Friction effects on the load capacity of a column and a hydraulic cylinder

Over the last years, a better comprehension of hydraulic cylinder performance is observed to be a prime objective of many owing to demanding applications. By observing these hydraulic cylinder applications, we see currently proposed models and design criteria do not take into account real factors, and further there are misalignment and boundary conditions in the end supports, mechanism interaction, dust, clearance and imperfections. Since these boundary conditions can develop progressive moments, the ideal simple supported bi-articulated configuration of the actuator is no longer valid, and virtual clamped configuration appears with friction moments that substantially modify the buckling analysis. In a previous work, misalignment effects were studied and discussed. In the present work a study of the influence of friction moments when misalignment effects are deliberately left aside is carried out. In order to separate these two phenomena (friction and misalignment) boundary conditions in a column are analysed. From this analysis, a theoretical and experimental work has been carried out for columns and an actuator characterizing the critical factors that cause the collapse. The aim of this paper is to describe the behaviour of actuators under load capacity with experimental validation when friction moment is taken into account and becomes an unknown variable. Experimental and theoretical results point out the importance and influence of the friction effects in columns and hydraulic cylinders. Then, it is recommended that knowledge of the hydraulic cylinder application to predict its load capacity owing to that direct extrapolation of results from current theories and criterions could lead to incorrect estimations.