On the Buckling Behaviour of Telescopic Hydraulic Cylinders

Telescopic cylinders are generally employed as linear actuators, when the desired moving span is several times the length of the closed device, like in cargo trucks lifting applications, for instance. During the active phase of the actuation, hydraulic power is normally used to feed pressurized fluid inside the cylinder, thus providing the progressive extension of the cylinder elements and the required operative axial thrust. In this condition, therefore, cylinders must bear external compressive loadings in an increasingly slenderness configuration, which can give rise to buckling failures. In this study, experimental measurements of the limiting axial loadings of telescopic cylinders, in full extended conditions, have been performed both in laboratory and during real operations on the field. The strains of the material in the critical sections and the lateral deflections of the tested structures have been recorded as a function of the applied loads. The results of this investigation are presented and discussed, in order to identify the signals of incipient buckling and find out the ultimate load carrying capabilities of this kind of components.