Abstract
The appearance and exterior precision of passenger cars aesthetics has become an important factor in the automotive industry. During vehicle assembly, the curvature of the roof can change slightly and create cosmetic defects that affect the exterior appearance. The critical factor causing curvature change on the roof is the thermally driven expansion of an elastomer-based mastic sealer which is applied between the exterior roof panel and support rail during the frame assembly process. Therefore the expansion of the mastic sealer was modeled to predict the curvature change in the roof panel. In order to evaluate the causes and predict the curvature change quantitatively, a Finite Element (FE) simulation of the oven heating and mastic curing was performed. Validation of the simulation model was performed by comparing the local deformation and amount of the curvature change on the roof obtained from the actual process. In order to minimize the curvature change, the Taguchi method was used in conjunction with the FE model where a total of eight factors were chosen to perform a sensitivity analysis. In order to exclude the deformation due to residual stress resulting from the oven process, it was selected as a noise factor. Response was taken as the maximum curvature change calculated by a flexural function which was used to distinguish absolute curvature that is not affected by the horizontal or vertical movement of roof panel. A total of 18 cases were analyzed with length of each sealer, pitch of sealer, and rail location being identified as the most influential factors affecting the curvature change. Using the optimum values, the amount of curvature change in the roof panel was reduced by 12 percent.
Similar content being viewed by others
References
Biba, N., Stebounov, S. and Lishiny, A. (2001). Cost effective implementation of forging simulation. J. Materials Processing Technology 113, 1-3, 34–39.
Chung, K. W., Lee, J. M., Keum, Y. T., Lee, S. Y., Ahn, I. H., Hwang, E. J. and Park, J. S. (2004). Simulation and field try-out fender panel stamping processes. Fall Conf. Proc., Korean Society of Automotive Engineers, 1171–1176.
Hwang, J. H., Lee, S., Hwang, S. Y. and Kim, N. (2014). Development of analysis technique to predict the material behavior of blowing agent. Korea-Australia Rheology Journal 26, 4, 389–400.
Jacobs, M. A., Kemmere, M. F. and Keurentjes, J. T. F. (2004). Foam processing of polyethylene-co-vinylacetate rubber using supercritical carbon dioxide. Polymer 45, 22, 7539–7547.
Jarderet, V., Zahouani, H., Loubet, J. L. and Mathia, T. G. (1998). Understanding and quantification of elastic and plastic deformation during a scratch test. Wear 218, 1, 8–14.
Kim, Y. H., Cha, S. W. and Rizwan, Z. (2007). Study of baseline to determine foaming temperature in microcellular foaming process. Proc. KSME Spring Annual Meeting.
Koo, S. (2011). Pedestrian protection law and auto-body design changes. J. Korean Society of Design Science 24, 4, 181–190.
Krupicka, A., Johansson, M. and Hult, A. (2003). Use and interpretation of scratch tests on ductile polymer coatings. Progress in Organic Coatings 46, 1, 32–48.
Lee, J. M., Ahan, B. J., Lee, S. C. and Keum, Y. T. (1994). Study on the forming and structural evaluation of stamping dies for optimal design. Fall Conf. Proc., Korean Society of Automotive Engineers, 475–480.
Liao, R., Yu, W. and Zhou, C. (2010). Rheological control in foaming polymeric materials: II. Semi-crystalline polymers. Polymer 51, 26, 6334–6345.
Najib, N. N., Ariff, Z. M., Bakar, A. A. and Sipaut, C. S. (2011). Correlation between the acoustic and dynamic mechanical properties of natural rubber foam: effect of foaming temperature. Material & Design 32, 2, 505–511.
Rodriguez-perez, M. A., Campo-arnaiz, R. A., Aroca, R. F. and De Saja, J. A. (2005). Characterisation of the matrix polymer morphology of polyolefins foams by raman spectroscopy. Polymer 46, 26, 12093–12102.
Sarier, N. and Onder, E. (2007). Thermal characteristics of polyurethane foams incorporated with phase change materials. Thermochimica Acta 454, 2, 90–98.
Shen, W., Ji, C., Jones, F. N. and Everson, M. P. (1996). Measuring scratch resistance and microhardness of crosslinked coatings with a scanning force microscope. Polymeric Materials, 74, 346–347.
Wang, T. Y. and Huang, C. Y. (2007). Improving forecasting performance by employing the Taguchi method. European J. Operational Research 176, 2, 1052–1065.
Yanhui, Y., Dong, L., Ziyan, H. and Zijian, L. (2010). Optimization of preform shapes by RSM and FEM to improve deformation homogeneity in aerospace forging. Chinese J. Aeronautics 23, 2, 260–267.
Yoon, B., Kim, K. and Kim, B. (2002). A study on cooling of automotive audio system using looped heat pipe. Fall Conf. Proc., Korean Society of Automotive Engineers, 896–900.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Hwang, S.Y., Jeong, H.S., Kim, N. et al. Design process to minimize roof surface defects using a flexural function and Finite Element analysis. Int.J Automot. Technol. 17, 127–133 (2016). https://doi.org/10.1007/s12239-016-0012-2
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12239-016-0012-2