Spreading and retraction dynamics of drop impact onto elastic surfaces

The influence of vertical surface motion on droplet spreading and retraction dynamics upon impact on elastic substrates remains poorly understood. To address this, we derive a universal linear law for early-stage spreading. During retraction, the retraction speed is observed to oscillate with substrate vibrations. We identify the underlying mechanism driving this behavior and develop a predictive model for retraction on moving surfaces. This work offers new insights into droplet dynamics on elastic substrates.