Abstract
Lightweight design is one of the important ways to reduce automobile fuel consumption and exhaust emissions. At the same time, the fatigue life of automobile parts also greatly affects vehicle safety. This paper proposes a multi-objective reliability optimization method by integrating Monte Carlo simulation (MCS) with the NSGA-II algorithm coupled with entropy weighted grey relational analysis (GRA) for lightweight design of the lower control arm of automobile Macpherson suspension. The dynamic load histories of the control arm were extracted through dynamic simulations of a rigid-flexible coupling vehicle model on virtual proving ground. Then, the nominal stress method was used to predict its fatigue life. Six design variables were defined to describe the geometric dimension of the control arm, while mass and fatigue life were taken as optimization objectives. The multi-objective optimization design of the control arm was carried out based on the Kriging surrogate model and NSGA-II algorithm. Aiming at the uncertainty of design variables, the reliability constraint was added to the multi-objective optimization to improve the reliability of the fatigue life of the control arm. The optimal design of the control arm was determined from Pareto solutions by entropy weighted grey relational analysis (GRA). The optimization results show that the mass of the control arm was reduced by 4.1% and the fatigue life was increased by 215.8% while its reliability increased by 7.8%. The proposed multi-objective reliability optimization method proved to be feasible and effective for lightweight design of a suspension control arm.
Highlights
With the continuous growth of car ownership, automobile exhausts emit a large number of pollutants
This paper proposed a multi-objective reliability optimization method based on Monte Carlo simulation, NSGA-II algorithm and entropy weighted grey relational analysis, applied to perform the lightweight design of a lower control arm of McPherson suspension
The fatigue life of the control arm was predicted by a normal stress method, using the load spectrum acquired by dynamic simulations of the rigid-flexible coupling vehicle model running on the virtual durability road
Summary
With the continuous growth of car ownership, automobile exhausts emit a large number of pollutants. Lim et al [18] proposed a reliability-based multi-objective optimization design method to optimize the engine mount. A multi-objective reliability optimization method by integrating MCS with NSGA-II algorithm coupled with entropy weighted GRA is proposed, and the effectiveness of this method is verified by the lightweight optimization of the lower control arm of Macpherson suspension. The optimal Latin hypercube method is applied to generate the sample points for constructing Kriging surrogate models, which are used to describe the relationships between design variables of control arm and its structure performance including mass, fatigue life, stiffness, and mode. The multi-objective reliability optimization of the control arm is further performed by combining the NSGA-II algorithm and the Monte Carlo simulations. Between prediction point X∗ and sample point x; F is the (n × p ) design matrix
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