Optimisation of a bus body structure

This work concerns an optimisation of a bus body structure under transient vibrations. A simulation of a bus traversing an obstacle, with a cross-sect ion of 50 x 200 mm(2), is carried out and the response of the bus, due to t he rear axle impact, is calculated. An FE model of the complete bus has bee n used, and the obstacle has been modelled by prescribed displacements unde r tyres on the rear axle. Accelerations have been evaluated by use of the c omfort standard ISO2631:1997 at three different locations within the bus an d a global measure of the discomfort has been defined. Corresponding measur ements of the response within a test bus have been carried out and a satisf actory agreement between the computational model and the test bus is shown. A multicriteria approach to define the objective function, considering bot h discomfort and mass of the bus body, was adopted and the results showed t hat it was possible to reduce the discomfort with a minimum use of extra ma terial. However, an investigation regarding more time efficient optimisatio n algorithms for this particular problem is desirable.