Hydraulic Dynamic Damping Characteristics of an Asymmetric Valve-Controlled Asymmetric Cylinder: Theoretical Modeling, Simulation, and Experimental Validation on a Hydraulic Rolling Shear

Asymmetric valve-controlled asymmetric cylinder systems (AVCACSs) are key actuation components in mechatronic drive systems such as hydraulic rolling shears, yet conventional models treat hydraulic damping as a constant and neglect valve geometric asymmetry, resulting in considerable errors under bidirectional flow conditions. This paper develops a direction-dependent damping model based on the power-matching principle, in which the valve-geometry asymmetry is described by a piecewise transfer function. Directional load pressures and flows are redefined for forward extension and reverse retraction, and separate damping-ratio models are derived for the two motions. The analysis shows that the valve-port area-gradient ratio (VPAGR) and the rod-to-cap area ratio (RTCAR) affect the forward and reverse damping ratios in opposite ways: as the matching value i increases, the forward ratio rises while the reverse ratio falls, and the reverse ratio remains higher throughout. Even under perfect matching (i = m = n, 0 < i ≤ 1), the minimum forward and reverse ratios still differ; at i = 0.5 the gap reaches 0.14, quantifying the bidirectional asymmetry in flow gain and response speed, while at i = 1 the two ratios converge to the symmetric case, confirming the generality of the model. The model is validated by Simulink simulations and experiments on a hydraulic double-sided rolling shear, providing a quantitative basis for component matching and control design of hydraulic actuation systems.