the vehicle. This thesis constitutes a feasibility study on whether or not it is applicable for the car industry to utilize an inner floor structure comprising composite materials. The principal was the project SåNätt, in which the main participant was Volvo Cars Corp. In consultation with a reference group, consisting of delegates from the industry and KTH, a specification of requirements was produced. The prime requirement was to reduce the weight of the floor structure by 20-40%, in comparison to an equivalent structure in a reference car, without increasing the cost. Literature reviews with regards to environmental stress and production aspects were carried out, these reviews provided a basis for selecting a composite material that best met the requirements. Tensions and deformations emerging from various load cases were analysed by employing software for finite element methods. For educational purposes and to obtain more extensive material data of the selected composite, a series of experimental tests were conducted. For demonstrational purposes, a cross-section of the floor structure was produced. The essential conclusions that can be drawn from this thesis are:  That it is possible for the car industry to produce an inner floor structure out of composite materials. However, this result merits a more distinguished cost analysis.  That, owing to its high strength and stiffness as well as its low density, carbon fibre is the most suitable fibre type.  That the matrix-system that best suits the requirements is Vinyl Ester, since it has proved to have high resistance to environmental stresses, flexible curing time and it is also one of the most moderate in its range.  That the weight of the floor structure, by applying the above-mentioned composite material, can be reduced to 18 kg. Together with a lower steel frame consisting of 1 mm thick steel, the corresponding weight is 25 % lower compared to the equivalent structure in the reference car. If steel of the type Hybrix is used, the weight reduction calculates to 54 %.