Stability analysis of two-stage hydraulic cylinder

Abstract

A standard hydraulic cylinder consists of a piston rod with piston head and cylinder tube while a telescopic hydraulic cylinder consists of the two different cylinder tubes and a solid piston rod. It operates by the reciprocation of either piston rod or cylinder tube and mostly used to transmit mechanical power using the fluid linkage. The majority of the failures in hydraulic cylinders occur because of the buckling of the structure. Generally and more often, the piston rod is found to be failing in the buckling. This proposed work describes a new way of estimation of the buckling load of the telescopic hydraulic cylinder (two-stage) hinged at both extremes using Successive Approximation Method (SAM). SAM is traditionally applied to evaluate the buckling load in the bars where either the exact solution is not known or the mathematics is too complex. The method has been extended to the two-stage hydraulic cylinder with pin mounting boundary conditions at both the extremities. This method includes the number of iterations required to achieve better accuracy or in other words getting the minimum error. The critical load obtained after two iterations using the proposed method shows the minor deviation, i.e. it achieves the convergence. Further, the projected method has been modified to incorporate the effect of misalignment between the cylinder tube and the piston rod at the piston head junction. The analytical procedure for the buckling load evaluation of telescopic hydraulic cylinder is described. In continuation, finite element analysis of the hydraulic cylinder has also been performed to approximate and closely validate the findings using the analytical method of SAM. The Eigenvalue buckling analysis has been executed for the numerous dimensions of the hydraulic cylinder. Corresponding initial three buckling mode shape has also been described with the buckling load. The analytical buckling load and the simulated buckling load have been found in the close vicinity proving the approach used in this study to be a good candidate for the buckling load estimation of the hydraulic cylinder.