Abstract: The formulation of performance targets and the lightweight design method of aluminum alloy rear subframe are emphatically investigated in this paper. Firstly, a method combining forward design and competitive product analysis is adopted to determine the performance targets of aluminum alloy rear subframe, including mass,modal frequencies, static stiffness and strength etc. Then the ICM hybrid modeling method is introduced to obtain the skeleton of rear subframe and reduce its weight. Based on identifying the force transmission path of rear subframe, topology optimization is performed, redundant material is removed and the mathematical model is obtained.Twelve shape variables of parameterized subframe are selected as the lightweight design variables for multidisciplinary optimization to obtain the optimal shape meeting target requirements.After lightweighting,the mass reduces by 1.84 kg with a mass reduction rate of 7.4%, and the 1st-order bending frequency increases by 10.2 Hz, meaning a 4.5% of enhancement. The results of hard point static stiffness and strength analysis also show that the method is fast and reliable,with a good prospect of engineering application

Key words: aluminum rear subframe, lightweighting, performance targets, ICM hybrid modeling, multidisciplinary optimization