Motion analysis and parameter regulation of the needle in a piezoelectric jet dispensing valve: a fluid-structure interaction and multibody dynamics approach

Abstract To address the insufficient jetting stability and dispensing consistency caused by incomplete modeling of needle motion and unclear parameter regulation mechanisms in piezoelectric-driven jet dispensing valves, this study focuses on the motion behavior of the needle and conducts comprehensive investigations involving dynamic modeling, numerical simulation, and experimental validation. First, a two-dimensional transient fluid–structure interaction (FSI) model is established to reveal the effects of needle displacement, velocity, and non-ideal motions such as radial offset and inclination on droplet volume, jetting velocity, and structural stress. The optimal motion range of the needle is determined as follows: maximum displacement of 0.125–0.130 mm, maximum downward impact velocity of 1.0–1.1 m s −1 , radial offset ⩽0.005 mm, and tilt angle ⩽1°. Based on the Lagrange equation, the needle system is equivalently modeled as a second-order linear vibration system, and a corresponding dynamic model of the needle is developed. Subsequently, multibody dynamic simulations are performed to clarify the regulation mechanisms of key parameters including driving voltage, piezoelectric preload force, spring stiffness, and driving waveform timing on needle motion. The optimal parameter range is identified as a driving voltage of 66–72 V, a preload force of 500–600 N, a preload spring stiffness of 75 kN m −1 , an impact time of 80–100 μs, and a lifting time of 250–300 μs. Finally, an experimental platform is established for validation. The results show strong agreement between simulations and experiments. Under the optimal parameters, the generated droplets exhibit full morphology without tailing, with diameter deviation less than 5% and good dispensing repeatability. This study establishes a systematic methodology for needle motion modeling and parameter regulation under the tested 5000 cps Newtonian-equivalent fluid condition, providing theoretical and experimental support for precise control and engineering optimization of piezoelectric jet dispensing systems.