A Study on the Development of Concept Models Using Higher-Order Beams

In the early stages of vehicle development, it is critical to establish performance goals for the major systems. The fundamental modes of body and chassis frames are typically assessed using FE models that are discretized using shell elements. However, the use of the shell-based FE method is problematic in terms of fast analysis and quick decision-making, especially during the concept phase of a vehicle design because it takes much time and effort for detailed modeling. To overcome this weakness, a one-dimensional (1D) method based on beam elements has been extensively studied over several decades, but it was not successful because of low accuracy for thin-walled beam structures. This investigation proposes a 1D method based on thin-walled beam theory with comparable accuracy to shell models. Most body pillars and chassis frame members are composed of thin-walled beam structures because of the high stiffness-to-mass ratio of thin-walled cross sections. However, thin-walled cross-sections are also vulnerable to sectional deformations in out-of-plane and in-plane directions, called warping and distortion, respectively. The proposed higher-order beam elements employ these sectional deformations as additional degrees of freedom. The validity of the proposed method is verified by solving the frame and body structures of a vehicle, whose results are compared with those of shell models. Furthermore, we develop a pre/post-processing program for higher-order beam analysis. Through this program, we can save significant time and effort in not only building higher-order beam models but also conducting sensitivity analysis for various variations.