As a bus developer, Scania focus to construct a safe vehicle for the passengers, i.e. high strength of the bus structure and good comfort, which is also profitable for the operator, i.e. high passenger capacity and low fuel consumption. The trade-off when developing a bus body structure is to get both high stiffness and low weight. The bus body including exterior panels plays together with the chassis an important role for the stiffness of the bus. By gathering knowledge about how various exterior panels affects the stiffness of the bus body, the design of the panels can be optimized with respect to high stiffness and low weight. Also from a calculation point of view is it of interest to know how important different panels are for the stiffness of the bus body, in order to make conscious simplifications in the calculation model.

The aim with this master thesis was to investigate how the stiffening plate, side windows and roof sheet influence the strength of the bus body. How the thickness of the side windows affects the stiffness of the bus body is also investigated. The investigations were made as a relative comparison between a complete bus and comparison models.

The results showed that exterior panels participate in distributing load. By distributing the load, the load uptake gets more efficient since a bigger part of the bus structure is used to take up the load. The side windows affect the stiffness for all tested load cases, with increased importance for the load case where a gravity field is applied in the longitudinal direction, for the torsion load case and when a load is applied to the power train in vertical direction. The roof sheet has a high impact on the stiffness in the torsion load case, but has negligible influence on the stiffness of the bus body for the other tested load cases. The stiffening plate has little influence on the stiffness of the bus body in general and is negligible for all tested load cases except for when a lateral load is applied as either a gravity field or locally to the power train.

Thinner side windows are shown to have a positive influence on the stiffness of the bus body.