The paper will discuss the results of a study to develop lightweight steel proof-of-concept front lower control arm (FLCA) designs that are less expensive and achieve equivalent structural performance relative to a baseline forged aluminum FLCA assembly. A current production forged aluminum OEM sedan FLCA assembly was selected as an aggressive mass target based on competitive benchmarking of vehicles of its size.
CAE structural optimization methods were used to determine the initial candidate sheet steel and forged designs. Two (2) sheet steel FLCA designs and one (1) forged steel FLCA design were selected and developed to meet specified performance criteria. An iterative optimization strategy was used to minimize the mass of each design while meeting the specified stiffness, durability, extreme load, and longitudinal buckling strength requirements. The manufacturing cost was estimated for the sheet steel designs relative to the baseline design for production volumes ranging from 30,000 to 250,000 vehicles per year.
The results of the study showed that a clamshell design, based on DP780 steel sheet, achieves equal mass to the baseline assembly and up to a 34% reduction in manufacturing cost. An I-beam design based on DP780 and DP980 sheet, DP780 tube, and HSLA550 was predicted to have a 2% mass increase, relative to the baseline assembly, and up to a 21% reduction in manufacturing cost. A forged design, based on AISI 15V24 grade material and a 3 mm minimum gage target, was predicted to have a 4% mass increase relative to the baseline assembly.