A structural design method for an integrated die-cast aluminum alloy front cabin based on ESLM and MMTO

To reduce the weight, manufacturing complexity, and production cost of conventional welded steel front cabins, this study proposes a structural design method for an integrated die-cast aluminum alloy front cabin based on the Equivalent Static Load Method (ESLM) and Multi-Model Topology Optimization (MMTO). First, a full-scale FE model of the steel front cabin and vehicle body was established, and its accuracy was validated through comparisons between the simulation and experimental results under 100% FRB and 25% SOB impact conditions. Second, based on the principles of the ESLM, the equivalent static loads (ESLs) under the two impact conditions were extracted, and a MMTO framework was developed by simultaneously considering 100% FRB impact, 25% SOB impact, bending stiffness, and torsional stiffness. Subsequently, the primary load transfer path of the front cabin was identified through topology optimization. Combined with die-casting design criteria, this enabled the preliminary structural design of the integrated die-cast aluminum alloy front cabin. Finally, the proposed structure was evaluated through crashworthiness, stiffness, and modal analyses. The results indicate that, compared with the conventional steel structure, the integrated die-cast aluminum alloy front cabin reduces the peak acceleration of the B-pillar by approximately 19.7%–21.1% under 100% FRB impact condition. In addition, bending stiffness, torsional stiffness, and the first-order torsional modal frequency increase by 1.3%, 2.0%, and 0.9%, respectively, while the overall weight is reduced by approximately 19.6%. The proposed design method provides both a theoretical foundation and a technical reference for the lightweight design and engineering application of large integrated die-cast aluminum alloy structures.