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A CAE-based process design method was developed to improve formability in hot stamping by controlling the temperature distribution during the forming step. Specifically, areas where deformation is not desired should be cooled to make them harder, and areas where deformation is desired should be kept at higher temperature. In this study, a tailored initial temperature distribution was calculated through three-step analysis of the deformation behavior by a thermo-mechanical forming simulation. First, the deformation severity was evaluated from the damage value for each finite element by using a forming limit diagram (FLD) at elevated temperature. The cautionary damage value was then defined to determine whether the element should be cooled. Finally, the tailored initial temperature was calculated based on the temperature-dependent flow stress. This procedure was applied to a high-rigidity pillar model that could not be formed by the conventional hot stamping process without cracking. The improved formability was confirmed experimentally. Thus, controlling the temperature distribution increases the diversity of shapes achievable by hot stamping.

Vehicle horns must satisfy sound pressure level regulations in each country. Therefore, it is essential to optimize the horn location inside the front grille of the vehicle to maximize sound transmission through the grille opening and adhere to sound pressure level regulations. This study developed a computational method to determine optimal horn locations during early stages of vehicle development to reduce the number of trials during later stages. Therefore, an analytical model based on a one-dimensional standing-wave model was established using parameters obtained in the early stages. Subsequently, spectral changes were predicted for the transfer characteristics based on the horn location (i.e., from the horn to the exterior of the front grille). The analytical model was validated by comparing computed spectral images with those obtained experimentally from sample commercial vehicles. Image correlations between the analytical model and experimental results were greater than 80%. The high correlation suggests that the analytical model sufficiently represented the sound propagation phenomena, including transmission from the front grille. Finally, the model results established the optimal horn placement, which was validated using a commercial vehicle as a case study. The placement obtained by the proposed analytical model was in good agreement with that of the commercial vehicle.