Nowadays, OEM’s challenge is to harmonize vehicle’s performance, design and cost. Furthermore, all of these antagonistic key performance factors must be integrated in a much faster pace than ever before in the automotive industry. Thinner parts and low cost materials Body-in-White (BIW) systems struggles to deliver the same/higher performance and quality levels as the previous generations. On top of that, considering that BIW structures typifies almost 30% in a vehicle mass, and almost 40% of a vehicle cost, focusing in this system, this paper will study the body upper structure, more specifically its roof panels.
Currently, almost all small vehicles are composed by three to four roof bows (figure 1) within its structure. A Roof Bow is a sheet metal part, usually spot welded to the BIW inner frame, forming the inner structure of the vehicle body. Its primary function is to supporting the roof panel loads, such as Oil Canning and local stiffness. Considering roof bows perform minor role in the structure torsional stiffness, a vehicle with three roof bows was chosen to be studied. With the single purpose to analyze the roof panel by modifying its curvature and/or shape as control factors, in order to delete one of its roof bow, thus reducing mass and costs with at least the same performance levels as before, without affect final customer perception of quality.