Abstract
This paper uses a steel engine hood as a prototype to design a carbon fiber reinforced plastic (CFRP) engine hood, analyzes the dynamic performance of the engine hood and optimizes the dynamic stiffness index while considering lightweight of the structure. Taking the layer thickness of each ply orientation of the CFRP engine hood as the design variable, the optimal Latin hypercube design (Opt-LHD) method is applied for uniform sampling. Moreover, the Kriging model method and response surface model (RSM) method are used to construct the surrogate model of the total mass, equivalent dynamic stiffness of critical points, and the first-order modal frequency. Then the Non-dominated Sorting Genetic Algorithm NSGA-II is used for multi-objective optimization with the equivalent dynamic stiffness and mass of the CFRP engine hood as the optimization objective. Finally, the optimized CFRP engine hood was trial-produced and compared with the original steel engine hood. The results indicate that the optimized CFRP engine hood has better dynamic stiffness performance; furthermore, the lightweight effect reaches 24.4 %.
Highlights
Automotive lightweight is mainly achieved through new lightweight materials, structural optimization design, and advanced material manufacturing methods [1]
The results indicated that the carbon fiber reinforced plastic (CFRP) engine hood has improved its mechanical properties, and the mass was reduced by 46 %
The dynamic stiffness of the CFRP engine hood has improved in the entire analysis frequency range compared with the steel engine hood, and its equivalent dynamic stiffness value is higher compared with the steel hood, which is consistent with the simulation results
Summary
Automotive lightweight is mainly achieved through new lightweight materials, structural optimization design, and advanced material manufacturing methods [1]. As a new lightweight material, carbon fiber reinforced plastic (CFRP) has many advantages, and it is widely used in automotive body structures [2]. Guo et al [3] used the principle of equal stiffness substitution to replace the material of the steel engine hood with CFRP, and compared the mechanical properties with each other. The results indicated that the CFRP engine hood has improved its mechanical properties (e.g., stiffness), and the mass was reduced by 46 %. The dynamic stiffness of the CFRP engine hood is used as the optimization objective for multi-objective optimization. The optimized CFRP hood is trial-produced, and dynamic stiffness tests and modal tests are carried out. MULTI-OBJECTIVE OPTIMIZATION OF CFRP ENGINE HOOD CONSIDERING DYNAMIC PERFORMANCE BASED ON SURROGATE MODEL.
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