Progressive buckling of hydraulic actuators

Hydraulic actuators are widely used in industrial and civil applications. Despite their compact size, they enable the movement of heavy loads. However, during service, they are often subjected to compressive stresses, which can lead to buckling. Accurately predicting the critical load that an actuator can withstand is essential to ensure performance and structural integrity. The progressive buckling behavior of an actuator could be influenced by several factors, such as the slenderness of the rod and cylinder, the boundary conditions, the geometric imperfections, the straightness errors, and the stiffness of the wear rings, which serve to reduce friction and minimize wear on the main assembly components. This study experimentally investigates the progressive buckling behavior of a slender hydraulic actuator under axial compression. Two boundary conditions – pinned-pinned and fixed-pinned – were analyzed, along with two different wear ring materials – PLA and nylon. For each configuration, the actuator was subjected to gradually increasing pressure until buckling occurred or material yielding was approached. Stresses were measured using strain gauges, and the resulting stress–pressure curves were analyzed to identify the critical pressure. Results indicate that the critical pressure increases under more restrictive boundary conditions and that wear ring material has negligible influence on the buckling behavior for the tested cases. The experimental data provide valuable information for improving hydraulic actuator design and reliability.