Limit load assessment of hydraulic actuators for moving appliances under progressive buckling

Hydraulic actuators are key components in moving appliances, that enable large load-carrying capacities despite their compact dimensions. During operation, they are subjected to compressive forces and time‑variable actions, such as vibrations and oscillations induced by moving payloads, which may significantly influence their stability. Under these conditions, actuators can be exposed to progressive buckling, which is affected by geometric imperfections, component slenderness, boundary conditions, straightness deviations, and the stiffness of wear rings. Accurate prediction of the limit load of hydraulic actuators (i.e., the maximum load that prevents buckling and material yielding) is essential for improving structural safety and obtaining optimized designs. The present work investigates the progressive buckling behavior of a hydraulic actuator through laboratory experiments, conducted with two boundary conditions and different wear ring materials. The analysis of bending stress vs. applied pressure curves enabled the identification of the critical load values for the analyzed actuator in the various loading configurations. The tested wear ring materials were found to have a negligible influence on both limit and critical pressures for pinned-pinned configuration, while a small influence can be noticed for fixed-pinned case. The obtained results contribute to a deeper understanding of the structural behavior of hydraulic actuators used in moving appliances and support the development of more reliable and efficient design methodologies.