Composite suspension arm optimization for the city vehicle XAM 2.0

The use of composite materials is very important in the automotive field to meet the European emission and consumption standards set for 2020. The most important challenge is to apply composite materials in structural applications not only in racing vehicles or supercars, but also in mass-production vehicles. In this chapter is presented a real case study, that is the suspension wishbone arm (with convergence tie and pull-rod system) of the XAM 2.0 urban vehicle prototype, that has the particular characteristics that the front and rear, and left and right suspension system has the same geometry. The starting point was from an existing solution made in aluminum in the XAM urban vehicle to manufacture a composite one, in particular in carbon fiber. The first step was the development of a dynamic model of the vehicle to understand the suspension loads and behavior to define the suspension weight and stiffness targets with respect to the aluminum arm, because it was necessary to understand the tensile strain on the component to simplify and optimize the geometry. Once the wishbones external surfaces have been defined, a carbon fiber layer thickness and orientation optimization have been made to define the lamination lay-out. Generally, after the analysis of the composite thickness optimization result, it would be possible to build up a new CAD model that encounters the process constrains and would define the lamination process. The results of the final suspension in carbon fiber compared to aluminum one were a weight reduction of 5% and an increasing of stiffness of 78%. The final purpose of this work is not only to find the best suspension solution but to define an engineering methodology to design suspension in composite materials thanks to simulation and virtual analysis