###### Abstract  
Under the context of the dual-carbon policy, reducing energy consumption and emissions in automobiles has garnered significant attention, with automotive lightweighting being particularly important. This paper focuses on the lightweight design of automotive subframes, aiming to minimize weight while meeting performance requirements. Research has revealed that the original subframe allows further room for lightweighting and performance optimization. A topology optimization model was established using the Solid Isotropic Material with Penalization (SIMP) method and solved using the Method of Moving Asymptotes (MMA) algorithm. Integration of the SIMP method was achieved on the Abaqus-Matlab (2022x) platform via Python (3.11.0) and Matlab (R2022a) coding, forming an effective optimization framework. The optimization results provided clear load transfer paths, offering a theoretical basis for geometric model conversion. The subframe model was subsequently reconstructed in CATIA. Material redundancy was identified in the reconstructed subframe model, prompting secondary optimization. Multi-objective size optimization was conducted in OptiStruct, reducing the subframe's mass from 33.73 kg to 17.84 kg, achieving a 47.1% weight reduction. Static stiffness and modal analyses performed in HyperMesh confirmed that results met all relevant standards. Modal testing revealed a minimal deviation of only \(-2.7\%\) from the simulation results, validating the feasibility and reliability of the optimized design. This research demonstrates that combining topology optimization with size optimization can significantly reduce weight and enhance subframe performance, providing valuable support for future automotive component design. topology optimization; lightweight design; finite element analysis; structural optimization; model reconstruction +
Footnote †: journal: Applied sciences  
18 June  
weight by half. [PERSON] et al. [3] employed ANSYS for topology optimization, enhancing the structural efficiency of side rails without increasing mass. [PERSON] and [PERSON] et al. [4] improved frame performance through optimization of modal parameters; [PERSON] et al. [5] combined sensitivity assessment with FEA techniques to achieve structural lightweighting for heavy-duty trucks. [PERSON] et al. [6] adopted the ICM hybrid modeling method, reducing subframe weight by 1.84 kg and increasing modal frequency by 10.2 Hz. [PERSON] [7] established a multi-body dynamics simulation system using the ADAMS platform to analyze force characteristics and refine the design. [PERSON] et al. [8] integrated implicit parametric modeling with topology optimization, achieving a subframe weight reduction of 2.41 kg. [PERSON] [9] improved topology optimization methods to satisfy engineering constraints while enhancing performance. [PERSON] et al. [10] employed finite element techniques with inertia relief methods to investigate strength characteristics of the subframe, realizing a 9.9% weight reduction. [PERSON] et al. [11] developed a bidirectional progressive structural topology optimization approach by integrating the ABAQUS-MATLAB platform. This methodology effectively addresses the limitations associated with the closed architecture of existing finite element software's topology optimization modules, thereby enhancing both the flexibility and efficiency of the optimization process. The proposed method has exhibited significant advantages in practical engineering applications, offering a more effective solution for structural design. In summary, existing research primarily focuses on finite element analysis, topology optimization, and composite material applications, but further improvements in comprehensive performance require continued exploration. This paper proposes an efficient and practical subframe design optimization methodology, aiming to provide new perspectives and references. The technical roadmap centers on lightweight subframe design.