Integration of fibre-optical sensor in a GFRP transverse leaf spring for validation purposes of finite-element-simulation

Abstract

Fibre-reinforced components are increasingly being used in today's automobiles. In the chassis area, glass-fibre reinforced longitudinal and transverse leaf springs have been used in passenger cars and vans since the early 1980s. In research and in patents, there are various approaches to provide wheel guidance by glass-fibre reinforced transverse leaf springs without wishbones. A real implementation however, has not yet been found in the relevant literature. Two innovations are explored in this work. The first is the implementation of a glass-fiber reinforced transverse leaf spring, replacing metal coil springs and the stabiliser bar. In combination with a newly compiled development process based on a virtual optimization process on stacking and geometry, significant lightweight advantages can be achieved. The second is a method for comparing FE-Simulations (Finite-Element) to an extensive examined physical testing campaign on a prototype glass-fiber reinforced transverse leaf spring. The implementation of optical fiber sensors (beside strain gauges, DIC and photogrammetry) allows to extract thousand strain measurements per meter and per timestep during testing. Focus is placed on the development and usage of a virtual fiber sensor that automatically builds up in (and connects to) the simulation model allowing the direct comparison of measured strain with simulated strain. The deformation of the FE model with the virtual or real sensor fibre can be directly visualized in a developed graphical user interface (GUI). The evaluations provide statements on the validity of the selected boundary condition modelling between leaf spring and vehicle body, so that the transverse leaf spring can be optimised in the overall chassis context. The approach is promising and has, due to its simplicity in application, the potential to be used in the future on all kind of mechanical structural tests for extensive simulation validation or adjustment purposes.