Design of Light-Weight Vehicle Front End Structure for Pedestrian Protection

With a significant increase in awareness of sustainability and increased interest towards low-cost solutions, every automobile manufacturer is looking for light-weight, safer and modularized solutions for many systems involved in the vehicle. Weightage for these three factors can vary depending on the location and functionality of the system. Front end system of a vehicle is a typical example, where all the three factors assume equal importance. The system consists of a front end module (FEM) mounted with an energy-absorbing system designed to meet pedestrian safety requirements. The focus of this paper is to develop a methodology for the design of thermoplastic light-weight pedestrian-safe front end structure.

The proposed front end structure consists of an injection-molded long glass fiber polypropylene (LGF-PP) FEM and an energy-absorbing system, which consists of an energy absorber (EA), mounted on the bumper beam, and a lower-leg protector (also referred to as an undertray) mounted on the bottom portion of the FEM. The full plastic FEM is observed to offer substantial reduction in both the weight and the cost in addition to the other benefits such as integrated functionality and modular assembly. The EA and undertray are designed to give desired stiffness distribution along the vehicle width to meet pedestrian impact requirement. A concurrent design approach is used to optimize both these systems to achieve the desired weight and cost targets and the required performance. Finally, case studies are presented to understand the structural performance of the LGF-PP FEM and pedestrian impact performance of the complete front end system.