This paper highlights the facilities of VHDL-AMS to model multi-physical systems and deal with time discontinuities. The modeling and simulation of a piezo-electric device used to spray liquids are presented. Since it is composed of several piezoelectric and metallic parts, a modular approach is proposed. A generic behavioral model for each part typeconsidered as a mechanical transmission line -is first developed. Then, the whole device is modeled with a shuctural description. Besides, since there are nonpermanent mechanical contacts between some of the parts, a shocks management is added.