Finite Element Analysis of Side-Load Springs for McPherson Front Suspensions

In the present work, the operating conditions of “side-load” springs, which are typically employed in McPherson suspensions, were analysed by finite element analysis. The finite element model, including the spring and the upper and lower spring seats, is firstly described in the paper; the spring geometry was accurately obtained by a reverse engineering procedure based on two video cameras and a video projector. Surface to surface contact elements were defined between spring and seats; the initial assembling phase of the spring between the seats was also included in the finite element analysis. The experimental rig, employed for spring characterisation, and the performed numerical analyses are then presented; results are discussed in comparison with experimental data, in terms of spring characteristic, side-load force and thrust axis spatial position, as a function of spring compression. A fully satisfactory agreement was generally observed between numerical results and experiments. The effect of lower spring seat orientation on results was also investigated by numerical analysis. A higher inclination of the lower seat appeared to increase the side-load force; at the same time, for a given configuration, the thrust axis orientation, remained almost constant during suspension compression.