FEM modeling of the piezoelectric driving system in the design of direct-acting diesel injectors

A detailed mathematical model of a direct-acting prototypal piezo-injector has been developed to help experimentation, design and component optimization. The thermo-fluid dynamics of the hydraulic circuit components, including the injector feeding pipe, injector drilled pipes and nozzle, was modeled in conjunction with the mechanics of the mobile elements in the injector. A Finite Element Method (FEM) model of the piezo-stack has been developed to predict the temporal distribution of the elongation of the piezo-actuator. The piezoelectric submodel was based on the experimental trace of the current provided to the piezo-stack and was verified to correctly reproduce the dynamic response of the injector piezoelectric driving system.