Abstract:

A bus-body concept-design for an electric-bus was made using a forward design method considering the strength and rigidity of battery compartment, which has a mass of about 2 t. A mathematical model of stiffness-chain of bus-body was obtained using a simplified geometry model of body taking the beam section width, the height and the thickness as design variables by using a transfer stiffness matrix method of semi-rigid beam element. A group of beam section property parameters satisfied the requirement of bus body performance were obtained taking bus-body lightweight as objective function, with the constraints of the staticdynamic stiffness, the natural frequency and the local strength of bus-body battery-cabin and then by usinggenetic algorithm optimal solution. The results by this method were compared with that by the FEM for the staticdynamic stiffness and the local strength of battery compartment of the benchmarking vehicle body. The results show that the torsional stiffness and first natural frequency of the optimized model are increased. The bending stiffness, body mass, and the battery cabin stress under bending and torsion conditions are reduced. Therefore, the design method of the stiffness-chain of electric-bus body is feasible.

Key words: pure electric buses, forward design of bus-body, transfer stiffness matrix method, stiffness- chain,  local strength, bus-body lightweight